Soizig Le Stradic

Elise Buisson

& G Wilson Fernandes

Chapter 1 -Baseline data for the conservation of campos rupestres: Vegetation heterogeneity and diversity

Keywords: Biodiversity, herbaceous communities, mountain grassland, Rupestrian grasslands

The recognition and the classification of plant communities are fundamental to implementing conservation programs or restoration projects. Campos rupestres are speciesrich Neotropical mountain grasslands belonging to the Cerrado in Brazil, covering 130 000km

Remerciements 7 Août 2012: j'attends le bus de Belo Horizonte au bord de la route, c'était mon dernier jour de terrain dans la Serra do Cipó. Une fois n'est pas coutume, je me décide à prendre un peu d'avance et je commence à faire la liste des personnes qui ont participé de près ou de loin à la réalisation de cette thèse.

La veille de rendre ce manuscrit: pour ne pas déroger à la règle, je finis cette section de remerciements au dernier moment.

Je tiens tout d'abord à adresser un énorme merci à Elise qui m'a permis de traverser l'Atlantique pour la première fois il y a presque 5 ans, d'avoir eu confiance en moi pour réaliser cette thèse, d'avoir dépensé une énergie folle à la recherche de financements, pour les innombrables relectures de projets/CV/lettres de motivation, pour avoir su garder le moral et remonter le mien, pour son enthousiasme, pour m'avoir fait partager ses connaissances en écologie et en restauration, pour l'aide sur le terrain, pour l'encadrement même à distance, pour m'avoir hébergé quand je descendais à Avignon et claro pour m'avoir fait partager son goût pour le Brésil, les pães de queijos et la samba, muito obrigada mesmo; Quero também agradecer a Geraldo (o Geraldinho!), que aceitou que eu fizesse meu doutorado no LEEB, que me apoiou e acreditou nesse projeto, me dando liberdade para a realização de minhas ideias, por sempre apresentar um novo ponto de vista (ou dar mil ideias para um novo projeto) e transmitir sua alegria e seu entusiasmo pela pesquisa. Muito obrigada Ge; I am grateful to Pr. William J. Bond, from the University of Cape Town (South Africa), Pr. Grégory Mahy, from the Gembloux Agro-Bio Tech, Université de Liège (Belgium), Dr. Gerhard E. Overbeck from the Universidade Federal do Rio Grande do Sul (Brazil), Dr. Giselda Durigan from the Instituto Florestal do Estado de São Paulo (Brazil) and Pr. Jose Pires de Lemos Filho from the Universidade Federal de Minas Gerais (Brazil) who have accepted to review this work and evaluate the oral defense; Financial support for this thesis was provided by the French Ministry of Foreign affair (EGIDE: bourse Lavoisier & Collège doctoral franco-brésilien), the CNPq, the CNRS and the CEMAGREF/IRSTEA, the University of Avignon (Programme Perdiguier), the Federal University of Minas Gerais & the US Fish & Wildlife Service, the SFE; Je remercie l'Institut Méditerranéen de Biodiversité et d'Ecologie et son directeur Thierry Tatoni, ainsi que Thierry Dutoit, qui s'est toujours disposé à relire et/ou commenter ce projet et faire de nouvelles suggestions; merci également à Freddy Rey qui a commenté et orienté les premiers pas de cette thèse, à Arne Saatkamp pour avoir répondu à mes questions concernant les germinations et m'avoir aidé à monter ces expérimentations; je remercie également l'IUT d'Avignon, sa direction et tout le personnel d'enseignants qui m'ont accueillie durant mes passages express, merci à Aline Le Menn de m'avoir permis de faire des vacations;

x Quero agradecer aos membros da banca de qualificação na UFMG: José Eugênio Côrtes Figueira, Yumi Oki e Frederico Neves, que ajudaram com correções e sugestões a esse trabalho; agradeço também ao programa de Pos-graduação ECMVS e a todos os professores que me mostraram um jeito de ensinar diferente da França e que avaliaram esse trabalho durante os seminários de avaliação; agradeço também a Frederico e a Cristiane da Secretaria que sempre responderam às minhas perguntas diversas e variadas ; Muito obrigada a Patricia Morellato por acolher a Swanni e a mim em Rio Claro, por ter nos ajudado a descobrir o que tinha por trás dessas tabelas de fenologia, além de todas as discussões a esse respeito.Obrigada também a todo o laboratório de fenologia pela alegria ambiente e Alessandra Fidelis para todos os conselhos; meus agradecimentos também a Alan, sua família e Rafael por nos acolher na casa dele durante nossa estadia em Rio Claro; sua companhia foi ótima; Agradeço também aos botanistas que colocaram nome nas minhas plantas (même si Erioc. petit pompom c'était aussi sympa): Benoit Loeuille (Asteraceae), Pedro Lage Viana (Poaceae), Renato de Mello-Silva (Velloziaceae), Livia Echternacht (Eriocaulaceae), Nara de O. Mota Furtado (Xyridaceae) & Fernando A. O. Silveira (Melastomataceae); quero agradecer também ao professore Alexandre Salino e Bruno por se disponibilizarem para que eu pudesse usar o herbário da UFMG; I am also grateful to Alice N Endamne, Kolo D Wamba and Viviane Ramos who revised and improved greatly the english of this thesis;

Meus agradecimentos especiais para a Jucelino e Elena pela ótima companhia durante esse tempo todo na Serra do Cipó (aprendi português assistindo ao Jornal Nacional na casa de vocês), pelas comidas deliciosas, pelas noites de cinema no meio de nada, pelos churrascos que tinham que fazer quando a energia acabava ; quero agradecer também a Wellington que tentou me ensinar a jogar truco mas já esqueci as regras, tentou também me ensinar gírias malucas, por sua ótima companhia (raramente conheci alguém que falasse tanto héhé), foram muitas risadas e tempos bons com você; além disso agradeço a todo mundo com quem convivi na Serra : Cláudio, Wemerson, Evaldo, Ronaldo, Toni, Genário (ou Genimar !); o que seria de mim sem incentivo pra ir ao campo, guardarei para sempre lembranças dos pães de queijo com lingüiça de Chapéu do sol ; Une mention spéciale à mes deux compatriotes de galère la mamasita et el papasito qui m'ont soutenue spécialement pendant la phase finale : Swanni 'viva la cooperación' et sa témérité légendaire, merci de m'avoir fait découvrir Madagascar et Ibity (et aussi les voanjobory, les massages et le caveau), m'avoir aidée sur le terrain, de partager nos expériences qui ratent et surtout d'avoir acceptée de partager le lit alors que je ronfle; Renaud, l'agent qui vient régulièrement à notre Rescousse, pour les magnifiques fonctions R qui changent la vie, pour m'avoir offert son canapé quand j'en avais besoin et pour les bons moments passés ensemble (dont un brownie au milieu d'une bataille de boulettes de papier au coeur de San Diego!); finalement cette thèse on l'a commencée ensemble et on va la finir ensemble! Merci également à toute l'équipe d'Avignon pour la bonne ambiance ; merci également à Daniel P. pour ma dose annuelle de Provence, pour l'hébergement (la seule maison où l'on dort avec un jambon espagnol) et les bons petits plats, même sans beurre salé c'était toujours un régal (et une petite pensée pour la fonction pyrolyse de votre four); xi Obrigadão Daniel N., você foi o primeiro a me fazer descobrir os campos rupestres. Me lembro ainda do dia em que você me mostrou seus campos rupestres de "sonho" ! Obrigada por compartilhar seu amor por essas plantas, muito obrigada mesmo por sempre se entusiasmar com esse projeto e compartilhar tudo que você sabe, e por todas as releituras que você fez dessa tese. Um super obrigada também para Lêle (Pr. Fernando agora), pela ajuda no campo, pela ajuda com a germinação, com as releituras das partes dessa tese, por dar idéias ótimas, por ser muito e sempre entusiasmado e por sua alegria contagiante. Muito obrigada também à Vanessa por sua amizade, sua inestimável ajuda e sua disponibilidade para cuidar e contar tantas sementes! (inclusive durante Natal!).

Un grand merci également à Kevin, pour toutes les petites graines que tu as dû couper, les centaines de données de phénologie que tu m'a aidée à rentrer, les plats du chef préparé dans la Serra, les nombreux coups de bêches, toutes ces touffes qu'on a transplantées et les feuilles qu'on a comptées.... bon au final j'ai quand même réussi à te convaincre de ne pas faire de terrain pendant le doctorat, j'ai peut être abusé! Merci à Pauline pour le terrain, il y a eu beaucoup d'attaque de mouches mordeuses mais nous sommes restées fermes, et aussi pour les pauses petits gateaux et bière : je me sens moins coupable comme ça.

Um carinho muito especial para meus colegas do LEEB: a Renata que carregou pra mim muito solo pra lá e pra cá na Serra e que ficou firme no episódio da Jibóia, para a amizade, as baladas, o metrô às 6h da manhã em SP e as cervejas. A Cris e a Camila porque diversão é bom, mesmo se a gente demora 6 meses para se encontrar às vezes, o importante é continuar a se encontrar; o Marcelzinho, que me agüentou durante todo esse tempo que passamos juntos na salinha do fundo; mesmo se seus gostos musicais duvidosos me dão medo às vezes e mesmo sem camaro amarelo : você é doce!; meus colegas da famosa salinha do fundo que colocaram muita alegria nesses 4 anos: Miltinho que já virou Lord, Newtinho (vou ter que pegar dicas para conseguir ficar calma igual você!), Fernando, Manu, Tate e as famosas meninas do A2: Yumi (obrigada mesmo por sua disponibilidade imensa para sempre ajudar qualquer um dentro nós), Carol, Fabíola, Ana, Barbara, Leandra e me perdoem se me esquecer de um monte de gente, mas tem tanta gente!! Quero agradecer os amigos de BH que animaram meu dia-dia, no topo da lista Camille e Daniel M., pela amizade e apoio incondicional, por compartilharem comigo os problemas específicos da condição de expatriada, pelos encontros para poder desabafar, para conhecer o prazer que é falar francês de vez em quando, por nossos « apéros paté-vin rouge » ; Léo, Fernando, Paulinho, Flavia, Dani M., Roberta, Débora, Wellington: a gente ganha muito mas se diverte; obrigada ao Júlio que me ensinou a cozinar feijão quando cheguei e pelas nossas conversas quando falava ainda apenas 10 palavras de português; obrigadão ao Paulo e ao Nilton que aceitaram botar uma mulherzinha na casa deles e me agüentaram esse tempo todo, inclusive quando fiquei doida pela novela (as discussões pra saber quem vai tirar o lixo vão ficar para a eternidade agora); Of course un super merci à mes geeks-amix : Jeff (mention spéciale pour l'aide sur le terrain pendant les vacances), Anlor, Max, Clem, Eric, Noum, Tristan, Antho, Nico, Marie, pour leur amitié (il y a 25 ans nous étions déjà ensemble dans les bacs à sable), parce que d'avoir toujours eu un comité d'accueil à la descente de l'avion ça n'a xii pas de prix surtout quand il est question de victuailles tels que du pâté, du saucisson, du vin et des projections de sylvain Mirouf, pour aider à porter les valises jusqu'au RER dans l'autre sens, et aussi pour les messages de soutien quand y'a eu besoin ; un énorme merci également à Estelle, Maria et Aurélie pour leur amitié, leur soutien, les messages d'encouragement ; un grand merci également à Tony qui m'a apportée tout son soutien et m'a encouragée quand j'ai fait mes premiers pas au Brésil.

Enfin, et surtout, je remercie toute ma famille (Sébastien inclu bien sur !), mon parrain et ma marraine, pour leur soutien, les messages d'encouragement, les Noëls au mois d'Août, pour le ravitaillement en mets gastronomiques divers et variés qui ont mis un peu de Bretagne sous mes tropiques (sauté de veau, palets bretons, paté henaff, foie gras, rillettes, St Emilion, Gewurztraminer); plus particulièrement mes parents, Gaëlle et Renan qui m'ont toujours soutenue et encouragée, et ont accepté mon absence, pour les nombreux dimanches aprés-midi sur skype, pour être devenue ce que je suis aujourd'hui; partir n'est jamais une chose facile, mais nécessaire pour gouter au plaisir de revenir.

Merci aussi à Daniel T., pelo apoio e pela compreensão, pela música (inclusive Roberto Carlos domingo de manhã), pela poesia (que seja Hölderlin ou Anderson Silva), pelas viagens, por agüentar de mim (sic) inclusive na fase final da redação, por aceitar que eu coloque bagunça na vida dele, para a confitura, as courbaturas e as dezenas de palavras que so existem entre a gente, por ser meu guichet de reclamações preferido, por ser o ombro onde podia chorar quando a saudade apertava, por corrigir meus textos em português à 1h da manhã, por fazer buracos na serra do Cipó até acabar com nossas mãos, por mais que tudo.

Merci à la Serra do Cipó, pour tous les bons moments que j'y ai passés, j'avais 22 ans quand j'ai débarqué là-haut, et, d'une certaine façon cet endroit m'a vu grandir. Une bonne BO est toujours utile, alors merci aussi à Radiohead, M.I.A, Seu Jorge, Chico Science et tant d'autres, écoutés en boucle et qui m'ont accompagnée quand il fallait grimper la montagne à 6h du matin. Hommage également à mes 3 pantalons de terrain dont il a fallu se séparer, mes dizaines de tee-shirts usés par le soleil, la douzaine de crayons et de gommes perdue dans les campos, mes chaussures de terrain mortes pour la recherche et la caravane qui est partie en cendre.

Et si j'ai oublié quelqu'un qu'il me pardonne. Long cycle is considered with a phenophase duration > 2 months and short cycle with a phenophase duration < or = 2 months. Species with continuous and subannual frequency patterns were not taken into account. w indicated that the χ 2 tests were realized without the data from transition season Dry/Rainy due to the low number of species. *: p-value<0.05 and **: p-value<0.01, ***:p-value <0.001. ........ 80

Table 10: Flower and fruit production per site (average number and standard error) in sandy (Sa) and stony (St) grasslands for the main families based on peak production. z indicated the result of GLM procedures (family: Poisson, link: log).

xix Letters indicate significant differences between families among grassland-types according to the result of the GLM procedures (family: Poisson, link: log). ............. 82

Table 11: Average fruit production by site and number of fruits per individual for the 31 selected species. z indicates the result of GLM procedures with a quasibinomial error distribution and logit link function. * indicates significant differences with p<0.05. T-tests were performed using numbers of fruits per individual as dependent variables and grassland-types as categorical predictors, * indicates p<0.05. .......... 83

Table 12: Dissimilarity matrix (Bray-curtis indices) of the plant composition between the degraded areas: with Latosol substrate (DL), stony substrate (DSt) and sandy substrate (DSa) and the reference grasslands: the sandy (Sa) and the stony (St) grasslands, based on species percent cover data (n=3 sites x 5 types of areas). . 105

Table 13: Mean and standard error values of soil texture, from soils collected in reference grasslands: 3 sandy, and 3 stony grasslands, and in degraded areas: 3 latosol, 3 sandy and 3 stony (3 samples x 3 sites x 5 types of areas, n=45 Table 14: Result of the one-way nested ANOVAs run on chemical soil parameters, from soils collected in reference grasslands: 3 sandy, and 3 stony grasslands, and in degraded areas: 3 latosol, 3 sandy and 3 stony (3 samples x 3 sites x 5 types of areas: n=45). NS: non-significant difference, * significant difference with P<0.05, *** significant difference with P<0.001. See Figure 4 Table 16:: Dissimilarity matrix (Jaccard indices) of the seed bank composition between the degraded areas with latosol substrate (DL), stony substrate (DSt) and sandy substrate (DSa) and reference grasslands: the sandy (Sa) and the stony (St) grasslands based on presence-absence data (n=3 sites x 5 types of areas). ....... 109

Table 17: Plant list with family, plant form, distribution range, period of dissemination, mean IVI in both sandy and stony grasslands and mean relative dominance in both sandy and stony grasslands (Chapter 1). Family: P: Poaceae, C: Cyperaceae, A: Asteraceae, V: Velloziaceae and X: Xyridaceae. Plant forms: F: Forbs, G: Graminoids, Ss: Sub-shrub. Distribution range (Giulietti et al. 1987, Forzza et T3) with percent survival. Individuals were translocated to a degraded sandy area (DSa) and to a reference sandy grassland (RSa), broken into two groups, one with and added nutrient supply (N) and one without (n). To test the effect of nutrient supply and substrate type, GLM procedures were run with a binomial family distribution and logit link function. ns: non significant. .................. 160

Table 23: Number and percentage survival of translocated individuals in December 2011 (T9) and in March 2011 (T12). Individuals were translocated to a degraded sandy area (DSa), and to a reference sandy grassland (RSa) broken into two groups, one with an added nutrient supply (N) and one without (n). To test the effect of nutrient supply and substrate type, GLM procedures were run on data recorded in March 2012, with a binomial family distribution and logit link function. ns: non significant. At T0, more graminoids were observed in TSa than in TSt (p<0.01, Table 26). Graminoids decreased with time (p<0.001), more drastically in TSt than in TSa (p<0.05, Table 26). On the contrary, more forbs were observed in TSt than in TSa at xxi the beginning of the translocation (T0). Forb number did not decrease in TSa, but it did decrease drastically in TSt (p<0.001, Table 26), especially Velloziaceae and Eriocaulaceae species. There was no difference in sub-shrub number between TSa and TSt at T0, and their number increased with time in both kinds of turfs (Table 26).

List of figures

Figure 1: The role of biodiversity and restoration activities in global change. Human activities (1) are now causing environmental and ecological changes of global significance (2). Through a variety of mechanisms, these global changes contribute to changing biodiversity (3), and changing biodiversity feeds back on susceptibility to species invasions (4). Changes in biodiversity, can have direct consequences for ecosystem services impacting human economic and social activities (5). In addition, changes in biodiversity can influence ecosystem processes and feedback to further alter biodiversity (6). Altered ecosystem processes can thereby influence the ecosystem services that benefit humanity (7). Global changes may also directly affect ecosystem processes (8). Figure 6: The main processes / filters that structure a plant community. Each process/filter is represented by a pair of horizontal lines. Solid arrows depict the movement of species through the filters. Grey boxes indicate how ecosystem degradation may affect the different levels (inspired by [START_REF] Lortie | Rethinking plant community theory[END_REF][START_REF] Fattorini | The dynamic environmental filter model: how do filtering effects change in assembling communities after disturbance?[END_REF][START_REF] Belyea | Beyond ecological filters: feedback networks in the assembly and restoration of community structure, in: Assembly rules and restoration ecologybridging the gap between theory and practice[END_REF], Buisson 2011, Le Stradic unpublished). ......................... 17 Figure 30: Correspondence analysis on the matrix of species percent cover in 40cmx40cm quadrats in January 2010, in references areas: 3 stony (St) and 3 sandy grasslands (Sa) and in degraded areas: 3 with latosol substrate (DL), 3 with sandy substrate (DSa) and 3 with stony substrate (DSt)

Introduction

1.Context

In recent decades, the relationship between human society and the environment have been highlighted and have resulted in increasing awareness of the importance of ecosystems in maintaining and improving the collective well-being of humanity, particularly because the world is now changing rapidly. Current economic development and its impact on the environment are unsustainable: degradation of remaining natural habitats is decreasing long-term human welfare in favor of short-term economic gain.

Obviously this kind of development does not deliver human benefits in the way that it should: it increases the vulnerability of some of human populations and creates large disparities around the world while the level of poverty remains high [START_REF] Balmford | Economic reasons for conserving wild nature[END_REF], MEA 2005[START_REF] Carpenter | Scenarios for Ecosystem Services: An Overview[END_REF]. Humans have already greatly altered Earth's surface, especially through land-use changes, which are responsible for about half of terrestrial ecosystem transformations (Daily 1995[START_REF] Vitousek | Human Domination of Earth's Ecosystems[END_REF], Chapin et al. 2000[START_REF] Klink | Past and Current Human Occupation, and Land Use, in: The Cerrados of Brazil -Ecology and natural history of a neotropical savanna[END_REF][START_REF] Sala | Chapter 10: biodiversity across scenarios[END_REF][START_REF] Steffen | The Anthropocene : Are Humans Now Overwhelming the Great Forces of Nature ?[END_REF], leading to the current Anthropocene epoch [START_REF] Steffen | The Anthropocene : Are Humans Now Overwhelming the Great Forces of Nature ?[END_REF][START_REF] Zalasiewicz | The New World of the Anthropocene[END_REF].

Ecosystem services are the human benefits provided directly or indirectly by ecosystem functions (i.e., the properties or processes of ecosystems) [START_REF] Costanza | The value of the world's ecosystem services and natural capital[END_REF]). These services, such as climate stabilisation, drinking water supply, flood alleviation, crop pollination, and recreation opportunities, among others [START_REF] Osborne | Riparian vegetated buffer strips in water-quality restoration and stream management[END_REF], FAO 1998, Chapin et al. 2000[START_REF] Balmford | Economic reasons for conserving wild nature[END_REF], MEA 2005[START_REF] Sala | Chapter 10: biodiversity across scenarios[END_REF], depend to some extent on biodiversity [START_REF] Rands | Biodiversity Conservation: Challenges Beyond 2010[END_REF]) (Figure 1). However, many recent human activities have led to biodiversity erosion [START_REF] Rands | Biodiversity Conservation: Challenges Beyond 2010[END_REF][START_REF] Barnosky | Has the Earth's sixth mass extinction already arrived?[END_REF], altering functional diversity and modifying ecosystem properties [START_REF] Loreau | Biodiversity and ecosystem functioning: current knowledge and future challenges[END_REF]) (Figure 1). The Millennium Ecosystem Assessment (MEA 2005) report indicates that 12-16% of the world's species will be lost over the period of 1970 to 2050 due to habitat loss alone [START_REF] Sala | Chapter 10: biodiversity across scenarios[END_REF] and that currently approximately 60% of the ecosystem services are being degraded (MEA 2005). Biodiversity responses to environmental changes (land use and climate changes) are likely to be complex [START_REF] Chazal | Land-use and climate change within assessments of biodiversity change: A review[END_REF], but it is now widely accepted that these changes in biodiversity also alter ecosystem processes and modify the resilience and resistance of ecosystems to General introduction 2 further environmental changes [START_REF] Chapin | Consequences of changing biodiversity[END_REF], Figure 1). According the stabilitydiversity hypothesis, biodiversity should promote resistance and resilience to disturbance [START_REF] Mcnaughton | Diversity and stability of ecoogical communities: a comment on the role of empiricism in Ecology[END_REF][START_REF] Pimm | The complexity and stability of ecosystems[END_REF][START_REF] Tilman | Biodiversity and stability in grasslands[END_REF], Chapin et al. 2000[START_REF] Mccann | The diversity-stability debate[END_REF][START_REF] Loreau | Biodiversity and ecosystem functioning: current knowledge and future challenges[END_REF]. This implies that ecosystem stability depends on the ability of communities to harbor species or functional groups that can respond to disturbances in myriad ways. In this sense, biodiversity provides a kind of "insurance" against environmental fluctuations [START_REF] Chapin | Consequences of changing biodiversity[END_REF][START_REF] Mccann | The diversity-stability debate[END_REF][START_REF] Loreau | Biodiversity and ecosystem functioning: current knowledge and future challenges[END_REF]. Effective conservation of biodiversity is fundamental to maintaining ecosystem processes, but the traditional arguments in support of ecosystem conservation alone are insufficient [START_REF] Turner | The ecosystem services framework and natural capital conservation[END_REF][START_REF] Rands | Biodiversity Conservation: Challenges Beyond 2010[END_REF]. Marked economic benefits generated by the conservation of undisturbed natural habitats are an incentive to preserve nature [START_REF] Balmford | Economic reasons for conserving wild nature[END_REF][START_REF] Ring | Challenges in framing the economics of ecosystems and biodiversity: the TEEB initiative[END_REF][START_REF] Nahlik | Where is the consensus ? A proposed foundation for moving ecosystem service concepts into practice[END_REF]. However conservation in certain locales can be limited because the areas in question are either too small, too few, or too degraded to preserve biological processes and diversity [START_REF] Anderson | Ecological restoration and creation: a review[END_REF][START_REF] Hobbs | Towards a conceptual framework for restoration ecology[END_REF]. In this context, ecological restoration can be a viable strategy for enhancing biodiversity and improving ecosystem services [START_REF] Hilderbrand | The Myths of Restoration Ecology[END_REF][START_REF] Rey-Benayas | Enhancement of biodiversity and ecosystem services by ecological restoration: a meta-analysis[END_REF], Bullock et al. 2011[START_REF] Schneiders | Biodiversity and ecosystem services : Complementary approaches for ecosystem management ?[END_REF], especially with the development of Payment for Ecosystem Services (PES)

schemes, which are designed to compensate actions that maintain, improve, and provide some ecosystem services [START_REF] Turpie | The working for water programme: Evolution of a payments for ecosystem services mechanism that addresses both poverty and ecosystem service delivery in South Africa[END_REF][START_REF] Farley | Global mechanisms for sustaining and enhancing PES schemes[END_REF], Farley & Contanza 2010). The Strategic Plan for Biodiversity specifies that at least 15% of degraded ecosystems must be restored by 2020 (CBD 2011). [START_REF] Roberts | The Rise of Restoration Ecology[END_REF] emphasize that "our planet's future may depend on the maturation of the young discipline of ecological restoration". However, focusing ecological restoration on ecosystem services should not come at the expense of biodiversity conservation, and damage prevention should always be considered first because restoration possibilities cannot be an excuse for ongoing damage or destruction of ecosystems [START_REF] Young | Restoration ecology and conservation biology[END_REF][START_REF] Hobbs | Setting Effective and Realistic Restoration Goals : Key Directions for Research[END_REF][START_REF] Hobbs | Restoration Ecology : Interventionist Approaches for Restoring and Maintaining Ecosystem Function in the Face of Rapid Environmental Change[END_REF]. [START_REF] Young | Restoration ecology and conservation biology[END_REF] highlights the important points that 1) restoration can improve conservation efforts but has to remain a secondary resort to the preservation of habitats and 2) the use of ex-situ "restoration", such as mitigation, will never produce an outcome resembling the perfect reversal of habitat and population destruction.

2.Objectives

This thesis contributes both to 1) an improved theoretical understanding of the functioning of a type of neotropical mountain grasslands, the campos rupestres and their dynamics following strong disturbances and 2) novel insights into the implementation of restoration techniques for such environments (Figure 2). The second objective is to identify the main effects of a strong disturbance on soil and seed bank composition and to assess the resilience of campos rupestres (Chapter 3) (Figure 2); in other words, are campos rupestres resilient to strong disturbances?

Land-use changes provide an opportunity to study vegetation recovery and community assembly [START_REF] Prach | Four opportunities for studies of ecological succession[END_REF]. According to theoretical models, three main filters, which, when applied to the global species pool determine the ultimate community structure. These are the dispersal, environmental and biotic filters [START_REF] Keddy | Assembly and responses rules: two goals for predictive community ecology[END_REF][START_REF] Lortie | Rethinking plant community theory[END_REF]) (Figure 2). In order to establish whether restoration is actually necessary, we surveyed plant community characteristics, chemical and physical soil properties, and seed banks, in the areas that were first degraded eight years ago by the harsh but common activity of road construction-related quarrying. Our objective was to determine how this type of degradation modifies soil properties, and whether or not the internal species pool recomposed itself with target species following the degradation. The main questions addressed in the third part of this thesis are (Chapter 3, 4 & 5) (Figure 2): Can we restore campos rupestres? By using restoration experiments, we identified the factors that limit resilience by acting first on the dispersal filter, then we aimed to overcome the dispersal filter and the germination and to improve environmental conditions, and finally we aimed to overcome the dispersal, the abiotic and part of the biotic filters. Our ultimate aim was to identify efficient techniques for restoring these species-rich grasslands along with, hopefully, some services they once provided. Some evidence has shown that restoration actions that focus on biodiversity are also effective at supporting the increased provision of ecosystem services [START_REF] Rey-Benayas | Enhancement of biodiversity and ecosystem services by ecological restoration: a meta-analysis[END_REF], even where it is incorrect to assume that restoring biodiversity must inevitably enhance ecosystem services, or vice versa [START_REF] Bullock | Restoration of ecosystem services and biodiversity: conflicts and opportunities[END_REF].

The ecosystem in the present study is the campos rupestres, or tropical mountain grasslands located into the Cerrado domain, or Brazilian savanna. We chose to work with herbaceous species because the herbaceous stratum is the quintessence of these grasslands and regulates fundamental processes, such as post-fire recovery, water balance, annual productivity or mineral cycling [START_REF] Sarmiento | The Ecology of neotropical savannas[END_REF]. Moreover, in recent decades, herbaceous ecosystems, which represent more than 31% of world vegetation, have been drastically damaged and fragmented throughout the world [START_REF] Green | Agricultural intensification and the loss of habitat, species and amenity in British grasslands: a review of historical change and asseement os future prospects[END_REF][START_REF] Hoekstra | Confronting a biome crisis: global disparities of habitat loss and protection[END_REF][START_REF] Gibson | Grasses and grassland ecology[END_REF]). Biodiversity scenarios indicate that grassland ecosystems, and tropical ecosystems in general, are expected to be the most strongly impacted by land-use changes in the future [START_REF] Chapin | Consequences of changing biodiversity[END_REF], Sala et al. 2000, 2005); in this context, the Cerrado has already been classified as a priority area for conservation due to the anthropogenic pressures that it faces [START_REF] Myers | Biodiversity hotspots for conservation priorities[END_REF], Mittermeier et al. 2004[START_REF] Hoekstra | Confronting a biome crisis: global disparities of habitat loss and protection[END_REF]. It is therefore important to preserve and restore diverse grasslands since it can aim at conserving both biodiversity and locally important ecosystem services, and this is particularly true of mountain grasslands (CBD 2004, MEA 2005).

Having discussed the background and objectives of this study, we now turn to the main relevant theoretical concepts as well a good general overview of the field.

3.Restoration ecology

Definitions

Ecological restoration is the practice of restoring ecosystems and restoration ecology is the science upon which this practice is based (SER 2004). Restoration ecology is intended to offer clear concepts, models, methodologies and tools for practitioners. As will be discussed later, restoration ecology also plays an important role in ecological theory.

Ecological restoration is also the process of intentionally aiding in the recovery of an ecosystem that has been degraded, damaged, or destroyed (SER 2004). Ecological restoration sensu stricto, is an intentional activity that initiates or accelerates ecosystem recovery in order to re-establish all of the attributes of the reference ecosystem: its biotic integrity in terms of species composition and community structure, its functional processes, its sustainability in terms of overall resilience and resistance to disturbances, its productivity, and its services (SER 2004[START_REF] Clewell | The SER International Primer on Ecological Restoration[END_REF]) (Figure 3).

This objective is theoretical and often unrealistic: it is very difficult to achieve complete restoration of an ecosystem back to its original state [START_REF] Lockwood | When does restoration succeed?[END_REF], Palmer et al. 2006[START_REF] Choi | Ecological restoration for future sustainability in changing environment[END_REF][START_REF] Hobbs | Intervention Ecology: Applying Ecological Science in the twenty-first century[END_REF]. Alternative, less ideal ecological restoration activities can also be carried out, and these usually fall under the designation ecological restoration sensu lato (SER 2004). Examples include such activities as rehabilitation or reclamation (SER 2004) (Figure 3). Rehabilitation, in which preexisting ecosystems are also taken as models, places its emphasis on the reestablishment of some function, ecosystem processes, productivity, or services, and this may involve only partial re-establishment of the original ecosystem attributes (SER 2004) (Figure 3). Clearly this can be said of a majority of restoration projects.

Complexity or function

Time

Goals & Reference Ecosystem

In each restoration project, the fundamental starting point is to define realistic and achievable goals based on a reference ecosystem, and to plan the restoration process and measure its success accordingly (SER 2004[START_REF] Hobbs | Restoration ecology: The challenge of social values and expectations[END_REF][START_REF] Hobbs | Restoration Ecology : Interventionist Approaches for Restoring and Maintaining Ecosystem Function in the Face of Rapid Environmental Change[END_REF].

In setting goals and deciding what type of intervention, if any, is required, it is essential to identify a reference ecosystem i.e. to establish what we want to restore, and to understand exactly how the reference works [START_REF] Hobbs | Restoration ecology: The challenge of social values and expectations[END_REF][START_REF] Hobbs | Restoration Ecology : Interventionist Approaches for Restoring and Maintaining Ecosystem Function in the Face of Rapid Environmental Change[END_REF]. It is possible to use the pre-disturbance state as reference ecosystem, but only if enough is known about historical conditions and/or if large areas of the pre-disturbance state are still found in the landscapes [START_REF] Choi | Ecological restoration for future sustainability in changing environment[END_REF][START_REF] Buisson | Community and restoration ecology, importance odfdisturbance, natural resilience and assembly rules[END_REF]. The reference can also be defined as whatever state is expected to arise out of the natural progression of the ecosystem's historical trajectory [START_REF] Aronson | On the need to select an ecosystem of reference, however imperfect: a reply to Pickett and Parker[END_REF][START_REF] Clewell | The SER International Primer on Ecological Restoration[END_REF]. To be realistic and reachable, goals should include multiple endpoints of functional or structural equivalence [START_REF] Hilderbrand | The Myths of Restoration Ecology[END_REF]. Indeed, if reference ecosystems are dynamically resilient to stresses or endogenous disturbances, they may occur in a number of alternative states [START_REF] Aronson | On the need to select an ecosystem of reference, however imperfect: a reply to Pickett and Parker[END_REF][START_REF] Suding | Threshold models in restoration and conservation : a developing framework[END_REF]. Restoration therefore attempts to bring an ecosystem to its reference trajectory so that it may evolve normally along its appropriate successional pathway, and this allows it to synchronize with any potential variations of the natural ecosystem (Figure 3).

Restoration goals are obviously subjective because they are determined by humans, although there may be significant reference to nature [START_REF] Choi | Ecological restoration for future sustainability in changing environment[END_REF]. Setting restoration goals involves a set of values, including the ethical and philosophical bases for our actions, concepts of "good" restoration, humanity's place in nature, the influence of indigenous peoples on the environment, and local popular support, which is often closely linked with socio-economic sustainable development [START_REF] Hobbs | Restoration ecology: The challenge of social values and expectations[END_REF][START_REF] Aronson | Ecological restoration: A new frontier for nature conservation and economics[END_REF][START_REF] Hobbs | Setting Effective and Realistic Restoration Goals : Key Directions for Research[END_REF][START_REF] Choi | Ecological restoration for future sustainability in changing environment[END_REF]. Finally, economic feasibility will determine the level and extent of intervention that can be considered [START_REF] Hobbs | Setting Effective and Realistic Restoration Goals : Key Directions for Research[END_REF].

Type of intervention

The assessment of current, degraded conditions, relative to the reference ecosystem, is followed by considerations of which intervention possibilities are likely to improve the situation [START_REF] Hobbs | Restoration Ecology : Interventionist Approaches for Restoring and Maintaining Ecosystem Function in the Face of Rapid Environmental Change[END_REF]. There are three approaches to restoring a disturbed site: (1) to rely completely upon spontaneous succession: the "do nothing" approach, (2) to exclusively adopt technical measures: interventionist approaches, and (3) to combine both previous approaches by manipulating spontaneous succession toward a target [START_REF] Hobbs | Restoration Ecology : Interventionist Approaches for Restoring and Maintaining Ecosystem Function in the Face of Rapid Environmental Change[END_REF][START_REF] Prach | Spontaneous Succession versus Technical Reclamation in the Restoration of Disturbed Sites[END_REF][START_REF] Hobbs | Intervention Ecology: Applying Ecological Science in the twenty-first century[END_REF]). The "do nothing" approach could be as simple as removing of the cause of disturbance [START_REF] Palmer | Ecological theory and restoration ecology[END_REF][START_REF] Hobbs | Restoration Ecology : Interventionist Approaches for Restoring and Maintaining Ecosystem Function in the Face of Rapid Environmental Change[END_REF], and is most effective in cases where the disturbance intensity is low to moderate, e.g. in traditional land-use abandonment [START_REF] Prach | Spontaneous Succession versus Technical Reclamation in the Restoration of Disturbed Sites[END_REF]. In case of harsh to extreme disturbances, intervention is often necessary: the recovery through natural processes either does not occur or does so too slowly [START_REF] Palmer | Ecological theory and restoration ecology[END_REF][START_REF] Hobbs | Restoration Ecology : Interventionist Approaches for Restoring and Maintaining Ecosystem Function in the Face of Rapid Environmental Change[END_REF][START_REF] Prach | Spontaneous Succession versus Technical Reclamation in the Restoration of Disturbed Sites[END_REF][START_REF] Hobbs | Intervention Ecology: Applying Ecological Science in the twenty-first century[END_REF]. It is therefore important to determine whether active restoration is required, and this involves the identification of restoration thresholds, which are essentially barriers (arising from either abiotic or biotic factors) to recovery of degraded systems [START_REF] Hobbs | Setting Effective and Realistic Restoration Goals : Key Directions for Research[END_REF][START_REF] Hobbs | Restoration Ecology : Interventionist Approaches for Restoring and Maintaining Ecosystem Function in the Face of Rapid Environmental Change[END_REF][START_REF] Suding | Threshold models in restoration and conservation : a developing framework[END_REF].

Legislation

Among the most drastic disturbances, quarrying and mining activities cause major soil damage, leading to uncontrolled soil erosion and water quality alteration [START_REF] Pimentel | Environmental and economic costs of soil erosion and conservation benefits[END_REF][START_REF] Valentin | Gully erosion: Impacts , factors and control[END_REF]. As a result, many countries have passed laws that require the reclamation, rehabilitation, or restoration of quarries and mines once exploitation is over. Examples of such legislation include, in the US, the Surface Mining Control and Reclamation Act of 1977; in Australia, the National Environment Protection Measures Act; in Canada, the Law for environment quality (L.R.Q., c. Q-2, a. 20, 22, 23, 31, 46, 70 & 87)

Restoration Ecology & Community Ecology

The study of ecological theory and the science of restoration are mutually beneficial. This is because ecological restoration allows the implementation of restoration ecology experiments, which can form the basis of important experimental tests of ecological theory [START_REF] Peterson | The ecology of restoration : historical links, emerging issues and unexplored realms[END_REF], Palmer et al. 2006). [START_REF] Bradshaw | Restoration : an acid test for ecology, in: Restoration Ecology, A Synthetic Approach to Ecological Research[END_REF] has even described restoration a kind of acid test of our ecological understanding (Figure 4). To paraphrase, if the processes at work in an ecosystem are not understood, then reconstructing the ecosystem is unlikely. Theoretical ecology thus provides fundamental knowledge that can serve as helpful guidance for restoration ecology. Conversely, restoration ecology results and outcomes can help us to comprehend how natural communities work and can reveal the deficiencies in our theoretical understanding of such systems [START_REF] Palmer | Ecological Theory and Community Restoration Ecology[END_REF](Palmer et al. , 2006) ) (Figure 4).

Figure 4: The relationship between ecological theory, restoration ecology, and ecological restoration can be viewed in a hierarchical fashion [START_REF] Palmer | Ecological theory and restoration ecology[END_REF].

Central questions in community ecology are: How do species coexist? What factors govern the composition and abundance of species in communities? These questions are also central to ecological restoration because they can be applied to the reference ecosystem, and thereby serve to frame the discussion on how exactly to reach the restoration goals. Land use changes and ecological restoration provide a good opportunity to study community assembly, since restoration tends to initiate or accelerate species assembly [START_REF] Prach | Four opportunities for studies of ecological succession[END_REF].

Community Theory

Ecological community

At the beginning of the 20 th century, two contrasting perceptions of communities were proposed. [START_REF] Clements | Plant succession: An analysis of the development of vegetation[END_REF] favored a holistic conceptualization, and considered the different species in a community to be tightly integrated and interdependent, essentially assimilating into a kind of super-organism. In contrast, [START_REF] Gleason | The individualistic concept of the plant association[END_REF] adopted more of an individualistic notion of plant association noting that "an association is not an organism, scarcely even a vegetational unit, but merely a coincidence".

The formal definition of community is an assemblage of organisms of multiple species living in a specified place and time [START_REF] Vellend | Conceptual synthesis in community ecology[END_REF]. Conceptually, it would be useful when General introduction 12 describing a community to take into account the spatial context of local communities within the region, and to consider the role of historical events in driving the relevant ecological patterns and processes [START_REF] Agrawal | Filling key gaps in population and community ecology[END_REF][START_REF] Ricklefs | Disintegration of the Ecological Community[END_REF].

Patterns of species composition and diversity, observed on a local scale, are the outcomes of disturbance, succession, and filter models within the broader community [START_REF] Young | Community Succession and Assembly Comparing, Contrasting and Combining Paradigms in the Context of Ecological Restoration[END_REF], White & Jentsch 2004, Weiher et al. 2011) This represents a convergence of concepts from diverse areas coming together to provide ideas relevant to ecological restoration (Hobbs et al. 2007a): the succession theory comes from plant biology, and assembly rules come from the study of animal, rather than plant communities [START_REF] Young | Community Succession and Assembly Comparing, Contrasting and Combining Paradigms in the Context of Ecological Restoration[END_REF]

Community ecology

Community ecology is the study of a set of species co-existing at a given time and place. It deals with patterns in the diversity, abundance, and composition of species within communities, and of the processes underlying these patterns. There has been considerable debate surrounding the ability of community ecology to provide useful guiding principles, given the complex nature of communities themselves. There are vast numbers of processes, each system appears unique [START_REF] Lawton | Are There General Laws in Ecology ?[END_REF][START_REF] Simberloff | Community Ecology : Is It Time to Move On ?[END_REF], and this amounts to a perfect storm in which well-constructed models fail to provide general rules about many species communities. In addition, [START_REF] Ricklefs | Disintegration of the Ecological Community[END_REF] questions the degree to which ecological communities are sufficiently coherent for objective study.

To address this, Vellend (2010) provides a conceptual synthesis of community ecology and points out that in the most general sense, patterns in the composition and diversity of species are influenced by four classes of processes: selection (deterministic fitness difference between individuals of different species), drift (random changes in species' relative abundance), speciation (the creation of new species), and dispersal (the movement of organisms across space) (Figure 5). [START_REF] Mcgill | Rebuilding community ecology from functional traits[END_REF] assert that community ecology should be re-built using general traits, as opposed to specific species, to create a more quantitative and predictive science, bringing general patterns to community ecology. Community ecology is currently crucial to understanding why and how the environment affects communities across space, which helps to predict the ecological impact of global changes [START_REF] Simberloff | Community Ecology : Is It Time to Move On ?[END_REF][START_REF] Mcgill | Rebuilding community ecology from functional traits[END_REF].

Disturbance & Resilience

A disturbance is a relatively discrete event in time that disrupts an ecosystem, community, or population structure, changing resource availability along with the underlying substrate or physical environment regardless of whether these are perceived as "normal" for the given system (White & Pickett 1985). Disturbances have a wide range of effects, which may depend upon the state of the communities prior to the disturbance, among other biotic and physical factors (White & Pickett 1985, White & Jentsch 2001). Disturbances occur on a wide range of spatial and temporal scales, affecting all levels of organization (White & Jentsch 2004). Disturbances usually produce heterogeneous and patchy effects (White & Pickett 1985), which alter competition and impact the structure of communities [START_REF] Temperton | Order of arrival and availability of safe sites: an example of their importance for plant community assembly in stress ecosystems[END_REF].

Disturbance can have a variety of quantitative and qualitative causes; they can be exogenous or endogenous. Exogenous disturbances are those in which the force originates outside the ecosystem; endogenous disturbances are those in which the force originates either within the ecosystem or as a byproduct of its successional development (White & Jentsch 2004). Disturbance descriptors, such as temporal and spatial characteristic, magnitude, specificity, and synergism are used to describe disturbance regimes. Disturbances vary greatly in severity, and so do their consequences, producing a large variation in potential succession, which ranges from primary to secondary (see 4.4 for definitions) (White & Jentsch 2004).

The type of intervention required for restoration depends greatly on the type and extent of the damage to the ecosystem [START_REF] Hobbs | Setting Effective and Realistic Restoration Goals : Key Directions for Research[END_REF]. Before launching a restoration project, one must therefore first identify the processes that led to the degradation and determine whether restoration is actually necessary [START_REF] Clewell | The SER International Primer on Ecological Restoration[END_REF]. By evaluating the resilience and resistance of an ecosystem, one can assess the impact of disturbances.

Resistance (also called ecological resilience, [START_REF] Beisner | Alternative stable states in ecology[END_REF][START_REF] Van Nes | Slow Recovery from Perturbations as a Generic Indicator of a nearby catastrophic shift[END_REF] is defined as the ability of ecosystems to withstand the disturbance (it is commonly associated with the width of the basin of attraction, representing the amount of disturbance necessary to change the system's state); while resilience (also called recovery rate or engineering resilience, [START_REF] Beisner | Alternative stable states in ecology[END_REF][START_REF] Van Nes | Slow Recovery from Perturbations as a Generic Indicator of a nearby catastrophic shift[END_REF] is the process/rate/time of recovery for ecosystems returning to equilibrium following a disturbance or period of stress (usually connected with the slope of the basin of attraction) [START_REF] Leps | Community stability, complexity and species life history strategies[END_REF][START_REF] Lockwood | An alternative to succession: assembly rules offer guide to restoration efforts[END_REF][START_REF] Mitchell | Ecosystem stability and resilience: a review of their relevance for conservation management of lowland heaths[END_REF][START_REF] Beisner | Alternative stable states in ecology[END_REF][START_REF] Van Nes | Slow Recovery from Perturbations as a Generic Indicator of a nearby catastrophic shift[END_REF]). Hysteresis appears when a parameter is changed, resulting in landscape changes, and leading to a change in the position of the equilibrium point; following a perturbation, the return trajectory leads the community to a different state (i.e. alternative stable state (ASS)), from which it is difficult to return to the original state [START_REF] Beisner | Alternative stable states in ecology[END_REF].

The alternative stable state model suggests that while communities are structured and restricted to some extent, they can also end up in any of a number of possible ASS. This is because an element of randomness is inherent in all ecosystems [START_REF] Beisner | Alternative stable states in ecology[END_REF][START_REF] Temperton | The search for ecological assembly rules and its relevance to restoration ecology, in: Assembly rules and restoration ecologybridging the gap between theory and practice[END_REF]). If communities/ecosystems follow this model, their recovery from degradation will follow one of several possible trajectories, depending on their particular histories, the availability and order of arrival of organisms, and some element of randomness [START_REF] Lockwood | Assembly models and the practice of restoration[END_REF][START_REF] Temperton | The search for ecological assembly rules and its relevance to restoration ecology, in: Assembly rules and restoration ecologybridging the gap between theory and practice[END_REF]. With this in mind, a restoration effort should aim at placing the resilience of the degraded system on a desirable trajectory. However, since alternative states exist, restoration can result in unexpected trajectories [START_REF] Lockwood | Assembly models and the practice of restoration[END_REF][START_REF] Temperton | The search for ecological assembly rules and its relevance to restoration ecology, in: Assembly rules and restoration ecologybridging the gap between theory and practice[END_REF].

Although disturbance does play a role in community structure, restoration efforts cannot simply reintroduce species. Rather one must consider using and/or restoring natural disturbances and assess how they influence the sustainability of the restored community [START_REF] Palmer | Ecological Theory and Community Restoration Ecology[END_REF]. Moreover, disturbance management can be a useful tool in ecological restoration, especially if the degraded community is locked in an undesirable state, because it makes it possible to move the community to a more desirable state [START_REF] Hobbs | Towards a conceptual framework for restoration ecology[END_REF][START_REF] Temperton | Order of arrival and availability of safe sites: an example of their importance for plant community assembly in stress ecosystems[END_REF].

Succession: How do ecosystems change following a disturbance?

According to [START_REF] Clements | Plant succession: An analysis of the development of vegetation[END_REF], ecological succession is the sequential replacement of species following a disturbance. Succession deals with the overall changes in substrates and the associated species turnover, and deals with such issues as facilitation, competition, herbivory, invasive species, priority effects, biodiversity loss, climate change, and plant-soil interaction in both the short and long term (Walker et al. 2007, Walker & Del Moral 2009[START_REF] Prach | Four opportunities for studies of ecological succession[END_REF]. Today, the notion of community climax is used far less frequently because stable succession end points are too simplistic of an idea. However, the fact remains that some terrestrial communities do tend to return to pre-disturbance states in a more or less predictable way [START_REF] Young | Community Succession and Assembly Comparing, Contrasting and Combining Paradigms in the Context of Ecological Restoration[END_REF], especially if the disturbance is endogenous. Primary succession involves species change on substrates with little or no biological legacy following severe disturbances (e.g. lava flows, landslides and mine wastes). Secondary succession begins with some biological legacy (i.e. internal species pool) following a disturbance, such as fire or abandonment of agricultural lands (Walker & Del Moral 2003). Both types of succession can take place after natural or anthropogenic disturbances (Walker & Del Moral 2003).

In case of extreme disturbances, such as volcano eruptions, urban clearances, and mine and quarry exploitations, regeneration processes resulting from primary succession are usually dependent on the availability of propagule sources in the surrounding areas because seed banks are usually destroyed [START_REF] Bakker | Constraints in the restoration of ecological diversity in grassland and heathland communities[END_REF][START_REF] Bradshaw | The use of natural processes in reclamation -advantages and difficulties[END_REF][START_REF] Shu | Natural Colonization of Plants on Five Lead/Zinc Mine Tailings in Southern China[END_REF]. Succession in terrestrial communities involves the arrival of plants and their establishment, along with changes in the physical environment and the nature of the resources generated by the community itself [START_REF] Bradshaw | The use of natural processes in reclamation -advantages and difficulties[END_REF], White & Jentsch 2004). Spontaneous vegetation succession can be determined by both landscape (i.e. proximity of seed sources) and local site factors (Rehounková & Prach 2006).

Ecological restoration can attempt to initiate, accelerate, improve, slow down, turn back, or mimic successional sequences [START_REF] Palmer | Ecological Theory and Community Restoration Ecology[END_REF], Walker et al. 2007[START_REF] Prach | Four opportunities for studies of ecological succession[END_REF]. Understanding the possible role of site factors and external forces in driving succession is essential for predicting, and possibly even manipulating, further succession [START_REF] Young | Community Succession and Assembly Comparing, Contrasting and Combining Paradigms in the Context of Ecological Restoration[END_REF], Walker & del Moral 2003, Del Moral et al. 2007, Walker & del Moral 2009[START_REF] Prach | Four opportunities for studies of ecological succession[END_REF]. Both success and failure can be important factors in improving restoration practices and the development of theoretical concepts concerning succession (Hobbs et al. 2007b).

Assembly rules: How do species assemble into communities?

The concept of pool-filter-subset underlies the main approach in community assembly theory (Weiher et al. 2011). Local assemblages are non-random and viewed as subsets of the regional species pool determined by assembly rules that are a set of abiotic and biotic filters [START_REF] Keddy | Assembly and responses rules: two goals for predictive community ecology[END_REF], Weiher & Keddy 1995[START_REF] Gotelli | Species co-occurence: a meta-analysis of J M Diamond's assembly rules model[END_REF][START_REF] Temperton | The search for ecological assembly rules and its relevance to restoration ecology, in: Assembly rules and restoration ecologybridging the gap between theory and practice[END_REF][START_REF] Temperton | Order of arrival and availability of safe sites: an example of their importance for plant community assembly in stress ecosystems[END_REF], Weiher et al. 2011). Contrary to succession, assembly theory focuses mainly on the final community composition (White & Jentsch 2004). A hierarchical filter model was adapted by [START_REF] Lortie | Rethinking plant community theory[END_REF] (Figure 6) to include abiotic filters that determine whether a species would colonize, establish and persist in a given habitat through (i) stochastic processes (i.e. the dispersal filter); (ii) specific tolerances of species to the site local abiotic conditions (i.e. the environmental filter); (iii) a set of biotic filters that are imposed by positive and negative direct and indirect interactions among plants; and (iv) direct interactions with other organisms (both are biotic filters) (see also [START_REF] Fattorini | The dynamic environmental filter model: how do filtering effects change in assembling communities after disturbance?[END_REF], Weiher et al. 2011) (Figure 6). New species may come in from the surroundings via dispersal (i.e. from the external seed pool), from the seed bank, or from surviving individuals (i.e. the internal seed pool) [START_REF] Fattorini | The dynamic environmental filter model: how do filtering effects change in assembling communities after disturbance?[END_REF]) (Figure 6). The relative importance of each process varies in space and time [START_REF] Lortie | Rethinking plant community theory[END_REF]), and their dependence on each other arises from feedback loops [START_REF] Belyea | Beyond ecological filters: feedback networks in the assembly and restoration of community structure, in: Assembly rules and restoration ecologybridging the gap between theory and practice[END_REF][START_REF] Fattorini | The dynamic environmental filter model: how do filtering effects change in assembling communities after disturbance?[END_REF]. White & Jentsch (2004) suggested adding a disturbance filter that acts acts on survival, reproduction, colonizing ability and adaptations. Ecosystem degradation may affect some or all processes [START_REF] Belyea | Beyond ecological filters: feedback networks in the assembly and restoration of community structure, in: Assembly rules and restoration ecologybridging the gap between theory and practice[END_REF] and lead to a reduced species pool at the degraded site (Figure 6). The inherent goal in many restoration activities is to bypass dispersal and environmental constraints, thereby allowing desired species to arrive and to establish [START_REF] Belyea | Beyond ecological filters: feedback networks in the assembly and restoration of community structure, in: Assembly rules and restoration ecologybridging the gap between theory and practice[END_REF].

From this it follows that every restoration project involves asking the following implied questions [START_REF] Menninger | Restoring ecological communities: from theory to practice[END_REF]):

1. How do regional processes determine species composition?

2. What environmental conditions and habitat characteristics favor species survival and influence community structure?

3. How do biotic interactions shape community structure?

Filter models can be very useful at the beginning of a project for determining what constrains the arrival of species to a system [START_REF] Temperton | The search for ecological assembly rules and its relevance to restoration ecology, in: Assembly rules and restoration ecologybridging the gap between theory and practice[END_REF][START_REF] Belyea | Beyond ecological filters: feedback networks in the assembly and restoration of community structure, in: Assembly rules and restoration ecologybridging the gap between theory and practice[END_REF]).

Once the constraining mechanisms are identified, remedial action can be taken to bypass them. Restoration interventions are designed to act on the different filters and modify one or all of them in order to reach a reference community. However, due to the stochasticity inherent in all ecosystems, it is a myth to think that only controlling initial species composition and succession is sufficient to achieve the desired end point [START_REF] Temperton | The search for ecological assembly rules and its relevance to restoration ecology, in: Assembly rules and restoration ecologybridging the gap between theory and practice[END_REF][START_REF] Belyea | Beyond ecological filters: feedback networks in the assembly and restoration of community structure, in: Assembly rules and restoration ecologybridging the gap between theory and practice[END_REF][START_REF] Hilderbrand | The Myths of Restoration Ecology[END_REF]. Understanding assembly is fundamental to determining the most relevant management that allows direct succession to the desired state, since the order of arrival of different species (priority effects) can drastically change the development trajectory of a community [START_REF] Bradshaw | Underlying principles of restoration[END_REF][START_REF] Young | Community Succession and Assembly Comparing, Contrasting and Combining Paradigms in the Context of Ecological Restoration[END_REF][START_REF] Temperton | The search for ecological assembly rules and its relevance to restoration ecology, in: Assembly rules and restoration ecologybridging the gap between theory and practice[END_REF], del Moral 2007).

5.Biological model

Savanna ecosystems

5.1.1.Definition

The word sabana is of Amerindian origin and is currently used in ordinary Spanish.

Originally, savanna designated a flat, grassy landscape that may or may not have isolated shrubs and trees in addition to the other the vegetation that characterizes this landscape [START_REF] Bourlière | The Ecology of Tropical Savannas[END_REF][START_REF] Sarmiento | The Ecology of neotropical savannas[END_REF]). However, this original meaning has been lost [START_REF] Sarmiento | The Ecology of neotropical savannas[END_REF]. [START_REF] Richards | The tropical rain forest: an ecological study[END_REF] notes that the definition of savanna is complex because savannas represent a considerable heterogeneity of physiognomies, of ecological status, and of floristic composition throughout the world. Walter (2006) also underlines the multitude of definitions and concepts. Working definitions were originally based on the physiognomy (i.e. vegetation structure), and later on the environmental conditions that led to savannas (i.e. climate, soil, hydrography or geomorphology). As a follow-on to this analysis, [START_REF] Eiten | The cerrado vegetation of Brazil[END_REF] points out that floristic composition is also an important consideration.

In this thesis, we consider the following definition, which refers to the savanna's most important ecological and physiognomic characteristics: we think of savanna as a heterogeneous formation in time and space, which can be defined as a tropical formation where the grass stratum is dominant, continuous, and occasionally interrupted by trees and shrubs, where the stratum is burnt from time to time, and where the main growth patterns are closely associated with alternating wet and dry seasons [START_REF] Bourlière | The Ecology of Tropical Savannas[END_REF], 1983[START_REF] Sarmiento | The Ecology of neotropical savannas[END_REF]. The contribution of trees to the structure of the savanna (i.e. cover or density) determines to a large extent the physiognomy of the savanna (for more details, see section 5.2 Cerrado). [START_REF] Sarmiento | The Ecology of neotropical savannas[END_REF] adds to this definition the notion that tropical savannas are to be found in warm, lowland tropics, but Colinsson (1988) notes that savannas can also be found in warmclimate highlands.

5.1.2.Geographic distribution

Because of the difficulties presented by the lack of a standardized definition of savanna (Walter 2006), the exact geographic distribution of savannas is not particularly well established. Tropical savannas cover some 20% of the world's land surface and occur in Central and South America, India, southeastern Asia, northern Australia and occupy a large part of the African continent [START_REF] Bourlière | Present-day savannas: an overview[END_REF], Collinsson 1988[START_REF] Osborne | Tropical ecosystems and ecological concept[END_REF] (Figure 7). Yet there are major differences among the savannas of the various continents. The soils of the American savannas are considerably less fertile than the others [START_REF] Sarmiento | Adaptive strategies of perennial grasses in South American savannas[END_REF]. Additionally, because of the large mammal extinction connected with a sharp decrease in open vegetation during the mid-Holocene epoch (De Vivo & Carmignotto 2004), large herbivores do not play a key role in the function and vegetation structure of Neotropical savannas (Central and South America), in stark contrast to Paleotropical savannas (African, Asiatic and Australian savannas) [START_REF] Sarmiento | Adaptive strategies of perennial grasses in South American savannas[END_REF]. Fire, which is a characteristic of all savannas, has many analogies with mammal herbivory because it "consumes" the above-ground herbaceous biomass and greatly impacts the overall vegetation, structure and function [START_REF] Bond | Fire as a global "herbivore": the ecology and evolution of flammable ecosystems[END_REF]) of the savanna. Fire regime is defined according to its intensity, its severity, its frequency, its seasonality, and also its fuel consumption and spread pattern [START_REF] Bond | Fire as a global "herbivore": the ecology and evolution of flammable ecosystems[END_REF].

Fire alters the soil water regime along with the carbon and nutrient fluxes [START_REF] Cochrane | Tropical fire ecology: climate change, land use and ecosystem dynamics[END_REF]. It also acts as a selective force, having at different times a neutral, positive, or negative impact on plant demography and phenology by affecting plant growth, recruitment, and sexual or vegetative reproduction (Hoffman 1998[START_REF] Miranda | The fire factor, in: The Cerrados of Brazil -Ecology and natural history of a neotropical savanna[END_REF], 2009[START_REF] Pausas | Plant Functional Traits in Relation to Fire in Crown-Fire Ecosystems[END_REF]). At the beginning of the 20 th century, the climatic theory (i.e. the presence of a dry season during winter as a driver for savanna formation) was a popular explanation for the origin of savannas [START_REF] Beard | The savanna vegetation on Northern Tropical America[END_REF]. More recently, various alternative hypotheses have been proposed, with current debate seeming fall under two main schools of thought: one favoring a bottom-up model (formation and regulation by, e.g., water and soil nutrients);

and the other, top-down (formation and regulation principally through fire and herbivory) [START_REF] Bourlière | The Ecology of Tropical Savannas[END_REF][START_REF] Sarmiento | The Ecology of neotropical savannas[END_REF][START_REF] Collinson | Introduction to world vegetation[END_REF][START_REF] Mistry | World Savannas: Ecology and Human Use[END_REF][START_REF] Van Langevelde | Effects of fire and herbivory on the stability of savanna ecosystems[END_REF][START_REF] Bond | Fire as a global "herbivore": the ecology and evolution of flammable ecosystems[END_REF][START_REF] Scanlon | Dynamic response of grass cover to rainfall variability: implications for the function and persistence of savanna ecosystems[END_REF][START_REF] Bond | What Limits Trees in C4 Grasslands and Savannas ?[END_REF][START_REF] Midgley | Savanna woody plant dynamics: the role of fire and herbivory, separately and synergistically[END_REF]) (Figure 8). The details of, and some of the problems with, the main competing hypothesis can be summarized as follows:

1) Climate: Savannas only occur in climates characterized by the alternation of wet and dry seasons. On the contrary, we now know that savannas are found in climates capable of supporting forests.

2) Edaphic factors (i.e. nutrient and water availability): savannas occur on soils too nutrient-poor to allow forest establishment.

3) Fires and herbivory: fires prevent forest re-establishment and grazing activity by large herbivores serves to maintain open vegetation. In tropical America, dry savannas do not exist; rather, tropical American semi-arid areas contain woodlands or shrub-lands that do not have a continuous layer of perennial graminoids [START_REF] Sarmiento | Adaptive strategies of perennial grasses in South American savannas[END_REF]. Neotropical savannas can be classified into the following three categories based on the degree of seasonal variation in water availability in their soils [START_REF] Sarmiento | The Ecology of neotropical savannas[END_REF][START_REF] Sarmiento | Adaptive strategies of perennial grasses in South American savannas[END_REF]: seasonal, hyper-seasonal and semi-seasonal. Seasonal savannas have a well-marked dry season (3 to 7 months); hyper-seasonal savannas alternately exhibit periods of water shortage, water availability, and water excess in an annual cycle, with topsoil becoming water-saturated (such as on bottomlands and areas with poor drainage) during water excess; semi-seasonal savannas lack extended dry periods, so the soil remains water-saturated for several months.

Cerrado

5.2.1.What is the Cerrado?

The Cerrado domain (Cerrado sensu lato) covers approximately 2 million km 2 of Central Brazil, representing about 23% of the land surface of the country (Furley & Ratter 1988[START_REF] Ratter | The Brazilian Cerrado Vegetation and Threats to its Biodiversity[END_REF] (Figure 9). In terms of areal coverage, it is the second most important vegetation formation in Brazil (Furley & Ratter 1988[START_REF] Ratter | The Brazilian Cerrado Vegetation and Threats to its Biodiversity[END_REF]. Cerrado has the richest flora among the world's savannas (>7,000 species) [START_REF] Mendonça | Flora vascular do Cerrado[END_REF][START_REF] Furley | The nature and diversity of neotropical savanna vegetation with particular reference to the Brazilian cerrados[END_REF][START_REF] Castro | How Rich is the Flora of Brazilian Cerrados ?[END_REF][START_REF] Klink | A conservação do Cerrado brasileiro[END_REF].

Figure 9. The distribution of cerrado and associated vegetation formations in Brazil. 1, cerrado; 2, chaco; 3, Atlantic forest; 4, Pantanal (wetlands); 5, caatinga. Letters refer to Brazilian states: B=Bahia; DF=Federal District; GO=Goias; MA= Maranhão; MG=Minas Gerais; MS=Mato Grosso do Sul; MT=Mato Grosso; PA=Pará; PI=Piaui; RO=Rondônia; SP= SãoPaulo; TO=Tocantins. From [START_REF] Furley | The nature and diversity of neotropical savanna vegetation with particular reference to the Brazilian cerrados[END_REF].

Like other tropical savannas1 , the Cerrado is not uniform in physiognomy; its various physiognomies are primarily differentiated by their degree of woody strata cover [START_REF] Goodland | A Physiognomic Analysis of the "Cerrado" Vegetation of Central Brasil[END_REF][START_REF] Sarmiento | The Ecology of neotropical savannas[END_REF]. Indeed, loosely speaking, the Cerrado category encompasses a gradient of physiognomies ranging from grassland (campo limpo) to dense-canopy woodland (cerradão), with many others that are intermediate (campo sujo, campo cerrado, cerrado sensu stricto) [START_REF] Coutinho | O conceito de cerrado[END_REF]) (Figure 10). Several reasons have been proposed as explanations for the varying physiognomies (Oliveira-Filho & Ratter 2002); examples of which include the availability of nutrients and water [START_REF] Askew | Interrelationships of Soils and Vegetation in the Savanna-Forest Boundary Zone of North-Eastern Mato Grosso[END_REF][START_REF] Goodland | The Brazilian Cerrado Vegetation: A Fertility Gradient[END_REF][START_REF] Haridasan | Nutrição mineral das plantas nativas do Cerrado[END_REF][START_REF] Jr | Comparação da vegetação arbórea e características edáficas de um cerradão e um cerrado sensu stricto em áreas adjacentes sobre solo distrófico no leste de Mato Grosso , Brasil[END_REF], the nature of the associated fire regimes [START_REF] Coutinho | Fire in the ecology of the Brazilian Cerrado[END_REF][START_REF] Miranda | The fire factor, in: The Cerrados of Brazil -Ecology and natural history of a neotropical savanna[END_REF], and the distribution of aluminium content [START_REF] Haridasan | Aluminium accumulation by some cerrado native species of central[END_REF]) (Figure 10).

5.2.2.The controversial Cerrado

Like the definition of savanna, the definition of Cerrado is also controversial: Is Cerrado a savanna? Is Cerrado a biome? Indeed, the cerrado has been variously referred to as a biome (Oliveira-Filho & Ratter 2002), as the Brazilian savanna vegetation [START_REF] Ratter | The Brazilian Cerrado Vegetation and Threats to its Biodiversity[END_REF], as a complex of biomes [START_REF] Coutinho | O conceito de bioma[END_REF][START_REF] Batalha | O cerrado não é um bioma[END_REF], or as a unique entity [START_REF] Eiten | The cerrado vegetation of Brazil[END_REF]) (Figure 10). [START_REF] Eiten | Vegetation forms. A classification of stands of vegetation based on structure, growth form of the components, and vegetative periodicity[END_REF][START_REF] Eiten | The cerrado vegetation of Brazil[END_REF], who has published several influential articles about the Cerrado, points out that the Cerrado is a unique entity, and cannot be considered a true savanna because its floristic richness greatly differentiates it from typical tropical savannas. He defines the Cerrado as a mix of xeromorphic woodland, scrub, savannah, and grassland vegetation in central Brazil [START_REF] Eiten | Vegetation forms. A classification of stands of vegetation based on structure, growth form of the components, and vegetative periodicity[END_REF]). The cerrado forms a vegetational and floristic province in an intermediate-rainfall region with a definite dry season [START_REF] Eiten | The cerrado vegetation of Brazil[END_REF]. The Cerrado cannot be uniquely classified as savanna because of its rich variety of physiognomies [START_REF] Coutinho | O conceito de cerrado[END_REF]. [START_REF] Coutinho | O conceito de cerrado[END_REF], in his "forest-ecotone-grassland" concept, states that the Cerrado is a complex of oreadic 2 formations, representing savanna-intermediary formations (campo sujo, campo cerrado, cerrado sensu stricto) and two extreme formations: a forest formation (cerradão) and a grassland formation (campo limpo). He concludes that the Cerrado is a mosaic of three biomes (see also Walter (2006) and [START_REF] Batalha | O cerrado não é um bioma[END_REF]). [START_REF] Coutinho | O conceito de bioma[END_REF] later reviews the concept of the biome, strengthening his prior definition [START_REF] Coutinho | O conceito de cerrado[END_REF] while noting that all tropical savannas have a physiognomic complexity, which leads to a kind of mosaic that manifests as a gradient of communities. At the same time, he also acknowledges the fact that savannas are considered biomes by the majority of authors. [START_REF] Olson | Terrestrial Ecoregions of the World : A New Map of Life on Earth[END_REF] include the Cerrado in the ecoregion3 of "tropical & subtropical grasslands, savannas and shrublands," underlining a certain unicity between the Cerrado and other savanna formations.

Recent work, by such authors as [START_REF] Ratter | The Brazilian Cerrado Vegetation and Threats to its Biodiversity[END_REF], [START_REF] Silva | Biogeographic Patterns and Conservation in the South American Cerrado: A Tropical Savanna Hotspot[END_REF] and Oliveira & Marquis (2002), considers the entire Cerrado, in which the cerradão is explicitly included (Figure 10), a savanna. On the other hand, [START_REF] Coutinho | O conceito de bioma[END_REF] concludes that the Cerrado is a savanna biome, and because the Cerradão is actually a distinct seasonal forest, he considers it separately (see also Rizzini 1997 andWalter 2006) (Figure 10).

Finally [START_REF] Batalha | O cerrado não é um bioma[END_REF] corroborates the "forest-ecotone-grassland" concept of [START_REF] Coutinho | O conceito de cerrado[END_REF] and emphasizes that Cerrado is not a biome but a complex of biomes (Figure 10). Ratter (2002) Cerrado sensu lato Cerrado is considered as the Brazilian savanna Rizzini (1997) [START_REF] Coutinho | O conceito de bioma[END_REF] Cerrado province [START_REF] Eiten | Vegetation forms. A classification of stands of vegetation based on structure, growth form of the components, and vegetative periodicity[END_REF][START_REF] Eiten | Delimitation of the Cerrado concept[END_REF] Cerrado province [START_REF] Goodland | A Physiognomic Analysis of the "Cerrado" Vegetation of Central Brasil[END_REF] Fertility gradient Fire gradient

5.2.3.Brief history of the evolution of the Cerrado

During the Cretaceous epoch, angiosperm was spread, creating a [START_REF] Crane | Angiosperm diversification and paleolatitudinal gradients in Cretaceous floristic diversity[END_REF][START_REF] Lupia | Comparing Palynological Abundance and Diversity: Implications for Biotic Replacement during the Cretaceous Angiosperm Radiation[END_REF][START_REF] Mcelwain | Cretaceous CO2 Decline and the Radiation and Diversification of Angiosperms, in: A History of Atmospheric CO2 and Its Effects on Plants, Animals, and Ecosystems[END_REF]) new fire regime by increasing fuel availability [START_REF] Bond | Fire and the spread of flowering plants in the Cretaceous[END_REF]. The savanna's origin, marked by the expansion and the predominance of C4 grasses, is estimated to have occurred during the Miocene epoch some 8 million years ago, and is thought to have been the result of environmental pressures associated with intense light levels, high temperature, low CO 2 , and fire [START_REF] Keeley | Fire and the Miocene expansion of C4 grasslands[END_REF], Bond et al. 2005[START_REF] Beerling | The origin of the savanna biome[END_REF], Edward et al. 2010). Fire played an important role in promoting the spread of grasslands and savannas at that time, accelerating forest loss (by slowing the recovery rates of tree species following destruction by fire), and generating positive feedback loops which promoted drought and more fire [START_REF] Bond | The importance of low atmospheric CO2 and fire in promoting the spread of grasslands and savannas[END_REF][START_REF] Beerling | The origin of the savanna biome[END_REF].

Neotropical vegetation was structured by four major events [START_REF] Burnham | The History of Neotropical Vegetation : New Developments and Status[END_REF][START_REF] Safford | Brazilian Paramos I . An introduction to the physical environment and vegetation of the campos de altitude[END_REF][START_REF] Fiaschi | Review of plant biogeographic studies in Brazil[END_REF]): (1) isolation (break-up of West Gondwana and separation of South America from Africa), (2) the uplift of the Andes and changing drainage systems, (3) the closure of the Isthmus of Panama, and (4) quaternary climate fluctuations. [START_REF] Vuilleumier | Pleistocene changes in the fauna and flora of South America[END_REF] highlights the evidence for climatic events that occurred during the last million or so years and have affected the biota of South America. The last glacial period was wetter than the Holocene epoch (90 000 to 21 000 Years Before Present) [START_REF] Van Der Hammen | The pleistocene changes of vegetation and climate in tropical South America[END_REF]. However, during the Last Glacial Maximum (LGM) (20,000 to 18,000 YBP, late Pleistocene) there was a decrease in precipitation and a very dry period (drier than the Holocene), associated with lower temperatures and lower atmospheric humidity (due to the slight recession of glaciers) [START_REF] Van Der Hammen | The pleistocene changes of vegetation and climate in tropical South America[END_REF][START_REF] Ledru | Late Quaternary History and Evolution of the Cerrados as Revealed by Palynological Records[END_REF]. Werneck et al. (2012) demonstrates that the LGM and LIG (Last Interglacial, 120 000 YBP) were the periods of narrowest and widest Cerrado distributions, respectively. During the LMG, climatic conditions did not allow for the development of the Cerrado [START_REF] Ledru | Late Quaternary History and Evolution of the Cerrados as Revealed by Palynological Records[END_REF], Werneck 2012). The late Pleistocene was marked by the extinction of the South American megafauna, and the mid-Holocene, by the loss of other large-mammal lineages due to the reduction of open formations in South America (De Vivo & Carmignotto 2004). The increase in seasonality beginning ca. 7 000 YBP was necessary for Cerrado vegetation to grow on the Central Plateau and to eventually result in the physiognomy of the Cerrado we know today [START_REF] Ledru | Late Quaternary History and Evolution of the Cerrados as Revealed by Palynological Records[END_REF][START_REF] Ledru | Millenial-scale climatic and vegetation changes in a northern Cerrado (Northeast, Brazil) since the Last Glacial Maximum[END_REF].

Cerrado lineages began to diversify less than 10 Million years (MY) ago, with most lineages diversifying 4 MY ago or more recently, coinciding with the expansion of the savanna biome worldwide [START_REF] Grether | Recent assembly of the Cerrado, a neotropical plant diversity hotspot, by in situ evolution of adaptations to fire[END_REF]: the near-synchronous expansion of C4 grasses around the world dating back to 8 MY ago marked the origin of the modern savanna biome (late Miocene) [START_REF] Beerling | The origin of the savanna biome[END_REF], Edward et al. 2010[START_REF] Grether | Recent assembly of the Cerrado, a neotropical plant diversity hotspot, by in situ evolution of adaptations to fire[END_REF] also show that the Cerrado formed in situ via recent and frequent adaptive shifts to resist fire, rather than via the dispersal of lineages already adapted to fire.

Campos rupestres

5.3.1.Definition

Campos rupestres, one physiognomy of the Cerrado, are a mosaic of grasslands found at altitudes of between 800m and 2000m and covering around 130 000 km 2 of total area (according to potential distribution models Barbosa 2012) (Figure 11). They are especially found along the Espinhaço Range, although some isolated campos rupestres occur also in the state of Goiás [START_REF] Romero | Diversidade da flora dos campos rupestres de Goiás, sudoeste e sul de Minas Gerais, in: Biodiversidade, conservação e uso sustentável da flora do Brasil[END_REF]. They have been defined as a more or less continuous herbaceous stratum with sclerophyllous evergreen shrubs and subshrubs growing between rocky outcrops (Giulietti et al. 1997). [START_REF] Eiten | Delimitation of the Cerrado concept[END_REF] notes that "whereas cerrado woody plants cannot grow on bare rock (except where it can find a deep crack), campo rupestre woody plants, may form groves of open or even closed scrub over outcropping hard bedrock, so that not all this upland vegetation is really 'campo'" (i.e., grassland). Barbosa (2012) has shown that they are stable ecosystems and points out that there was no significant expansion of campos rupestres during the middle Holocene and during the last glacial maximum, probably due to the strong edaphic specificity of this ecosystem.

5.3.2.Espinhaço range

Excluding the Andean vegetation, there are three main highland vegetation formations in South America: Tepuis on the Guayana shield, campos de altitudes (i.e. Brazilian páramos) in southeast Brazil, and campos rupestres, principally along the Espinhaço Range in eastern Brazil but also in the state of Goias. Although they have strong physiognomy similarities, each of the three is characterized by a unique flora comprising a large number of endemic and vicarious species [START_REF] Maguire | On the Flora of the Guayana Highland[END_REF], Giulietti et al. 1997[START_REF] Safford | Brazilian Paramos I . An introduction to the physical environment and vegetation of the campos de altitude[END_REF][START_REF] Alves | Can campo rupestre vegetation be floristically delimited based on vascular plant genera?[END_REF]. As previously discussed, Cerrado woody lineages span from the late Miocene to the Pliocene (during the tertiary) [START_REF] Grether | Recent assembly of the Cerrado, a neotropical plant diversity hotspot, by in situ evolution of adaptations to fire[END_REF]), but the floristic composition of these mountain formations were also impacted by the quaternary climatic and vegetation fluctuations (Vuilleumier 1970[START_REF] Van Der Hammen | The pleistocene changes of vegetation and climate in tropical South America[END_REF][START_REF] Fiaschi | Review of plant biogeographic studies in Brazil[END_REF], Werneck et al 2012).

The Espinhaço range or Serra do Espinhaço in portuguese ("Backbone Range"), is one of the most important biogeographic regions in Brazil, located in the states of Minas Gerais and Bahia (eastern Brazil). The Espinhaço range corresponds to the watershed between the Atlantic Ocean and the São Francisco River Basin (Derby 1906). The Espinhaço range is oriented north-south and covers an area about 1,000km long by 50 to 100km kilometers wide, with a mean elevation of over 1,000m and occasional peaks reaching 1,800-2,100 m. It is divided in various massifs, such as the Serra da Piedade, Serra do Caraça, Serra do Cipó (in which the present studies were carried out), Diamantina plateau, Serra do Cabral, Serra do Grão-Mogol, Chapada Diamantina (Pico das Almas, Mucugê), Morro do Chapéu, Serra da Jacobina (Giulietti et al. 1997) (Figure 12).

Although the mean elevation is only 1,000m, the local relief has rugged topographic features. Schistose rocks make up the predominant formations, and these consist in particular of precambrian quartzites, sandstones subject to metamorphism, and ferruginous schists (Derby 1906). The present form of the range is the result of a combination of long erosive processes and more recent tectonic (tertiary) processes [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF]). The soils are in general shallow and sandy, highly acidic, and extremely nutrient poor as a result of the aforementioned erosion processes (Giulietti et al. 1997, Benites et al. 2007)

5.3.3.Characteristics of the campos rupestres

The presence of quartzitic rocky outcrops is a fundamental property of campos rupestres as well as the associated coarse texture and shallow sandy soil, with high Al 3+ and low nutrient contents [START_REF] Benites | Solos e vegetação nos complexos rupestres de altitude da Mantiqueira e do Espinhaço[END_REF](Benites et al. , 2007)). In contrast to the Cerrado, campos rupestres are almost all well-drained dry grasslands (with the notable exception of the peat bog physiognomy) [START_REF] Eiten | Delimitation of the Cerrado concept[END_REF]. The local drainage systems, together with the heterogeneity of the topography, create humid and arid sites that are often separated from each other by just a few centimeters [START_REF] Vitta | Composição florística e ecologia de comunidades campestres na Serra do Cipó, Minas Gerais[END_REF][START_REF] Alves | Can campo rupestre vegetation be floristically delimited based on vascular plant genera?[END_REF]. Campos rupestres are subjected to stressful climatic conditions, such as high daily temperature oscillations, intense irradiation (UV), strong winds, and a marked dry season. [START_REF] Alves | Angiosperm disjunction " Campos rupestresrestingas ": a re-evaluation[END_REF] defined campos rupestres as "a species-rich, extrazonal vegetation complex bound to Precambrian quartzite outcrops which emerge as a mosaic surrounded mainly by cerrado and caatinga". They are composed of many distinct plant communities [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF], Meguro et al. 1994[START_REF] Queiroz | Flora vascular da Serra da Jiboia, Santa Terezinha-Bahia. I: O campo rupestre[END_REF][START_REF] Conceição | Delimitação de habitats em campos rupestres na Chapada Diamantina, Bahia: substratos, composição floristica e aspectos estruturais[END_REF], Conceição et al. 2007c) and this makes it difficult to define campos rupestres as a floristic unit [START_REF] Alves | Can campo rupestre vegetation be floristically delimited based on vascular plant genera?[END_REF], a problem rendered even more difficult by the high level of endemism [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF], 1997[START_REF] Alves | Plant species endemism in savanna vegetation on table mountains (Campo Rupestre) in Brazil[END_REF][START_REF] Pereira | Estrutura das comunidades vegetais de afloramentos rochosos dos campos rupestres do Parque Nacional da Serra do Cipó, MG. Dissertação de Mestrado[END_REF], Pirani et al. 1994[START_REF] Harley | Introduction[END_REF][START_REF] Vitta | Composição florística e ecologia de comunidades campestres na Serra do Cipó, Minas Gerais[END_REF], Rizzini 1997, Conceição & Pirani 2007). Just as in the Tepuis formation (Venezuela), the campos rupestres is a General introduction 29 center of diversity for Xyridaceae and Eriocaulaceae. Distant campos rupestres can share many similar families and genera that confer a certain unicity on the ecosystem.

Examples include Eriocaulaceae (Leiothrix, Paepalanthus, Syngonanthus), Velloziaceae (Vellozia, Barbacenia), Xyridaceae (Xyris), Melastomataceae (Cambessedesia, Marcetia) Asteracae (Lychnophora) or Lythraceae (Cuphea, Diplusodon), and so on (Giulietti et al. 1997). Because of the high level of endemism, the combination of species is not equipped to circumscribe campos rupestres [START_REF] Alves | Can campo rupestre vegetation be floristically delimited based on vascular plant genera?[END_REF]. The combination of the topography, the nature of the substrate and, the peculiar climatic conditions are generally identified as the reason for the speciation and adaptation phenomena that have brought about an extraordinary biodiversity. Campos rupestres support more than 4,000 plant species (Giulietti et al. 1997) and 1,590 plant species in the Serra do Cipó [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF] with one of the highest level of endemism in Brazil as previously noted.

Botanical collection in campos rupestres began in the 19 th century (Saint-Hilaire 1833), but it was only the later decades that saw growing interest in understanding the structure and functioning of campo rupestre communities. We have identified, within the present bibliography, some floristic survey studies dealing with granitic, quartzic, or ironstone outcrops [START_REF] Pereira | Estrutura das comunidades vegetais de afloramentos rochosos dos campos rupestres do Parque Nacional da Serra do Cipó, MG. Dissertação de Mestrado[END_REF][START_REF] Vincent | Florística, fitossociologia e relações entre a vegetação e o solo em área de campos ferruginosos no Quadrilátero Ferrífero, Minas Gerais. Tese de doutorado[END_REF], Conceição et al. 2007c, Jacobi et al. 2007, Ribeiro et al. 2007[START_REF] Scarano | Rock outcrop vegetation in Brazil: a brief overview[END_REF], campos rupestres located in Bahia [START_REF] Queiroz | Flora vascular da Serra da Jiboia, Santa Terezinha-Bahia. I: O campo rupestre[END_REF][START_REF] Conceição | Delimitação de habitats em campos rupestres na Chapada Diamantina, Bahia: substratos, composição floristica e aspectos estruturais[END_REF], 2007, Conceição et al. 2007a, b, c), campos rupestres associated with an iron substrate (i.e. canga) [START_REF] Vincent | Florística, fitossociologia e relações entre a vegetação e o solo em área de campos ferruginosos no Quadrilátero Ferrífero, Minas Gerais. Tese de doutorado[END_REF][START_REF] Viana | Floristica e caracterização dos campos rupestres sobre canga na Serra da Calçada, Minas Gerais, Brasil[END_REF][START_REF] Mourão | Levantamento da flora do campo rupestre sobre canga hematica couraçada remanescente na mina do Brucutu, barão de cocais, Minas Gerais, Brasil[END_REF][START_REF] Messias | Fitossociologia de campos rupestres quartzíticos e ferruginosos no Quadrilátero Ferrífero , Minas Gerais Introdução Material e métodos[END_REF], and campos de altitude (Caifa & Silva 2005, Ribeiro et al. 2007).

Most of these studies deal with the shrubby physiognomy occurring on rocky outcrops while very few studies address physiognomies dominated by grasses, and these represent the matrix, and therefore the quintessence, of campos rupestres [START_REF] Conceição | Delimitação de habitats em campos rupestres na Chapada Diamantina, Bahia: substratos, composição floristica e aspectos estruturais[END_REF][START_REF] Viana | Floristica e caracterização dos campos rupestres sobre canga na Serra da Calçada, Minas Gerais, Brasil[END_REF][START_REF] Borges | Altitudinal distribution and species richness of herbaceous plants in campo rupestres of the Southern Espinhaço range, Minas Gerais, Brazil[END_REF][START_REF] Messias | Fitossociologia de campos rupestres quartzíticos e ferruginosos no Quadrilátero Ferrífero , Minas Gerais Introdução Material e métodos[END_REF].

We have thus a knowledge gap concerning the composition and structure of the herbaceous components of campos rupestres. The direct consequence of this is that it is currently quite difficult to set up tailored conservation and restoration efforts, because the reference ecosystem is poorly understood.

5.3.4.What about the terminology?

Considering the heterogeneity and richness of ecosystems within campos rupestres, it is sometimes difficult to limit them to a single name. Walter (2006) reviews the richness of the nomenclature and concepts relative to the phyto-physionomy of the Cerrado biome, reflecting the difficulty in clearly defining the different vegetation formations of the Cerrado domain (see the section 5.2.Cerrado for more details). [START_REF] Magalhães | Sobre os cerrados de Minas Gerais[END_REF] considers all vegetation formations in the state of Minas Gerais as related to the Cerrado and was the first to use the term "campo rupestre" (from Latin "rupestris" meaning ''rocky'', campos rupestres means rupestrian grasslands) to define the main vegetation formation occurring on the mountaintops along the Espinhaço range. Without defining the campos rupestres, he highlights characteristic plant families, such as Melastomataceae, Eriocaulaceae, Velloziaceae and Xyridaceae and the occurrence of some endemic species. Various definitions and terminology have been successively proposed [START_REF] Vasconcelos | O que são campos rupestres e campos de altitude nos topos de montanha do Leste do Brasil?[END_REF], first by [START_REF] Eiten | Delimitation of the Cerrado concept[END_REF] who notes that campos rupestres constitute a complex. [START_REF] Rizzini | Tratado de fitogeografia do Brasil: aspectos ecológicos, sociológicos e florísticos[END_REF], improves upon the definition and proposes subdividing the category into quartzite grasslands (campos quartzicos) occurring on quartzite rocks along the Espinhaço range, and altitude grasslands (campos de altitude) occurring on diverse crystalline rocks located in the Serra do Mar and Serra da Mantiqueira. This distinction is maintained by [START_REF] Semir | Revisão taxonômica de Lychnophora Mart. (Vernoniaceae:Compositae). Dissertação (Doutorado em Biologia Vegetal)-UNICAMP[END_REF] who reintroduced the term "complex" and proposes the name quartzic rupestrian complexes (complexos rupestres de quartzito) to refer to the vegetation of Espinhaço range and granitic rupestrian complexes (complexos rupestres de granito) to refer to the vegetation of Mantiqueira range. [START_REF] Harley | Florula of Mucugê, Chapada Diamantina -Bahia, Brazil[END_REF] restrict the use of "campo rupestre" to the vegetation that grows on quartzite-sandstone substrates. [START_REF] Benites | Solos e vegetação nos complexos rupestres de altitude da Mantiqueira e do Espinhaço[END_REF] prefer the terms quartzite altitude rupestrian complexes and granitic altitude rupestrian complexes. While vegetation formations of campos de altitude and campos rupestres are structurally similar, their respective floristic compositions differ, and this has led to the apparent nomenclature dichotomy [START_REF] Vasconcelos | O que são campos rupestres e campos de altitude nos topos de montanha do Leste do Brasil?[END_REF]. Campos rupestres is also used to designate the vegetation formations of the Espinhaço range found on ferruginous substrates (i.e., locally called "canga", e.g., [START_REF] Viana | Floristica e caracterização dos campos rupestres sobre canga na Serra da Calçada, Minas Gerais, Brasil[END_REF].

Moreover several English translations of campo rupestre have also been proposed, such as "rocky grassland" (Oliveira-Filho & Ratter 2002[START_REF] Alves | Angiosperm disjunction " Campos rupestresrestingas ": a re-evaluation[END_REF] or "rupestrian field," [START_REF] Marques | Distribution of adult male and female Baccharis concinna (Asteraceae) in the rupestrian fields of Serra do Cipó, Brasil[END_REF][START_REF] Carvalho | The mosaic of habitats in the high-altitude Brazilian rupestrian fields is a hotspot for arbuscular mycorrhizal fungi[END_REF]) and this further exacerbates the confusion, particularly because campo in Portuguese means both field and grassland, while pristine campos rupestres were never cultivated. More and more often, the term campo rupestre is used [START_REF] Conceição | Delimitação de habitats em campos rupestres na Chapada Diamantina, Bahia: substratos, composição floristica e aspectos estruturais[END_REF], Conceição et al. 2007b[START_REF] Rapini | A flora dos campos rupestres da Cadeia do Espinhaço[END_REF], even in papers written in English [START_REF] Alves | Angiosperm disjunction " Campos rupestresrestingas ": a re-evaluation[END_REF], Conceição et al. 2007a,c, Alves & Kolbek 2010), indicating the adequacy of this terminology. 5.3.5.Are campos rupestres included in the Cerrado?

A major source of debate is the question of whether or not the campos rupestres are part of the Cerrado domain. [START_REF] Martius | Flora Brasiliensis[END_REF][START_REF] Martius | Flora Brasiliensis[END_REF] initially includes campos rupestres in his oreadic formations4 , which later serves as the inspiration for [START_REF] Coutinho | O conceito de cerrado[END_REF] "forestecotone-grassland" concept. Several authors agree with this and many of them currently treat campos rupestres as a physiognomy of the Cerrado, occurring at altitude and included in grassland formations such as the campo limpo [START_REF] Silva | Biogeographic Patterns and Conservation in the South American Cerrado: A Tropical Savanna Hotspot[END_REF], Walter 2006). However, Campos rupestres, though usually associated with the Cerrado, also occur within the Caatinga biome in the northern portion of the Espinhaço range. [START_REF] Eiten | Delimitation of the Cerrado concept[END_REF] considers campos rupestres and Cerrado as "essentially different vegetations", describing campos rupestres as a complex of well-drained dry grasslands, in stark contrast to the Cerrado. Similarly, in their listing of the physionomic forms of the Cerrado, [START_REF] Ribeiro | Fitofisionomias do bioma Cerrado[END_REF] use Magalhães' earlier work (1966) and define campos rupestres as a vegetation formation in its own right.

Although there is a high level of endemism in campos rupestres, they share some similarities with the grassland formation of the Cerrado, and some species occurring on campos rupestres are also found in the Cerrado [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF]. Therefore, according to a part of the literature [START_REF] Silva | Biogeographic Patterns and Conservation in the South American Cerrado: A Tropical Savanna Hotspot[END_REF], Walter 2006[START_REF] Alves | Can campo rupestre vegetation be floristically delimited based on vascular plant genera?[END_REF], in this study, campos rupestres were included in the Cerrado (Figure 11).

Current Threats on Mountains ecosystems: focus on the campos rupestres

In 2002, the Parties of the Convention on Biological Diversity (CBD) adopted a work program on mountain biological diversity (1) in order to reduce the loss of global and regional mountain biodiversity and (2) to help foster increased knowledge of ecosystem functioning and community composition, because, as it is often the case in tropical regions, there is insufficient understanding of critical processes [START_REF] Escudero | Community patterns on exposed cliffs in a Mediterranean calcareous mountain[END_REF][START_REF] Romdal | An indirect area effect on elevational species richness patterns[END_REF], and this presents a serious barrier to implementing effective conservation or restoration programs. Indeed, the CBD has recognized the fragility of mountain ecosystems and species, as well as their vulnerability to man-made and natural disturbances, particularly in the current context of land-use and climate changes (CBD 2012). Mountain ecosystems are hot spots of biodiversity with many endemic species (Giulietti et al. 1997[START_REF] Price | Mountains: globally important ecosystems[END_REF][START_REF] Chaverri-Polini | Mountains, biodiversity and conservation[END_REF][START_REF] Porembski | Granitic and gneissic outcrops (inselbergs) as centers of diversity for desiccation-tolerant vascular plants[END_REF], Barthlott et al. 2005, 2007, Kier et al. 2005[START_REF] Martinelli | Mountain biodiversity in Brazil[END_REF]), most of which play an essential role in ensuring the regional and global diversity [START_REF] Burke | Inselbergs in a changing worldglobal trends[END_REF]. One of the great intrinsic values of mountains lies in their being the source of many of the world's rivers (FAO 1998). Mountain degradation has thus become a worldwide concern because of the consequences it has in terms of ecosystem service losses (FAO 1998), including degradation of water-quality, increasing soil erosion, and biodiversity loss.

There is current evidence of adverse human impact on mountains worldwide [START_REF] Burke | Inselbergs in a changing worldglobal trends[END_REF], and Brazil is no exception [START_REF] Jacobi | Plant communities on ironstone outcrops: a diverse and endangered Brazilian ecosystem[END_REF][START_REF] Ribeiro | Impactos potenciais das alterações no Código Florestal sobre a vegetação de campos rupestres e campos de altitude[END_REF]. Pending changes in Brazilian environmental legislation (Law n°12.651, May 25 th 2012) will further complicate the conservation of mountain ecosystems because it eliminates hilltops as environments that can be considered Permanent Preservation Areas (PPA) (Ribeiro andFreitas 2010, Codigo florestal 2012). Mountain ecosystems are also known to be poorly resilient to disturbances and therefore require restoration once they have been degraded [START_REF] Urbanska | High-elevation ecosystem, in: Handbook of ecological restoration: principles of restoration[END_REF]. Though well-adapted to constrained environmental conditions, such as shallow and nutrient-poor soils and endogenous disturbances (sensu White & Jentsch 2001) such as fire, campos rupestres seem highly sensitive to land conversions, mainly because of their precise adaptation to their original environments [START_REF] Ribeiro | Impactos potenciais das alterações no Código Florestal sobre a vegetação de campos rupestres e campos de altitude[END_REF].

General introduction 34 One of the most important defining characteristics of the Espinhaço Range is the presence of gold, diamonds, and iron, which are responsible for the bulk of human activity in the region since the 18 th century. Over the course of many decades, the mining industry presented the main threat to campos rupestres, and today, abandoned mine areas remain bare without vegetation regeneration. Poorly planned road construction is also leading to soil erosion and biological invasions [START_REF] Barbosa | Distribution of non-native invasive species and soil properties in proximity to paved roads and unpaved roads in a quartzitic mountainous grassland of southeastern Brazil (rupestrian fields)[END_REF].

Campos rupestres were subjected to decades-long impacts by cattle breeding, usually associated with annual burnings intended to stimulate the regrowth of the vegetation; these activities are still a major occurrence in this region. Even if vegetation is adapted to fire, frequent fires often end up favoring some species over others. On another hand, the shallow and poor nutrient soils limit crop cultivation on campos rupestres contrary to the other grassland formations of the Cerrado. Some activities, such as wood extraction, eucalyptus plantation, and collection of plants with ornamental value (Orchids, Bromeliads, Eriocaulaceae) also occur, and, though currently sporadic, have already led to the diminution of some species populations (Giulietti et al. 1997). Nowadays, increasing uncontrolled tourism and human settlement also threaten campos rupestres [START_REF] Giulietti | Campo Rupestre, in: Lista vermelha das espécies ameaçadas de extinção de Minas Gerais[END_REF], Plano de manejo PARNA Serra do Cipó 2009). Between the 16 th century and the 1960s, [START_REF] Magnanini | Aspectos fitogeográficos do Brasil, Áreas e Características no Passado e no Presente[END_REF] estimates that natural campos rupestres of Minas Gerais and Bahia were reduced by 80%.

6.Study areas: Serra do Cipó campos rupestres

Geographic situation

Our study area is located in the southern portion of the Espinhaço Range (Brazil) (Figure 12), in the Environmental Protected Area (Area de Proteção Ambiental in Portuguese) Morro da Pedreira, in the buffer zone of the Serra do Cipó National Park (state of Minas Gerais). The creation of the Serra do Cipó National Park and the Environmental Protected Area of Morro da Pedreira (Área de Proteção Ambiental) in 1984 has helped to preserve natural areas of campos rupestres which are the main vegetation formation on shallow soils in the Serra do Cipó region (Figure 14), usually mixed with Cerrado, General introduction 35 Atlantic rain forest, riparian forests and small groves on deeper soils, totaling more than 16005 plant species [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF].

Climate

The regional climate is classified as Cwb with a warm temperature, a dry winter and a warm summer, according to the Köppen system [START_REF] Köppen | Versuch einer Klassifikation der Klimate, vorzugsweise nach ihren Beziehungen zur Pflanzenwelt[END_REF]. It is markedly seasonal, with two distinguishable seasons: a rainy season from November to April and a dry season from May to October. The mean annual precipitation is 1622 mm and the mean annual temperature is 21.2°C (Madeira and Fernandes 1999).

Study sites

Based on the topography, we designated and studied two main grassland-types of campos rupestres. We selected 10 grasslands: 5 sites with sandy substrates located on flat areas (Sa) and 5 sites with stony substrate on slopes (St) (Table 1, Figure 13, Figure 14). The sites are at altitudes between 1100m and 1300m. Degraded areas found along the road were exploited for gravel and/or were used to park machines. When the road was complete, the degraded areas left behind represented several kinds of substrate.

Small quarries are common in the region and their creation leas to vegetation being destroyed and soils being disturbed. Even when exploitation stops, soils are not entirely restituted, and they may be heavily contaminated by construction debris. These degraded areas are surrounded by pristine campos rupestres.

We thus also chose 9 degraded areas on 3 kinds of substrate (Figure 15): 1) degraded latossol substrate (DF), 2) degraded sandy substrate (DSa) and 3) degraded stony substrate (DSt) (Figure 16). Campos rupestres are peculiar species-rich tropical grasslands, but not enough is known about them at present for them to be efficiently restored. The following chapters are aimed at increasing knowledge about the functioning these grasslands and will address three restoration methods.

Chapter 1 will deal with the composition and structure of the two main herbaceous communities in order to define more clearly the reference ecosystem.

We will also analyze the reproductive phenological patters of both communities in Chapter 2. Resilience to, and the impact of, strong disturbances will be discussed in Chapter 3, together with some discussion of the potential for hay transfer to play a role in restoring these grasslands.

Germination behavior of some herbaceous species will be addressed in Chapter 4.

Finally, in Chapter 5 species and turf transplantation will be assessed as methods of introducing native species in degraded campos rupestres. A final consideration of the main ideas and a conclusion will provide the closing material for this thesis.

and commonly defined as a mosaic of grasslands and rocky outcrops. From a conservation standpoint we may ask: 1) Are the grasslands homogeneous or are they composed of distinct plant communities? 2) Can soil characteristics explain plant community patterns? We have selected 10 grasslands: 5 on stony substrates and 5 on sandy substrates on which we have carried out vegetation surveys and soil analyses. Species were classified according to their life-form, plant form, habitats in Brazil, distribution range, IUCN status, and life-cycle. Soil samples were collected during the rainy and dry seasons and chemical and granulometric analyses were performed. The results show that five grassland soils were richer in nutrients and have a coarser structure (stony substrate). Both soil-types are strongly acidic, present low fertility, and exhibit the following seasonal variation: phosphorus increases and pH and organic carbon decrease during the dry season. During the vegetation survey 222 species were found among which 12.6% are endemic to the Serra do Cipó region and several others are exclusively found on campos rupestres (38.6%). Our study brings to light the lack of information on numerous species (e.g. 21.9% of the species have an unknown distribution), underlying the need for research into their biology, distribution and ecology. There is also a clear relationship between soil and vegetation composition. The two grassland types have to be considered as two different species-rich plant communities. These differences are closely related to differences in soil granulometry and composition, which leads to significant plant community heterogeneity. Some species are confined to either one or the other grassland type, which confers a real singularity in plant composition to each community, for example Richterago polymorpha, Lagenocarpus velutinus and Xyris insignis were only found in sandy grasslands, and Spigelia aceifolia and Trimezia fistulosa in stony grasslands. No exotic species were found. Because they are seriously threatened due to land-use changes and because of their great biodiversity, campos rupestres must have their conservation made a priority, and this must take into account the two communities and the close relationship between their respective vegetation and soils.

Introduction

The recognition, precise description, and understanding of plant communities are fundamental to environmental management, conservation programs, biodiversity surveys, and restoration projects [START_REF] Soulé | Research Priorities for Conservation Biology[END_REF]Kohm 1989, Alves and[START_REF] Alves | Can campo rupestre vegetation be floristically delimited based on vascular plant genera?[END_REF].

Focusing on plant communities can help reconcile the species approach with the ecosystem approach to conservation because they are basic components of the landscape and have consequences for species survival and for ecosystem processes [START_REF] Heywood | Plant conservation: old problems, new perspectives[END_REF]. For instance, the implementation of the conservative network NATURA 2000 in Europe is driven by bird and habitat directives, which are based on lists of habitats and species that are recognized as being of interest (European Commission 2000). These habitats are described by their environmental characteristics and their plant communities (European Commission 2007).

In 2002, the Parties of the Convention on Biological Diversity (CBD) adopted a work program on mountain biological diversity due to the lack of knowledge of ecosystem functioning and community composition (as is often the case in tropical regions) which is a common barrier to implementing conservation or restoration activities. Indeed, they recognized the fragility of mountain ecosystems and species and their vulnerability to man-made and natural disturbances, particularly in the current context of land-use and climate changes. Mountain ecosystem conservation is essential for many reasons: such ecosystems host a great biodiversity, they act as refuges for species, they are important for water resources, and their proper function insures good water quality as they participate in soil erosion control (FAO 1998). Excluding the Andean vegetation, there are three main highland vegetation formations in South America: Tepuis on the Guayana shield, and campos de altitudes (i.e. Brazilian páramos) and campos rupestres, both in Brazil. These formations show strong physiognomy similarities; however each is characterized by a unique flora [START_REF] Maguire | On the Flora of the Guayana Highland[END_REF], Giulietti et al. 1997[START_REF] Safford | Brazilian Paramos I . An introduction to the physical environment and vegetation of the campos de altitude[END_REF]) mainly resulting from Pleistocene climatic variations (Vuilleumier 1970[START_REF] Van Der Hammen | The pleistocene changes of vegetation and climate in tropical South America[END_REF][START_REF] Fiaschi | Review of plant biogeographic studies in Brazil[END_REF].

Campos rupestres are included in the Cerrado domain (Brazilian savanna, covering 22% of the country), encompassing around 130 000 km 2 (6% of the Cerrado) (Barbosa 2012) and are usually found on precambrian quartzite formations above 900 meters of altitude, primarily along the Espinhaço range, the largest mountain range in Brazil. They have been stable grassland ecosystems for about 20,000 years (Barbosa 2012). Campos rupestres are defined as a more-or-less continuous herbaceous stratum with small sclerophyllous evergreen shrubs growing between rocky quartzic outcrops forming a rich mosaic of plant communities (Giulietti et al. 1997, Medina and Fernandes 2007[START_REF] Carvalho | The mosaic of habitats in the high-altitude Brazilian rupestrian fields is a hotspot for arbuscular mycorrhizal fungi[END_REF]). Several physiognomies have been observed, ranging from a physiognomy found on rocky outcrops with trees and shrubs to physiognomies dominated by grasses, such as grasslands or peat bogs (Alves andKolbek 2010, Carvalho et al. 2012) ( Benites et al. 2007). Such soils are shallow, acidic and coarsely textured, with high aluminum and low nutrient content [START_REF] Benites | Solos e vegetação nos complexos rupestres de altitude da Mantiqueira e do Espinhaço[END_REF](Benites et al. , 2007)). Podzolization, consisting of the eluviation of aluminum and iron, associated with organic compounds from surface areas that accumulate in depth, leads to residual quartz concentration in the form of sand particles in the upper horizons (Benites et al. 2007), and is an important process that occurs in these high-altitude ecosystems. On the other hand, the local topography (e.g. quartzic rocky outcrops, stony slopes, or sandy flat areas) dictates local drainage and water availability. Although substrate and topography are commonly cited as factors contributing to the differentiation of plant physiognomies leading to high heterogeneity and rich biodiversity, few studies deal with the relationship between soil composition and vegetation.

Campos rupestres are constrained ecosystems, subjected to stressful climatic conditions with large daily temperature oscillations, intense irradiation (UV), strong winds, and a marked dry season (Giulietti et al. 1997). Despite these harsh conditions, such grasslands are important centers of biodiversity [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF], 2005[START_REF] Lara | The highest diversity of galling insects: Serra do Cipó, Brazil[END_REF], FAO 1998[START_REF] Carvalho | The mosaic of habitats in the high-altitude Brazilian rupestrian fields is a hotspot for arbuscular mycorrhizal fungi[END_REF]) due to adaptation processes and speciation [START_REF] Giulietti | Biodiversity and Conservation of Plants in Brazil[END_REF]). In the Espinhaço Range alone, more than 4,000 plant species have been reported; these comprise one of the highest levels of endemism in the Cerrado biome [START_REF] Alves | Plant species endemism in savanna vegetation on table mountains (Campo Rupestre) in Brazil[END_REF], Giulietti et al. 1997[START_REF] Silva | Biogeographic Patterns and Conservation in the South American Cerrado: A Tropical Savanna Hotspot[END_REF]Echternacht et al. 2011).

Human disturbances of campos rupestres began in the 18 th century, and were mainly associated with mining activities (i.e. gold, precious stones, iron, manganese) in the region. Disturbances also resulted from annual anthropogenic burnings (to support cattle breeding), wood extraction, eucalyptus cultivation, harvesting of ornamental plants (orchids, bromeliads, Eriocaulaceae) (Giulietti et al. 1997), and road construction [START_REF] Barbosa | Distribution of non-native invasive species and soil properties in proximity to paved roads and unpaved roads in a quartzitic mountainous grassland of southeastern Brazil (rupestrian fields)[END_REF]. Recent changes in Brazilian environmental legislation have weakened the already modest conservation requirements for the region, thereby increasing the threat to campo rupestre biodiversity and the ecosystem services that they provide. While threats increase, limited or inadequate data on conservation targets, such as plant communities (Henwood and Iriondo 2003), can prejudicially affect the conservation of the campos rupestres.

The huge biodiversity of the campos rupestres is commonly associated with the wide variety of habitats generated by the combination of microclimate, topography, and substrates. However, little is known about the relationship between biodiversity and habitats, and about the composition and structure of campo rupestre communities.

Botanical collection in campos rupestres began in the 19th century (Saint-Hilaire 1833), but only during later decades was there a growing interest in understanding the structure and functioning of campo rupestre communities [START_REF] Meguro | Phytophysiognomy and composition of the vegetation of Serra do Ambrósio, Minas Gerais, Brazil[END_REF][START_REF] Queiroz | Flora vascular da Serra da Jiboia, Santa Terezinha-Bahia. I: O campo rupestre[END_REF][START_REF] Conceição | Delimitação de habitats em campos rupestres na Chapada Diamantina, Bahia: substratos, composição floristica e aspectos estruturais[END_REF], 2007, Conceição et al. 2007a,b,c, Jacobi et al. 2007[START_REF] Scarano | Rock outcrop vegetation in Brazil: a brief overview[END_REF][START_REF] Viana | Floristica e caracterização dos campos rupestres sobre canga na Serra da Calçada, Minas Gerais, Brasil[END_REF][START_REF] Borges | Altitudinal distribution and species richness of herbaceous plants in campo rupestres of the Southern Espinhaço range, Minas Gerais, Brazil[END_REF]).

The problem is that most of these studies dealt with the shrubby physiognomy occurring on rocky outcrops while very few studies addressed physiognomies dominated by grasses, which represent the matrix and thus the quintessence of campos rupestres [START_REF] Conceição | Delimitação de habitats em campos rupestres na Chapada Diamantina, Bahia: substratos, composição floristica e aspectos estruturais[END_REF][START_REF] Viana | Floristica e caracterização dos campos rupestres sobre canga na Serra da Calçada, Minas Gerais, Brasil[END_REF][START_REF] Borges | Altitudinal distribution and species richness of herbaceous plants in campo rupestres of the Southern Espinhaço range, Minas Gerais, Brazil[END_REF]) and offer valuable ecosystem services such as maintaining water-quality and controlling soil erosion. Furthermore, this grassland is defined as a more-or-less continuous herbaceous layer (Figure 14) (see campos rupestres definition in Giulietti et al. 1997). However, local topography with stony slopes (Figure 14) and sandy flatter areas (Figure 14) potentially generate different environmental conditions, and probably lead to distinct plant communities, which were never studied as such.

For the first time, we address the floristic and ecological aspects of these Neotropical mountain grasslands to obtain solid information on which to base conservation strategies. Our objectives were to find out 1) whether soil properties (granulometry and chemical composition) are different between grasslands and 2) whether the grasslands have homogeneous vegetation. We hypothesized that soil composition varies at small scale, leading to plant composition heterogeneity, and that this generates distinct plant communities. We therefore presupposed that soil granulometry and composition differ with topography thus influencing plant composition. We considered the complexity of these ecosystems, which confers on them a high conservation value, and how it can have important consequences in the context of landscape fragmentation and its relevance to future conservation programs.

Material and Methods

Study area and sites

Our study area was located in Brazil in the southern portion of the Espinhaço Range, in the buffer zone of the Serra do Cipó National Park (state of Minas Gerais).

Campos rupestres are the main vegetation formation on shallow soils in the Serra do Cipó region, usually mixed with savannas, riparian forests and small groves on deeper soils, totalling more than 1600 plant species [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF]. Over recent decades, the region has gone through some land conversion (e.g. pasture associated with introduction of invasive species and annual burning) and anthropological pressure due to tourism activities along a major road, the highway MG 010. On the other hand, the creation of the Serra do Cipó National Park and the Environmental Protection Area of Morro da Pedreira (Área de Proteção Ambiental) in 1984 has helped to preserve pristine areas of campos rupestres. The regional climate is classified as Cwb with a warm temperature, a dry winter and a warm summer, according to the Köppen's system [START_REF] Köppen | Versuch einer Klassifikation der Klimate, vorzugsweise nach ihren Beziehungen zur Pflanzenwelt[END_REF]. It is markedly seasonal, with two distinguishable seasons: a rainy season from November to April and a dry one from May to October. The mean annual precipitation and temperature are respectively 1622 mm and 21.2°C (Madeira and Fernandes 1999). Based on topography, we designated and studied two main types of campos rupestres. Of the 10 grasslands we selected overall, 5 sites were on a sandy substrate on flatted areas and 5 sites were on a stony substrate on slopes. Sites were located between 1100 m and 1300 m.

Soil analyses

Three soil samples were taken at each site and air dried prior to the physical (granulometry) and chemical (pH, C org , total N, P, K, Mg 2+ , Ca 2+ , Al 3+ ) soil analyses.

Each soil sample consisted of three pooled sub-samples randomly taken in each site at the 10 first cm. To assess the granulometry of the coarse fraction of the soil, each sample was sieved through 1cm and 2mm mesh sieves. The fine fraction (<2mm) was used for physical (granulometry) and chemical (pH, MO, total N, P, K, Mg 2+ , Ca 2+ , Al 3+ ) soil analyses: P and K in mg/dm 3 , N and C in dag/kg, Mg 2+ , Al 3+ , Ca 2+ in cmol c /dm 3 , Organic Carbon (C org ) in dag/kg. P, N and K were analysed with the Mehlich 1 extraction method; Ca 2+ , Mg 2+ , Al 3+ with 1 mol/L KCl extraction; C Org following the Walkley-Black method. Soil sampling was done once during the rainy season (February) and once during the dry season (July) (n = 3 samples × 10 sites × 2 seasons = 60 samples). Analyses were conducted at the soil laboratory of Viçosa Federal University, Viçosa, Minas Gerais, Brazil. Soil analysis followed the recommendations of EMBRAPA (1997).

Plant survey

We surveyed fifteen 1m² quadrats at each sandy site and twenty 1m² quadrats at each stony site according to the minimal area which was previously assessed in December 2008 for each grassland type (species/area curves -Mueller-Dombois and Ellenberg 1974). At each quadrat the following information was collected: (1) percent cover of bare ground, litter, moss and lichen (hereafter "cryptogams"), forbs, ligneous species, Velloziaceae, and graminoids; (2) a list of the species, (3) the abundance of each species (number of individuals or clumps per m 2 ), ( 4) the percent cover of each species visually estimated, based on the vertical projection of all aerial plant parts (Mueller-Dombois and Ellenberg 1974), (5) the frequency of each species, based on the number of subquadrats (25 20x20cm subquadrats / m 2 ) in which each species was found. Plants were identified by experts and by using specific literature [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF][START_REF] Forzza | Lista de Espécies da Flora do Brasil[END_REF]) and the Herbarium BHCB at the Universidade Federal de Minas Gerais in Belo Horizonte, Brazil.

In order to find out whether the two grassland types had different plant communities, the Importance Value Index (IVI -Mueller-Dombois and Ellenberg 1974) and Relative Dominance were calculated for each species and at each site. The IVI is the sum of the Relative Density (D r ), the Relative Dominance (Do r ) and the Relative Frequency (F r ) and allows a species with high frequency but low cover to be considered as important. IVI was used to compare the importance of each species (maximum value = 300): the higher is the IVI, the higher is the importance of the species (Muller-Dombois & Ellenberg 1974). As D r , Do r and F r are proportions, they range from 0 to 100.

1) The Relative Density (D r ) is D r =100*D a /D t , where D a (Absolute Density) is the number of individuals / m 2 and D t (Total Density) is the sum of the all the D a . The Absolute Density is D a =Σn i *S/A with n i = number of individuals of species i, S= quadrat area, A= total area of sampling at the site.

2) The Relative Dominance (Do r ) is Do r =100*Do a /Do t , where Do a (Absolute Dominance) is the area in cm 2 occupied by the species / m 2 and Do t (Total Dominance) is the sum of the all the Do a . The Absolute Dominance (cm 2 /m 2 ) is Do a =100*ΣR i *S i /A with R i = area covered by species i (percent cover), S i = plot area, A= total area of sampling at the site.

3) The Relative Frequency (F r ) is F r =100*F a /F t , where F a (Absolute Frequency) is the percent of subquadrats occupied by the species at a site and F t (Total Frequency) the sum of the all the F a . The Absolute Frequency is F a =100 *ΣSq i /Sq t with Sq i = number of subquadrats occupied by species i and Sq t = total number of subquadrats / site.

In order to analyse the structure and the characteristics (i.e. geographic distribution, endemism and IUCN threatening status) of the species, all species were classified according to (1) life-form according to Raunkiaer's life form modified by [START_REF] Mueller-Dombois | Aims and methoods in vegetation ecology[END_REF], ( 2) their plant forms, (3) habitats, (4) distribution ranges, (5) IUCN status and (6) life cycle. (1) The life-forms were assessed according to Raunkiaer (1904) modified by [START_REF] Mueller-Dombois | Aims and methoods in vegetation ecology[END_REF].

(2) The considered plant forms were: forbs, graminoids, sub-shrub, shrub, liana, fern.

(3) Habitats in Brasil were determined based on literature: campos rupestres, altitude grassland, cerrado (sensu-lato including campos rupestres), caatinga, Atlantic rainforest, Amazon rainforest, wet grassland [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF][START_REF] Forzza | Lista de Espécies da Flora do Brasil[END_REF]).

(4) The distribution ranges, also based on the literature and a database, comprised:

(a) endemic from the Serra do Cipó, (b) endemic from the Espinhaço Range in the state of Minas Gerais, (c) endemic from the Espinhaço Range (states of Minas Gerais and Bahia), (d) distributed in the state of Minas Gerais, (e) distributed in Brazil, (f) wide distribution [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF], Forzza et al. 2010, database SpeciesLink: http://splink.cria.org.br/). ( 5) The IUCN status was evaluated according to Mendonça and Lins 2000: vulnerable, critical, and endangered. (6) We also included the life cycle: perennial or annual.

Statistical analyses

To compare the fine fraction granulometry between campos rupestres types, t-tests were performed after checking the data for normality and homogeneity of variance.

To compare the coarse fraction granulometry between grassland types, the paired ttest with estimated separate variance was performed as the variances were not homogenous. To compare chemical soil composition between grassland types and seasons we used a nested two-way ANOVA for each chemical element. Logtransformations were applied before comparing P, K, Ca 2+ , Mg 2+ and Organic Carbon [START_REF] Sokal | Biometry: the principles and practice of statistics in biological research[END_REF].

To assess plant similarity between stony and sandy grasslands, the Steinhaus similarity index, based on species abundance, was calculated (Steinhaus = 1-Bray-Curtis index, values range between 1 and 0, the higher the Steinhaus value, the more similar plant compositions, [START_REF] Legendre | Numerical Ecology[END_REF]) and an ANOSIM was performed. ANOSIM analyses were also carried out within each grassland type, to evaluate the within grassland type plant similarity. To assess the differences of the Steinhaus index when comparing sites belonging to the same or to different types of grasslands, we performed a GLM procedure using a Gaussian distribution and identity link function, with similarity index as the response variable and the modality (comparison between stony and sandy grasslands, within stony grasslands and within sandy grasslands) as explicative variables. To identify groups a ward clustering of a matrix of chord distances among sites was performed using species percent cover data. Then, to corroborate classifications and find out if the cluster overlapped or not, we plotted the cluster membership using a Correspondence Analysis (CA) on plant percent cover matrix (222 species x 175 quadrats). We therefore identified which species discriminated each groups to establish the community type.

Kruskall-Wallis tests were performed to compare plant form and life-form within sandy and stony grasslands followed by multiple comparisons with Bonferroni correction, while Wilcoxon tests were performed to test differences in plant form and life-form between sandy and stony grasslands. To test the difference between the two grassland types in the number of species per site and m 2 , the number of individuals per m 2 as well as the number of each plant form per site, t-test, or Wilcoxon tests when data were not normal, were performed.

To analyse the relationship between soil and plant composition, a co-inertia analysis was run between plant and soil data. This type of analysis is used to determine if there is a co-structure between two data tables by performing simultaneous analysis of the two tables. The optimizing criterion in co-inertia analysis is that the resulting sample scores (environmental scores and floristic scores) are the most covariant Chapter 1 -Campos rupestres communities 50 (Doledec and Chessel 1994). The co-inertia analysis was based on one CA (222 species) and one PCA (18 physico-chemical variables) at the 10 sites (10 points); a test based on permutations was performed to find out about the co-inertia significance.

All analyses were carried out in R version 2.9.1 (R Core Development Team, 2010) using ADE-4 and stats packages.

Results

Soil analyses

As expected, grasslands with a stony substrate (stony grasslands) presented a significantly greater proportion of gravel (gravel > 1cm represented 28%) compared to grasslands with a sandy substrate (sandy grasslands) (Table 2). On the other hand, sandy grasslands were characterized by a significantly higher proportion of fine sand (< 2mm) than stony grasslands (t= 4.65, P<0.001) (Table 2). In stony grasslands, N, P, K, Ca2+, Mg2+ concentrations and Corg content were significantly higher and the soil was more acidic than in sandy grasslands (Table 3, Figure 17).

Both grasslands presented seasonal variation for P and Corg content and pH. During the dry season, P concentrations were significantly higher while Corg contents and pH were significantly lower (Table 3, Figure 17). The aluminum concentration did not vary between grasslands or between seasons (Table 3, Figure 17). Open circles represent dry season and full circles rainy season. See Table 2 for twoway ANOVA results.

Plant survey

The mean Steinhaus similarity index between sites belonging to different grasslands (0.25 ± 0.07) was significantly lower than the mean Steinhaus similarity index within sandy grassland sites (0.46 ± 0.04) or stony grassland sites (0.40 ± 0.06) (GLM procedure P<0.001). Furthermore, differences in similarity were significant between and within the grasslands (R between stony and sandy grasslands= 0.49, R within stony grasslands= 0.45 and R within sandy grasslands= 0.29, P<0.001), highlighting also the presence of heterogeneity within the communities. A Ward clustering analysis allowed the distinction of two floristic groups based on floristic composition and structure: the sandy and the stony grasslands (Figure 18).

Axes 1 and 2 of the correspondence analysis performed on the matrix of the plant percent cover explained 47% of the total inertia. Axis 1 (29%) separated sandy from stony grasslands while axis 2 (18%) showed an inter-site variability in plant composition, particularly in the stony grasslands (Figure 19). Some species, such as Vellozia albiflora, V. resinosa, V. caruncularis, Bulbostylis lombardii, B. paradoxa, Diplusodon orbicularis, Xyris minarum, X. melanopoda, Paepalanthus geniculatus, Sebastiana ditassoides and Vochysia pygmaea were typical of the stony grasslands, while Xyris asperula, X. insignis, X. nubigena, Syngonanthus cipoensis, Panicum cyanescens, Vellozia epidendroides and Rhynchospora ciliolata were strongly associated with sandy grasslands (Figure 19). We found one species of pteridophytes and 221 species of angiosperms, distributed into 34 plant families: 120 monocotyledons and 101 dicotyledons, in the 10 investigated sandy and stony grasslands (Appendix 1). The analyses of the distribution pattern of 174 species showed that 28 species (i.e.12.6% of the total number of species) are endemic to the Serra do Cipó, while 48 species (21.6%) are restricted to the Espinhaço range whether in the state of Minas Gerais or in the states of Bahia and Minas Gerais (Figure 20, Appendix 1). Among the 160 species for which bibliographical data were available, 86 (38.6% of the total number of species) are restricted to the campos rupestres and 31 (13.9%) are cerrado species (Figure 20, Appendix 1). To summarize, 34.2% of the flora are endemic to the Espinhaço Range and 38.6% of the species are restricted to the campos rupestres. Twenty-four species (i.e. 10.7%

of the total) are classified as either endangered, critical, or vulnerable according to the IUCN criteria (Appendix 1). One hundred and fifty-eight species were found in the sandy grasslands and 170 species were found in the stony grasslands of which 13.9% and 17.1% were endemic species, respectively (Table 4). Fifty-two species (32.9%) are exclusively found in sandy grasslands while 64 (37.6%) species are restricted to stony grasslands. A large part of the species is perennial in both communities (95.6% in sandy grasslands and 98.2% in stony grasslands), and monocotyledons represent more than 50% of the species (56.9% in sandy grasslands and 55.9% in stony grasslands) (Table 4). Only 12 species (5.3% of all species) were found in all sites, 47 species (21%) were found in 7, 8 or 9 sites while 87 species (39%) were encountered at only one site (singletons The mean number of species/m 2 (t=2.93, P<0.01) as well as the mean number of shrubs (W=1, P<0.05) were higher in the stony grasslands (Table 4, Appendix 1).

Graminoids (representing 45% and 39% of species in sandy and stony grasslands, respectively) were the dominant form of plant growth in both communities (Figure 21). Forbs (27% and 31% of species in sandy and stony grasslands, respectively)

and sub-shrubs (23% and 22%) were also well represented (Figure 21). In both sandy and stony grasslands, more than 80% of the species were hemicryptophytes (Figure 22). In both types of grassland, the families with the most species were Poaceae (26 and 28 species in sandy and stony grasslands, respectively), Cyperaceae (23 and 25 species), Xyridaceae (20 and 14 species), Eriocaulaceae (9 and 14 species) and Velloziaceae (5 and 7 species) for the Monocotyledons and Asteraceae (14 and 13 species), Melastomataceae (6 and 8 species), Polygalaceae (7 and 1 species) and Apocynaceae (4 and 5 species) for the Dicotyledons (Figure 23).

We observed a strong co-structure between soil and vegetation data (RV= 0.70, P<0.001), revealing a significant relationship between soil and community composition and structure (Figure 24). Velloziaceae, ligneous species, and bare ground primarily characterized the stony grasslands as well as the N, P, K, Ca 2+ , Mg 2+ concentrations and C org content while the sandy grasslands are characterized by cryptogams, graminoids, finer soil and a less acidic pH (Figure 24).

Discussion

Soils

The stony grasslands are characterized by a coarse granulometry, particularly quartzic stones, and a smaller proportion of fine sand. Indeed, as they are usually located on slopes, they are potentially more impacted by water erosion. In dry systems, water availability is a source of heterogeneity (Jobbagy et al. 1996), and local drainage further diversifies the environment by creating relatively humid or arid sites. We can expect stony grasslands to be drier than sandy grasslands since stony grasslands are never flooded while sandy grasslands can experience temporary flooding during the rainy season [START_REF] Vitta | Composição florística e ecologia de comunidades campestres na Serra do Cipó, Minas Gerais[END_REF]. Vellozia spp. are strongly associated with dry environments [START_REF] Porembski | Granitic and gneissic outcrops (inselbergs) as centers of diversity for desiccation-tolerant vascular plants[END_REF] and may be an indicator species for stony grassland in the campos rupestres.

The soils of campos rupestres are globally poor in nutrients: clays, which are usually associated with a higher capacity of nutrient retention, are almost entirely absent.

This pattern might have been exacerbated by periods of intense leaching followed by long-term podzolization [START_REF] Turenne | Influence de la saison des pluies sur la dynamique des acides humiques dans les profils ferrallitiques et podzoliques sous savanes de Guyane française[END_REF], Benites et al. 2007). In spite of this, our data indicate that the soil of stony grasslands is more acidic and richer in nutrients (N, P, K, Ca 2+ , Mg 2+ ) and carbon content than sandy grassland soil. As sandy grasslands are found in flatter areas, they accumulate water, which slowly percolates, and this might facilitate the eluviation of the soluble organic compounds that are associated with iron and aluminum, which can leach throughout and into deeper soil. This translocation is favored by humic acid, which is common in these soils (Schaeffer and Ker 2003). Normally, at lower pH phosphorus (a critical element in the development of the vegetation [START_REF] Sarmiento | The Ecology of neotropical savannas[END_REF])) precipitates, for example, with aluminum, and becomes less available to plants. However, in the stony grasslands we studied, it was found that during the dry season, soil pH was decreased while phosphorus concentrations were elevated in what may be related to a reduction in the loss of mineral nutrients due to the absence of rainfall [START_REF] Sarmiento | The Ecology of neotropical savannas[END_REF].

Similarities between the two grassland types

Both sandy and stony grasslands are species-rich plant communities highlighting the relevance of campos rupestres for the maintenance of biodiversity. Lythraceae (Diplusodon, Cuphea). These genera have been observed previously in several campos rupestres in the Serra do Cipó [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF] as well as in other areas of the Espinhaço range [START_REF] Meguro | Phytophysiognomy and composition of the vegetation of Serra do Ambrósio, Minas Gerais, Brazil[END_REF][START_REF] Queiroz | Flora vascular da Serra da Jiboia, Santa Terezinha-Bahia. I: O campo rupestre[END_REF], Pirani et al. 2003[START_REF] Zappi | Lista das plantas vasculares de Catolés, Chapada Diamantina, Bahia, Brasil[END_REF][START_REF] Conceição | Delimitação de habitats em campos rupestres na Chapada Diamantina, Bahia: substratos, composição floristica e aspectos estruturais[END_REF][START_REF] Viana | Floristica e caracterização dos campos rupestres sobre canga na Serra da Calçada, Minas Gerais, Brasil[END_REF][START_REF] Borges | Altitudinal distribution and species richness of herbaceous plants in campo rupestres of the Southern Espinhaço range, Minas Gerais, Brazil[END_REF]. No exotic species were found in our study sites, even though the distance of closest approach between highway MG-010 and our study sites is just 130 m, from which we could conclude either that our sites are very well conserved or that the environmental conditions are unfavorable to the establishment of most invasives. With the recent study by [START_REF] Barbosa | Distribution of non-native invasive species and soil properties in proximity to paved roads and unpaved roads in a quartzitic mountainous grassland of southeastern Brazil (rupestrian fields)[END_REF] indicating the presence of invasive species along the MG-010 road, we can safely rule out the latter conclusion.

Differences between the two grassland types

One of the main findings of this study was the stark heterogeneity of these grasslands: the sandy and the stony grasslands represent distinct plant communities. According to the results of the co-inertia analysis, each plant community is closely related to a specific soil composition. The nature of the substrate and its heterogeneity, even at a scale of a few centimeters, separate the grassland types from one another and determine the community composition. The extreme abiotic conditions of the campos rupestres have strong consequences in terms of plant adaptation to constrained environmental conditions. However, each campo rupestre physiognomy is characterized by its own constraints (e.g. type of substrate) which might impose different adaptations (see [START_REF] Carvalho | The mosaic of habitats in the high-altitude Brazilian rupestrian fields is a hotspot for arbuscular mycorrhizal fungi[END_REF]. For instance, in stony grasslands the presence of small white stones (i.e. quartzic stones) could induce higher insolation, higher temperatures and higher radiations than in sandy grasslands, inducing adaptations for water-storage, transpiration control, leaf reduction, seedling adaptation to growth on sunny areas while in sandy grasslands humidity can be preserved at the ground surface (Giulietti et al. 1997).

Another part of the heterogeneity of plant composition both between and within the sandy and stony grasslands is due to endemism, which is a characteristic of the campo rupestre flora. Seventy percent of Vellozia species are restricted to the state of Minas Gerais (Mello-Silva 1995). [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF] noted that a large number of Eriocaulaceae species are endemic to the Espinhaço Range. For Xyridaceae, Wanderley (2011) recorded 14 endemic taxa in the Serra do Cipó and attributed the recent origin of Xyris species to explain their restricted distribution. Endemism in the Espinhaço Range may be explained by its tectonic history and climate fluctuations.

These phenomena led to expansion following by reduction and fragmentation of populations and therefore the evolution of new species, often with very limited distribution [START_REF] Alves | Plant species endemism in savanna vegetation on table mountains (Campo Rupestre) in Brazil[END_REF], Giulietti et al. 1997, Barbosa 2012). Despite the lack of geographically broader studies, many campo rupestre species have been said to be endangered because of their restricted distribution [START_REF] Ribeiro | Impactos potenciais das alterações no Código Florestal sobre a vegetação de campos rupestres e campos de altitude[END_REF].

Numerous species (38.6%) are found exclusively on campos rupestres, conferring a certain uniqueness to these ecosystems, though vicariant species can contribute to a high floristic variation among them (Giulietti et al. 1997, Alves and[START_REF] Alves | Can campo rupestre vegetation be floristically delimited based on vascular plant genera?[END_REF].

Alves and [START_REF] Alves | Can campo rupestre vegetation be floristically delimited based on vascular plant genera?[END_REF] have already noted that genera alone are not sufficient to separate campos rupestres from other vegetation formations, such as highland grasslands (campos de altitude), and that floristic studies at the species-level must be combined with environmental variables to help design general functioning patterns for the campos rupestres. Our study also brings to light the lack of information on numerous species, underscoring the need for research into their biology, distribution and ecology.

Conclusions

This study has shown that these neotropical mountain grasslands are species-rich communities, adapted to harsh abiotic conditions with nutrient poor soils. It has also demonstrated that there are two distinct plant communities, the sandy and the stony grasslands. The vegetation composition is strongly related to specific soil composition, and this explains why some species are confined to one or another grassland type, indicating finely tuned adaptations to environmental conditions. This complex relationship between soil and vegetation leads to a high heterogeneity and therefore generates a rich biodiversity, even at small scale and even among the herbaceous layer that was previously considered homogeneous. The large proportion of endemism along the Espinhaço Range generates variability among campos rupestres and confers a great conservation value, which at the moment is very threatened. It is important to consider these two grassland types as distinct plant communities, and, as consequence, ecological strategies must be targeted accordingly to improve their conservational and restorative efficacy. This species present two morphotypes on Serra do Cipó campos rupestres, while we firstly thought it was two different species. In this thesis Lagenocarpus rigidus subsp.

tenuifolius designate the morphotype "glauco" and Lagenocarpus tenuifolius designate the morphotype "vede-amarelo."

Transition to Chapter 2

The first chapter highlighted that campos rupestres host at least two kinds of tropical grasslands each characterized by its own vegetation composition and its own soil

properties, but we suppose the mosaic to be even more diversified [START_REF] Alves | Can campo rupestre vegetation be floristically delimited based on vascular plant genera?[END_REF]. As for the two plant communities identified (i.e. sandy and stony grasslands), although physical factors are important to explain plant community structure, life-history traits, such as phenology, can also be of major interest to explain the different patterns that we observed.

Indeed phenology is an important aspect of population biology [START_REF] Fenner | The phenology of growth and reproduction in plants[END_REF][START_REF] Schwartz | Phenology: an integrative environmental science[END_REF][START_REF] Hudson | Phenological Research -Methods for Environmental and Climate Change Analysis[END_REF], since it affects the dynamics of interspecific interactions linked to the timing of plant reproductive and growth cycles, such as herbivory, pollination and frugivory [START_REF] Van Schaik | The Phenology of Tropical Forests: Adaptive Significance and Consequences For Primary Consumers[END_REF], Diaz et al. 1994, Apko 1997[START_REF] Bosch | Flowering phenology, floral traits and pollinator composition in a herbaceous Mediterranean plant community[END_REF][START_REF] Gribel | Flowering phenology and pollination biology of Ceiba pentandra (Bombacaceae) in Central Amazonia[END_REF], Conceição et al. 2007a). In addition, the study of phenological patterns is also crucial to understand plant community dynamics, biological invasion [START_REF] Wilsey | Biodiversity, phenology and temporal niche differences between native-and novel exotic-dominated grasslands[END_REF]) and the co-occurrence of species, especially in species-rich tropical plant communities [START_REF] Janzen | Synchronization of Sexual Reproduction of Trees Within the Dry Season in Central America[END_REF], Frankie et al. 1974[START_REF] Gentry | Flowering phenology and diversity in tropical Bignoniaceae[END_REF][START_REF] Grubb | The Maintenance of Species-Richness in Plant Communities: the Importance of the Regeneration Niche[END_REF][START_REF] Fenner | The phenology of growth and reproduction in plants[END_REF][START_REF] Batalha | Reproductive phenology of the cerrado plant community in Emas National Park (central Brazil)[END_REF][START_REF] Pau | Predicting phenology by integrating ecology, evolution and climate science[END_REF]. The first phenological studies were mainly realized in temperate zones where patterns are now well described.

However, in tropical systems, cycles are complex and irregular as plants can display a wide variety of patterns [START_REF] Sarmiento | Life forms and phenology[END_REF]; the major issue is therefore the recognition of some general patterns (Newstrom et al. 1994a[START_REF] Morellato | South America, in: Phenology: an integrative environmental science[END_REF].

The objective of the following chapter (chapter 2) is then to describe phenological patterns of both sandy and stony grasslands, to assess if flowering, fruiting and dissemination are seasonal, if phenology differs between grassland-types and to analyze which species participate in the reproductive phenology (Figure 25). This latter issue allows determining the composition of the external species pool, useful to restore degraded areas (Figure 25).

I Reference Ecosystem:

Campos rupestres

Stony grasslands Sandy grasslands

What are the phenological patterns in both communities?

What species supply the external seed pool, useful to restore degraded areas?

Figure 25: The theoretical objective of the second chapter is to describe the phenological patterns of two herbaceous communities; the applied objective of the second chapter is to identify the species which produce seeds and thus might potentially colonize degraded areas.

Chapter 2 -Reproductive phenological patterns of two Neotropical mountain grasslands.

Soizig Le Stradic In South America, just a small percentage of herbaceous vegetation has been examined from the point of view of its seasonal changes. However, the study of phenological patterns is crucial to understand plant community dynamics, especially in species-rich tropical plant communities. In a harsh and heterogeneous environment, the campos rupestres (Neotropical mountain grasslands located on southeastern Brazil), we monitored the phenology of the two dominant herbaceous communities, the sandy and the stony grasslands, for two consecutive years. The aim of this study was to assess if plant species reproduce seasonally; to test whether the phenological patterns as well as the fruit and flower production, are different between these two communities; to test if there are intra-specific variations in terms of fruit production between the two grassland types, considering only species co-occurring in both grasslands. Several phenological patterns occur among the herbaceous communities: likewise other physiognomies of Cerrado, herbaceous communities of campos rupestres have a flowering peak during the rainy season, but some species reproduce preferentially during the transition from the rainy to the dry season or during the dry season. Phenological patterns were similar in both communities, however, the amplitude of phenophases, i.e. net production by species, varied among communities according to each species' density. In both communities, Cyperaceae and Xyridaceae were families with the highest species contribution to overall phenology. Some dominant species belonging to Poaceae, among others, were not observed reproducing, which implies limited chances to disperse on degraded areas.

Keywords: dissemination, phenophase duration, flowering, fruiting, phenophase frequency, seasonality, phenophase timing.

1.Introduction

Phenology is defined as the study of the timing of recurring biological events, the causes of their timing in regard to biotic and abiotic forces, and the interrelation among phases of the same or different species [START_REF] Lieth | Phenology and seasonality modeling[END_REF]. For plants, biological events or phenophases include reproduction, such as bud formation and flowering, fruiting, and seed germination, along with vegetative events like leaf flushing and shedding [START_REF] Morellato | The Influence of Sampling Method, Sample Size, and Frequency of Observations on Plant Phenological Patterns and Interpretation in Tropical Forest Trees[END_REF]. The cycles of plant growth and reproduction are crucial to understand ecosystem functioning [START_REF] Lieth | Phenology and seasonality modeling[END_REF]) and processes of primary production [START_REF] Sarmiento | Life forms and phenology[END_REF]) and recruitment, such as seed dispersal and seed germination [START_REF] Garwood | Seed Germination in a Seasonal Tropical Forest in Panama : A Community Study[END_REF][START_REF] Johnson | Climatic and phylogenetic determinants of flowering seasonality in the Cape flora[END_REF], Silveira et al. 2012a). Phenological variations can be analyzed as plant adaptive strategies [START_REF] Van Schaik | The Phenology of Tropical Forests: Adaptive Significance and Consequences For Primary Consumers[END_REF][START_REF] Elzinga | Time after time: flowering phenology and biotic interactions[END_REF]). For instance, abiotic factors, such as precipitation, temperature and photoperiod influence phenology, especially in areas with a seasonal climate; the detection of such environmental signals is fundamental since it ensures plant flowering when climatic conditions are the most suitable for reproduction [START_REF] Rathcke | Phenological patterns of terrestrial plants[END_REF][START_REF] Fenner | The phenology of growth and reproduction in plants[END_REF][START_REF] Shackleton | Rainfall and topo-edaphic influences on woody community phenology in South African savannas[END_REF][START_REF] Morellato | Phenology of Atlantic Rain Forest Trees: A Comparative Study[END_REF][START_REF] Ramirez | Reproductive phenology, life-forms and habitats of the Venezuelan Central plain[END_REF]). Flowering time is also controlled by both genetic [START_REF] Koornneef | Genetic control of flowering time in arabidopsis[END_REF][START_REF] Putterill | It's time to flower: the genetic control of flowering time[END_REF]) and biotic interactions, such as pollination, which can modulate the selection of the timing of flowering, and fruiting phenology [START_REF] Fenner | The phenology of growth and reproduction in plants[END_REF][START_REF] Elzinga | Time after time: flowering phenology and biotic interactions[END_REF]).

In addition, phenology is an important aspect of population biology [START_REF] Fenner | The phenology of growth and reproduction in plants[END_REF][START_REF] Schwartz | Phenology: an integrative environmental science[END_REF][START_REF] Hudson | Phenological Research -Methods for Environmental and Climate Change Analysis[END_REF], since it affects the dynamics of interspecific interactions linked to the timing of plants' reproductive and growth cycles, such as herbivory, pollination and frugivory [START_REF] Van Schaik | The Phenology of Tropical Forests: Adaptive Significance and Consequences For Primary Consumers[END_REF], Diaz et al. 1994[START_REF] Bosch | Flowering phenology, floral traits and pollinator composition in a herbaceous Mediterranean plant community[END_REF][START_REF] Gribel | Flowering phenology and pollination biology of Ceiba pentandra (Bombacaceae) in Central Amazonia[END_REF], Conceição et al. 2007a). The study of phenological patterns is also crucial to understand plant community dynamics, biological invasion [START_REF] Wilsey | Biodiversity, phenology and temporal niche differences between native-and novel exotic-dominated grasslands[END_REF]) and the co-occurrence of species, especially in species-rich tropical plant communities [START_REF] Janzen | Synchronization of Sexual Reproduction of Trees Within the Dry Season in Central America[END_REF], Frankie et al. 1974[START_REF] Gentry | Flowering phenology and diversity in tropical Bignoniaceae[END_REF][START_REF] Fenner | The phenology of growth and reproduction in plants[END_REF][START_REF] Batalha | Reproductive phenology of the cerrado plant community in Emas National Park (central Brazil)[END_REF][START_REF] Pau | Predicting phenology by integrating ecology, evolution and climate science[END_REF].

In South America, open tropical vegetation, such as mountain grasslands, savannas, flooded savannas or grasslands, cover around 14% of land surface while areas occupied by agriculture represent 24% [START_REF] Eva | A land cover map of South America[END_REF]). However, on this continent, phenological studies mainly concern tropical moist forests and dry forests, while a few only describe seasonal changes of these open tropical vegetations [START_REF] Morellato | South America, in: Phenology: an integrative environmental science[END_REF]. Campos rupestres, species-rich tropical grasslands, are harsh ecosystems established on quartzite-derived soils occurring in altitude between 800m and 2,000m, and covering around 130,000km 2 (Barbosa 2012). Campos rupestres are constituted of a very heterogeneous mosaic of stony and sandy grasslands, bogs situated along streams, and scattered rocky outcrops that harbour sclerophyllous evergreen shrubs and sub-shrubs (Giulietti et al. 1997[START_REF] Alves | Can campo rupestre vegetation be floristically delimited based on vascular plant genera?[END_REF][START_REF] Carvalho | The mosaic of habitats in the high-altitude Brazilian rupestrian fields is a hotspot for arbuscular mycorrhizal fungi[END_REF], Chapter 1). These grasslands are stressful ecosystems that have shallow, nutrient-poor and highly acidic soils (Benites et al. 2007, Chapter 1) that sustain a highly diverse vegetation with one of the highest levels of endemism in Brazil (Giulietti et al. 1997, Echternacht et al. 2011). Due to its coarser soil and lower water retention, the stony grasslands seem to constraint plant vegetation more than sandy grasslands (Vitta 1995, Chapter 1). Campos rupestres are included in the cerrado savanna domain [START_REF] Silva | Biogeographic Patterns and Conservation in the South American Cerrado: A Tropical Savanna Hotspot[END_REF] and, like other savannas, is under a seasonal climate with a dry season from May to October and a rainy season from November to April (Madeira & Fernandes 1999).

According to some studies, the seasonal climate imposes a restrictive growing season and tends to decrease the diversity of phenological patterns within a site while aseasonal environments, such as tropical moist forests, present a higher diversity of phenological patterns [START_REF] Van Schaik | The Phenology of Tropical Forests: Adaptive Significance and Consequences For Primary Consumers[END_REF][START_REF] Bawa | Relationships among time, frequency, and duration of flowering in tropical rain forest trees[END_REF][START_REF] Pau | Predicting phenology by integrating ecology, evolution and climate science[END_REF]). In the Cerrado savannas, as in other tropical vegetations characterized by seasonal climate, the leaf, flower and fruit production are strongly related to abiotic factors (VanSchaik et al. 1993[START_REF] Pau | Predicting phenology by integrating ecology, evolution and climate science[END_REF]. Regarding savannas, studies have highlighted that the majority of herbaceous species flower during the wet season [START_REF] Monasterio | Phenological strategies of plant species in the tropical savanna and the semi-deciduous forest of the Venezuelan Llanos[END_REF][START_REF] Sarmiento | Life forms and phenology[END_REF][START_REF] Almeida | Grupos fenologicos da comunidae de gramineas perenes de um campo cerrado no Distrito Federal, Brasil[END_REF][START_REF] Seghieri | Plant Phenology in Relation to Water Availability: Herbaceous and Woody Species in the Savannas of Northern Cameroon[END_REF], Apko 1997[START_REF] Batalha | Reproductive phenological patterns of cerrado plant species at the Pé-de-Gigante Reserve (Santa Rita do Passa Quatro, SP, Brazil): a comparison between the herbaceous and woody floras[END_REF][START_REF] Williams | Savanna landscapes[END_REF][START_REF] Ramirez | Reproductive phenology, life-forms and habitats of the Venezuelan Central plain[END_REF][START_REF] Batalha | Reproductive phenology of the cerrado plant community in Emas National Park (central Brazil)[END_REF][START_REF] Freitas | Pollination Biology in a Tropical High-Altitude Grassland in Brazil : Interactions at the Community Level[END_REF][START_REF] Tannus | Fenologia reprodutiva em campo sujo e campo umido numa area de cerrado no sudeste do Brasil, Itirapina -SP[END_REF], however the occurrence of diverse strategies was already pointed out, including flowering during the dry season [START_REF] Monasterio | Phenological strategies of plant species in the tropical savanna and the semi-deciduous forest of the Venezuelan Llanos[END_REF][START_REF] Almeida | Grupos fenologicos da comunidae de gramineas perenes de um campo cerrado no Distrito Federal, Brasil[END_REF][START_REF] Barbosa | Biologia reprodutiva de uma comunidade de campo sujo[END_REF][START_REF] Ramirez | Reproductive phenology, life-forms and habitats of the Venezuelan Central plain[END_REF].

Due to their great diversity and heterogeneity, tropical communities may display a wide variety of phenological patterns [START_REF] Sarmiento | Life forms and phenology[END_REF][START_REF] Newstrom | A new classification phenology based on flowering patterns in lowland tropical rain forest trees at La Selva, Costa Rica[END_REF][START_REF] Morellato | South America, in: Phenology: an integrative environmental science[END_REF]), therefore more studies are necessary to explore the variety of possible phenological patterns in order to draw general pictures. Because of this complexity, [START_REF] Newstrom | A new classification phenology based on flowering patterns in lowland tropical rain forest trees at La Selva, Costa Rica[END_REF] proposed a classification to describe phenological patterns using the following variables: frequency, regularity, duration, amplitude, date or timing, and synchrony of phenological events. Here we follow this classification using frequency, duration, timing and amplitude to assess phenological patterns of the two dominant herbaceous physiognomies of campos rupestres: the sandy and the stony grasslands. We used quantitative amplitude of the different phenophases; although few studies incorporated quantitative data, it seems to be a good tool as it allows comparison among sites.

Our objective is to address the following questions, at the community and species level: (i) do the plant species of each grassland type flower, fruit and disseminate seasonally? ; (ii) are the phenological patterns (defined as based on frequency, timing and duration of each phenophase) similar between both physiognomies?; (iii) do the fruit and flower production differ between the grassland types, and vary among families?; (iv) are there intra-specific variations in term of fruit production between the two grassland types, considering only species co-occurring in both grasslands? We expected seasonal phenological patterns with flower peak during the rainy season. In addition, we expected that both grassland types would differ in their phenology because the constraints imposed by soil properties and topography are more severe on vegetation growing on stony than on sandy grasslands (i.e. lower water retention in stony grasslands during the rainy season [START_REF] Vitta | Composição florística e ecologia de comunidades campestres na Serra do Cipó, Minas Gerais[END_REF], Silveira 2011). and the mean annual temperature is 21.2°C (Madeira & Fernandes 1999). It is markedly seasonal, with two distinguishable seasons: a rainy season from November to April with higher mean temperatures and a dry one from May to October with colder temperatures (Figure 26). We defined a transition season from rainy to dry between March and June and a transition season from dry to rainy between September and December (Figure 26).

2.Material & Methods

Study area

Plant survey

To study the phenological patterns of these two main grassland-types of campos rupestres, we selected five sandy grasslands and five paired stony grassland sites, all located between 1,100m and 1,300m. We then used frequency, timing and duration in order to describe and classify the main phenological strategies occurring on sandy and stony grasslands of campos rupestres.

We classified species phenology according to four phenological frequencies: continual short -(phenophase lasting less than two months) and long (phenophase lasting more than two months).

We also selected thirty-one species that co-occurred in both grassland types (which were present in at least two sites among the five sites sampled for each grassland-type (Appendix 2) and produced enough seeds to allow comparison between sandy and stony grasslands, in order to compare, at species level, phenological patterns between sandy and stony grasslands. For each species, for each grassland type, we assessed the fruit production by site and the fruit production per individuals.

Statistical analyses

To characterize the flowering, fruiting and disseminating seasonality of the two communities, we applied circular statistics analyses [START_REF] Morellato | Phenology of Atlantic Rain Forest Trees: A Comparative Study[END_REF][START_REF] Morellato | The Influence of Sampling Method, Sample Size, and Frequency of Observations on Plant Phenological Patterns and Interpretation in Tropical Forest Trees[END_REF]. For

Chapter 2 : Phenology of the campos rupestres 74 each phenophase, the number of species on the peak date (considered as the moment where the highest number of flowers, fruits or dissemination was observed) of a given phenophase per month was treated as a circular frequency distribution with data grouped at 30° (30° = interval between 2 months) intervals, with January as the starting point (15°). The mean angle µ represents the mean date of the flowering/fruiting/disseminating period, and r is the measure of the concentration of the circular distribution of frequencies around the mean angle and ranges from 0 (when data are completely dispersed in all angles) to 1 (when all the data are concentrated in one angle or date) [START_REF] Zar | Biostatistical analysis[END_REF]. In order to describe the different phenological strategies (i.e.

frequency, duration, timing) encountered on campos rupestres, the number of species in each category (i.e. frequency, timing, duration per grassland types) was then analyzed using Pearson χ 2 tests. Continual and sub-annual species were not included in these tests as they represented too few species.

To analyze flower and fruit production at each site according to the grassland type and plant families, GLM procedures were performed assuming a Poisson distribution and a logarithmic link function. The numbers of flowers and fruits were the dependent variables while grassland-types and families were the categorical predictors [START_REF] Mccullagh | Generalized Linear Models[END_REF]Nelder 1989, Crawley 2007). For the analysis we used the seven most important families in campos rupestres (Chapter 1) while the other species were classified as forbs or subshrubs because there were too few species in the other species families. For the thirtyone species selected, GLM procedures were performed using a Poisson distribution and log link function in order to compare the species fruit production by site between both grassland types [START_REF] Crawley | The R Book[END_REF]. T-tests were performed to compare the number of fruits on each individual between sandy and stony grasslands. Normality and homoscedasticity assumptions were previously checked [START_REF] Sokal | Biometry: the principles and practice of statistics in biological research[END_REF].

All analyses were carried out in R version 2.14.0 (R Core Development Team, 2010) except the circular analyses that were performed using the software Oriana 3.0 (Kovach Computing Services 2012).

3.Results

One hundred and forty-six species were surveyed in sandy grasslands and 155 species in stony grasslands, of which the majority were perennial species (138 species or 94.5%

and 151 species or 97.4%, for stony and sandy grasslands respectively) (Table 5). As a consequence of the high proportion of perennial species, the vegetation cover did not vary along the years. The percentage of species not showing reproductive phenophases ranged between 26.7% and 34.1% for the stony and sandy grassland species, respectively (Table 5).

Flowering, fruiting and dissemination patterns in sandy and stony grasslands.

The mean angle or date µ (measuring central tendency) and the r (measuring of concentration) were obtained for each phenophase and each grassland-type (Table 6, Figure 27). We were unable to identify a well-defined flowering, fruiting or dispersing time for the stony grassland (Figure 27 b, d andf) with marginally significant or no significant mean dates (µ) and a very low r; i.e. low concentration of species flowering or fruiting around the mean date. Similarly, dissemination time in the sandy grasslands did not have a significant mean date (µ) (Table 6, Figure 27 e), while flowering and fruiting in sandy grasslands were significant, but presented a very low r (Table 6, Figure 27 a andc). Considering the timing of flowering, fruiting and dissemination, the phenological patterns did not differ between sandy and stony grasslands (Table 7). The majority of species produced flowers during the rainy season (R) (42.9% in sandy grasslands, and 47.5% in stony grasslands) while around 20% flowered during the transition from the rainy to the dry season (RD) and 14% to 20% during the dry season (D). Few species (less than 6%) produced flowers during the transition from dry to rainy season (DR).

Fruits were mainly produced during the rainy (R) or dry (D) season: 30% and 33%

(respectively in sandy and stony grasslands) produced fruits during the rainy season, while between 41% and 37% (respectively in sandy and stony grasslands) fruited during the dry season (Table 7). The dissemination occurred during the rainy season (R) (30% to 42% of species respectively in sandy and stony grasslands); other species disseminated during the dry season (D) (24% to 20% of species respectively in sandy and stony grasslands) or the transition from dry to rainy season (DR) (24% to 21%, respectively in sandy and stony grasslands) (Table 7). Among the species presenting supra-annual phenology, the majority flowered during the rainy season (representing 23.7% and 15.5% species, in sandy and stony grasslands respectively) (Table 8).

Among species with an annual flowering frequency, the larger proportion produced flowers during the rainy season (24.7% and 39.5% in sandy and stony grasslands, respectively), but also during the transition from rainy to dry season (22.6% and 19.8% in sandy and stony grasslands, respectively), and during the dry season (between 17.2% and 9.3% in sandy and stony grasslands, respectively) (Table 8). In addition, we analyzed the duration of flowering, fruiting and disseminating phenophases according to the timing of the phenophase (Table 9). There was a relationship between phenophase duration and timing in both grassland types and for the three analyzed phenophases (Table 9). In both sandy and stony grasslands, a high number of species flowering during the rainy season presented a short flowering cycle (29.5% and 34.3% of species, respectively; in sandy grasslands χ 2 =12.75, p<0.05 and in stony grasslands χ 2 =7.68, p<0.01), while in sandy grasslands, species flowering during the transition from rainy to dry season had a longer cycle (Table 9); there is no difference between both short and long cycles for this period in stony grasslands (Table 9). In both grasslands, many species producing fruit during the rainy season had a short cycle (between 17.1% and 20.2% in sandy and stony grasslands respectively) while species fruiting during the dry season had a longer cycle (in sandy grasslands χ 2 =13.58, p<0.001 and in stony grasslands χ 2 =14.80, p<0.001, Table 9). In the same way, higher proportion of species disseminating during the rainy season had a short cycle (between 24.9% and 28.3% in sandy and stony grasslands respectively. On the contrary most species had a longer cycle when disseminated during the transition season (dry to rainy) (in sandy grasslands χ 2 =31.31, p<0.001 and in stony grasslands χ 2 =8.35, p<0.05, Table 9). In sandy grasslands, 16% of species disseminating during the dry season had a short cycle while 7.6% had a long cycle. The proportion of species disseminating during the dry season, with a long or a short cycle in stony grasslands was the same (around 10%, Table 9). For flowering and dissemination, there was no relationship between phenophase duration and grassland-types: the number of species with short and long cycles was similar in both grasslands (for flowering, 50% of species in sandy grasslands and 58% in stony grasslands with a short cycle, χ 2 =1.0, p=0.31, and for dissemination, 55% of species in sandy grasslands and 51% in stony grasslands had a short cycle χ 2 = 0.29, p=0.59). There was no difference between the two grassland-types for fruiting as well: in both sandy and stony grasslands, most species had long phenological cycles (68% and 66% of species in sandy and stony grasslands, respectively, χ 2 =0.11, p=0.74) (Appendix 3).

Flower and fruit production among grassland types and among families

The mean flower production by site was higher on sandy than on stony grasslands (respectively 227.7 ± 26.6 and 211.6 ± 12.48, z=-2.42, p=0.01). Likewise, the mean fruit production was higher in sandy than in stony grasslands (respectively 532.6 ± 45.9 and 464.8 ± 47.5, z=-6.78, p<0.001). Cyperaceae and Xyridaceae were among the families that produced a large number of flowers and fruits while Poaceae, although represented by a great number of species and covering a large area (Table 10), did not produce a significant amount of seeds. Asteraceae, Velloziaceae, Xyridaceae and several subshrubs produced the highest number of flowers and fruits in stony grasslands while

Chapter 2 : Phenology of the campos rupestres 81 Cyperaceae, Poaceae and forbs had the highest flower and fruit production in sandy grasslands (Table 10). Conversely, Melastomataceae species flower production was higher in sandy grasslands, while the fruit production was greater in stony grasslands.

Eriocaulaceae flower and fruit production did not differ between the two grassland-types.

Phenology and fruit production of species co-occurring in both

grassland types. and Xyris itatiayensis). Ten species produced more fruits in the sandy grasslands while nine species produced more fruits in the stony grasslands (Table 11). Generally, the fruit production per individual was low and equal between both sandy and stony grasslands, except for Lagenocarpus rigidus subsp. tenuifolius which recorded a higher production per individual in sandy than in stony grasslands (Table 11). Table 10: Flower and fruit production per site (average number and standard error) in sandy (Sa) and stony (St) grasslands for the main families based on peak production. z indicated the result of GLM procedures (family: Poisson, link: log). Letters indicate significant differences between families among grassland-types according to the result of the GLM procedures (family: Poisson, link: log). 22.9 ± 3.8 2.0 ± 0.6 -8,23 *** 1.4 ± 0.1 1.0 ± 0.3 1,5 NS Pseudotrimezia cipoana 5.0 ± 2.9 4.9 ± 2.2 -0,1 NS 0.7 ± 0.2 0.7 ± 0.1 0,18 NS Rhynchospora consanguinea 6.5 ± 2.4 6.1 ± 1.4 -0,35 NS 0.7 ± 0.1 0.8 ± 0.1 -1,31 NS Rhynchospora riedeliana 60.0 ± 20.8 44.6 ± 11.6 -4,74 *** 1.6 ± 0.1 1.5 ± 0.2 0,65 NS Rhynchospora sp1 24.7 ± 11.4 11.5 ± 7.4 -4,88 *** 2.0 ± 0.8 1.6 ± 0.7 0,48 NS Rhynchospora tenuis 34.4 ± 12.4 6.3 ± 4.5 -8,23 *** 3.0 ± 0.8 1.3 ± 0.9 -1,54 NS Rhynchospora tenuis subsp austro-brasiliensis 51.9 ± 8.9 48.5 ± 21.3 -1,01 NS 2.0 ± 0.2 2.9 ± 0.6 -1,55 NS Rhynchospora terminalis 15.6 ± 4.7 1.3 ± 0.4 1,48 NS 0.8 ± 0.1 0.9 ± 0.2 -0,37 NS Richterago arenaria 1.3 ± 0.4 1.6 ± 0.9 0,56 NS 0.5 ± 0.1 0.6 ± 0.2 -0,29 NS Sebastiana ditassoides 0.8 ± 0.5 3.8 ± 1.9 2,65 ** 0.5 ± 0.3 1.4 ± 0.9 -1,06 NS Sisyrinchium vaginatum 1.5 ± 1.4 0.3 ± 0.2 -1,84 NS 0.9 ± 0.7 0.3 ± 0.2 0,86 NS Syngonanthus cipoensis 8.6 ± 2.3 3.0 ± 0.7 -4,56 *** 0.6 ± 0.1 0.6 ± 0.1 0,45 NS Syngonanthus vernonioides 2.2 ± 0.6 17.0 ± 5.5 8,06 *** 0.6 ± 0.1 0.8 ± 0.1 -1,33 NS Thesium brasiliense 1.8 ± 0.8 2.4 ± 1.3 0,93 NS 0.5 ± 0.2 0.4 ± 0.2 0,36 NS Vellozia epidendroides 2.4 ± 0.7 16.0 ± 7.8 7,59 *** 1.1 ± 0.2 1.5 ± 0.2 -1,55 NS Vochysia pygmaea 1.5 ± 1.0 3.1 ± 0.9 1,61 NS 0.6 ± 0.3 0.7 ± 0.2 -0,33 NS Xyris blanchetiana 7.1 ± 1.9 2.0 ± 0.8 -3,36 *** 0.7 ± 0.1 0.6 ± 0.3 0,22 NS Xyris hilariana 17.5 ± 7.0 28.5 ± 11.6 3,43 *** 0.8 ± 0.3 0.5 ± 0.2 0,87 NS Xyris itatiayensis 1.3 ± 0.9 1.7 ± 0.9 0,52 NS 0.2 ± 0.1 0.4 ± 0.2 -0,85 NS Xyris melanopoda 1.5 ± 1.0 9.4 ± 2.1 4,31 *** 0.4 ± 0.2 0.5 ± 0.1 -0,5 NS Xyris nubigena 13.1 ± 6.5 7.0 ± 2.7 -3,53 *** 0.7 ± 0.1 0.5 ± 0.2 1,51 NS Xyris obtusiuscula 14.7 ± 3.9 52.8 ± 14.5 13,34 *** 0.9 ± 0.1 0.7 ± 0.1 1,13 NS Xyris pilosa 41.6 ± 21.9 34.9 ± 9.3 -2,13 * 0.9 ± 0.1 0.9 ± 0.1 0,76

Discussion

Our study highlights that about one fourth and one third of the species have not participated in the reproductive phenology during our 2-year survey, either because they

Flowering, fruiting and dissemination patterns in sandy and stony grasslands.

In 1899 Warming wrote that, in the tropics, "different species have different flowering time, some of them even blooming in the winter, that is, in the dry season, and in consequence we may find flowers at almost all times of the year." Even if savannas are characterized by a seasonal climate, and even if seasonal phenological patterns are expected, at the community level, campos rupestres produce flowers and fruits all year long and distinctive seasonal patterns are not clearly depicted even based on a circular analysis. The main issue in such tropical ecosystems, as already noticed by [START_REF] Newstrom | A new classification phenology based on flowering patterns in lowland tropical rain forest trees at La Selva, Costa Rica[END_REF], is then to recognize and classify those patterns. Using some classification tools based on frequency, timing and duration, we were able to underline the diversity of campo rupestre phenological patterns, corroborating with studies dealing with herbaceous species in savannas [START_REF] Monasterio | Phenological strategies of plant species in the tropical savanna and the semi-deciduous forest of the Venezuelan Llanos[END_REF][START_REF] Almeida | Grupos fenologicos da comunidae de gramineas perenes de um campo cerrado no Distrito Federal, Brasil[END_REF][START_REF] Ramirez | Reproductive phenology, life-forms and habitats of the Venezuelan Central plain[END_REF].

We show that, even if flowering is distributed throughout the year, in both grassland types there is a flower peak during the rainy season, which is in agreement with results from other seasonal systems in the tropics (Monasterio & Sarmiento 1976, Seghieri et al. Chapter 2 : Phenology of the campos rupestres 85 1995, Ramirez 2002) as well as in the Cerrado [START_REF] Barbosa | Biologia reprodutiva de uma comunidade de campo sujo[END_REF][START_REF] Batalha | Variações fenológicas das espécies do cerrado em Emas (Pirassununga, SP)[END_REF][START_REF] Batalha | Reproductive phenological patterns of cerrado plant species at the Pé-de-Gigante Reserve (Santa Rita do Passa Quatro, SP, Brazil): a comparison between the herbaceous and woody floras[END_REF][START_REF] Batalha | O cerrado não é um bioma[END_REF]Martins, 2004, Munhoz &[START_REF] Munhoz | Reproductive phenology of an herbaceous-subshrub layer of a Savannah (Campo Sujo) in the Cerrado Biosphere Reserve I, Brazil[END_REF]. This phenological pattern is frequently related to climatic factors, especially water availability as well as the acute water shortage during the following drought [START_REF] Sarmiento | Life forms and phenology[END_REF][START_REF] Almeida | Grupos fenologicos da comunidae de gramineas perenes de um campo cerrado no Distrito Federal, Brasil[END_REF][START_REF] Ramirez | Reproductive phenology, life-forms and habitats of the Venezuelan Central plain[END_REF][START_REF] Batalha | Reproductive phenology of the cerrado plant community in Emas National Park (central Brazil)[END_REF]. In a seasonal system, some authors have argued that herbs must complete their vegetative growth and have to accumulate carbohydrates to flower [START_REF] Batalha | Reproductive phenological patterns of cerrado plant species at the Pé-de-Gigante Reserve (Santa Rita do Passa Quatro, SP, Brazil): a comparison between the herbaceous and woody floras[END_REF][START_REF] Ramirez | Reproductive phenology, life-forms and habitats of the Venezuelan Central plain[END_REF][START_REF] Batalha | Reproductive phenology of the cerrado plant community in Emas National Park (central Brazil)[END_REF], which explains why most of the species produced flowers during late wet season or during the transition from rainy to dry season. Species with supra-annual phenological frequency flower mainly during the rainy season. This might be a strategy to avoid years of sub-optimal climate and expending high resources in optimal years [START_REF] Venable | Bet hedging in a guild of desert annuals[END_REF]. We expected a shorter cycle in stony grasslands due to a potential water stress, but duration patterns are the same between both grassland types; most of the species flowering, fruiting and disseminating during the rainy season have a short phenological cycle. Thus, the strategy of these species is based on the capacity to disseminate fruits at the end of the rainy season. A relationship between seed dispersal and seedling establishment has been showed in Neotropical savannas for woody species (Salazar et al. 2011, Silveira 2011, Silveira et al. 2012a): most seeds dispersed in the wet season are non-dormant and exhibit high moisture content (Salazar et al. 2011), but we might expect that seeds produced during the rainy season and dispersing at the end of it (period of transition with the dry season) have dormancy (Silveira et al. 2012a).

On the other hand, in both grasslands, other species belonging to Xyridaceae, Asteraceae, Fabaceae, Melastomataceae or Eriocaulaceae families, flower and fruit preferentially either during the transition between rainy to dry season or during the dry season. These species are, in majority, species that have an annual flowering frequency, underlining the regularity of such pattern. On the other hand, most of these species present longer phenological cycles. One hypothesis is that these species need a longer period of vegetative growth in order to reproduce. However, another possibility is that these species, flowering and fruiting during the transition rainy to dry season or the dry season, are preferentially pollinated by animals such as wasps or dipterans which are important pollinators during the dry season while bees decrease their activities during this season [START_REF] Freitas | Pollination Biology in a Tropical High-Altitude Grassland in Brazil : Interactions at the Community Level[END_REF]. Pollinators are commonly designated to impose selection on flowering phenology [START_REF] Elzinga | Time after time: flowering phenology and biotic interactions[END_REF], which might explain why many species present an annual frequency. In such cases, longer cycles or massive flowering are necessary to ensure the attraction of pollinators; since the latter are attracted by a species only after a certain flower density threshold is passed [START_REF] Elzinga | Time after time: flowering phenology and biotic interactions[END_REF].

Massive flowering has already been observed for species of Velloziaceae and Xyridaceae (personal observation).

Pollination ecology is poorly studied in campos rupestres, but grasses and sedges are usually pollinated by the wind [START_REF] Oliveira | Pollination and reproductive biology in cerrado plant communities, in: The Cerrados of Brazil -Ecology and natural history of a neotropical savanna[END_REF]. However, entomophily has already been demonstrated for some Eriocaulaceae and Xyridaceae species [START_REF] Ramos | Pollination in Brazilian Syngonanthus (Eriocaulaceae) Species : Evidence for Entomophily Instead of Anemophily[END_REF][START_REF] Faria | Recursos florais e sindromes de polinização e dispersão de espécies de campos rupestres no parque estadual da serra dos pireneus[END_REF][START_REF] Oriani | Pollination biology of Syngonanthus elegans (Eriocaulaceae -Poales)[END_REF][START_REF] Oriani | Reproductive biology of Abolboda pulchella and A. poarchon (Xyridaceae : Poales)[END_REF]. Indeed, in Eriocaulaceae, pollination by small insects was pointed out to increase the reproductive success [START_REF] Oriani | Pollination biology of Syngonanthus elegans (Eriocaulaceae -Poales)[END_REF]. Xyridaceae, although included in the Poales, group which has usually non-attractive flowers and is therefore probably wind-pollinated [START_REF] Linder | Evolutionary history of Poales[END_REF], have large, colorful and attractive flowers, indicating animal pollination [START_REF] Oriani | Reproductive biology of Abolboda pulchella and A. poarchon (Xyridaceae : Poales)[END_REF]. Moreover, in altitude grasslands similar to campos rupestres, the relationship between pollination and phenology were pointed out: grassland species with nectar-or pollen-flowers pollinated by bees flower during the rainy season with a small flowering peak observable in June because bee activity decreases during the dry season [START_REF] Freitas | Pollination Biology in a Tropical High-Altitude Grassland in Brazil : Interactions at the Community Level[END_REF]. On the other hand, species with nectar-flowers are pollinated either by wasps and/or by dipterans reaching their flowering peak during the dry season [START_REF] Freitas | Pollination Biology in a Tropical High-Altitude Grassland in Brazil : Interactions at the Community Level[END_REF].

Finally, several species disseminate during the dry season or transition from dry to rainy season, including species that flower during the rainy season. These species preferentially have a long dissemination cycle, probably linked to abiotic factors, such as wind or rain. Anemochory and autochory have already been pointed out as the two main seed dispersal syndromes in campos rupestres [START_REF] Faria | Recursos florais e sindromes de polinização e dispersão de espécies de campos rupestres no parque estadual da serra dos pireneus[END_REF], Conceição et al. 2007a[START_REF] Dutra | Fenologia reprodutiva, sindromes de polinização e dispersão em espécies de Leguminosae dos campos rupestres do parque estadual do Itacolomi, MInas Gerais, Brasil[END_REF]), the end of the dry season being usually marked by more wind, this period seems then the optimal period to disseminate for this species. Zoochory has already been reported for cactaceae and woody species [START_REF] Fonseca | Dispersão de sementes de Melocactus glaucescens e M. paucispinus (Cactaceae), no Município de Morro do Chapéu , Chapada Diamantina -BA[END_REF], Silveira et al. 2012b). No study has reported hydrochory, but the importance of water as a dispersal mechanism in campos rupestres cannot be underestimated: sandy grasslands are regularly flooded during the rainy season and sedges seeds are known to be buoyant (Leck & Schutz 2005).

Flower and fruit production in sandy and stony grasslands.

Our results highlight that flower production varies between sandy and stony grasslands, with a higher flower and fruit productions in sandy grasslands perhaps due to the higher plant density in this habitat (Chapter 1). Cyperaceae, Eriocaulaceae and Xyridaceae species ensure most of the flower and fruit productions in campos rupestres.

Eriocaulaceae species are known to present a wide range of reproductive strategies, which might be affected by climate seasonality, including vegetative propagation [START_REF] Figueira | Dinâmica de populações de Paepalanthus polyanthus (Eriocaulaceae) na Serra do Cipó[END_REF][START_REF] Coelho | Seasonal Timing of Pseudoviviparous Reproduction of Leiothrix (Eriocaulaceae) Rupestrian Species in South-eastern Brazil[END_REF], 2007). In campos rupestres, Xyridaceae species have particularly been studied from the point of view of their ability to germinate since they produce many small seeds in each capitulate [START_REF] Abreu | Efeito da luz e da temperatura na germinação de sementes de quatro espécies de Xyris L .(Xyridaceae) ocorrentes na Serra do Cipó, MG, Brasil[END_REF], however little is known about their phenological strategies. Very few studies have been carried out on the Cyperaceae of campos rupestres however sedges are known to present various reproductive strategies within habitats, persistence, and ability of many species to colonize disturbed habitats [START_REF] Leck | Regeneration of Cyperaceae, with particular reference to seed ecology and seed banks[END_REF]. On the other hand, Poaceae and Velloziaceae, which are important families in campos rupestres almost did not reproduce during the study period.

Comparison between sandy and stony grasslands.

Our results show that the large majority of species co-occurring in both grasslands (83.8%) adopt the same phenological behavior, suggesting that there were no or few variations in the phenological patterns due to an important genetic control, or stony grasslands do not represent a more constrained environment. Nineteen species produced more fruits in one preferential grassland type but this only reflects that each species occurs preferentially in one grassland type (Chapter 1). Indeed, the production by individuals did not vary between grasslands except for Lagenocarpus rigidus subsp.

tenuifolius, which has a significantly higher fruit production on sandy grasslands. We thus assume that these species are adapted to both habitats and their occurrence on either habitat could be linked to establishment success and/or biotic interaction.

5.Conclusion

Campos rupestres are tropical grasslands that have complex phenological patterns with diverse phenological strategies. This is the first rigorous study examining the phenology of the campo rupestre herbaceous flora. Like other physiognomies of the Cerrado, herbaceous communities of campos rupestres have a flowering peak during the rainy season; but other phenological strategies are also observed: some species flower during the transition from rainy to dry season or during the dry season. Rainy and dry seasons are both marked by fruit production. Dissemination takes place during the rainy season for species that realize their entire phenological cycle during this period (species with a short cycle); but other species disseminate during the dry season, and the transition from dry to rainy season. Most of the studied species have an annual phenological frequency; some others are supra-annual while few are continual or sub-annual. While we draw some phenological patterns for the herbaceous campo rupestre communities using frequency, timing and duration, we do not find differences among grassland types: both sandy and stony grasslands present similar phenological patterns. Cyperaceae, Xyridaceae and Ericaulaceae mainly ensure seed production, whereas Poaceae produce very few seeds. This underlined that Poaceae, which are an important family in campos rupestres, do not contribute to supply the seed pool that could disperse and establish on degraded areas. This is a strong limiting factor to the spontaneous succession of campos rupestres.

Transition to Chapter 3

Restoration of herbaceous plant communities, especially in altitude, is important for many reasons including their key role in maintaining habitat integrity and in the water cycle: ensuring water for drinking and irrigation, providing medicinal plants and offering cultural services, such as recreation (MEA 2005).

What about grassland restoration?

Grassland restoration projects are often hampered by abiotic constraints, such as increased soil nutrients (i.e. eutrophication and acidification) in case of degradation by intensive agriculture [START_REF] Bakker | Constraints in the restoration of ecological diversity in grassland and heathland communities[END_REF] or the alteration of soil chemical and physical characteristics (i.e. limited nutrient availability, low water availability) in case of degradation by quarrying and mining activities [START_REF] Yuan | Soil Formation and Vegetation Establishment on the Cliff Face of Abandoned Quarries in the Early Stages of Natural Colonization[END_REF]. Therefore, early studies on grassland restoration have concentrated on site limitation with a special emphasis i) on the removal of nutrients (i.e. topsoil removal, carbon addition) when extensive agriculture is the main source of degradation [START_REF] Berendse | Experiments on the restoration of species-rich meadows in The Netherlands[END_REF] crushing, rewetting, compacting, ripping, grading, or drainage) and on adding fertilizers to improve physical conditions of mine degraded soils [START_REF] Davis | Early Seral Communities in a Limestone Quarry: An Experimental Study of Treatment Effects on Cover and Richness of Vegetation[END_REF][START_REF] Ash | The introduction of native plant species on industrial waste heaps : a test of immigration and other factors affecting succession primary[END_REF][START_REF] Jim | Ecological and Landscape Rehabilitation of a Quarry Site in Hong Kong[END_REF][START_REF] Wong | Ecological restoration of mine degraded soils , with emphasis on metal contaminated soils[END_REF].

Unfortunately, in many cases, such measures alone are not sufficient in restoring the target species-rich grassland communities, although environmental conditions are improved [START_REF] Berendse | Experiments on the restoration of species-rich meadows in The Netherlands[END_REF][START_REF] Donath | The impact of site conditions and seed dispersal on restoration success in alluvial meadows[END_REF]. Numerous studies recognized that biotic constraints often impeded the restoration of species-rich grasslands and identified as the main obstacles: 1) the lack of viable seeds in the soil seed bank and 2) the limited dispersal of target species [START_REF] Wilson | Chapter 19. Prairies[END_REF][START_REF] Shu | Natural Colonization of Plants on Five Lead/Zinc Mine Tailings in Southern China[END_REF][START_REF] Kiehl | Plant species introduction in ecological restoration : Possibilities and limitation[END_REF][START_REF] Piqueray | Revue bibliographique sur la restauration des pelouses calcicoles en Europe : contraintes rencontrées et solutions proposées[END_REF][START_REF] Török | Grassland restoration on former croplands in Europe: an assessment of applicability of techniques and costs[END_REF].

Lack of seed bank

The potential for plant communities to regenerate after a given disturbance represents an important aspect of their resilience and thus an important point for their conservation

Inter-Chapter 90 and restoration (Leck et al. 1989, Bakker et al. 1996[START_REF] Prach | Using spontaneous succession for restoration of humandisturbed habitats: Experience from Central Europe[END_REF][START_REF] Prach | Spontaneous Succession versus Technical Reclamation in the Restoration of Disturbed Sites[END_REF]. In general, in communities subjected to periodic disturbances, the dominant species produce large numbers of seeds that persist in the soil for a long time (i.e.

persistent seed-banks); whereas the dominant species in communities without disturbance tend to produce smaller numbers of seeds, which remain viable in the soil for a short time (i.e. transient seed-banks) [START_REF] Thompson | Ecological correlates of seed persistence in soil in the north-west European flora[END_REF]. Although, annuals and biennials almost always have more persistent seeds than related perennials [START_REF] Thompson | Ecological correlates of seed persistence in soil in the north-west European flora[END_REF], Kalamees & Zobel (2002) demonstrated that the soil seed bank is important for population maintenance and regeneration in perennial grassland communities as well. On North America, [START_REF] Lavoie | Spontaneous revegetation of mined peatlands: An useful restoration tool ?[END_REF] noted that spontaneous regeneration from the seed bank occurred in peatlands; in mountain grasslands in South America, Funes et al. (2001) showed that the largest number of seeds, and thus the highest potential for regeneration, was found in wetter sites, but then the number decreased progressively from mesic to xeric habitats. This trend was also verified in European grasslands (Bossuyt & Honnay 2008).

In grasslands, viable seeds of the most abundant species in the established vegetation (i.e. characteristic species) are often absent in the soil seed bank either due to their low longevity or because of low seed production (Hutchings & Booth 1996[START_REF] Mcdonald | Seed bank classification and its importance for the restoration of species-rich flood-meadows[END_REF], Bakker et al. 1996, Bekker et al. 1997, Buisson et al. 2006); few target species build up long-term persistent soil seed banks (Von [START_REF] Blanckenhagen | Restoration of calcareous grasslands: the role of the soil seed bank and seed dispersal for recolonisation processes[END_REF], therefore the regeneration of natural communities from the seed-bank is low. Moreover, the seed bank of ex-arable fields present usually non desirable species (arable species), which could impede natural regeneration (e.g. competition) [START_REF] Bakker | Constraints in the restoration of ecological diversity in grassland and heathland communities[END_REF][START_REF] Wilson | Chapter 19. Prairies[END_REF][START_REF] Hausman | Plant community establishment in a restored wetland: Effects of soil removal[END_REF], Bossuyt & Honnay 2008) and/or lead to an undesirable restoration trajectory. Then, the potential for in situ spontaneous succession in several cases is slow or unpredictable (Bossuyt & Honnay 2008[START_REF] Török | Grassland restoration on former croplands in Europe: an assessment of applicability of techniques and costs[END_REF].

Lack of seed dispersal:

When there is no seed bank, species have to immigrate from source populations in the surroundings of degraded sites, but dispersal is, in many cases, a limiting factor. Due to the limited dispersal properties of the species, the colonization of degraded sites by seed rain from adjacent pristine sites is often unsuccessful [START_REF] Ash | The introduction of native plant species on industrial waste heaps : a test of immigration and other factors affecting succession primary[END_REF], Hutchings & Booth 1996, Bakker et al. 1996, Bradshaw 1997, Tilman 1997, Cooper & MacDonald Inter-Chapter 91 2000, [START_REF] Bischoff | Dispersal and establishment of floodplain grassland species as limiting factors in restoration[END_REF][START_REF] Wilson | Chapter 19. Prairies[END_REF][START_REF] Donath | The impact of site conditions and seed dispersal on restoration success in alluvial meadows[END_REF][START_REF] Shu | Natural Colonization of Plants on Five Lead/Zinc Mine Tailings in Southern China[END_REF][START_REF] Tormo | Is seed availability enough to ensure colonization success ? An experimental study in road embankments[END_REF], Buisson et al. 2006). [START_REF] Cousins | Remnant grassland habitats as source communities for plant diversification in agricultural landscapes[END_REF] showed that grassland specialists dispersed stepwise into the fields, and the number of grassland specialists decreased with distance from the source. Then, the more a degraded area is isolated, the more complicated its natural regeneration by seed rain is, what is often observed in our currently fragmented landscape. Another issue is the immigration of non-target species (e.g. competitive exotic species), which affect/hamper the establishment of target species [START_REF] Wilson | Chapter 19. Prairies[END_REF][START_REF] Török | Grassland restoration on former croplands in Europe: an assessment of applicability of techniques and costs[END_REF].

Interventions

Spontaneous succession can be relied upon in some restoration projects and primarily concerns sites where conditions were not strongly altered by the disturbance [START_REF] Prach | Using spontaneous succession for restoration of humandisturbed habitats: Experience from Central Europe[END_REF][START_REF] Prach | Spontaneous Succession versus Technical Reclamation in the Restoration of Disturbed Sites[END_REF]. For the more altered sites, the active introduction of Inter-Chapter 92

We highlighted in the previous chapter (chapter 2) the diversity of phenological patterns occurring in campos rupestres, with a gradient of seed production along the year, constituting the external species pool. The next chapter (chapter 3) goal is to assess the resilience of degraded areas, i.e. are species from the external species pool able to disperse to recompose the seed bank or/and to establish in such areas? (Figure 28)

Concurrently, we carried out active restoration intervention in order to overcome the dispersal filter: i.e. hay transfer (Figure 28). As the landscape becomes increasingly fragmented, regeneration of plant communities (including seed bank) mainly depends on dispersal. We thus collected hay (i.e. diaspore and plant material), potentially composed by species from the external species pool, and spread it on degraded areas. As campos rupestres are composed of two grassland communities, we have run the protocol on both the sandy and stony grasslands.

Abstract

The campos rupestres are species-rich tropical grasslands located in a region that is currently under assault by economic interests that are developing mining operations in the area. This study was designed firstly to evaluate the natural resilience of degraded campo rupestre areas by evaluating the degree of spontaneous succession eight years following the disturbance (i.e. quarrying for gravel exploitation during the asphalting of highway MG-010), by describing potential site limitations (i.e. chemical characteristics of the degraded soil) and by assessing the internal species pool, mainly represented in the seed bank. Secondly, we tested the restoration technique of hay transfer as a means of strengthening seed dispersal. Nine degraded areas representing three kinds of substrate (latosol, sandy, and stony) were selected. To evaluate the resilience, a plant survey along with seed bank and soil studies were carried out in 2010. Eight years after degradation, plant composition and soil composition differed greatly between the degraded areas and the reference ecosystem (stony and sandy grasslands). The seed banks of the reference ecosystem are extremely seed and species poor, while those of the degraded areas are mainly composed of non-target ruderal species; regeneration via the seed bank is therefore rather limited. Campos rupestres are poorly resilient face to a harsh degradation, which implies the necessity of restorative intervention (i.e. hay transfer). Hay transfer was carried out using hay that was collected year-round in 2010 in order to maximize the seed pool. The hay was distributed among the three kinds of degraded areas with and without geotextile at the end of 2010 according to the following protocol: hay from sandy grasslands was placed in all types of degraded areas, while hay from stony grasslands was used on stony substrates only. The seedlings that were observed on the degraded areas 14 months following hay application were mainly ruderal species. Our results highlight the inherent difficulty in restoring degraded areas of campos rupestres by attempting to overcome the dispersal filter using hay transfer.

Key words: grassland restoration, hay transfer, quarrying, seed bank, regeneration

1.Introduction

Humans have strongly altered the global environment especially through land-use changes [START_REF] Chapin | Consequences of changing biodiversity[END_REF][START_REF] Steffen | The Anthropocene : Are Humans Now Overwhelming the Great Forces of Nature ?[END_REF]), which has been responsible for ca. half of terrestrial ecosystem transformations (Daily 1995[START_REF] Vitousek | Human Domination of Earth's Ecosystems[END_REF][START_REF] Klink | Past and Current Human Occupation, and Land Use, in: The Cerrados of Brazil -Ecology and natural history of a neotropical savanna[END_REF]. These profound changes have resulted in many prejudicial effects on diversity and ecosystem services [START_REF] Osborne | Riparian vegetated buffer strips in water-quality restoration and stream management[END_REF], FAO 1998, Sala et al. 2000MEA 2005). Grassland ecosystems and tropical ecosystems are expected to be the most strongly impacted by future land-use changes [START_REF] Sala | Global Biodiversity Scenarios for the Year 2100[END_REF]. Among the most drastic of land-use changes, quarrying and mining activities cause major soil damage, leading to uncontrolled soil erosion and water quality alteration [START_REF] Pimentel | Environmental and economic costs of soil erosion and conservation benefits[END_REF][START_REF] Valentin | Gully erosion: Impacts , factors and control[END_REF]. Currently, ecological restoration has become one strategy for enhancing biodiversity, rescuing degraded areas, and reinstating ecosystem services. Ecological restoration sensu lato is the process of intentionally assisting the recovery of degraded ecosystems (SER 2004) [START_REF] Aronson | What Role Should Government Regulation Play in Ecological Restoration? Ongoing Debate in São Paulo State, Brazil[END_REF]. In spite of these laws and increasing restoration know-how, authorities sometimes still allow the ill-advised and widespread use of exotic species to revegetate ecologically compromised areas.

Before launching a restoration project, one must first assess the resilience of the degraded ecosystemi.e. the efficiency with which an ecosystem returns to a reference trajectory following a disturbance or period of stress [START_REF] Leps | Community stability, complexity and species life history strategies[END_REF][START_REF] Lockwood | An alternative to succession: assembly rules offer guide to restoration efforts[END_REF][START_REF] Mitchell | Ecosystem stability and resilience: a review of their relevance for conservation management of lowland heaths[END_REF]. This makes it possible to assess the impact of the disturbance (White & Jentsch 2001), and to identify whether restoration is necessary, and, if it is, to gather information useful for restoration planning [START_REF] Bradshaw | The use of natural processes in reclamation -advantages and difficulties[END_REF][START_REF] Prach | Spontaneous Succession versus Technical Reclamation in the Restoration of Disturbed Sites[END_REF][START_REF] Prach | Four opportunities for studies of ecological succession[END_REF]. Two main factors hamper the resilience of a given ecosystem. The first is site limitation: oftentimes, site conditions are inappropriate due to the alteration of the Chapter 3 -Resilience and restoration of campos rupestres 96 chemical and physical properties of the soil (i.e. limited nutrient availability, low water availability) [START_REF] Ash | The introduction of native plant species on industrial waste heaps : a test of immigration and other factors affecting succession primary[END_REF][START_REF] Wong | Ecological restoration of mine degraded soils , with emphasis on metal contaminated soils[END_REF][START_REF] Yuan | Soil Formation and Vegetation Establishment on the Cliff Face of Abandoned Quarries in the Early Stages of Natural Colonization[END_REF]). The second is the lack of target species in the internal species pool, for example within the soil seed bank or among surviving individuals, or even in the external species pool from species that are capable of dispersing to the site via the seed rain [START_REF] Ash | The introduction of native plant species on industrial waste heaps : a test of immigration and other factors affecting succession primary[END_REF], Bakker et al. 1996, Bradshaw 1997[START_REF] Bakker | Constraints in the restoration of ecological diversity in grassland and heathland communities[END_REF][START_REF] Wilson | Chapter 19. Prairies[END_REF][START_REF] Shu | Natural Colonization of Plants on Five Lead/Zinc Mine Tailings in Southern China[END_REF][START_REF] Kiehl | Plant species introduction in ecological restoration : Possibilities and limitation[END_REF])).

Sites degraded by quarry or mining activities often have inappropriate abiotic conditions and do not enjoy an internal species pool because the incumbent soil seed bank and vegetation have both been totally destroyed. Consequently, the seed supply in such areas is mainly dependent on seed dispersal from surrounding sites (Bradshaw 1983, 1997[START_REF] Davis | Early Seral Communities in a Limestone Quarry: An Experimental Study of Treatment Effects on Cover and Richness of Vegetation[END_REF][START_REF] Campbell | Determining the immigration potential of plants colonizing disturbed environments : the case of milled peatlands in Quebec[END_REF][START_REF] Shu | Natural Colonization of Plants on Five Lead/Zinc Mine Tailings in Southern China[END_REF]. Spontaneous succession occurs preferentially wherever environmental conditions are not too extreme [START_REF] Prach | Spontaneous Succession versus Technical Reclamation in the Restoration of Disturbed Sites[END_REF]; it is therefore often difficult to rely on spontaneous succession in case of mining degradation.

Grassland species often disperse poorly and at a low rate (Bishoff 2002, Buisson et al. 2006[START_REF] Oster | Agriculture, Ecosystems and Environment Plant colonization of ex-arable fields from adjacent species-rich grasslands : The importance of dispersal vs . recruitment ability[END_REF]; consequently the restoration of species-rich grasslands may include direct seeding [START_REF] Cooper | Restoring the Vegetation of Mined Peatlands in the Southern Rocky Mountains of Colorado[END_REF][START_REF] Turner | Influence of Polymer Seed Coatings , Soil Raking , and Time of Sowing on Seedling Performance in Post-Mining Restoration[END_REF], Kirmer et al. 2012[START_REF] Ballesteros | Vegetation recovery of gypsum quarries : short-term sowing response to different soil treatments[END_REF], transposition of soil with diaspores [START_REF] Rochefort | North American approach to the restoration of Sphagnum dominated peatlands[END_REF][START_REF] Cobbaert | Experimental restoration of a fen plant community after peat mining[END_REF]), native species transplantation [START_REF] Cooper | Restoring the Vegetation of Mined Peatlands in the Southern Rocky Mountains of Colorado[END_REF][START_REF] Soliveres | Irrigation, organic fertilization and species successional stage modulate the response of woody seedlings to herbaceous competition in a semi-arid quarry restoration[END_REF]) and hay transfer (Hölzel & Otte 2003[START_REF] Kiehl | Effect of Hay Transfer on Long-Term Establishment of Vegetation and Grasshoppers on Former Arable Fields[END_REF]. Soil stockpiling and transposition can also be used, particularly for the rehabilitation of quarries and mines following exploitation [START_REF] Ramsay | Bulk soil handling for quarry restoration[END_REF][START_REF] Rokich | Topsoil Handling and Storage Effects on Woodland Restoration in Western Australia[END_REF], Koch 2007[START_REF] Rivera | The fate of herbaceous seeds during topsoil stockpiling : Restoration potential of seed banks[END_REF]. Environmental legislation usually requires that the original surface soils be conserved and replaced, and this is partly because they may contain propagules. In Brazil, despite the legal requirement to produce recovery plans, current practices are only partially effective (Neri & Sanchez 2010), and it has long been standard practice to mix topsoil with sterile soil (Griffith & Toy 2001, Toy & Griffith 2001).

At the same time, it is common for topsoil stockpiles to exhibit loss of viable seed and non-negligible reduction in germination potential as a function of storage time [START_REF] Rivera | The fate of herbaceous seeds during topsoil stockpiling : Restoration potential of seed banks[END_REF]. All of these factors underscore the need for alternative restoration techniques.

In recent decades, especially in Europe, hay transfer (i.e. diaspore transfer with plant material) has been increasingly tested as a supplementary technique for overcoming the dispersal limitations of target species (Hölzel & Otte 2003, Kiehl et al. 2010, Baasch et Chapter 3 -Resilience and restoration of campos rupestres 97 al. 2012). Hay transfer has some advantages, such as potentially allowing the introduction of the entire species-pool of the desired community (Rasran et al. 2006), preserving genetic integrity, improving seedling recruitment by the creation of a safer site (e.g. shade), and having a relatively low implementation cost when compared to direct seeding (Hölzel & Otte 2003). This technique has already been used on various grassland types, such as calcareous grasslands [START_REF] Kiehl | Effect of Hay Transfer on Long-Term Establishment of Vegetation and Grasshoppers on Former Arable Fields[END_REF], flood meadows (Hölzel & Otte 2003;[START_REF] Donath | Large scale application of diaspore transfer with plant material in restoration practice -Impact of seed and microsite limitation[END_REF]), chalk grasslands [START_REF] Edwards | Hay strewing, brush harvesting of seed and soil disturbance as tools for the enhancement of botanical diversity in grasslands[END_REF], magnesian limestone grasslands [START_REF] Craft | Restoration of Magnesian Limestone Grassland : Optimizing the Time for Seed Collection by Vacuum Harvesting[END_REF]), fen meadows [START_REF] Patzelt | Restoration of Wet Fen Meadows by Topsoil Removal : Vegetation Development and Germination Biology of Fen Species[END_REF][START_REF] Klimkowska | Vegetation Re-development After Fen Meadow Restoration by Topsoil Removal and Hay Transfer[END_REF]), peatlands [START_REF] Graf | Techniques for restoring fen vegetation on cut-away peatlands in North America[END_REF], dry grasslands (Baasch et al. 2012), and Mediterranean steppe [START_REF] Coiffait-Gombault | Hay Transfer Promotes Establishment of Mediterranean Steppe Vegetation on Soil Disturbed[END_REF]. However, we are not aware of its use in restoring degraded tropical grasslands. Hay transfer can be used whether the donor grasslands are dominated by perennial species (Hölzel & Otte 2003) or by annual species [START_REF] Coiffait-Gombault | Hay Transfer Promotes Establishment of Mediterranean Steppe Vegetation on Soil Disturbed[END_REF], and the technique is well adapted to restoring plant communities with limited natural regeneration (i.e. from seed banks or seed rain) but only one pilot study has been carried out in tropical grasslands [START_REF] Stradic | Restoration of rupestrian fields, physiognomy of Cerrado threatened by land use changes[END_REF].

Campos rupestres are species-rich tropical grasslands and one of the physiognomies of the Cerrado (Brazilian savanna), representing c.a. 130 000 km 2 (Barbosa 2012), and are found at altitudes ranging from 800m to 2 000m. They are composed of a mosaic of stony and sandy grasslands, bogs situated along streams, and scattered rocky outcrops that harbour small sclerophyllous evergreen shrubs and sub-shrubs (Giulietti et al. 1997, Chapter 1). Campos rupestres are constrained ecosystems with shallow soils that are nutrient-poor and highly acidic [START_REF] Ribeiro | Patterns of abundance of a narrow endemic species in a tropical and infertile montane habitat[END_REF], Benites et al. 2007, Chapter 1). They also comprise highly diverse vegetation with one of the highest levels of endemism in Brazil (Giulietti et al. 1997, Echternacht et al. 2011[START_REF] Carvalho | The mosaic of habitats in the high-altitude Brazilian rupestrian fields is a hotspot for arbuscular mycorrhizal fungi[END_REF].

As many mountain grasslands, they play a major role in water quality control over entire large watersheds. While campos rupestres are encountered in a region impacted by increasing mining operations, virtually nothing is known about their resilience and restoration (Le [START_REF] Stradic | Réintroduction et impacts sur leur environnement de plantes indigènes du Cerrado[END_REF][START_REF] Stradic | Restoration of rupestrian fields, physiognomy of Cerrado threatened by land use changes[END_REF]. Moreover, mountain grasslands are known to be poorly resilient to disturbances and therefore usually require restoration once they have been degraded [START_REF] Urbanska | High-elevation ecosystem, in: Handbook of ecological restoration: principles of restoration[END_REF].

Within this context, the present study was designed to quantitatively evaluate the resilience of these tropical grasslands, to provide a description of these sites' limitations Chapter 3 -Resilience and restoration of campos rupestres 98 (i.e. in terms of the chemical characteristics of degraded soils compared to the reference soil), and to provide an assessment of the potential for regeneration in such sites via the seed bank. We expected these rich grasslands to be poorly resilient in the face of quarrying as it was already assumed by some authors [START_REF] Negreiros | Caracterização fisico-quimica de solos quartziticos degradados e areas adjacentes de campo rupetsre na Serra do Cipo, MG, Brasil[END_REF]). In addition, because [START_REF] Burnside | Habitat suitability modelling for calcareous grassland restoration on the South Downs, United Kingdom[END_REF] have noted previously that reinstallation from soil seed bank alone is often insufficient (see also Medina & Fernandes 2007, Appendix 4), we were interested in testing hay transfer as an alternative means of restoring these two peculiar grasslands.

Material and Methods

Study area

Our study area is located in the southern portion of the Espinhaço Range, approximately 100 km northeast of Belo Horizonte, in the state of Minas Gerais; the area is within the Environmental Protected Area (Area de Proteção Ambiental in Portuguese) of Morro da Pedreira, a buffer zone of the Serra do Cipó National Park. The climate in this area is classified as Cwb according to the Köppen's system, exhibiting warm, wet summers and dry winters. It is markedly seasonal, with two distinguishable seasons: a rainy season from November to April and a dry one from May to October. The study area mean annual precipitation is 1622 mm and its mean annual temperature is 21.2°C (Madeira & Fernandes 1999).

Reference ecosystem -The main herbaceous plant communities of campos rupestres, namely the sandy and stony grasslands (Chapter 1) (Figure 14), were taken as the reference ecosystems for this study. They are species-rich, and mainly composed of Poaceae (Paspalum, Mesosetum, Axonopus, Andropogon) and Cyperaceae (Lagenocarpus, Rhynchospora, Bulbostylis), with Xyridaceae (Xyris), Eriocaulaceae (Paepalanthus, Leiothrix, Syngonanthus) and Velloziaceae (Vellozia, Barbacenia), together with some forbs and sub-shrub species belonging to Asteraceae (Lychnophora, Richterago) or Melastomataceae (Lavoisiera, Marcetia) among others. The majority of the species are perennial and hemicryptophytes (Chapter 1).

Degraded areas -Three kinds of areas degraded by quarrying were selected: (i) three with stony substrates (DSt), (ii) three with sandy substrates (DSa) and (iii) three with latosol substrates (DL) (Figure 16). Studies had reported the presence of degraded areas in the region as early as 1996 (Negreiro et al. 2011), but the overall start of degradation may actually date back to 1980. In 2002, a new disturbance occurred when highway MG010 was asphalted. Degraded areas found along the road were exploited for gravel and/or were used to park machines. When the road was complete, the degraded areas left behind represented several kinds of substrate. Small quarries are common in the region and their creation leas to vegetation being destroyed and soils being disturbed. Even when exploitation stops, soils are not entirely restituted, and they may be heavily contaminated by construction debris. All of these degraded areas are surrounded by pristine campos rupestres, that is why we chose them as the reference ecosystem.

Resilience of the campos rupestres

2.2.1.Vegetation

In order to assess the resilience of the vegetation on the degraded areas, we compared the plant community composition in the reference ecosystem with that of the degraded areas eight years after the end of quarrying. Plant surveys were carried out in January 2010 in the following six reference grasslands: 3 stony (St) and 3 sandy grasslands (Sa).

Surveys were also conducted in all degraded areas (3 kind of areas × 3 sites=9 total).

For each site, 24 plots of 40cm × 40cm (0.16m 2 ) were investigated in order to record (1) a list of the species, (2) the percent cover of each species as visually estimated from the vertical projection of all aerial plant parts.

2.2.2.Soils

In order to assess the resilience of soil chemistry in the degraded areas, three soil samples were taken at each site (reference and degraded) and dried prior to analysis (n = 3 samples x 15 sites). Each soil sample consisted of three pooled sub-samples randomly taken from each site. To assess soil texture the coarse fraction was first separated through a 2mm mesh sieve. On the fine fraction (<2mm), physical (soil texture) and chemical (pH, C org , total N, P, K, Mg 2+ , Ca 2+ , Al 3+ ) soil analyses were run, from which chemical concentrations were derived as follows: P and K in mg/dm 3 , N and C in dag/kg, Mg 2+ , Al 3+ , Ca 2+ in cmol c /dm 3 , Organic Carbon (C. org ) in dag/kg. P, Na and K were analysed using the Mehlich 1 extraction method, Ca 2+ , Mg 2+ , Al 3+ using 1 mol/L KCl extraction, and C org following the Walkley-Black method. Soil sampling was carried Chapter 3 -Resilience and restoration of campos rupestres 100 out during the rainy season (February). Analyses were conducted at the Soil Laboratory of the Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil.

2.2.3.Seed banks

In order to assess potential of regeneration from the seed bank, we studied the seed banks of the reference grasslands (n=6). We also made an effort to find out what species may have colonized the degraded sites, without fully establishing themselves in the years following 2002, by studying the seed banks of the degraded areas (n=9). At each site, five 1L soil samples were taken at the end of the dry season (September), April to July being the peak period of fruit production (Chapter 2) (n = 5 samples × 15 sites). Each sample consisted of 10 pooled sub-samples, randomly taken at each site to overcome seed bank heterogeneity. Samples were washed with water on sieves with 4 mm and 200 µm mesh sizes to remove 1) plant fragments and stones and 2) the finest soil fraction (clay and silt) respectively. The remaining seed-containing soil was spread as a thin layer on trays (25cm x 35cm) on compresses placed over a 3 cm thick layer of vermiculite (a neutral substrate). Control trays (n=3) (made of compresses over vermiculite) and controls of the finest soil fraction (<200 µm) (n=3) (made of the finest fraction spread out on compresses over vermiculite) were also set in order to 1) ensure that no species could colonize the greenhouse and contaminate samples and 2) ensure that no seed <200 µm may have been lost to sieving. No seeds were found to germinate in the finest soil fraction or in any of the control trays. All trays were kept in a greenhouse, were regularly moved, and were watered. Emerging seedlings were identified on a weekly basis and removed or replanted in pots for later identification. This was done to minimize competition within the trays and to reduce susceptibility to the emission of allelopathic substances. If no germinations were observed for a period of one month, the samples were each dried and microplowed before initiating a second, fresh germination period, this procedure being a well-known technique for stimulating additional germination (Roberts 1981).

Restoration using hay transfer

The hay was collected monthly during 10 months to maximize seed pool (January 2010 -October 2010) on two donor sites for each kind of reference grasslands (two sandy and two stony grasslands). Once a month, hay was manually mown with a scythe and immediately collected using hand vacuum equipment of a variety normally used to suck The samples taken on various dates were mixed together prior to sowing. Sowing occurred in December 2010 during the rainy season. For each of the designated plots, 120g of hay was applied on 40cm × 40cm quadrats (i.e. 750 g/m2). This weight is similar to the biomass of hay that was dispersed during previous experiments in Northern Europe [START_REF] Kiehl | Effect of Hay Transfer on Long-Term Establishment of Vegetation and Grasshoppers on Former Arable Fields[END_REF]. Each treatment was replicated four times at each site in blocks (Figure 29). Prior to spreading the hay, the soil was lightly harrowed in order to improve seed adherence. This was also done on the control plots onto which no hay was transferred. All quadrats were watered (0.5 liters/quadrat), before and after sowing in order to assist the germination and facilitate the adherence of the seeds to the soil.

Two experiments were set up (Figure 29):

A) The aim of the first experiment was to assess the influence that the type of degraded area has on seedling emergence. We manipulated 2 or 3 levels of 3 treatments in a multifactorial experiment: (i) substrates of the degraded areas (Latosol (DL)/sandy (DSa)/stony (DSt)), (ii) with/without geotextile (G/wg) in order to try to improve microsite conditions for germination (i.e. potentially increased shade for germinating seeds, increased moisture and reduced the impact of rain on the soil), (iii) hay from sandy donor grasslands (HSa)/no hay (h, control) (i.e. hay provides seeds but the plant parts included in the hay also potentially increase shade, increase moisture and might slightly reduce the impact of rain on the soil).

B) The goal of the second experiment was to test the effect of the origin of the hay in order to restore both kinds of reference grasslands. On stony substrates, in addition to performing the first experiment, we spread out 120g of hay collected on stony donor grasslands (HSt) with/without geotextile (G/wg). As controls, the same protocol was repeated in reference areas of sandy (3 sites) and stony (3 sites) grasslands. Hay was spread out as follows: hay from stony donor sites on stony grasslands and hay from sandy donor sites on sandy grasslands (Figure 29).

In order to assess the composition and seed abundance in the hay, six 120g samples of each kind of hay were sown in a greenhouse. Each sample was spread out in two trays of 35cm × 22cm on gauze-covered substrate composed 50% of potting soil and 50% of vermiculite. Half of the trays were covered with geotextile to test the impact of geotextile on germination. Six trays containing only substrate was installed to control seed contamination, and half of them were covered with geotextile. Trays were watered several times per week and regularly moved. Seedlings were identified, counted and Chapter 3 -Resilience and restoration of campos rupestres 103 removed to avoid competition. Three 120g samples of each kind of hay were also selected to perform a manual counting of seeds.

To assess the success of these restoration treatments, vegetation surveys were carried out in the field on all 40cm × 40cm quadrats in February 2012 (t 14 =14 months). In all quadrats, (1) a list of the species, (2) the number of seedlings per species (3) the respective percent covers of bare ground, litter, and vegetation were recorded.

Statistical analysis

2.4.1.Resilience

To assess plant dissimilarity between the different types of areas (Sa, St, DL, DSa and DSt), a dissimilarity matrix using Bray-curtis indices based on species percent cover data was calculated and an ANOSIM was performed. A Correspondence Analysis (CA) on the plant percent cover recorded in January 2010 (288 quadrats × 178 species) was performed to identify groups and establish community types.

To compare soil fine fraction and soil chemical composition between types of areas, oneway nested ANOVAs were performed, followed by Tukey post-hoc tests when significant. Normality and variance homogeneity were checked and the root square transformation was applied wherever necessary [START_REF] Sokal | Biometry: the principles and practice of statistics in biological research[END_REF]. To analyse the soil coarse fraction between these areas, Kruskal-Wallis tests were performed, as variances were not homogenous, and this was followed by Wilcoxon tests with the Bonferroni correction when significant.

To analyse the number of species and the number of germinated seeds in the seed banks, GLM models for total germinated seeds per litre of soil as well as for total species richness found per site were built assuming a Poisson distribution of errors and a logarithmic link function [START_REF] Mccullagh | Generalized Linear Models[END_REF]Nelder 1989, Crawley 2007). A dissimilarity matrix using Jaccard index, based on species presence/absence data was calculated to assess the plant composition dissimilarity between the different seed banks (i.e. from St/Sa/DL/DSa/DSt), and an ANOSIM was performed. We also performed Spearman's correlation test to determine whether there exists a relationship between the number of seeds in the seed bank at each site and the proximity of each site either to undisturbed campos rupestres areas or to the road.

.Restoration using hay transfer

To evaluate the effect of restoration treatments on vegetation cover, one-way nested ANOVAs, followed by Tukey post-hoc tests when significant, were performed on vegetation percent cover among sites. An ANOSIM was performed to estimate the similarity/dissimilarity between the different areas, using Bray-curtis indices based on species abundance. Finally, a Correspondence Analysis (CA) was performed based on the abundance of plant species recorded in February 2012 (T=14 months; 232 points × 161 species) to visualise groups and to establish community type. The effect on seedling number of (a) type of substrate, (b) geotextile and, (c) type of hay were tested using generalized linear mixed model, (LMER) assuming a Poisson error distribution and using a log link function [START_REF] Crawley | The R Book[END_REF]. Fixed effects were type of substrate, geotextile and type of hay, whereas the random effects were sites and replicates [START_REF] Crawley | The R Book[END_REF]).

Generalized linear model (GLM) was then used to specifically compare the number of seedlings per quadrat according to the substrate, the type of hay, or the presence of geotextile.

All analyses were carried out in R version 2.9.1 (R Core Development Team, 2010) using ADE-4 and stats packages.

3.Results

Resilience of the campos rupestres

Eight years following their respective disturbances, the degraded sites presented large areas of bare ground, comprising 91 ± 2% in degraded areas with latosol substrate, 77 ± 2% in degraded areas with stony substrate and 97.5 ± 0.5% in degraded areas with sandy substrate. The composition of the vegetation on degraded areas was consequently very different from that in the reference campos rupestres (ANOSIM R=0.45, p<0.001, Table 12). Aside from the obvious large differences, the stony degraded areas actually presented a few similarities with the reference ecosystems, having common species, such as Mesosetum loliiforme, Rhynchospora consanguinea, Echinolaena inflexa or Marcetia taxifolia (Table 12, Figure 30). By contrast, the other types of degraded areas presented a plant composition completely different from that of the reference ecosystems (Bray-curtis indices = 1.00, Table 12). According to the Correspondence Analysis, the plant composition of each type of degraded area depended upon on the particular substrate, and a large heterogeneity was found within the sites of each type of degraded area (Figure 30). Numerous ruderal species are found on the degraded areas, such as Andropogon bicornis, Chamaecrista rotundifolia or Zornia reticulata.

Table 12: Dissimilarity matrix (Bray-curtis indices) of the plant composition between the degraded areas: with Latosol substrate (DL), stony substrate (DSt) and sandy substrate (DSa) and the reference grasslands: the sandy (Sa) and the stony (St) grasslands, based on species percent cover data (n=3 sites x 5 types of areas).

DL

Vegetation establishment limitation

3.2.1.Site limitation

As expected, soil texture varied among the areas: both reference stony grasslands and degraded areas with latosol and stony substrates presented a significantly larger proportion of coarse soil (soil > 2mm): more than 46% (Table 13). Sandy grasslands were characterized by a significantly higher proportion of fine sand (>46%), and degraded areas were defined by a greater portion of silt (>36%), while in the latosol degraded areas we recorded higher percentage of clay (>33%) (Table 13).

In the reference grasslands, N concentrations were significantly higher and the soil was more acidic than that of the degraded areas (Table 14, Figure 31). The reference stony grasslands were characterized by higher K and C org content (Figure 31). Degraded areas having a latosol substrate presented the biggest difference in soil composition, having

Chapter 3 -Resilience and restoration of campos rupestres 107 high Ca 2+ and Mg 2+ concentrations, a much higher pH than the other areas. These areas presented also a higher P concentration than the other degraded areas, with stony and sandy substrates. The aluminum concentrations did not vary between the different types of area, although a tendency for higher aluminum concentrations in degraded areas with latosol substrate was found (Table 14, Figure 31).

Table 13: Mean and standard error values of soil texture, from soils collected in reference grasslands: 3 sandy, and 3 stony grasslands, and in degraded areas: 3 latosol, 3 sandy and 3 stony (3 samples x 3 sites x 5 types of areas, n=45 See Table 3 for one-way nested ANOVA results.

3.2.2.Few viable seeds in the soils

There were many more seeds in the seed banks of the degraded areas with stony and sandy substrate than in other sites (GLM procedures p(>|Chi|)<0.001, Table 15). In the degraded areas with latosol substrates we recorded a lower number of species at each site (p(>|Chi|)<0.001, Table 15). The composition of the seed banks in the degraded areas was completely different to that in the reference grasslands (ANOSIM R=0.137, Only Mesosetum loliiforme was found both in degraded areas with stony substrate and in reference grasslands. We found no significant relationship between the number of seeds found in the seed bank of each site and the site's proximity to natural campos rupestres areas (Spearman's Rho =-0.48, p=0.18) or to the road (Spearman's Rho =-0.35, p=0.34).

Restoration using campo rupestre hay transfer

3.3.1.Vegetation cover

More than one year after the hay was transferred, vegetation cover in degraded areas was quite low in comparison to the vegetation cover found on reference grasslands (F=106.1, p<0.001) (Figure 32). Moreover, plant community composition in degraded areas was still completely different from that of reference grasslands even with hay transfer (ANOSIM R= 0.53, p<0.001, Figure 33). Axis 1 of the correspondence analysis separated the reference grasslands from the degraded areas while axis 2 underlined a high heterogeneity among the degraded areas, each one characterized by its own plant composition (Figure 33), still mainly composed by ruderal species. No effect due to hay transfer was observed. Some quadrats received hay and some not and some had geotextile and some not. Projection of the two first axes, axis 1 (17.2%) and axis 2 (14.2%). Inertia=0.23, p<0.001, Monte-Carlo permutations.

3.3.2.Effect of substrate on the number of seedlings

Substrate type in the degraded areas had a major effect on the total number of seedlings. Fourteen months after the beginning of the experiment, quadrats on latosol substrate (DL) recorded many fewer seedlings (4.0 ± 0.6) than quadrats on sandy substrates (DSa) (25.1 ± 4.4) and stony substrates (DSt) (27.7 ± 3.7) which had the highest number of seedlings (LMER procedures with z=2.1, p=0.03). Like quadrats in the latosol substrate, those in reference sandy grasslands (Sa) recorded few seedlings (Figure 34). There was a significant interaction between substrate and hay (z=3.64, p<0.001): quadrats with hay (HSa) recorded lower seedlings on degraded sandy grasslands (DSa). Geotextile alone generally did not influence the number of seedlings per quadrat (18.6 ± 3.3 on quadrat with geotextile and 19.3 ± 2.7 on quadrat without Chapter 3 -Resilience and restoration of campos rupestres 112 geotextile, LMER procedures z= 0.64, p=0.52). However there was a significant interaction between substrate and geotextile (z=-1.91, p=0.05): on the reference sandy grasslands (Sa), quadrats with geotextile recorded more seedlings (Figure 34). Hay did not seem to influence the number of seedlings per quadrat (z=0.33, p=0.74). Finally, we found a significant interaction between the substrate, the type of hay and the geotextile: on degraded stony (DSt) and sandy substrates (DSa), quadrats without hay and with geotextile recorded more seedlings (36.6 ± 13.9 on sandy substrates and 31.5 ± 9.9 on stony substrates, z=-3.17 for degraded sandy substrates and z=-2.45 on degraded stony substrates, p<0.001) (Figure 34).

3.3.3.Effect of the type of hay on the number of seedlings

As previously shown, the kind of substrate had a great influence on the number of seedlings: many more seedlings became established in the stony degraded areas (DSt) (26.7 ± 3.1) than in the reference grasslands (5.7 ± 0.8 in reference sandy grasslands

Chapter 3 -Resilience and restoration of campos rupestres 113 (Sa) and 7.6 ± 1.00 in reference stony grasslands (St), LMER procedure p(>|Chi|)<0.01, Figure 35). Considering only the stony degraded substrate (DSt), where two kinds of hay were spread, there were more seedlings on quadrats without hay (z=4.39 p<0.001) while lower numbers of seedlings were counted on quadrats where hay from stony grasslands was spread (z=-2.27, p<0.05). Geotextile had a negative overall effect on seedling recruitment (z=4.10 p<0.001). However, there was a significant interaction between the type of hay and geotextile: with no hay (i.e. control quadrats), more seedlings per quadrat were found with geotextile (31.5 ± 9.8). On the contrary, on quadrats with hay, the highest number of seedlings per quadrat was found without geotextile (30.8 ± 8.8 and 31.5 ± 8.9 respectively with hay from sandy and stony grasslands, LMER procedure z=7.12, p<0.001) (Figure 35). On the reference stony grasslands, hay had a negative impact on the number of seedlings (LMER procedure z=-2.87 p=0.004), as did geotextile, which decreased the number of seedlings (z=2.21 p=0.02) (Figure 35). On the reference sandy grasslands, hay did not influence on the number of seedlings (z=-0.88 p=0.37), while geotextile had a positive impact on seedling establishment (z=-2.06 p=0.03) (Figure 35).

3.3.4.Limitation

The hay collected in stony donor grasslands had fewer seeds than the hay collected in sandy donor grasslands (157 ± 26 seeds vs. 361 ± 102 seeds in 120g of hay, GLM procedures z=-15.12, p<0.001). Both hays were mainly composed of Cyperaceae (Rhynchospora sp. and Lagenocarpus sp.), Poaceaea and Xyridaceae. Hay spread in control trays in the greenhouse recorded only a single, unique germination (Diplusodon orbicularis) from hay collected on stony grasslands.

4.Discussion

Resilience of campos rupestres

According to the stability-diversity hypothesis, biodiversity should promote resistance and resilience to disturbance [START_REF] Mcnaughton | Diversity and stability of ecoogical communities: a comment on the role of empiricism in Ecology[END_REF][START_REF] Pimm | The complexity and stability of ecosystems[END_REF][START_REF] Tilman | Biodiversity and stability in grasslands[END_REF].

While some studies have demonstrated that the campos rupestres are particularly tenuifolius, or Vellozia caruncularis (Chapter 1), did not recolonize the degraded areas although large populations of them occurred in adjacent campos rupestres. Various hypotheses could explain the lack of regeneration in such degraded areas [START_REF] Bradshaw | The use of natural processes in reclamation -advantages and difficulties[END_REF][START_REF] Campbell | Determining the immigration potential of plants colonizing disturbed environments : the case of milled peatlands in Quebec[END_REF]): i) species in the surroundings do not produce seeds, but we already showed that seeds are produced on the surrounding (Chapter 2); ii) these seeds do not disperse far enough to reach degraded sites; iii) dispersed seeds arrive to degraded areas but do not germinate or are not viable; iv) dispersed seeds are able to

Chapter 3 -Resilience and restoration of campos rupestres 115 germinate but the development of seedlings are hampered by constrained abiotic environmental conditions or lack the of symbiotic interaction with facilitating arbuscular mycorrhizal fungi (AMF) [START_REF] Carvalho | The mosaic of habitats in the high-altitude Brazilian rupestrian fields is a hotspot for arbuscular mycorrhizal fungi[END_REF].

Site conditions are regularly pointed out as a factor which hampers the resilience of a given ecosystem. Quarrying has strongly impacted soil composition of degraded areas, which is poorer in nitrogen and organic carbon, both of which are essential elements to plant growth. The reference grasslands are oligotrophic with low phosphorus and potassium [START_REF] Ribeiro | Patterns of abundance of a narrow endemic species in a tropical and infertile montane habitat[END_REF], Benites et al. 2007, Chapter 1); similarly degraded areas are also characterized by extremely low potassium and phosphorus, except latosol degraded areas, which tend to have higher phosphorus content together with higher magnesium and calcium and pH less acidic. Whereas there is little fine sand in the degraded areas having a latosol substrate, we noted a higher proportion of clay and silt in these areas. These elements may be related not only to a higher capacity of nutrient retention, but also to a higher compaction of the soil, which is somewhat unfavorable to plant establishment. By contrast, the two other degraded areas (i.e. with stony and sandy substrates) presented a soil composition that as more similar to that of the reference grasslands. The higher proportion of silt was not linked to a general increase in nutritional content; on the contrary, lower nitrogen and organic carbon content were found to better characterize these soils.

The fact that vegetation composition of campos rupestres is highly related to soil composition [START_REF] Ribeiro | Patterns of abundance of a narrow endemic species in a tropical and infertile montane habitat[END_REF] 116 habitats, such as some nearby gallery forests (Medina and Fernandes 2007). In European grasslands, Bekker et al. (1997) noted that usually species associated with poor nutrient conditions were relatively scarce in the seed bank. Moreover, the severe five-month dry season can lead to unfavorable environmental conditions for seed bank formation; indeed, wetter sites typically record the largest number of seeds in mountain communities (Funes et al. 2001). The ability to form a seed bank seems to vary in campos rupestres: while some species appear not to form seed banks (Velten & Garcia 2007), others may form only a small persistent seed bank (Velten & Garcia 2007, Giorni 2009, Silveira 2011). The diminished seed banks might be associated with the low quantity of annuals, which are obligate seeder species, in campos rupestres where perennial species are dominant (Chapter 1). However, in German grasslands, Hölzel & Otte (2004) found large proportion of perennial species with a strong tendency for seed accumulation in the soil. In addition, the lower density of emergences could also reflect the large quantity of dormant seeds reported before for some campo rupestre species (Gomes et al. 2001, Silveira & Fernandes 2006, Garcia et al. 2011, Silveira et al. 2012a).

Eight years after the end of the disturbance, the seed banks of degraded areas are rich in species and seeds but mainly composed by non-target species (i.e. ruderal species), while target species, such as Tatianyx arnacites, Lagenocarpus rigidus subsp. tenuifolius or Rhynchospora riedeliana are absent although forming seed bank on reference grasslands. As previously discussed, campos rupestres species are not likely to form seed banks, and the type of the disturbance studied here (i.e. quarrying) does not leave much hope for the conservation of a seed bank. The absence of seeds from adjacent campos rupestres suggests that the dispersion of these species to the degraded sites is limited. Both anemochory and autochory are the main dispersal modes in campo rupestres (Conceição et al. 2007a[START_REF] Dutra | Fenologia reprodutiva, sindromes de polinização e dispersão em espécies de Leguminosae dos campos rupestres do parque estadual do Itacolomi, MInas Gerais, Brasil[END_REF]). Sedges, common on campos rupestres, are known to have buoyant seeds [START_REF] Leck | Regeneration of Cyperaceae, with particular reference to seed ecology and seed banks[END_REF] that are probably dispersed by rain and water runoff. Zoochory was also reported in Melastomataceae [START_REF] Lima | Interactions between ants and nonmyrmecochorous fruits in species of Miconia (Melastomataceae) in a Neotropical savanna[END_REF], but more studies are needed to assess the dispersion pattern in these tropical grasslands. Considering the poverty of campos rupestres species in the seed bank, it is clear that the use of bulk topsoil transposition [START_REF] Ramsay | Bulk soil handling for quarry restoration[END_REF][START_REF] Rokich | Topsoil Handling and Storage Effects on Woodland Restoration in Western Australia[END_REF], Reis et al. 2003, Koch 2007[START_REF] Rivera | The fate of herbaceous seeds during topsoil stockpiling : Restoration potential of seed banks[END_REF]) would be limited to reestablish campo rupestre vegetation in degraded areas, however this could be useful to improve edaphic conditions.

Chapter 3 -Resilience and restoration of campos rupestres 117

Restoration using campo rupestre hay transfer

Our results have shown that hay transfer is not a successful means of restoring degraded areas of campos rupestres. The method, which proved effective in Europe [START_REF] Hölzel | Restoration of a species-rich flood meadow by topsoil removal and diaspore transfer with plant material[END_REF], Kiehl et al. 2010[START_REF] Coiffait-Gombault | Hay Transfer Promotes Establishment of Mediterranean Steppe Vegetation on Soil Disturbed[END_REF], appears inapplicable to the present tropical context. More than one year after the beginning of the experiment, established vegetation on degraded sites was mainly composed by ruderal species, which had either germinated from the seed bank or had been dispersed from the ruderal species that were already established in these degraded areas. Though both hays contained large numbers of seeds, the hay from the stony grasslands contained relatively fewer seeds than the hay from the sandy grasslands. Because the vegetation in the degraded areas is very sparse, we believe that competition with ruderal species is not the reason why the grassland species that were contained in the hay were unable to establish themselves. There are several hypotheses that could be explain why vegetation composition in the degraded areas remained quite different from that in the reference ecosystems, among them: i) failure in seed germination (i.e. seed dormancy, unviable seeds, unfavorable germination conditions) and/or ii) unfavorable site conditions leading to poor seedling establishment.

Among the factors that may have hampered the success of the hay transfer, poor target site condition (such as soil nutrient status and moisture regime) is one that has already been pointed out (Hölzel & Otte 2003). The nature of the substrate also appears to be important in the present study. Low nitrogen and organic carbon content or higher pH, calcium and magnesium might explain why the seedlings did not establish. Soil structure can also limit seedling establishment since higher soil compaction, especially in degraded latosol substrates (i.e. high silt and clay content), can hamper root development (Dexter 2004). However, we noted that degraded stony substrate seems to offer better conditions to seedling establishment than other substrates. Stones have been shown to positively influence the surroundings of seedlings [START_REF] Carlucci | Nurse rocks influence forest expansion over native grassland in southern Brazil[END_REF] in dry environments i) by increasing shade, thus reducing evaporation [START_REF] Fowler | What is a safe site?: neighbor, litter, germination date and patch effects[END_REF]; ii) by allowing water condensation (especially on large stones), thus increasing soil moisture and microbial activity under stones [START_REF] Lahav | The contribution of stone cover to biological activity in the Negev Desert, Israel[END_REF]; iii) by enhancing soil moisture (Noy-Meir 2001).

Chapter 3 -Resilience and restoration of campos rupestres 118

The second hypothesis is that germination issues (i.e. unviable seeds, dormant seeds or unvaforable condition to germinate) might be responsible to the restoration failure (i.e.

species composition and seed densities). Despite the fact that the hay contained a large number of seeds, we recorded few germination events in the reference grasslands where germination conditions were supposed to be optimal. This result could not have been due to competition with the native established vegetation because we recorded only one seedling under the controlled conditions of the greenhouse. Perennial resprouter species, common in Neotropical grasslands (Hoffman 1998[START_REF] Neves | Campo rupestre recém-queimado na Chapada Diamantina , Bahia , Brasil : plantas de rebrota e sementes, com espécies endêmicas na rocha[END_REF], Fidelis et al. 2010), are expected to have fewer viable seed sets than nonsprouter species due to a likely higher genetic load among resprouters [START_REF] Lamont | Are seed set and speciation rates always low among species that resprout after fire, and why ?[END_REF]. The limited soil resources and genetic predisposition of some species to use resources for structural components rather than for seed production have also been argued already argued to explain the poor seed quality (Meney 1997 cited in Leck & Schutz 2005). Besides the presence of unviable seeds in the hay, the presence of dormant seeds could also limit germination (Gomes et al. 2001, Silveira & Fernandes 2006, Garcia et al. 2011, Silveira et al. 2012a) to a degree similar to what could be expected from having unfavorable germination conditions to begin with. On reference sandy grasslands, the geotextile had a positive effect on seedling recruitment, while on reference stony grasslands germination occurrence was impacted negatively by both hay and geotextile. In these latter grasslands the vegetation is more open, so species may not be well adapted to the shade provided by the geotextile and the plant parts of the hay [START_REF] Franco | The Cerrados of Brazil -Ecology and natural history of a neotropical savanna[END_REF]. Indeed, the small-sized seeds of the herbaceous species of campos rupestres, such as Xyridaceae, are light demanding [START_REF] Abreu | Efeito da luz e da temperatura na germinação de sementes de quatro espécies de Xyris L .(Xyridaceae) ocorrentes na Serra do Cipó, MG, Brasil[END_REF][START_REF] Oliveira | Efeitos da luz e da temperatura na germinação de sementes de Syngonanthus elegantulus Ruhland, S. elegans (Bong.) Ruhland e S. venustus Silveira (Eriocaulaceae)[END_REF]. In degraded areas, it is mainly ruderal species that germinate, and the combination of hay and geotextile was found to have a generally negative effect on seedling recruitments. However, in these areas, quadrats with geotextile alone (i.e.

without hay) recorded the highest number of seedlings.

5.Conclusion

We have shown that campos rupestres, species-rich mountain grasslands, are poorly resilient to anthropogenic disturbances, such as quarrying. The poor seed banks of the reference grasslands limit the use of only bulk topsoil transposition to re-establish campo rupestre vegetation; even if this could be suitable to improve edaphic conditions of the degraded areas. We have argued that soil alteration has prejudiced the establishment of Chapter 3 -Resilience and restoration of campos rupestres 119 native species while favoring ruderal and/or exotic species. In addition, the restricted dispersal of target species from campos rupestres serves to limit the recomposition of a seed bank and the establishment of campo rupestre communities in degraded areas.

This implies that human intervention is absolutely necessary for rapidly re-establishing the main species. Although site conditions present a barrier (i.e. soil structure and composition) to vegetation establishment, the failure of seed to germinate seems to be the primary challenge to reintroducing target species by hay transfer or seeding. Indeed shade generated by hay and geotextiles may have hampered ruderal seed germination, but other factors related to germination (i.e. seed dormancy, unviable seeds, minimum temperature to germinate, etc.) could have frustrated our target species as well. This is why germination studies of the dominant species (Poaceae, Cyperaceae) are needed in order to understand germination behavior and limitation and to improve seeding success. In the meantime, other restoration techniques (such as seedling transplantation, turf transplantation) must be tested on these ecosystems. In conclusion, the protection of these grasslands must be made a high conservation priority.

Transition to Chapter 4

Chapter 3 shows that hay transfer is not a successful way to restore degraded campos rupestres, despite the large seed input. Several hypotheses are possible to explain this failure among which a possible germination issue. Successful restoration is often limited by the lack of information on how to reintroduce propagules, as well as the biology and ecology of these propagules; the establishment of target species requires knowledge of their germination behavior [START_REF] Budelsky | Effects of moisture, temperature, and time on seed germination of five wetland Carices: implications for restoration[END_REF], Leck & Schutz 2005). The restoration of some communities depends on the availability of viable seeds and nondormant seeds; it also depends on suitable condition to germinate: some species germinating only under particular conditions (Leck & Schutz 2005).

We then assessed the germination behavior of some common species in campos rupestres (germinability and viability) as well as their response to fire-related cues.

Campos rupestres are a fire prone environment which burns from time to time. In several fire-prone environments, fire was already pointed out as a factor enhancing germination [START_REF] Keeley | The ecology of regeneration in plant communities[END_REF][START_REF] Bond | Fire as a global "herbivore": the ecology and evolution of flammable ecosystems[END_REF][START_REF] Keeley | Fire as an evolutionary pressure shaping plant traits[END_REF]). This has never been tested in campos rupestres.

___________________________ Chapter 4

Chapter 4 -Diversity of germination strategies and dormancy of graminoid and forb species of campos rupestres.

Abstract:

In ecological restoration, the lack of information regarding the ecology and the biology of the target species hinders restoration actions. Campos rupestres, one physiognomy of the Cerrado, is a fire-prone environment, and the relationship between fire and germination is poorly understood for Cerrado species and is unknown for campo rupestre species. The aim of this work is to explore the diversity of germination strategies in the herbaceous communities of the campos rupestres. We also assess the germination of seeds produced immediately following a fire. Finally, we test whether seed dormancy evolved in species that shed seeds during unfavorable conditions for seedling establishment. Fifteen abundant species were selected, belonging to the Cyperaceae, Poaceae, Velloziaceae, Xyridaceae, and Asteraceae families. Seeds were subjected to various treatments (constant 25°C as control, temperature variations, heat, water, smoke, charred wood, and germination in campo rupestre soil), their germination behavior was studied, and viability tests were performed on ungerminated seeds. Additionally, seeds from four Cyperaceae and Poaceae species that produced seeds after an August 2011 wildfire were collected and germinated at 25°C. Our results showed that herbaceous species of campos rupestres have a wide range of germination strategies; some species belonging to the Velloziaceae and Xyridaceae families produce non-dormant, fast-germinating seeds, while species of Cyperaceae and Poaceae show an extremely low, or null, germination, due to a high proportion of unviable or embryolacking seeds. Moreover, our study found virtually no evidence that fire has a direct effect on seed germination in campo rupestre species; heat and charred wood did not promote germination while smoke enhanced the germination of only one grass species, A. torta, and improved the germination (MGT and synchrony) of Xyridaceae and Velloziaceae species. On the other hand, fire seems to have a positive effect on seed production: Cyperaceae and Poaceae both produce seeds rapidly following a fire and recorded high germination in this study. Finally, we have shown that some seeds are physiologically dormant and that seed dormancy has evolved at least five times in the studied herbaceous flora of campos rupestres. Our results suggest that herbaceous seed dormancy evolved independently of phylogeny. Seed dormancy and seed bank formation are essential to understanding herbaceous germination behavior as it applies to restoration projects aimed at improving vegetation establishment in disturbed areas.

Key-words: Fire-related cues, mountain grasslands, physiological dormancy, temperature, viability Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 123

1.Introduction

Two main factors can hamper natural succession in species-rich grasslands: (1) limitations in overall site condition and (2) the lack of target species from the seed bank or the seed rain [START_REF] Bakker | Constraints in the restoration of ecological diversity in grassland and heathland communities[END_REF][START_REF] Wilson | Chapter 19. Prairies[END_REF][START_REF] Myers | Seed arrival, ecological filters, and plant species richness: a meta-analysis[END_REF]). To restore grasslands, several methods can be used to overcome the lack of seed sources on-site and the lack of seed dispersal, such as targeted sowing or hay transfer (i.e. the transfer of plant material containing diaspores) [START_REF] Kiehl | Species introduction in restoration projects -Evaluation of different techniques for the establishment of semi-natural grasslands in Central and Northwestern Europe[END_REF] or 23% of the country (Oliveira & Marquis 2002), is a species-rich and heterogeneous savanna composed by a mosaic of tropical grasslands, savannas and seasonal forests [START_REF] Batalha | O cerrado não é um bioma[END_REF]. Campos rupestres, one of the Cerrado physiognomies, are species-rich grasslands established on quartzite-derived soils, found at altitudes of between 800m and 2000m, covering around 130 000km 2 (Barbosa 2012). They are a mosaic of stony and sandy grasslands, bogs along streams, and scattered rocky outcrops with sclerophyllous evergreen shrubs and sub-shrubs [START_REF] Alves | Can campo rupestre vegetation be floristically delimited based on vascular plant genera?[END_REF], Carvalho et al. 2012, Chapter 1). They are constraint ecosystems occurring on shallow, highly acidic, and nutrient-poor soil (Benites et al. 2007, Chapter 1), and at the same time harboring a highly diverse flora with one of the highest levels of endemism in Brazil [START_REF] Alves | Plant species endemism in savanna vegetation on table mountains (Campo Rupestre) in Brazil[END_REF], 2010, Giulietti et al. 1997, Echternacht et al. 2011). Like all savannas, campos rupestres are ecosystems subjected to recurrent fires (Simon et al.

2009

), an essential factor controlling vegetation dynamic in savannas [START_REF] Sarmiento | The Ecology of neotropical savannas[END_REF], Bond et al. 2005[START_REF] Cochrane | Tropical fire ecology: climate change, land use and ecosystem dynamics[END_REF]). [START_REF] Miranda | The fire factor, in: The Cerrados of Brazil -Ecology and natural history of a neotropical savanna[END_REF] and [START_REF] Grether | Recent assembly of the Cerrado, a neotropical plant diversity hotspot, by in situ evolution of adaptations to fire[END_REF] have argued that fire serves as an ecological determinant of the Cerrado by maintaining open vegetation physiognomies such as grasslands.

Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 124 Fire can enhance plant populations or drastically damage them. In fire-prone environments plant community assemblages comprise species that are able to persist and/or to thrive in the face of repeated defoliation [START_REF] Bond | Fire as a global "herbivore": the ecology and evolution of flammable ecosystems[END_REF]. These species can be classified as (1) fire-resistant, conserving part of their aboveground biomass; (2) sprouters, recovering after fire via vegetative regeneration; and (3) seeders, germinating from the seed bank or from newly dispersed seeds (Hoffmann 1998[START_REF] Keeley | The ecology of regeneration in plant communities[END_REF][START_REF] Pausas | Plant Functional Traits in Relation to Fire in Crown-Fire Ecosystems[END_REF][START_REF] Bond | Fire as a global "herbivore": the ecology and evolution of flammable ecosystems[END_REF]. Resprouting and firetriggered seedling recruitment are among the most functionally important traits in firecontrolled environments [START_REF] Bond | Fire as a global "herbivore": the ecology and evolution of flammable ecosystems[END_REF]). In the case of obligate seeders (species which are not able to resprout after fire), regeneration from seeds is the only way to subsequently recover from disturbances. The persistence of seeder species on a site depends on: (1) the ability to produce seeds during the inter-fire period, (2) seed survival during fires, and (3) the degree to which recruitment of new individuals is enhanced by fire [START_REF] Pausas | Plant Functional Traits in Relation to Fire in Crown-Fire Ecosystems[END_REF]). Many species in fire-prone environments have some of their recruitment processes restricted to the first post-fire year [START_REF] Bond | What Limits Trees in C4 Grasslands and Savannas ?[END_REF] because they are stimulated by some fire factors. In such cases, germination is usually triggered by either heat or smoke (or charred wood), and an increase in above-ground temperatures and smoke production are the direct consequences of fire [START_REF] Keeley | Role of fire in seed germination of Woody Taxa in California Chaparral[END_REF]Fotheringham 2000, Bond &Keeley 2005).

The relationships between germination patterns and fire are well-documented in fireprone environments in Spain [START_REF] Gonzalez-Rabanal | Effect of high temperatures and ash on germination of ten species from gorse shrubland[END_REF][START_REF] Pérez-Fernández | Effect of smoke, charred wood, and nitrogenous compounds on seed germination of ten species from woodland in central-western Spain[END_REF][START_REF] Crosti | Post-fire germination: The effect of smoke on seeds of selected species from the central Mediterranean basin[END_REF]), in Australian (William & al. 2003, 2005) and African savannas [START_REF] Gashaw | Influence of heat shock on seed germination of plants from regularly burnt savanna woodlands and grasslands in Ethiopia[END_REF], Danthu et al. 2003, Dayamba et al 2008), in African fynbos [START_REF] Keeley | Convergent seed germination in South African fynbos and Californian chaparral[END_REF], and particularly in California Chaparral [START_REF] Keeley | Role of Allelopathy, Heat and Charred Wood in the Germination of Chaparral Herbs and Suffrutescents[END_REF][START_REF] Keeley | Role of fire in seed germination of Woody Taxa in California Chaparral[END_REF][START_REF] Keeley | Trace Gas Emissions and Smoke-Induced Seed Germination[END_REF], 1998[START_REF] Keeley | Convergent seed germination in South African fynbos and Californian chaparral[END_REF]. To the best of our knowledge, there is one known multi-species study (Ribeiro et al. 2012) dealing with heat shock effects on the seed germination of woody Cerrado species, but the effects of fire on the germination of herbaceous species, together with the effects of fire-related cues, remain quite elusive. In campos rupestres, germination has been studied for some of the species typical of these grasslands, such as Xyridaceae [START_REF] Abreu | Efeito da luz e da temperatura na germinação de sementes de quatro espécies de Xyris L .(Xyridaceae) ocorrentes na Serra do Cipó, MG, Brasil[END_REF], Giorni 2009[START_REF] Carvalho | The mosaic of habitats in the high-altitude Brazilian rupestrian fields is a hotspot for arbuscular mycorrhizal fungi[END_REF], Velloziaceae [START_REF] Garcia | Comportamento germinativo de tres espécies de Vellozia da Serra do Cipó, MG[END_REF], Garcia et al. 2007), Eriocaulaceae [START_REF] Oliveira | Efeitos da luz e da temperatura na germinação de sementes de Syngonanthus elegantulus Ruhland, S. elegans (Bong.) Ruhland e S. venustus Silveira (Eriocaulaceae)[END_REF], 2011[START_REF] Nunes | Epoca de maturação, dispersão, colheita e qualidade fisiologica de sementes de sempre-viva (Syngonanthus elegans (Bong.) Ruhland)[END_REF][START_REF] Schmidt | Produção e germinação de sementes de "capim dourado", Syngonanthus nitens (Bong.) Ruhland (Eriocaulaceae): implicações para o manejo[END_REF], Fabaceae (Gomes et al. 2001[START_REF] Silveira | Light and temperature influence on seed germination of Calliandra fasciculata Benth. (Leguminosae)[END_REF] Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 125Silveira & Fernandes 2006), Melastomataceae [START_REF] Ranieri | Germinação de sementes de Lavoisiera cordata cogn. e Lavoisiera francavillana cogn. (Melastomataceae) espécies simpatricas da serra do cipo, Brasil[END_REF][START_REF] Silveira | Influência da luz e da temperatura na germinação de sementes de Marcetia taxifolia (A. St.-Hil.) DC. (Melastomataceae)[END_REF], 2012, Garcia et al. 2006) and Asteraceae [START_REF] Velten | Efeitos da luz e da temperatura na germinação de sementes de Eremanthus (Asteraceae), ocorrentes na Serra do Cipó, MG, Brasil[END_REF], Garcia et al. 2006).

These studies mainly deal with the effect of light and temperature on germination, singling them out as the most important abiotic factors that control germination [START_REF] Heschel | A new role for phytochromes in temperature-dependent germination[END_REF]), though no study has been carried out to verify the impact of fire on germination.

Seed dormancy is among the most important regeneration traits of a given ecosystem.

Dormancy evolved in species/populations as a mechanism for preventing seeds from germinating under unfavorable conditions for seedling establishment [START_REF] Linkies | The evolution of seeds[END_REF], Silveira et al. 2012a). Although there has been recent progress in understanding the germination of campos rupestres species, more study of dormancy and its geographic and phylogenetic distribution is needed in order to understand the dynamics of adaptive strategies in campos rupestres flora [START_REF] Baskin | Classification, biogeography and phylogenetic relationships of seed dormancy[END_REF]. Seed dormancy in many woody flora taxa from the campos rupestres appears to be determined by phylogeny (Gomes et al. 2001, Silveira & Fernandes 2006), but the determinants of dormancy in campos rupestres herbaceous flora and the historical forces driving its evolution are essentially unknown (Garcia et al. 2011).

The aim of this work is to explore the diversity of germination strategies in the herbaceous and dominant communities of the campo rupestre flora. To accomplish this task we i) describe the baseline germination behavior at 25°C that would exist in nature, in the presence of temperature fluctuations and soil; ii) test the hypothesis that seeds respond positively to fire-related cues; iii) test the hypothesis that species producing seeds immediately after a fire experience more significant, faster, and more synchronic germination compared to regular pre-fire seeders; and finally iv) test the hypothesis that seed dormancy evolved in species shedding seeds during unfavorable conditions for seedling establishment.

2.Material and methods

Seed collection

Fifteen abundant species from campos rupestres were selected according to their importance value index (IVI), from a phytosociological study (Chapter 1), and seed

Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 126 availability. Our sample included five sedges, two grasses, four Velloziaceae, two Xyridaceae and two Asteraceae (Table 17). All species are perennial hemicryptophytes (except for Vellozia variabilis which is nanophanerophyte), have an abiotic dispersal mode, and occur in both sandy and stony grasslands (Figure 14). All species were to observed re-sprout after a fire (Chapter 1). Seeds were collected manually in 2010 from different populations and from randomly selected individuals in unburnt (for at least the past 5 years) areas in the Private Reserve Vellozia, Serra do Cipó (19°17 S; 43°33 W), in the southern part of the Espinhaço Range, Minas Gerais, Brazil. There, the climate is classified as Cwb, having a warm temperate, a cool dry season (from May to October) and a warm rainy season (from November to April), according to the Köppen system.

The mean annual precipitation is 1622 mm and the annual temperature is 21.2°C (Madeira & Fernandes 1999).

To compare seed germination between pre-fire and post-fire conditions, seeds of four herbaceous plants were collected from recently burned (experienced fire in August 2011) campos rupestres (Appendix 5). Seeds from two sedges (Bulbostylis emmerichiae and Bulbostylis paradoxa) were collected on December 2011 and seeds from two grasses (Homolepis longispicula and Paspalum pectinatum) were collected in January 2012.

Nearly 2 weeks after the fire, these plant species had already re-sprouted and produced flowers (Le Stradic, personal observation).

Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 127 Table 17: Plant list with family, plant form, distribution range, period of dissemination, mean IVI in both sandy and stony grasslands and mean relative dominance in both sandy and stony grasslands (Chapter 1). Family: P: Poaceae, C: Cyperaceae, A: Asteraceae, V: Velloziaceae and X: Xyridaceae. Plant forms: F: Forbs, G: Graminoids, Ss: Sub-shrub. Distribution range [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF][START_REF] Forzza | Lista de Espécies da Flora do Brasil[END_REF]

Germination experiments

Seeds were set up to germinate under laboratory conditions. All seeds were monitored for 30 continuous days [START_REF] Baskin | Mistakes in germination ecology and how to avoid them[END_REF]) and they were checked for germination every 24 hours and were considered germinated upon radicule emergence. For the Poaceae, we used the entire diaspore without removing accessory structures such as lemma and palea [START_REF] Baskin | Mistakes in germination ecology and how to avoid them[END_REF]). We will henceforth refer to the achenes of the Asteraceae as seeds. Seed viability was assessed on all species through seed dissection procedures followed by a tetrazolium test on fresh seeds. Five replicates of 20 seeds were cut and placed in a 1% solution of 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) for 48h under

Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 128 dark conditions in chamber at 25°C [START_REF] Peters | Tetrazolium testing handbook[END_REF].

Seeds were set to germinate in Petri dishes (five replicates of 20 seeds/treatment), covered with filter paper, and moistened with Nistatina® suspension to prevent the development of fungus. We assessed the effect of fluctuating temperatures, heat, smoke, charred wood and soil on seed germination. Seeds were placed in germination chambers kept at the constant temperature of 25°C (for the control group and the heat, smoke, charred wood, and soil treatment groups) or fluctuating temperatures of 15°C/25°C and 20°C/30°C based on a 12-hr photoperiod (with highest temperature corresponding to the daytime portion of the cycle). For the soil treatment, seeds were sown in a 1cm deep layer of soil that had been collected in the natural grasslands from randomly selected locations. We expected the soil, by retaining more water, to modify imbibition which is an essential prerequisite for germination. Seeds were exposed to 27 μmol m -2 s -1 light conditions because the small-sized seeds of the herbaceous species of campos rupestres are light-demanding [START_REF] Abreu | Efeito da luz e da temperatura na germinação de sementes de quatro espécies de Xyris L .(Xyridaceae) ocorrentes na Serra do Cipó, MG, Brasil[END_REF], Munné-Bosch et al. 2011, Oliveira & Garcia 2011).

For the heat treatment, heat shocks were used to air-dry seeds in an oven at 100°C for 5 minutes, prior to sowing [START_REF] Keeley | Role of Allelopathy, Heat and Charred Wood in the Germination of Chaparral Herbs and Suffrutescents[END_REF], Gonzãlez-Rabanal & Casal 1995[START_REF] Keeley | Convergent seed germination in South African fynbos and Californian chaparral[END_REF]. For the cold smoke treatment, smoke was obtained by burning leaves and stems of wood material and funneled by a hose into an otherwise pure water sample.

Seeds were watered using a 1:10 diluted solution of this smoked water. For the charred wood treatment, seeds were watered with 10 ml of an aqueous suspension of charred wood (Gonzãlez-Rabanal & Casal 1995, Perez Fernandez & Rodriguez 2003). This suspension was obtained from the combustion of dried plant material collected in the grasslands in order to contain representative species of the campos rupestres. A starting biomass of 408 g was burned, resulting in 50g of charred wood, and sieved (2mm). The charred wood was diluted with distilled water to a concentration of 10 g of charred wood per liter of water.

Pre-fire vs. post-fire germination

Seeds of the four post-fire germinating species were set to germinate in Petri dishes (5 replicates of 20 seeds/species), covered withfilter paper, and moistened with Nistatina® suspension. Seeds were placed in germination chambers kept only at the constant Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 129 temperature of 25°C based on a 12-hr photoperiod, and this can be considered the optimum conditions for germination in the campos rupestres (Abreu & Garci 2005, Garcia et al. 2007, Silveira et al. 2012a).

Evolutionary ecology of seed dormancy

In this study, seed dormancy is defined as the absence of germination in viable seeds that are subject to conditions that are favourable to germination [START_REF] Hilhorst | Standardizing Seed Dormancy Research[END_REF]). We used [START_REF] Baskin | A classification system for seed dormancy[END_REF] dormancy classification system and [START_REF] Baskin | Classification, biogeography and phylogenetic relationships of seed dormancy[END_REF] dichotomous key to determine seed dormancy classes. Physical dormancy implies that the seed/fruit coat is impermeable to water. To determine if diaspores were water impermeable, four replicates of 25 seeds (100 seeds for Xyris) were weighed on a digital balance before being soaked in tap water for 72h at room temperature and reweighed.

Seed permeability was determined by the increase in seed mass between dried and soaked seeds (Silveira et al. 2012a).

To better understand the evolution of seed dormancy in the herbaceous flora of campos rupestres, we built a phylogenetic tree showing relationships among the studied taxa (Appendix 6). By having a phylogenetic hypothesis for the 15 species and the reconstruction of ancestral characters, we were able to make inferences on the evolution of seed dormancy [START_REF] Forbis | The evolution of embryo size in angiosperms and other seed plants: implications for the evolution of seed dormancy[END_REF], Silveira et al. 2012a). To determine whether seed dormancy evolved in species shedding seeds under conditions unfavourable to seedling establishment, we grouped species according to the seasonal peaks in seed dispersal:

the rainy season (R -December to February), the rainy to dry transition season (RD -March-May), the dry season (D -June-August), and the dry to rainy transition season (DR -September-November), following chapter 2. The rainy-to-dry season and the beginning of the dry season were considered as unfavorable seasons for seedling establishment due to the relative scarcity of water.

Statistical analyses

For each replicate, we calculated final germination percentage, mean germination time (MGT) according to [START_REF] Labouriau | A germinação das sementes. Organização dos Estados Americanos[END_REF] and germination synchrony (Ē) [START_REF] Ranal | How and why to measure the germination process ?[END_REF]:

Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 130

 MGT  n i t i / n i i1 k  i1 k 
where  t i is the time between the start of the experiment and the i th observation,  n i is the number of germinated seeds at time i (not the accumulated number) and k is the last time of germination. For A. torta, L. linearifolius, V. caruncularis, V. epidendroides, V. resinosa, V.

 E   f i log 2 f i i1 k  with  f i  n i / n i i1 k  where  f i is
variabilis, X. obtusiuscula, and X. pilosa (other species showed low or no germination), the effect of the various treatments (25°C, 15°C/25°C, 20°C/30°C, soil, heat, smoke water and charred wood) on germination percentage were tested using GLM procedures employing a quasibinomial distribution and a logit link function. The same type of GLM was also used to study the effect of species on the percentage of viable and empty seeds. The effects of the treatments on MGT were tested using GLM procedures employing a gamma distribution and an inverse link function. To analyze  E , for each species, simple ANOVAs, followed by post-hoc tests (Tukey tests) were performed in which  E was treated as the dependent variable with and treatment as the categorical predictor. Normality and homoscedasticity assumptions were checked and a square root transformation was applied wherever necessary [START_REF] Sokal | Biometry: the principles and practice of statistics in biological research[END_REF].

To assess the differences in germination percentage between pre-fire vs. postfire species as well as the differences between pre-fire vs. post-fire Poaceae and Cyperaceae species, GLM procedures were performed, again based on the quasibinomial distribution and logit link function, and germination percentage was treated as the dependent variable. The same sort of GLM analysis was also used to test the effect of species on germination percentage. For the effect of species on MGT, we turned to a gamma distribution and inverse link function based GLM analysis similar to what was used to analyse the relationship between MGT and treatment type. This time,

Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 131 for  E , simple ANOVAs, followed by post-hoc Tukey tests were performed with  E treated as the dependent variable and species as categorical predictors. As before, normality and homoscedasticity assumptions were checked and a square root transformation was applied wherever necessary. The seed permeability study was analysed using paired t-tests to quantify the differences in biomass between dried and soaked seeds . All analyses were carried out in R version 2.9.1 (R Core Development Team, 2010).

3.Results

Intraspecific patterns of seed germination requirements

Seeds of Echinolaena inflexa, Lagenocarpus alboniger, Lagenocarpus rigidus subsp.

tenuifolius, Rhynchospora ciliolata, Rhynchospora consanguinea, Rhynchospora riedeliana , and Richterago arenaria recorded low or null germination percentage irrespective of the treatment (Table 18). Vellozia epidendroides, Vellozia resinosa and Xyris pilosa experienced a germination percentage higher than 79% at 25°C, but the 15°C/25°C fluctuating temperature treatment had a negative effect on their germination (Table 18). Xyris obtusiuscula, which germinated around 30% at 25°C, recorded a lower germination percentage when subjected to the 20°C/30°C fluctuating temperatures (10%) (Table 18). Generally speaking, fluctuating temperatures had a negative overall effect on the MGT of all species (Table 19). The 20°C/30°C fluctuating temperatures increased the germination synchrony (  E ) only for X. pilosa (Table 20). Soil had a negative effect on seeds of Lessingianthus linearifolius, V. epidendroides, and V.

resinosa, decreasing the germination percentage (Table 18), but improved the MGT of Vellozia variabilis (Table 19). Vellozia caruncularis and V. variabilis had high germination percentage (always >75% and >88% respectively) no matter the treatment (respectively F=0.87, p=0.52 and F=1.75, p=0.14) (Table 18). Germination percentage of Aristia torta which was lower at 25°C, was not negatively or positively affected by any treatment (Table 18).

Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 132 Table 18: Germination percentage (mean and standard error) for each species, according to each treatment. GLM procedures (with quasibinomial distribution) were performed for Aristida torta, Lessingianthus linearifolius, Vellozia caruncularis, Vellozia epidendroides, Vellozia resinosa, Vellozia variabilis, Xyris obtusiuscula and Xyris pilosa.

Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 133 Table 19: Mean germination time MGT in days (mean with standard error) for each species according to each treatment. GLM procedures (with Gamma distribution) were performed for Aristida torta, Lessingianthus linearifolius, Vellozia caruncularis, Vellozia epidendroides, Vellozia resinosa, Vellozia variabilis, Xyris obtusiuscula and Xyris pilosa.

Effects of fire-related cues

A. torta presented higher germination percentage (21%) with smoke water while heat decreased its germination (1%) (Table 18). The heat treatment also decreased the MGT of V. resinosa but did not affect the other species (Table 18,Table 19,Table 20). No firerelated cues affected germination percentage of L. linearifolius (Table 18). Charred wood negatively affected the germination percentage of V. epidendroides, X. obtusiuscula and X. pilosa, but increased the MGT of V. resinosa (Table 18, Table 19). In addition, smoked water improved the MGT of X. pilosa (Table 19) and increased the synchrony (  E ) for V. epidendroides, V. resinosa and X. pilosa (Table 20).

Viability

Species, such as E. inflexa, L. alboniger, R. ciliolata, and R. arenaria exhibited a seed viability rate of less than 10%. Seed viability of A. torta, R. riedeliana, L. rigidus subsp. tenuifolius, R. consanguinea, and L. linearifolius ranged from more than 10% to less than 42%, while seeds of Xyridaceae and Velloziaceae often had viability higher than 85% (GLM procedure F=75.81, p<0.001) (Table 21). Among the species with low seed viability, E. inflexa, R. ciliolata, L. linearifolius, L. alboniger, and A. torta also had many empty seeds (more than 50%; GLM procedure F=88.76, p<0.001) (Table 21). For the Xyridaceae and Velloziacaea, the percentage of empty seeds was close to 10%.

Pre-fire vs. post-fire germination

Species fruiting under pre-fire conditions (i.e. annual seeders) had germination parameters that contrasted significantly with those of species fruiting after fire occurrence. We found significant differences in all germination parameters between the two species pools. Overall, post-fire germination was characterized by higher germination percentage, low germination time, and higher synchrony (for germination percentage, GLM procedure with poisson distribution F=4.64, p<0.05, for MTG, GLM procedure with gamma distribution f=39.70, p<0.001 and for the synchrony, t-test t=-2.3, p<0.05, Appendix 7). Poaceae species flowering immediately after fire registered a higher germination percentage than Poaceae species flowering in the absence of fire (respectively 51.00% ± 9.58% and 4.50% ± 1.83%, GLM procedure, F=30.37, p<0.001).

The same pattern could be observed for Cyperaceae species for which germination percentages were improved for species flowering immediately after the fire than for Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 136 species flowering without fire (respectively 76.50% ± 5.61% and 0.00% ± 0.00%, GLM procedure, F=600.85, p<0.001). Among species fruiting after fire, Homolepis longispicula, Bulbostylis emmerichiae, and Bulbostylis paradoxa germination percentage were higher than 75%, while Paspalum pectinatum registered lower germination (Figure 36). The two grasses H. longispicula and P. pectinatum had the shortest MGT in comparison with the other species (Figure 36). The two sedges, B. emmerichiae and B. paradoxa, also presented a low MGT equivalent to those of L. linearifolius, V. caruncularis, V. variabilis, and V. resinosa (Figure 36). Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 138

Evolutionary ecology of seed dormancy

The seeds from eight of the 15 species showed germination percentages lower than 10% under conditions that are suitable for germination. However, E. inflexa, L. alboniger, R. ciliolata, and R. arenaria produced high percentages of unviable seeds and embryoless seeds (Table 21). Thus, for these four species, lack of germination is attributed to low seed quality, as opposed to seed dormancy. Dormant seeds of A. torta, L. rigiddus, R. consanguinea, and R. riedeliana in percentages ranged from 68 to 100% (Table 21). Although 29% of X. obtusiuscula seeds germinated, nearly 57% of viable seeds did not germinate (Table 21). The seeds of all five species were therefore considered dormant. The increase in seed weight after soaking in tap water ranged from 6.2 to 217%. This increase in seed weight was significant for all studied species, except X. pilosa (Appendix 8), meaning that all species produce water-permeable seed coats. Mature seeds of the five dormant species produced differentiated embryos; these seeds are therefore considered physiologically dormant (PD).

Based on the reconstructed phylogenetic tree of the studied species, non-dormant seeds were assumed to be the ancestral condition and PD seems to be a derived character Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 139 that was selected for several times throughout the evolution of the herbaceous flora of campos rupestres (Figure 37). We did not to find significant relationship between seed dormancy and the peak of seed dispersal (X 2 =0.3, p= 0.6) or between seed dormancy and the amplitude of seed dispersal (X 2 =0, p= 1). We thus conclude that seed dormancy is unrelated to dispersal phenology.

4.Discussion

The results of our study show that graminoid and forb species of campos rupestres have evolved into a great diversity of life histories represented by a variety of seed germination behaviors. There is clear difference in germination strategies among species: Vellozia and Xyris species produce non-dormant, fast-germinating seeds, other species produce dormant seeds, while species of Cyperaceae and Poaceae showed extremely low or null germination.

Fluctuating temperatures had an overall negative effect on germination percentage and tended to increase the mean germination time of most species. It has already been demonstrated that cold temperatures (<20°C) have an unfavorable effect on the germination of Xyridaceae and Velloziaceae species [START_REF] Abreu | Efeito da luz e da temperatura na germinação de sementes de quatro espécies de Xyris L .(Xyridaceae) ocorrentes na Serra do Cipó, MG, Brasil[END_REF], Garcia et al. 2007). On the other hand, studies of species from Cerrado or campos rupestres, show that alternating temperatures enhance the germination of some species, such as Syngonanthus elegantulus Ruhland, S. elegans (Bong.) Ruhland, and S. venustus

Silveira [START_REF] Oliveira | Efeitos da luz e da temperatura na germinação de sementes de Syngonanthus elegantulus Ruhland, S. elegans (Bong.) Ruhland e S. venustus Silveira (Eriocaulaceae)[END_REF], but either decreased or had no effect on the germination of species such as Eremanthus elaeagnus (Mart. ex DC.) Schultz-Bip, E.

glomerulatus Less, E. Incanus (Less.), Less. [START_REF] Velten | Efeitos da luz e da temperatura na germinação de sementes de Eremanthus (Asteraceae), ocorrentes na Serra do Cipó, MG, Brasil[END_REF], and Melastomataceae sp. [START_REF] Carreira | Germinação de sementes de espécies de Melastomataceae de Cerrado sob condições controladas de luz e temperatura[END_REF]. In addition, [START_REF] Souza | Germinação de sementes de espécies da formação arbustiva aberta na restinga de Massambaba[END_REF] observed that fluctuating temperatures of 20-35ºC and 20-40ºC increased the germination of Lagenocarpus rigidus. The closed species in our study, L. rigidus subsp. tenuifolius, and the other Cyperaceae, such as L. alboniger, R. ciliolata, and R. riedeliana, also experienced some germination under fluctuating temperatures (<5%), but had no germination under any of the other treatments. Indeed, among the 15 species tested, 7 had only sporadic germination. [START_REF] Pearson | Germination ecology of Neotropical pioneers: Interacting effects of environmental conditions and seed size[END_REF] showed that alternating temperatures favor germination in tropical large-seeded pioneers, whereas we have small-seeded non-pioneer species whose grassland habitats have only been stable for c.a. 20 000 year (Barbosa 2012). For these small-sized seeds, light is probably a more reliable cue of favorable conditions for establishment than alternating temperatures.

Since most small-sized seeds lack the reserves needed to germinate under burial conditions [START_REF] Milberg | Large-seeded species are less dependent on light for germination than small-seeded ones[END_REF], it is very likely that photoblastism evolved independently in the lineages of small-sized species from campos rupestres [START_REF] Abreu | Efeito da luz e da temperatura na germinação de sementes de quatro espécies de Xyris L .(Xyridaceae) ocorrentes na Serra do Cipó, MG, Brasil[END_REF], Garcia et al. 2007, Oliveira & Garcia 2011, Silveira et al 2012). The seeds of A. torta, L. linearifoilus, all Vellozia sp., and all Xyris sp. that we have studied are non-dormant, do

Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 141 not exhibit integument inhibition, and germinated without treatment or scarification. We propose that low temperature, rather than fluctuating temperature, is what is most responsible for decreasing germination percentage, indicating that these species probably do not germinate during the dry season when temperatures are cooler.

The rigors of the environment will be of great significance to seeds germinating under natural conditions [START_REF] Harper | The behaviour of seeds in soil: II. The germination of seeds on the surface of a water supplying substrate[END_REF]. When a dry seed enters the soil, imbibition occurs prior to germination: a seed must absorb a certain amount of water to germinate, the critical hydration level being species-specific [START_REF] Hadas | Water Uptake by Seeds as Affected by Water Stress, Capillary Conductivity, and Seed-Soil Water Contact. II. Analysis of Experimental Data[END_REF]. Water imbibition seems to be crucial to the germination of some species, such as L. linearifolius, V. epidendroides and V. resinosa suggesting consequently that these species need an important water supply to germinate, and this is provided only during the rainy season. Unlike filter paper, soil modifies moisture and water potential, delaying or inhibiting water imbibition and therefore germination. [START_REF] Harper | The behaviour of seeds in soil: II. The germination of seeds on the surface of a water supplying substrate[END_REF] demonstrate that a seed sown on a substrate germinates only if it absorbs water from that substrate more rapidly than it loses it to the atmosphere; for this to occur, the seed must make good contact with the available water, the tension on the water must be relatively low, or the surrounding atmosphere must be moist. These conditions may not have all existed simultaneously in our germination chambers. Water supply is thus an important factor in campo rupestre species germination.

Among the fire-related cues tested, heat, which is a direct effect of fire [START_REF] Keeley | The ecology of regeneration in plant communities[END_REF], had a negative effect on the germination of A. torta, but did not have any significant impact on the other species. Heat-shock-stimulated germination is common in Fabaceae, Malvaceae, or Convolvulaceae, which have hard waterimpermeable seed coats. Heat-stimulated seeds exhibit physical dormancy imposed by a dense palisade tissue [START_REF] Keeley | Role of fire in seed germination of Woody Taxa in California Chaparral[END_REF]Fotheringham 2000, Ribeiro et al. 2012); heat disrupts this tissue, resulting in increased water permeability, but this may not be the case for A. torta. All of the species we studied have water-permeable seed coats to begin with, and they do not evolve towards physical dormancy. In the campos rupestres, heat-shock stimulated germination may be restricted only to those clades/species where physical dormancy has occurred (Gomes et al. 2001, Silveira & Fernandes 2006). In addition, although the seed coats of these species are permeable, heat does not prejudice germination, indicating that our species are fire-tolerant, like those from other fire-prone grasslands in southern Brazil [START_REF] Overbeck | Fine-scale post-fire dynamics in southern Brazilian subtropical grassland[END_REF] Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 142 2007).

On the other hand, germination might be stimulated chemically by smoke or charred wood in fire-prone habitats. Charred wood effects are probably chemically-mediated, however the particulary chemical compounds in charred wood that enhance germination remain unknown [START_REF] Keeley | Role of fire in seed germination of Woody Taxa in California Chaparral[END_REF][START_REF] Pérez-Fernández | Effect of smoke, charred wood, and nitrogenous compounds on seed germination of ten species from woodland in central-western Spain[END_REF]. Unlike the species from Mediterranean-like ecosystems, our results show that charred wood inhibits or decreases the germination of seeds of X. pilosa, X. obtusiuscula, V.

epidendroides, and V. resinosa while smoked water had a positive effect on the mean germination time and/or the germination synchrony of these species, and increased the germination of A. torta. Smoke does not change imbibition ability [START_REF] Keeley | Trace Gas Emissions and Smoke-Induced Seed Germination[END_REF], 2000), however the seed-coats of smoke-stimulated species are intrinsically structurally quite different from those of heat-stimulated species: (1) the outer seed coats are highly textured, (2) the outer cuticle is poorly developed, (3) the dense palisade tissue in the seed coat is lacking, and (4) the subdermal membrane is semipermeable, allowing water passage but blocking the entry of larger solutes [START_REF] Keeley | Smoke-Induced Seed Germination in California Chaparral[END_REF]. Smoke must therefore change the characteristics of this semipermeable subdermal cuticle and allows the diffusion of solutes that would otherwise be blocked [START_REF] Keeley | Trace Gas Emissions and Smoke-Induced Seed Germination[END_REF]. [START_REF] Keeley | Trace Gas Emissions and Smoke-Induced Seed Germination[END_REF], 2000) hypothesized that the strongest and the most consistent compounds responsible for triggering germination through smoke were nitrogen oxides. Recently, a butanolide compound (karrikinolide) was designated as the chemical compound present in the smoke responsible for either triggering germination or for breaking seed dormancy [START_REF] Flematti | A Compound from Smoke That Promotes Seed Germination[END_REF], Bradshaw et al. 2011a, Long et al. 2011a[START_REF] Keeley | Fire as an evolutionary pressure shaping plant traits[END_REF].

In this study, smoke-induced germination was observed only in A. torta. Smoke also decreased the mean germination time and increased germination synchrony in most studied species. It was has been independently demonstrated that a vast array of species responds to butanolide, including species occurring in non-fire-prone environments (Long et al. 2011a,b). Bradshaw et al. (2011a) therefore suggest that organic matter decay, rather than fire, was the primary force in the development of smoke-mediated germination and that this trait probably developed early in the evolution of angiosperms. However this point is controversial [START_REF] Keeley | Fire as an evolutionary pressure shaping plant traits[END_REF], Bradshaw et al. 2011b), since 1) the evolution of angiosperms are suspected to be related to novel fire regimes during the Cretaceous [START_REF] Bond | Fire and the spread of flowering plants in the Cretaceous[END_REF]; and 2) the spread of grasslands Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 143 and savannas was promoted in part by fire later [START_REF] Bond | The importance of low atmospheric CO2 and fire in promoting the spread of grasslands and savannas[END_REF]. We therefore suppose that fire was a strong selective pressure in campos rupestres.

In the Mediterranean region, smoke and charred wood effects are similar, both increasing germination [START_REF] Keeley | Smoke-Induced Seed Germination in California Chaparral[END_REF][START_REF] Pérez-Fernández | Effect of smoke, charred wood, and nitrogenous compounds on seed germination of ten species from woodland in central-western Spain[END_REF]. In our case, effects of charred wood and smoke are antagonistic. A first hypothesis might be that the chemical compounds produced by smoke and charred wood are different and so behave differently. A second hypothesis is that some seed responses require the combination of heat and smoke application, so that only the interaction of both stimuli can affect germination [START_REF] Thomas | Interactive effects of heat shock and smoke on germination of nine species forming soil seed banks within the Sydney region[END_REF][START_REF] Thomas | Response surfaces for the combined effects of heat shock and smoke on germination of 16 species forming soil seed banks in south-east Australia[END_REF]. A third hypothesis is that our seeds need time to become sensitive to fire-related cues (Long et al. 2011a,b). The fourth, according to Bradshaw et al. (2011a), is that seed germination triggered by smoke is not a fire-adapted plant trait and our species do not present firerelated cues for germination; it is rather quite the opposite, since charred wood significantly inhibits or decreases the germination of some of our seeds.

Therefore, our study has highlighted the point that species from campos rupestres exhibit different behaviors, when faced with fire, from those of species in other fire-prone environments, such as the Mediterranean ecosystems, where some species are very sensitive to fire-related cues [START_REF] Keeley | Role of Allelopathy, Heat and Charred Wood in the Germination of Chaparral Herbs and Suffrutescents[END_REF][START_REF] Keeley | Trace Gas Emissions and Smoke-Induced Seed Germination[END_REF].

Mediterranean vegetation seems to have expanded in the late Tertiary under tropical conditions, while its origin is usually attributed to the onset of Mediterranean-type climates during the Quaternary [START_REF] Verdú | Convergent" traits of mediterranean woody plants belong to pre-mediterranean lineages[END_REF]. Pausas & Verdú (2005) noted that in the Mediterranean basin, resprouter species correspond to older lineages (Tertiary), and non-resprouters (i.e. seeders) to younger lineages occurring during the Quaternary under Mediterranean conditions. Thus, Mediterranean species present variable behavior in response to fire-related cues [START_REF] Crosti | Post-fire germination: The effect of smoke on seeds of selected species from the central Mediterranean basin[END_REF]) and consequently, in such areas, resprouting is not the only way to recover after a disturbance, much unlike campos rupestres. Indeed our results did not show many direct effects of fire on germination, despite the fact that all these species occur in a fire-prone environment, suggesting then that sprouting is the predominant mechanism for recovering after fire.

In Brazil, the large presence of resprouters has already been noted in open vegetation (Hoffman 1998[START_REF] Overbeck | Adaptive strategies in burned subtropical grassland in southern Brazil[END_REF]; after fire, resprouting provides persistence in the environment as an alternative to seedling establishment (Hoffmann Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 144 1998, Fidelis et al. 2010). Sexual regeneration of species occurring in fire-prone environment is disadvantaged by recurrent burnings because seed supply is reduced;

this is why vegetative reproduction may increase under frequent fire regimes [START_REF] Setterfield | Seedling establishment in an Australian tropical savanna : effects of seed supply , soil disturbance and fire[END_REF], Hoffmann 1998). Resprouting improves fitness in fire-prone environments only if self-replacement is unlikely when the parent dies (i.e. production of few seeds), or if post-fire conditions for seedling recruitment are unfavorable or unpredictable [START_REF] Enright | The ecological signifcance of canopy seed storage in fire prone environments: a model for non-sprouting shrubs[END_REF]. However, due to the variety of germination behaviors [START_REF] Crosti | Post-fire germination: The effect of smoke on seeds of selected species from the central Mediterranean basin[END_REF]), the lack of knowledge is a significant limitation to drawing overall conclusions since some species, which were not tested, may actually have their germination enhanced by fire.

Moreover, the differential effect of charred wood and smoked water suggest that smoke may stimulate germination of the seed bank from surrounding populations. Smoke may also favor the flowering of the surrounding population [START_REF] Lamont | Fire-stimulated flowering among resprouters and geophytes in Australia and South Africa[END_REF].

Our results also indicate that some species, such as R. ciliolata or R. arenaria, produce many well-developed embryoless seeds or unviable seeds, such as in L. rigidus subsp.

tenuifolius, R. consanguinea, or R. riedeliana. This pattern seems to be common in Cyperaceae, Asteraceae, and Poaceae from other vegetation-types [START_REF] Overbeck | Adaptive strategies in burned subtropical grassland in southern Brazil[END_REF]. All the studied species are resprouters (personnal observation).

Low fecundity among resprouters in comparison to nonsprouters has already been noted [START_REF] Lamont | Are seed set and speciation rates always low among species that resprout after fire, and why ?[END_REF], Lamont et al. 2011). Three mechanisms have been suggested

to explain these trends: resource limitation, breeding system limitation, and the genetic load [START_REF] Lamont | Are seed set and speciation rates always low among species that resprout after fire, and why ?[END_REF]. According to these authors, resource limitation could explain the low seed set but does not explain the lower viability of intact seeds. [START_REF] Lamont | Are seed set and speciation rates always low among species that resprout after fire, and why ?[END_REF] point out that there is no evidence that resprouters are always outbreeders with self-incompatibility. Finally, it has been suggested that this trend could better be explained by a high genetic load of resprouters in association with strong selfincompatibility. Deleterious somatic mutations accumulate over successive disturbance events and they could be shared when outcrossing occurs between parents; since most mutations are harmful, this gradually leads to poor fruit and seed set as the plant ages [START_REF] Lamont | Are seed set and speciation rates always low among species that resprout after fire, and why ?[END_REF], Lamont et al. 2011).

Sometimes, resprouters can be pollen-limited [START_REF] Anderson | Many to flower, few to fruit: the reproductive biology of Hamamelis virginiana (Hamamelidaceae)[END_REF]. In our case we showed that the pre-fire flowering Cyperaceae and Poaceae, which are wind-pollinated, have large numbers of unviable seeds while Velloziaceae and Xyridaceae, which are animal-pollinated, had high seed viability. However, Asteraceae species, although

Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 145 animal-pollinated, registered low germination,and had many empty seeds. More studies are needed to understand the low viability observed in common species of campos rupestres.

In fire-prone grasslands, plant species could be classified into two groups according to survival after fire: (1) the sprouters/resprouters which are able to regrow after fire from belowground organs and (2) the seeders which germinate after fire from the seed bank or from newly dispersed seeds (Hoffman 1998[START_REF] Lamont | Are seed set and speciation rates always low among species that resprout after fire, and why ?[END_REF][START_REF] Pausas | Plant Functional Traits in Relation to Fire in Crown-Fire Ecosystems[END_REF], Pausas & Verdú 2005). The 15 studied species (representing the Xyridaceae, Velloziaceae, Asteraceae, Poaceae, and Cyperaceae families), collected in areas unburnt for at least the past 5 years, belong to the first group: all resprouted after fire and there was little evidence that their seed germination is enhanced by fire. On the contrary, the non-sprouters are commonly called obligate seeders, because their establishment from seed germination is the only way they can recover. H. longispicula, P. pectinatum, B. paradoxa and B. emmerichiae, whose seeds we collected after a fire, also belong to the first group (resprouters) since they are able to re-establish rapidly by resprouting after fire. Interestingly, they also produced viable seeds after the fire, resembling the seeders, but this may indicate that the ultimate role of seeds for these resprouters might be dispersal rather than recovery. Indeed, we found Poaceae and Cyperaceae, which were collected in unburnt areas and which had a lower or null germination rate, Poaceae and Cyperaceae species collected just after fire recorded a high germination percentage with lower mean germination time. To produce, lot of flowers just after fire favors outcrossed breeding that ensures vigorous seedlings with a wide habitat tolerance [START_REF] Lamont | Are seed set and speciation rates always low among species that resprout after fire, and why ?[END_REF]. Moreover fire decreases competition and increases resource availability (i.e. water, nutrients, light, and space); the strategy of producing seeds only after fire improves the chance of establishment of these seeds.

Thus, Lamont et al. (2011) noted that a superior fitness lies with those resprouters that have high levels of vegetative recovery, and retain the ability to produce seeds since this gives greater adaptive flexibility.

Finally some species, such as A. torta, X.obtusiuscula, L. rigidus subsp. tenuifolius, R. consanguinea or R. riedeliana, had some viable seeds which did not germinate, therefore leading to the conclusion that they are dormant. Seeds of these species presented water-permeable seed coats and well-developed, differentiated embryos.

Therefore, seeds of the five dormant species (one third of total species) are

Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 146 physiologically dormant [START_REF] Baskin | Classification, biogeography and phylogenetic relationships of seed dormancy[END_REF]. Physiological dormancy occurs in the vast majority of species of sedges (Leck & Schutz 2005) and grasses [START_REF] Baskin | Evolutionary considerations of claims for physical dormancy-break by microbial action and abrasion by soil particles[END_REF], but there were no reports on primary dormancy in the Xyridaceae (despite secondary dormancy has been recently reported in Xyris; Garcia et al. 2011). Seed dormancy in temperate grasses is widely recognized [START_REF] Baskin | Evolutionary considerations of claims for physical dormancy-break by microbial action and abrasion by soil particles[END_REF] as a consequence of a chemical inhibition or mechanical resistance of glumes, lemmas and palea [START_REF] Gasque | Seed dormancy and longevity in Stipa tenacissima L.(Poaceae)[END_REF][START_REF] Baskin | Mistakes in germination ecology and how to avoid them[END_REF][START_REF] Ma | Role of endogenous hormones, glumes, endosperm and temperature on germination of Leymus chinensis (Poaceae) seeds during development[END_REF]. Since different classes of dormancy require different methods of dormancy breaking [START_REF] Hilhorst | Standardizing Seed Dormancy Research[END_REF], the determination of the dormancy class is important in providing the grounds for dormancy overcome and use of native species in the restoration of the campos rupestres.

By assuming that nondormant seeds comprise the ancestral state, we have been able to show that seed dormancy evolved at least five times in the herbaceous flora of campos rupestres. Physiologically dormant and nondormant seeds are distributed over the entire phylogenetic tree of gymnosperms, basal angiosperms, and eudicots. Linkies et al.

(2010), therefore, have proposed that the gain and loss of physiological dormancy likely occurred several times during the evolution of flowering plants. To the best of our knowledge this is the first record of primary dormancy in sedges, grasses, and xyrids in tropical mountain grasslands (Leck & Schutz 2005, Garcia et al 2011).

The evolution of seed dormancy was independent of phylogeny, indicating several and independent origins, thus lending support to the hypothesis of convergent evolution of physiological dormancy. Seasonality seems to drive seed dormancy in temperate sedges (Leck & Schutz 2005), though we did not find a correlation between seed dormancy with dispersal phenology, species geographic distribution, or any life-history trait. Our nondetection of a correlation between dormancy and life-history traits may actually be due to the small sample size (15 species). Hence, it is difficult to infer the selective pressures that drive the evolution of dormancy. Further studies on the evolution of seed dormancy, particularly if they include a large number of additional species, will be needed in order to obtain a practical framework in which the relationship between seed dormancy and species life-history can be broadly tested (see Silveira et al. 2012a).

5.Conclusion

Our results have demonstrated that herbaceous species of campos rupestres exhibit a wide range of germination strategies; some species, belonging to the Velloziaceae and Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 147

Xyridaceae families, produce non-dormant, fast-germinating seeds, while species of Cyperaceae and Poaceae show extremely low, or null, germination. Moreover, while heat and charred wood do not promote germination, smoke enhances the germination of one grass, A. torta, and improves the germination (MGT and synchrony) of Xyridaceae and Velloziaceae species. Smoke as a fire-related cue remains a controversial topic. Our study shows almost no evidence that fire has a direct effect on seed germination of campo rupestre species. Regeneration after fire occurs preferentially by re-sprouting.

Poaceae, Cyperaceae (with a pre-fire flowering) and Asteraceae species, although they represent the most abundant family of campos rupestres, were characterized by low germinability and high amount of unviable or embryoless seeds contrary to Xyridaceae and Velloziaceae. Low seed set could be explained by genetic load. On another hand fire could have a positive effect on seed production: some Cyperaceae and Poaceae resprouted and produced seeds rapidly after the fire. Such seeds had fast and high germination suggesting that these resprouters species are able to produce viable seeds in order to establish rapidly in newly available microsites. Moreover we showed that some seeds are physiologically dormant and that seed dormancy evolved at least five times in the studied herbaceous flora of campos rupestres. Our results suggested that evolution of these herbaceous seed dormancy was independent of phylogeny while seed dormancy in many woody flora taxa from the campos rupestres appears to be determined by phylogeny (Gomes et al. 2001, Silveira & Fernandes 2006). This suggests that the ecological and historical forces driving the evolution of seed dormancy differ in the woody vs. herbaceous flora. Understand herbaceous germination behavior, seed dormancy and seed bank formation is now essential in order to extent restoration project and improve vegetation establishment in disturbed areas.

Transition to Chapter 5

In chapter 4, we reported that some species had high germinability, such as Velloziaceae or Xyridaceae, while others, such as Cyperaceae or Poaceae, representing an important family in these grasslands, have embryoless, non viable or dormant seeds.

This hampers considerably the potential to use them to restore degraded areas, since both low germinability and low viability limit the value of direct seeding. Germination therefore seems to be a key issue to restore campo rupestre grasslands. However without knowledge on the germination behavior of most of the herbaceous species and faced with the difficulty to obtain seedlings from the main species from seeds, it is necessary to find other ways to reintroduce target species (Figure 38). In the next chapter (chapter 5) we tested the translocation of eight species (accessory technique to increase target species according to Török et al. 2010) as well as the translocation of vegetation turfs on degraded areas in order to restore the sandy and stony grasslands (Figure 38). Using species translocation we expected to overcome the critical phase of the establishment in the degraded areas and to improve environmental conditions bringing together soil and translocated plant. Using turf translocation, we aimed to bring to the degraded areas i) a pool of target species, ii) soil of the reference ecosystem and iii) possible associated microorganisms [START_REF] Carvalho | The mosaic of habitats in the high-altitude Brazilian rupestrian fields is a hotspot for arbuscular mycorrhizal fungi[END_REF]; overcoming therefore the environmental filter and a part of the biotic filter.

___________________________ Chapter 5

Chapter 5 -Restoration of campos rupestres:

species and turf translocation as techniques for restoring highly degraded areas.

Abstract:

The restoration of highly degraded sites usually cannot rely on natural succession. Because site conditions and dispersal are common limiting factors, ecological restoration requires active re-introduction of native species. Species and turf translocation can be a suitable method for ensuring that the desired range of species is introduced and that the issues affecting seedling establishment are overcome. In order to test these two techniques, i.e. species and turf translocation, as possible methods for the restoration of Neotropical grasslands, two experiments have been carried out. Firstly, eight herb and forb species dominant in the reference grassland ecosystems were translocated from a donor site to a degraded area with sandy substrate and to a reference sandy grassland (as a control). Two translocation periods were tested: the end of the rainy season (in March 2011) and beginning of the rainy season (in November 2011). In one of the treatments we varied the nutrient levels between the following 2 alternatives: NPK 10.10.10 and no added fertilization. Survival and growth of translocated plants were recorded every three months over a 1 year period. Among the eight transplanted species only one, the grass Paspalum erianthum, survived, grew and produced flowers. Mortality of the other species was high, probably due to the trauma of transplantation, and it was also shown that nutrient supply had a negative impact. In a second experiment, turf translocation was tested in degraded areas with sandy and stony substrates. Translocation was carried out according to the following two schemes: 1) turfs from reference sandy grasslands were transferred onto a degraded area with sandy substrate having two different 10-cm-deep turf sizes: 40x40cm and 20x20cm (n=8); 2) 10-cm-deep turfs of 20x20cm from reference sandy and stony grasslands were transferred to the stony degraded soil (n= 8). This restoration method allows the introduction of native species on the degraded areas: although the number of translocated individuals decreased during the first 3 months, it stabilized afterwards. Transplantation of large turfs makes it possible to introduce a greater number of species, and this means that a potentially bigger species source becomes available to colonize degraded areas. Turf translocation should only be used with the understanding that the extant plant communities from which donor material is drawn will be irreparably sacrificed because donor sites generally have poor resilience.

Key-words: grassland restoration, herbaceous species, re-introduction, species translocation, turf translocation.

1.Introduction

Quarry activities are harsh degradations. They fragment landscapes, strongly alter abiotic conditions, and destroy internal species pools [START_REF] Bradshaw | The use of natural processes in reclamation -advantages and difficulties[END_REF]. As a result, the ecological restoration of sites degraded in this way mainly depends on restoring adequate abiotic conditions and dispersing seedsl from surrounding sites (Bradshaw 1997[START_REF] Campbell | Determining the immigration potential of plants colonizing disturbed environments : the case of milled peatlands in Quebec[END_REF][START_REF] Shu | Natural Colonization of Plants on Five Lead/Zinc Mine Tailings in Southern China[END_REF]). In such cases, a first step usually consists of returning some soil that contains few or no undesirable species. Following that, restoration usually cannot rely on natural succession, because of the limited potential of seed dispersal, which is severely handicapped as a result of landscape fragmentation [START_REF] Ash | The introduction of native plant species on industrial waste heaps : a test of immigration and other factors affecting succession primary[END_REF], Bakker et al. 1996, Bradshaw 1997[START_REF] Bakker | Constraints in the restoration of ecological diversity in grassland and heathland communities[END_REF][START_REF] Shu | Natural Colonization of Plants on Five Lead/Zinc Mine Tailings in Southern China[END_REF][START_REF] Kiehl | Plant species introduction in ecological restoration : Possibilities and limitation[END_REF]), and/or because environmental conditions are unfavorable to seedling establishment [START_REF] Ash | The introduction of native plant species on industrial waste heaps : a test of immigration and other factors affecting succession primary[END_REF][START_REF] Yuan | Soil Formation and Vegetation Establishment on the Cliff Face of Abandoned Quarries in the Early Stages of Natural Colonization[END_REF]). Active dispersion is therefore needed to accelerate grassland colonization by target species (Hutchings & Booth 1996[START_REF] Bischoff | Dispersal and establishment of floodplain grassland species as limiting factors in restoration[END_REF], Kiehl et al. 2010, Chapter 3).

Depending on the level of degradation, restoration interventions may include seed addition [START_REF] Cooper | Restoring the Vegetation of Mined Peatlands in the Southern Rocky Mountains of Colorado[END_REF][START_REF] Turner | Influence of Polymer Seed Coatings , Soil Raking , and Time of Sowing on Seedling Performance in Post-Mining Restoration[END_REF], Kirmer et al. 2012[START_REF] Ballesteros | Vegetation recovery of gypsum quarries : short-term sowing response to different soil treatments[END_REF], native species transplantation [START_REF] Ash | The introduction of native plant species on industrial waste heaps : a test of immigration and other factors affecting succession primary[END_REF][START_REF] Fattorini | Establishment of Transplants on Machine-Graded Ski Runs Above Timberline in the Swiss Alps[END_REF][START_REF] Krautzer | Restoration of alpine ecosystems[END_REF][START_REF] Menges | Restoration demography and genetics of plants: when is a translocation successful ?[END_REF], Kiehl et al. 2010[START_REF] Godefroid | How successful are plant species reintroductions ?[END_REF][START_REF] Soliveres | Irrigation, organic fertilization and species successional stage modulate the response of woody seedlings to herbaceous competition in a semi-arid quarry restoration[END_REF], or turf or rhizome transfer [START_REF] Ash | The introduction of native plant species on industrial waste heaps : a test of immigration and other factors affecting succession primary[END_REF][START_REF] Cooper | Restoring the Vegetation of Mined Peatlands in the Southern Rocky Mountains of Colorado[END_REF]. When sowing mixtures of seeds [START_REF] Poschlod | Plant species richness in calcareous grasslands as affected by dispersability in space and time[END_REF], Hölzel & Otte 2003, Jongepierová et al. 2007, Kiehl et al. 2010, Baasch et al. 2012) fails to improve natural dispersion processes (Chapter 3), the latter reintroduction methods are used, although they are usually more expensive [START_REF] Kirmer | Near-natural restoration methods for high nature value areas[END_REF].

Transplantation can be an effective method of reintroduction [START_REF] Fattorini | Establishment of Transplants on Machine-Graded Ski Runs Above Timberline in the Swiss Alps[END_REF][START_REF] Krautzer | Restoration of alpine ecosystems[END_REF][START_REF] Menges | Restoration demography and genetics of plants: when is a translocation successful ?[END_REF], Kiehl et al. 2010[START_REF] Godefroid | How successful are plant species reintroductions ?[END_REF], and is often more effective than seeding as it bypasses the vulnerable stages of germination [START_REF] Maschinski | Using ecological theory to plan restorations of the endangered Beach jacquemontia (Convolvulaceae) in fragmented habitats[END_REF][START_REF] Guerrant | Reintroduction of rare and endangered plants: common factors, questions and approaches[END_REF][START_REF] Menges | Restoration demography and genetics of plants: when is a translocation successful ?[END_REF]. Restoration projects commonly use transplantation of native trees [START_REF] Durigan | Riparian forest restoration in cerrado, Assis, SP, Brazil[END_REF], shrub seedlings [START_REF] Soliveres | Irrigation, organic fertilization and species successional stage modulate the response of woody seedlings to herbaceous competition in a semi-arid quarry restoration[END_REF]) and/or perennial grasses [START_REF] May | Success of transplanted Alpine Tundra plants on Niwot Ridge, Colorado[END_REF], Cooper & McDonald 2000[START_REF] Mottl | Seven-Year Survival of Perennial Herbaceous Transplants in Temperate Woodland Restoration[END_REF]. Reintroduction aims to establish a species in an area which was once part of its historical range, but from which it has either been extirpated or become extinct. On the other hand, translocation is the deliberate and mediated movement of Chapter 5 -Species and turf translocation to restore campos rupestres 153 wild individuals or populations from one part of their range to another (IUCN 1998).

Species translocation occurs within two contexts, which do not necessarily imply one another: 1) in attempting to save rare and endangered species [START_REF] Milton | A Protocol for Plant Conservation by Translocation in Threatened Lowland Fynbos[END_REF][START_REF] Maschinski | Using ecological theory to plan restorations of the endangered Beach jacquemontia (Convolvulaceae) in fragmented habitats[END_REF][START_REF] Guerrant | Reintroduction of rare and endangered plants: common factors, questions and approaches[END_REF], and 2) in attempting to restore populations or communities [START_REF] Fattorini | Establishment of Transplants on Machine-Graded Ski Runs Above Timberline in the Swiss Alps[END_REF]. The main advantage of species translocation is that translocated plants reproduce and recruit more rapidly than seeded plants: the chance to establish a self-sustaining population is, as a result, greater [START_REF] Godefroid | How successful are plant species reintroductions ?[END_REF]. However, studies have already shown that some plant species are difficult to reintroduce and are therefore not suited to restoration [START_REF] Fahselt | Is transplanting an effective means of preserving vegetation ?[END_REF][START_REF] Menges | Restoration demography and genetics of plants: when is a translocation successful ?[END_REF], Godefroid et al. 2010); disturbances provide new environmental conditions, to which even some native species are not adapted, especially in the case of strong degradation [START_REF] Yuan | Soil Formation and Vegetation Establishment on the Cliff Face of Abandoned Quarries in the Early Stages of Natural Colonization[END_REF][START_REF] Negreiros | Caracterização fisico-quimica de solos quartziticos degradados e areas adjacentes de campo rupetsre na Serra do Cipo, MG, Brasil[END_REF]. In this context, other reintroduction methods must be tested.

Community translocation, also known as habitat translocation, involves the removal of an assemblage of species from one site and the attempt to establish it as a functioning community in another, receptor site [START_REF] Bullock | Community translocation in Britain: setting objectives and measuring consequences[END_REF]. Community translocation was developed primarily in Britain, and was originally intended to move, out of harm's way, communities that would otherwise have been completely destroyed by civil engineering or excavation projects [START_REF] Bullock | Community translocation in Britain: setting objectives and measuring consequences[END_REF][START_REF] Good | Translocation of Herb-Rich Grassland from a Site in Wales Prior to Opencast Coal Extraction[END_REF][START_REF] Milton | A Protocol for Plant Conservation by Translocation in Threatened Lowland Fynbos[END_REF][START_REF] Bruelheide | Evaluating the transplantation of a meadow in the Harz Mountains, Germany[END_REF][START_REF] Butt | Development of earthworm communities in translocated grasslands at Manchester Airport, UK[END_REF][START_REF] Trueman | The effects of turf translocation and other environmental variables on the vegetation of a large species-rich mesotrophic grassland[END_REF][START_REF] Box | Experimental wet heath translocation in Dorset, England[END_REF]. Maintaining the entire original community intact, without damage, is unrealistic, and this is why such projects have often focused on preserving the main features of the communities while allowing some limited damage [START_REF] Bullock | Community translocation in Britain: setting objectives and measuring consequences[END_REF][START_REF] Bruelheide | Evaluating the transplantation of a meadow in the Harz Mountains, Germany[END_REF][START_REF] Trueman | The effects of turf translocation and other environmental variables on the vegetation of a large species-rich mesotrophic grassland[END_REF]). In fact, plant communities are modified when they are translocated [START_REF] Bruelheide | Translocation of a montane meadow to simulate the potential impact of climate change[END_REF][START_REF] Klimes | Restoration of a species-rich meadow on arable land by transferring meadow blocks[END_REF][START_REF] Trueman | The effects of turf translocation and other environmental variables on the vegetation of a large species-rich mesotrophic grassland[END_REF][START_REF] Box | Experimental wet heath translocation in Dorset, England[END_REF], Pywell et al. 2011), e.g. grass cover tends to increase while forb cover tends to fall [START_REF] Conlin | Restoration of an alpine differential disturbance : Success of species in Turf transplants, Colorado, U.S.A. Arctic[END_REF][START_REF] Bay | Success of Turf Transplants in Restoring Alpine Trails, Colorado[END_REF][START_REF] Trueman | The effects of turf translocation and other environmental variables on the vegetation of a large species-rich mesotrophic grassland[END_REF]). Community translocation thus does not guarantee to maintain the spatial vegetation mosaic, which seems to be a more complicated goal to achieve [START_REF] Bruelheide | Evaluating the transplantation of a meadow in the Harz Mountains, Germany[END_REF].

Derived from community translocation, turf translocation's goal is to restore species-rich plant communities, with the aim of maximizing the final number of species in the resulting community. This method has proven successful in many grassland types [START_REF] Pywell | A comparaison of techniques for restoring heathland on abandoned farmland[END_REF][START_REF] Conlin | Restoration of an alpine differential disturbance : Success of species in Turf transplants, Colorado, U.S.A. Arctic[END_REF][START_REF] Bay | Success of Turf Transplants in Restoring Alpine Trails, Colorado[END_REF][START_REF] Kidd | Site Characteristics and Plant Community Development Following Partial Gravel Removal in an Arctic Oilfield[END_REF] Chapter 5 -Species and turf translocation to restore campos rupestres 154 [START_REF] Klimes | Restoration of a species-rich meadow on arable land by transferring meadow blocks[END_REF], Pywell et al. 2011[START_REF] Aradottir | Turf transplants for restoration of alpine vegetation: does size matter?[END_REF]): turfs are suitable for rapid establishment in damaged areas [START_REF] Krautzer | Restoration of alpine ecosystems[END_REF]) and plant survival is usually high [START_REF] Pywell | Long-term heathland restoration on former grassland: The results of a 17-year experiment[END_REF]. Small turfs are sufficient for introducing some species [START_REF] Kidd | Site Characteristics and Plant Community Development Following Partial Gravel Removal in an Arctic Oilfield[END_REF][START_REF] Klimes | Restoration of a species-rich meadow on arable land by transferring meadow blocks[END_REF][START_REF] Aradottir | Turf transplants for restoration of alpine vegetation: does size matter?[END_REF] provided those turfs can act as a species source from which new colonization occurs (Reis et al. 2003[START_REF] Klimes | Restoration of a species-rich meadow on arable land by transferring meadow blocks[END_REF]). In addition, other factors, such as vegetation type, can influence translocation success; for example, dry grasslands seem to transfer more successfully [START_REF] Bullock | Community translocation in Britain: setting objectives and measuring consequences[END_REF][START_REF] Trueman | The effects of turf translocation and other environmental variables on the vegetation of a large species-rich mesotrophic grassland[END_REF], Pywell et al. 2011) than wet meadows, and this has to do with the particular hydrological patterns associated with such systems.

While several methods of restoring temperate grasslands are demonstrably efficient and well documented [START_REF] Kiehl | Species introduction in restoration projects -Evaluation of different techniques for the establishment of semi-natural grasslands in Central and Northwestern Europe[END_REF], well-researched techniques for restoring tropical grasslands are scarce. Campos rupestres, one physiognomy of the Cerrado (Brazilian savanna), are species-rich grasslands (Giulietti et al. 1997, Echternacht et al. 2011), established on quartzite-derived soils, found at altitudes of between 800m and 2000m, and covering around 130 000km 2 of total area (Barbosa 2012). They are constraint ecosystems occurring in shallow, extremely nutrient-poor, and highly acidic soils (Benites et al. 2007, Chapter 1). They occur in a region that is attractive for mining activities; thus, they are highly threatened [START_REF] Klink | A conservação do Cerrado brasileiro[END_REF][START_REF] Hoekstra | Confronting a biome crisis: global disparities of habitat loss and protection[END_REF].

Although currently mandatory, environmental recovery practices have been only partially effective in Brazil (Neri & Sanchez 2010).

Because hay transfer proved to be an inconclusive method of restoring campos rupestres (Chapter 3), and since some important Cyperaceae and Poaceae species seeds showed low viability and germinability (Chapter 4), in the present work we opt for translocating individuals of native campo rupestre species along with vegetation turfs from reference areas (donor sites) to degraded areas (receptor sites). Our objective is to assess the effectiveness of these two restoration methods in ensuring that the desired range of species is introduced and that problems affecting seedling establishment are overcome. We have evaluated 1) the feasibility of translocating selected native species (survival and growth) and relative impact of nutrient supply and transplantation period on their survival; 2) the feasibility of translocating vegetation turfs and the comparative effects of turf size, turf origin, and degraded substrate type on translocation success (as measured by the number of surviving translocated individuals and species); 3) the resilience of grasslands from which translocated turfs were drawn in order to assess the Chapter 5 -Species and turf translocation to restore campos rupestres 155 destructive impact of the technique.

2.Material and Methods

Study area

Our study area is located in the southern portion of the Espinhaço Range, approximately 100 km northeast of Belo Horizonte, in the state of Minas Gerais, in the Environmental Protected Area (Area de Proteção Ambiental in Portuguese) of Morro da Pedreira, buffer zone to the Serra do Cipó National Park. There, the climate is classified as Cwb (C: warm temperate, w: dry winter, b: warm summer) according to the Köppen's system. It is markedly seasonal, with a warm rainy season and a cool dry one. The mean annual precipitation is 1622 mm and the annual temperature is 21.2°C (Madeira & Fernandes 1999). The sandy and the stony grasslands, which are the main herbaceous physiognomies of campos rupestres, are species-rich grasslands, dominated primarily by Poaceae, Cyperaceae and Velloziaceae (Chapter 1). Most of the species are perennial and resprouter.

Two degraded sites were selected for our experiments. Studies had reported the presence of degraded areas in the region as early as 1996 [START_REF] Negreiros | Caracterização fisico-quimica de solos quartziticos degradados e areas adjacentes de campo rupetsre na Serra do Cipo, MG, Brasil[END_REF]), but the overall start of degradation may actually date back to 1980. In 2002, a new disturbance occurred when highway MG010 was asphalted. Degraded areas found along the road were exploited for gravel and/or were used to park machines. When the road was complete, the degraded areas left behind represented two kinds of substrate: degraded sandy substrate and degraded stony substrate.

Small quarries are common in the region and their creation leas to vegetation being destroyed and soils being disturbed. Even when exploitation stops, soils are not entirely restituted, and they may be heavily contaminated by construction debris (Figure 16).

Translocation of individuals

In the first experiment, four grasses, two sedges, and two Velloziaceae all having a high dominance index in campos rupestres were chosen (Chapter 1): Tatianyx arnacites, Mesosetum exaratum, Homolepsis longispicula, Paspaslum erianthum, Lagenocarpus rigidus subsp. tenuifolius, Rhynchospora riedeliana, Vellozia resinosa, and Vellozia

Chapter 5 -Species and turf translocation to restore campos rupestres 156 epidendroides. Twenty similar-size individuals of each species were collected, with soil (around 10cm deep), in campo rupestre donor sites and transplanted to a degraded area with a sandy substrate (hereafter named degraded sandy substrate -DSa) in March 2011 (Experiment 1A, Figure 39). Of the 20 individuals, 10 were selected to receive an artificial nutrient supply (NPK: 10.10.10). As a control, 10 additional individuals of each species were translocated to an adjacent pristine area hereafter referred to as the reference sandy grassland (Sa); five of these individuals received the artificial nutrients.

In order to test the impact of the period of transplantation, new translocations were carried out in November 2011 (Experiment 1B, Figure 39). Ten individuals of each species were collected from donor grasslands and five were transplanted to the DSa and five to the Sa without fertilization. The Relative Growth Rate (RGR) was calculated for height and defined as: RGR= (Ln h 2 -Ln h 1 ) / (t 2t 1 ) where h i is the height in metres at time t i in weeks.

Turf transfer

To check whether translocation is a possible method of restoring the two campo rupestre grassland types, we transferred soil-vegetation turfs from two donor reference grasslands (i.e. a sandy (Sa) and a stony grassland (St)) to two kinds of degraded areas, one having a degraded sandy substrate (DSa), and the other, a stony substrate (DSt)).

The degraded receptor sites (DSa and DSt) were located less than 1 km from the donor sites. The soil of the receptor sites was excavated to create beds of an appropriate depth to accomodate the turfs. In the first experiment (Experiment 2A, Figure 40 Chapter 5 -Species and turf translocation to restore campos rupestres 158 of species observed on each turf, their respective number of individuals, and their respective percent cover. In addition, we monitored the vegetation recovery on the two donor reference sites on each quadrat where turf was removed on May 2012. In St, there were 32 20x20cm quadrats and in Sa there were 32 40x40cm quadrats and 32 20x20cm quadrats. For each quadrat the species list with respective number of individuals were recorded.

Statistical analysis

2.4.1.Individual translocation

To understand the influence of substrate type and nutrient supply on survival, GLM procedures using binomial errors and logit link functions were run, with survival (1 or 0) as the response variable and substrate type and nutrient supply as explicative variables.

For all GLM, site effects were removed using the offset component of the GLM procedure; offset component allows including an a-priori known component in the linear predictor during fitting (using the R package stats) [START_REF] Crawley | The R Book[END_REF]. The impact of translocation period and substrate type on survival were also assessed using the same GLM method with translocation period and substrate as explicative variables.

Due to high mortality, statistical analyses were not carried out for Lagenocarpus rigidus subsp. tenuifolius, Rhynchospora riedeliana, Mesosetum exaratum, Homolepis longispicula, Vellosia resinosa and Vellozia Epidendroides. For Paspalum erianthum, two-way ANOVA was used to evaluate the effect of substrate type and nutrient supply on height RGR between T0 and T14. Normality and homoscedasticity assumptions were checked and a square root transformation was applied [START_REF] Sokal | Biometry: the principles and practice of statistics in biological research[END_REF]. In addition, the effect of substrate type and nutrient supply on the number of new leaves was tested by GLM procedures using a poisson distribution and log link function. We also used a GLM with a poisson distribution and log link function to test the effect of substrate type and nutrient supply on the number of lost leaves in T. arnacites.

2.4.2.Turf translocation

In order to assess the impact of turf size, turf origin, translocation substrate, and time on the percentage of vegetation, a generalized linear mixed model (LMER) with a quasibinomial distribution was used, treating sites and replicates as random effects. In order to assess the impact of turf size, turf origin, substrate type, and time on the number Chapter 5 -Species and turf translocation to restore campos rupestres 159 of individuals or species occurring by turf, we used another generalized linear model having a poisson distribution, with sites and replicates once again treated as random effects. Species were classified into three plant forms: graminoids (Cyperaceae, Iridaceae, Poaceae and Xyridaceae), forbs (including Eriocaulaceae, Velloziaceae, Amaranthaceae, some Asteraceae and other forbs), and subshrubs (including Melastomataceae and some Asteraceae). The same analyses were used to study the impact of turf size, turf origin, substrate type, and time on the number of individuals in each plant form. The relationship between turf size, time, and the proportion of surviving individuals was assessed using a generalized linear mixed model with a binomial distribution and sites and replicates treated as random effects.

The effect of turf size on vegetation percentage recovery was assessed using a generalized linear mixed model employing a quasibinomial distribution and taking sites and replicates as random effects. Finally, a generalized linear mixed model with a poisson distribution and with sites and replicate taken as random effects was used to analyze the effects of substrate on the number of colonizing seedlings.

3.Results

Individual translocation

3.1.1.Effect of substrate type (natural VS. degraded substrate) and nutrient supply The first survey of species translocation was realized in June 2011 (T3) and showed a high mortality among translocated individuals. There was an overall negative effect of nutrient supply on survival (z=3.10, p<0.01), whereas substrate type of the translocation (i.e. on Sa or DSa) did not impact individual survival (z=1.78, p=0.08). At the species level, neither nutrient nor substrate type had a significant effect on survival (Table 22).

Homolepis longispicula, Rhynchospora riedeliana, Vellozia epidendroides and Vellozia resinosa registered the highest mortality, with an upper limit of only 40% of individuals surviving the first 3 months following translocation. In some cases, no individuals survived (Table 22). Among the other species, Lagenocarpus rigidus subsp. tenuifolius, and Mesosetum exaratum registered a moderate survival rate, higher than 60% in some cases (i.e. in Sa with nutrient and in DSa without added nutrients), but just exceeding 20% in the case of translocation to DSa with added nutrients (Table 22). Finally, 3

Chapter 5 -Species and turf translocation to restore campos rupestres 160 months after their translocation, individuals of Paspalum erianthum and Tatianyx arnacites recorded high survivability (>80%), no matter the treatment (Table 22).

Table 22: Number of individuals translocated in March 2011 (T0) and still surviving 3 months later in June 2011 (T3) with percent survival. Individuals were translocated to a degraded sandy area (DSa) and to a reference sandy grassland (RSa), broken into two groups, one with and added nutrient supply (N) and one without (n). To test the effect of nutrient supply and substrate type, GLM procedures were run with a binomial family distribution and logit link function. ns: non significant. 23). For Mesosetum exaratum the pattern was similar, with only 30% of individuals translocated to DSa without added nutrients surviving at T12 (Table 23). Tatianyx arnacites individuals, which had survived well in the first 3 months, recorded survival only on DSa at T9 and T12 (between 50% and 60%); all individuals translocated to Sa died (Table 23). Paspalum erianthum was the only species to survive very well one year after the translocation; s only 2 individuals died on Sa (Table 23).

Chapter 5 -Species and turf translocation to restore campos rupestres 161 However, there was an impact of the substrate on the number of new leaves: individuals translocated to DSa showed higher numbers of new leaves (z=-2.67, p<0.01), whereas nutrient supply had no effect on new leaf production (z=0.70, p=0.48). Moreover, on the DSa, 10 individuals out of 20 produced flowers 14 months after translocation, while only 1 individual out of 10 produced flowers in the reference area.

For Tatianyx arnacites, there was an impact of substrate type and nutrient supply on leaf loss, with individuals translocated to Sa showing lower leaf loss (z=-6.26, p<0.001).

Moreover, whereas nutrient supply appeared to decrease leaf loss on Sa, it actually increased leaf loss on DSa (z=4.04, p<0.001).

Turf transplantation

At T0 on the degraded sandy area (DSa), we translocated 39 species using 40x40cm turfs and 32 species using 20x20cm turfs, both from the reference sandy grasslands

Chapter 5 -Species and turf translocation to restore campos rupestres 163 (TSa). At T0, on the stony degraded area (DSt), 30 species were translocated using 20x20cm tufs from the reference sandy grassalnds (TSa) and 31 species using 20x20cm turfs from the reference stony grasslands (TSt). The percent cover of vegetation decreased with time no matter the treatment (z=-5.83, p<0.001) and was higher on TSa (z=-9.59, p<0.001), higher on bigger turfs (i.e. 40x40cm) (z=32.04, p<0.001), and higher on DSa (z=14.33, p<0.001) and ((Figure 41).

3.2.1.Effects of the turf size

This experiment was carried out on degraded sandy areas (DSa), and as expected, at T0 significantly more individuals were translocated using 40x40cm turfs (103.4 ± 4.0 individuals in 40x40cm turf and 32.4 ± 2.6 in 20x20cm turf, z=32.61, p<0.001, Figure 42a). The number of individuals decreased during the first three months on both kinds of turf (z=-4.67, p<0.001), however, after that, the proportion of surviving individuals (compared to the number of individuals transplanted at T0) remained stable at around 67% of surviving individuals on 40x40cm turfs and 70% of surviving individuals on 20x20cm turfs (values in May 2012, T14, z=0.74, p=0.45, Figure 42a). The number of individuals remained higher on bigger turfs (z=37.29, p<0.001) at T14 (Figure 42a). The

Chapter 5 -Species and turf translocation to restore campos rupestres 164 number of species present on each turf was higher on 40x40cm turf (z=7.32, p<0.001)

and did not vary significantly with time ( z=-1.70, p=0.08, Figure 42b). 25). 40x40cm turfs allowed to translocate more graminoids (Table 25). The same number of forbs was translocated onto 40x40cm turfs and 20x20cm turfs (p=0.4), and the number remaining decreased significantly with time (z=-2.26, p<0.01, Table 4). Few sub-shrubs occurred on translocated turfs whatever turf size, this did not vary with time (Table 25).

3.2.2.Effects of the turf origin

This experiment was carried out on degraded stony substrate (DSt), and we noted that the origin of the turf had an impact on the number of individuals (z=3.86, p <0.001), and

Chapter 5 -Species and turf translocation to restore campos rupestres 165 so did time (z= -5.47, p<0.001), as did the combination of the two (z=-5.22, p<0.001) (Figure 43). At T0, there was a higher number of individuals in turfs from stony grasslands (TSt) (22.7 ± 2.0 individuals) than in turfs from sandy grasslands (TSa) (19.6 ± 1.8 individuals) (z=-3.18, p<0.01); between the three first months, the number of individuals decreased drastically (z=-12.28, p<0.001) and became similar between the two kinds of turf at T3 (9.2 ± 2.4 individuals in TSt and 7.8 ± 1.0 individuals in TSa, z=1.79, p=0.07, Figure 43a). Latter, between T9 and T14, the number of individuals increased in both kinds of turf (z=4.33, p<0.001) and TSa became denser than TSt (12.7 ± 1.1 individuals in TSa and 10.0 ± 0.6 individuals in TSt, z=-3.18, p<0.001, Figure 43a).

On the other hand, the number of species present on each turf was slightly higher in TSa than in TSt (5.1 ± 0.3 species in TSa and 4.4 ± 0.2 species in TSt, z=-1.95, p=0.05) and did not vary with time (z=0.5, p=0.61, Figure 43b). At T0, more graminoids were observed in TSa than in TSt (p<0.01, Table 26).

Graminoids decreased with time (p<0.001), more drastically in TSt than in TSa (p<0.05, Table 26). On the contrary, more forbs were observed in TSt than in TSa at the beginning of the translocation (T0). Forb number did not decrease in TSa, but it did decrease drastically in TSt (p<0.001, Table 26), especially Velloziaceae and Eriocaulaceae species. There was no difference in sub-shrub number between TSa and TSt at T0, and their number increased with time in both kinds of turfs (Table 26). The substrate of the degraded area had an impact on the number of translocated individuals (z=-4.00, p <0.001), as did time (z= -7.48, p<0.001), whitout interaction between both (z=-0.01, p=0.99, Figure 44a). At T0, there were more individuals on turfs transplanted to degraded sandy substrates (DSa) (32.4 ± 2.6 individuals) than degraded stony substrates (DSt) (19.6 ± 1.8individuals, z=-4.78, p<0.001, Fig. Figure 44a). During the first three months, the number of individuals by turf decreased (z=-10.03, p<0.001) on both kinds of substrate (Figure 44a). Latter, between T9 and T14 the number of individuals increased in both degraded areas (z=2.46, p=0.01); the number of individuals in turfs translocated on DSa remained higher (21.7 ± 2.7 individuals) than on turfs translocated on DSt (12.7 ± 1.1 individuals, z=-4.04, p<0.001, Figure 44a). At T0, there was no difference in species richness between the two kinds of substrate where translocation occurred (z=-1.52, p=0.12, Fig. Figure 44b). The number of species did not vary on turf translocated to DSt over time (z=0.50, p=0.6), but decreased slightly on turf translocated to DSa with time (z=-2.29, p=0.021, Figure 44b).

At the beginning of the experiment (T0), turfs translocated to DSa had a higher number of graminoids than turfs translocated to DSt (p<0.001, Table 27), and this number decreased with time in both degraded substrates. The same number of forbs were translocated to the two degraded substrates (p=0.09) and this decreased with time (p<0.001, Table 27). The number of sub-shrubs decreased only on turfs translocated to DSa, but it remained stable on turfs translocated to DSt (p<0.001, Table 27).

Chapter 5 -Species and turf translocation to restore campos rupestres

4.Discussion

Natural succession can be relied upon for some restoration projects [START_REF] Prach | Using spontaneous succession for restoration of humandisturbed habitats: Experience from Central Europe[END_REF][START_REF] Vieira | Principles of Natural Regeneration of Tropical Dry Forests for Restoration[END_REF], however the restoration or rehabilitation of highly degraded areas (e.g. by mining or civil engineering), is more challenging, and sometimes requires species introduction. In our case, a large proportion of species (i.e. seven out of eight)

showed high mortality, indicating that they are particularly difficult to translocate.

Information on transplantation failure is scarce, but some studies have reported that plant species can be difficult to reintroduce [START_REF] Pavlik | Defining and measuring success, in: Restoring diversity. Strategies for reintroduction of endangered plants[END_REF][START_REF] Menges | Restoration demography and genetics of plants: when is a translocation successful ?[END_REF][START_REF] Godefroid | How successful are plant species reintroductions ?[END_REF]. The selected species were expected to be suitable candidates for reintroduction because they present some traits, such as vegetative reproduction, which is common in such environments [START_REF] Figueira | Dinâmica de populações de Paepalanthus polyanthus (Eriocaulaceae) na Serra do Cipó[END_REF], Hoffmann 1998[START_REF] Coelho | Seasonal Timing of Pseudoviviparous Reproduction of Leiothrix (Eriocaulaceae) Rupestrian Species in South-eastern Brazil[END_REF][START_REF] Coelho | Vegetative propagation strategies of four rupestrian species of Leiothrix (Eriocaulaceae)[END_REF][START_REF] Figueira | Clonal growth and dispersal potential of Leiothrix flagellaris Ruhland (Eriocaulaceae) in the rocky grasslands of Southeastern Brazil[END_REF], Fidelis et al. 2010), and this should favor the success of plant translocation in the long-term, ensuring species' expansion in the area [START_REF] Farnsworth | Plant life history traits of rare versus frequent plant taxa of sandplains: Implication for research and management trials[END_REF][START_REF] Pywell | Plant Traits as Predictors of Performance in Ecological Restoration[END_REF]).

However, establishment is a crucial step, and some stress-tolerant species, such as our campo rupestre species, perform badly [START_REF] Pywell | Plant Traits as Predictors of Performance in Ecological Restoration[END_REF]). Individuals of Tatianyx arnacites survived but they tended to wilt (i.e. loose leaves). Only one species, Paspalum erianthum, was able to survive and grow. In addition, some individuals reproduced, producing flowers, which is, in the context of ecosystem restoration, the ultimate goal and a key measure of the fate of reintroduction [START_REF] Fahselt | Is transplanting an effective means of preserving vegetation ?[END_REF][START_REF] Menges | Restoration demography and genetics of plants: when is a translocation successful ?[END_REF][START_REF] Godefroid | How successful are plant species reintroductions ?[END_REF]. Paspalum erianthum is a grass widely distributed from

North to South America and probably has higher adaptation abilities [START_REF] Farnsworth | Plant life history traits of rare versus frequent plant taxa of sandplains: Implication for research and management trials[END_REF] than other species which have narrower distributions and therefore higher specialization.

As a result, we have been able to show that it is possible to transplant some native herbaceous species onto degraded areas.

Mortality was particularly high during the first months, which are fundamental for plant establishment. Desiccation has been cited as an important factor causing mortality in reintroduction experiments [START_REF] Godefroid | How successful are plant species reintroductions ?[END_REF][START_REF] Soliveres | Irrigation, organic fertilization and species successional stage modulate the response of woody seedlings to herbaceous competition in a semi-arid quarry restoration[END_REF]. However the plant translocation that was done at the beginning of the wet season did not increase species survival: even though individuals were less water-stressed compared to those

Chapter 5 -Species and turf translocation to restore campos rupestres 169 translocated at the end of the dry season, they tended to suffer more the effects of translocation. On the other hand, herbaceous savanna species accumulate carbohydrates during the wet season as part of their mechanism for coping with drought [START_REF] Batalha | Reproductive phenology of the cerrado plant community in Emas National Park (central Brazil)[END_REF] and are thus potentially more resistant to stressful situations, such as translocation, at the end of the wet season.

In addition, in our case, translocation in sandy reference grasslands, where environmental conditions are potentially suitable, did not improve translocated species' survival, which underscores the point that limited or unsuitable soil conditions in degraded areas is not the unique reason for failure [START_REF] Maunder | Plant reintroduction: an overview[END_REF][START_REF] Bottin | Reestablishment trials in endangered plants: A review and the example of Arenaria grandiflora, a species on the brink of extinction in the Parisian region (France)[END_REF].

We also noted a negative effect of nutrient supply on plant survival; this result is not in agreement with [START_REF] Negreiros | Seedling growth and biomass allocation of endemic and threatened shrubs of rupestrian fields[END_REF] who demonstrated that despite the fact that campo rupestre species are adapted to low nutritional quality soils (Benites et al. 2007, Chapter 1), shrub seedlings developed well with high fertility substrate conditions, but this tendency can sometimes be reversed in the face of competition [START_REF] Buisson | Restauration écologique de communautés végétales herbacées méditerranéennes: exemples dans le sud-est de la France et sur la cote californienne[END_REF].

Our results suggest that more than site conditions or water supply, translocation itself damages individuals. Indeed, establishment of adult plants following translocation can be considered problematic due to the unavoidable disturbance of the root system [START_REF] Milton | A Protocol for Plant Conservation by Translocation in Threatened Lowland Fynbos[END_REF][START_REF] Fahselt | Is transplanting an effective means of preserving vegetation ?[END_REF]. Clonal reproduction was demonstrated for some species of Eriocaulaceae in campos rupestres [START_REF] Coelho | Vegetative propagation strategies of four rupestrian species of Leiothrix (Eriocaulaceae)[END_REF][START_REF] Figueira | Clonal growth and dispersal potential of Leiothrix flagellaris Ruhland (Eriocaulaceae) in the rocky grasslands of Southeastern Brazil[END_REF]), but we suspect that it is present in many other species such as Cyperaceae, Velloziaceae or Poaceae. Because root connections are what underly clonal reproduction, it appears likely that root damage is probably fatal. It is worth recalling that these species are characterized by a high habitat specificity (Chapter 1, 3), a vulnerability that was exacerbated by root damage. Together, these effects may have hampered their establishment [START_REF] Farnsworth | Plant life history traits of rare versus frequent plant taxa of sandplains: Implication for research and management trials[END_REF][START_REF] Pywell | Plant Traits as Predictors of Performance in Ecological Restoration[END_REF]).

Although seedling transplantation has been already highlighted as a successful method of restoring alpine vegetation [START_REF] Fattorini | Establishment of Transplants on Machine-Graded Ski Runs Above Timberline in the Swiss Alps[END_REF], seeds and seedlings are also more susceptible to environmental hazards [START_REF] Urbanska | High-elevation ecosystem, in: Handbook of ecological restoration: principles of restoration[END_REF]. As in previous studies [START_REF] Conlin | Restoration of an alpine differential disturbance : Success of species in Turf transplants, Colorado, U.S.A. Arctic[END_REF][START_REF] Bay | Success of Turf Transplants in Restoring Alpine Trails, Colorado[END_REF], our results demonstrate that turf translocation is effective in introducing herbaceous species in highly damaged mountain grasslands, as evidenced by the numerous native species surviving more than a year after translocation. Compared to hay transfer (Chapter 3) or to individual translocation at

Chapter 5 -Species and turf translocation to restore campos rupestres 170 the same locale, the transfer of campo rupestre turfs is the most effective restoration method we studied. Even though turf transplantation allowed the introduction of various species, plant composition in the turf changed over course of the first year [START_REF] Bullock | Community translocation in Britain: setting objectives and measuring consequences[END_REF][START_REF] Bruelheide | Translocation of a montane meadow to simulate the potential impact of climate change[END_REF][START_REF] Klimes | Restoration of a species-rich meadow on arable land by transferring meadow blocks[END_REF][START_REF] Trueman | The effects of turf translocation and other environmental variables on the vegetation of a large species-rich mesotrophic grassland[END_REF][START_REF] Box | Experimental wet heath translocation in Dorset, England[END_REF], Pywell 2011).

The decrease in individuals especially during the three first months reflected the "trauma" associated with translocation. Because the natural rate species turn-over in campos rupestres is quite low due to a preponderance of perennial species, we consider these initial changes to be the result of the translocation. Nonetheless, in many turfs, species richness was maintained over time. This response to translocation (i.e. strong initial decline in individuals) was observed on all turfs, independently of the turf size, receptor site substrate, or turf origin.

As bigger turf allowed the introduction of an initially larger pool of individuals/species, and considering the important initial loss, we suggest that the use of bigger turfs can guarantee better translocation success. In our case, turf size did not appear to have an impact on translocation success between the different plant-forms. Although it has been reported that sub-shrubs are more sensitive to small turf than grasses [START_REF] Aradottir | Turf transplants for restoration of alpine vegetation: does size matter?[END_REF], in campos rupestres, sub-shrubs are scattered on donor grasslands and their translocation is thus limited to a few individuals, even when bigger turfs are used.

Nevertheless, response to translocation might vary between plant-forms [START_REF] Conlin | Restoration of an alpine differential disturbance : Success of species in Turf transplants, Colorado, U.S.A. Arctic[END_REF][START_REF] Bay | Success of Turf Transplants in Restoring Alpine Trails, Colorado[END_REF][START_REF] Trueman | The effects of turf translocation and other environmental variables on the vegetation of a large species-rich mesotrophic grassland[END_REF]). Graminoids, especially

Poaceae and Cyperaceae, which are dominant on campos rupestres (Chapter 1), are the most well-represented among the species we translocated, especially on turf from sandy grasslands; they thus suffer the most drastic population reductions following translocation. The introduction of forbs was globally ensured by using turf from stony grasslands, but they showed a high mortality, especially Velloziaceae and Eriocaulaceae, which are characteristic to campos rupestres. The origin of turfs did not appear to have an effect on translocation success (i.e. as measured by the number of individuals or species) until our final survey; turfs from sandy grasslands tended to regenerate with new individuals, both from campos rupestres and from the surrounding degraded areas, more rapidly than turfs from stony grasslands.

We did not found any sign of colonization outside the turfs whatever the turf size, the turf origin or the substrate; although small turfs have already been underlined as an efficient species source useful to initiate colonization [START_REF] Klimes | Restoration of a species-rich meadow on arable land by transferring meadow blocks[END_REF], it was already reported that species do not always spread up [START_REF] Kardol | Soil Organism and Plant Introductions in Restoration of Species-Rich Grassland Communities[END_REF]. Successful establishment outside the turf can be precluded by differences in chemical and physical soil properties between the donor and the receptor site [START_REF] Pywell | Plant Traits as Predictors of Performance in Ecological Restoration[END_REF]. Moreover, changes and expansion of the vegetation to fill in adjacent areas occur on the long-term [START_REF] Kidd | Site Characteristics and Plant Community Development Following Partial Gravel Removal in an Arctic Oilfield[END_REF]. For example, [START_REF] Trueman | The effects of turf translocation and other environmental variables on the vegetation of a large species-rich mesotrophic grassland[END_REF] showed that species density gradually declined on the translocated turf for the first four years after translocation but recovered in the fifth year. Short-term observations of plant establishment are not sufficient [START_REF] Pywell | Long-term heathland restoration on former grassland: The results of a 17-year experiment[END_REF] and our experiment will have to be monitored on the longer-term.

An interesting result is that turfs can be establish on different kinds of soil even if soil characteristics of the receptor site are often limiting factors to establishment [START_REF] Pywell | A comparaison of techniques for restoring heathland on abandoned farmland[END_REF][START_REF] Bullock | Community translocation in Britain: setting objectives and measuring consequences[END_REF], On the other hand, degraded site substrate may impact the implementation of translocation: turf translocation was more complicated on degraded stony substrate due to the high quantity of little rocks complicating excavation.

Conserving the integrity of the turfs was in such case more difficult, resulting in lower number of transplants.

So far, our results showed that turf translocation is possible to introduce native campos rupestres species in degraded areas. This approach had also the benefit of translocating key functional components of the soil microbial community, and the above-and belowground invertebrate community [START_REF] Pywell | Long-term heathland restoration on former grassland: The results of a 17-year experiment[END_REF]. However it is an expensive method [START_REF] Kirmer | Near-natural restoration methods for high nature value areas[END_REF], Pywell et al. 2011) and the regeneration of both donor sites is really low and damages almost irreversible. For all these reasons, campo rupestre translocation should only be considered as a mean of habitat rescue, in circumstances when complete habitat destruction is otherwise unavoidable.

5.Conclusion

The translocation of native herbaceous species with the aim of restoring campos rupestres is clearly very complicated. In our experiments, only one species, the grass Paspalum erianthum, survived, grew, and produced flowers, indicating promising longterm viability of this species upon translocation. As for the other species, the mortality rate was disappointingly high, and probably resulted from the trauma of transplantation and the root damage it probably inflicted. We found a similar effect in turf translocation where there was an important decrease, followed by immediate stabilization, in the number of individuals during the first months. We suppose that these plants, being perennial and reproducing primarily vegetatively, are constructed such that damage to their root system is probably fatal. In spite of this, turf translocation has proven to be an effective method for reintroducing native herbaceous species to degraded areas. Longterm monitoring will be necessary to find out if turfs can actually act as species sources.

Turf translocation should only be used with the understanding that the extant plant communities from which donor material is drawn will be irreparably sacrificed, because donor sites generally have poor resilience, and thus,should only be used when communities are planned on being completely destroyed.

General Discussion

The basic objective of this thesis was to improve the understanding of the functioning of campos rupestres: by defining what species compose campos rupestres and how they are structured; and by assessing their dynamics i.e. the seasonal changes in reproduction at community level and the resilience of communities after human disturbances.

The applied goal of this thesis project was to conduct the scientific studies necessary to find the most efficient method to restore these diverse and endangered communities.

In this discussion, I aim to answer the three questions set in the introduction: what do we want to restore? ; Are campos rupestres resilient to a strong disturbance? ; And, can we restore campos rupestres? I have therefore drawn the main conclusion of this study and have highlighted how these results contribute to ecological theory and/or to ecological restoration.

1.What do we want to restore?

Composition and structure of herbaceous communities of campos rupestres

Defining the reference ecosystem in a restoration project is fundamental to set goals, to monitor restoration processes and to assess success (SER 2004). Campos rupestres are peculiar tropical mountain grasslands and the main vegetation formation encountered along the Espinhaço range. The choice of the reference ecosystem is therefore obvious; we set the campos rupestres as the reference because 1) there are the main vegetation formation still encountered on the intact surrounding areas, which suggest that it is the pre-disturbance state [START_REF] Choi | Ecological restoration for future sustainability in changing environment[END_REF][START_REF] Buisson | Community and restoration ecology, importance odfdisturbance, natural resilience and assembly rules[END_REF]; 2) of the high biodiversity and endemism they host, hence their conservation value; and, 3) like other mountain ecosystems, they provide valuable ecosystem services, such as water purification, medicinal plants, recreational services, etc. (MEA 2005)

Campos rupestres are usually described as a more or less continuous herbaceous stratum with small sclerophyllous evergreen shrubs and subshrubs, subjected to environmental constraints, such as seasonal drought, fire, high insulation, high temperatures and high radiations (Giulietti et al. 1997). In chapter 1 we demonstrated that rather than a homogeneous herbaceous stratum, campos rupestres are composed of a mosaic of communities, formed by at least two kinds of grasslands. The large majority of species are perennial (chapter 1 & 2) and resprouters (chapter 1 & personal observation after a fire). Each grassland-type is characterized by its own vegetation (Giulietti et al. 1997, Conceição & Pirani 2007) A part of the heterogeneity of plant composition both between and within the sandy and stony grasslands can be attributed to the high level of endemism at local scale or at the scale of Espinhaço Range: 12% of species are micro-endemic (Serra do Cipó), 12% are endemic from the Espinhaço range in Minas Gerais and 10% are found only along the Espinhaço Range. Corroborating with that, 39 % of species are confined to the campos rupestres, while 14% of species are in common with the cerrado and 19% are also found in other biomes. Then even if campos rupestres can be included into the Cerrado (as mentioned in the introduction), it remains that these ecosystems are a truly unique physiognomy.

Because there is considerable local diversity in the different campos rupestres along the Espinhaço Range (Echternacht et al. 2011), it is difficult to clearly define them based on a list of species. However, within all Espinhaço Range, many species show morphological convergence and their functioning is thus most probably similar (Giulietti et al. 1997[START_REF] Alves | Can campo rupestre vegetation be floristically delimited based on vascular plant genera?[END_REF]. Within a restoration context, we therefore argue that what we show in this thesis about the campos rupestres of the Serra do Cipó (in term of functioning and dynamics) is also true for other campos rupestres in the Espinhaço Range.

From the regional species pool to the external species pool: patterns of reproduction in campos rupestres

In chapter 2, we have highlighted the variety of phenological strategies occurring in campos rupestres, which underline that, beyond species diversity, campos rupestres also harbor a diversity of ecological strategies among the herbaceous flora. Flowering patterns of the herbaceous flora of the campos rupestres are related to seasonal climate variations: the reproduction of many species are confined to the rainy season; these species should therefore be strongly impacted by climate change (Werneck et al. 2012).

In addition, other species reproduce during the transition from the rainy to the dry season or during the dry season. Consequently, dissemination occurs both during the rainy or the dry season, which implies different germination and establishment strategies. A relationship between seed dispersal and seedling establishment has already been showed in Neotropical savannas for woody species (Salazar et al. 2011, Silveira et al. 2012): most seeds dispersed in the wet season are non-dormant (Salazar et al. 2011), but we might expect that seeds produced during the rainy season and dispersing at the end of it (period of transition with the dry season) to have dormancy (Silveira et al. 2012).

We have also shown a large diversity of reproduction frequency. Some species adopted a continuous reproduction, producing seeds almost all year long; other species reproduce sporadically, others regularly every year, others reproduce only one year out of two. Finally some species were not observed reproducing during our two-year survey, among these some dominant species, such as Tatianyx arnacites, Mesosetum exaratum, Homolepis longispicula, Paspalum pectinatum, Bulbostilys paradoxa, or

Bulbostylis emmerichiae. This indirectly illustrates how campos rupestres are constrained ecosystems subjected to disturbances: indeed, campos rupestres are nutrient poor ecosystems and stress-tolerant species are often long-lived clonal species (Bekker et al. 1997;[START_REF] Chang | Relationship between vegetation and soil seed banks in an arctic coastal marsh[END_REF][START_REF] Matus | Impact of management on vegetation dynamics and seed bank formation of inland dune grassland in Hungary[END_REF][START_REF] Coelho | Seasonal Timing of Pseudoviviparous Reproduction of Leiothrix (Eriocaulaceae) Rupestrian Species in South-eastern Brazil[END_REF], 2007[START_REF] Figueira | Clonal growth and dispersal potential of Leiothrix flagellaris Ruhland (Eriocaulaceae) in the rocky grasslands of Southeastern Brazil[END_REF].

Finally according to the phenological study, Cyperaceae, Xyridaceae, Ericaulaceae, Melastomataceae and other sub-shrubs mainly ensure seed production in campos rupestres, whereas Poaceae, an important family, produces very few seeds. Chapter 2 stresses that, if spontaneous succession occurs in campos rupestres, the low or irregular seed production of some species is a strong limiting factor.

2.Plant community dynamics after disturbance

Regeneration after a natural disturbance

Plant establishment in campo rupestre reference grasslands from the seed bank is limited (Chapter 3 & Appendix 4): seed banks are poor in species and in seeds in comparison to other habitats, such as nearby gallery forests (Medina and Fernandes 2007), Cerrado (Salazar et al. 2011) or other tropical savannas (Perez and Santiago 2001). The ability to form a seed bank varies in campos rupestres: while some species appear not to form seed banks (Velten & Garcia 2007), others may form only a small persistent seed bank (Velten & Garcia 2007, Giorni 2009, Silveira 2011). Bekker et al. (1997) already noted that species associated with poor nutrient conditions were relatively scarce in the seed bank. It was also suggested that increasing habitat disturbance always selects for increased seed persistence (Hölzel & Otte 2004), but it is not the case in campos rupestres, where fire is the main disturbance and where seed persistence were not demonstrated.

Indeed, in the Cerrado, in response to fire, vegetative reproduction is a frequent strategy, much more successful than sexual reproduction (Hoffmann 1998). Fidelis et al.

(2010, see also Fidelis 2008) also pointed out the importance of bud banks in tropical grasslands that are subjected to fire, which would replace the seed bank in such communities. This corroborates with our chapter 4 results: we were not able to find evidence that fire-related cues enhance germination, which suggests that campos rupestres species adopt other strategies to establish after fire.

Campos rupestres are not resilient to a strong disturbance

The main degradation which occurred in this ecosystem in the last decades, was the construction of highway MG-010, followed, in 2002, by its asphalting. The processes created some quarries along the road, which were exploited for gravel and/or were used to stock gravel and/or park machines, destroying campo rupestre vegetation. The regeneration of communities subjected to strong disturbances, such as quarries or mining, mainly relies on primary succession, since the entire vegetation is lost, seed bank destroyed and soil completely altered [START_REF] Bradshaw | The use of natural processes in reclamation -advantages and difficulties[END_REF]. However primary succession is known to be slow (Walker and del Moral 2003): its rate depends strongly to the proximity of colonist sources. Thereby surrounding vegetation is a very important factor affecting the process of colonization [START_REF] Rehounkova | Spontaneous vegetation in disused gravel-sand pits: role of local site and landscape factors[END_REF] The main impact of such strong disturbance was the complete destruction of the seed bank and vegetation (absence of internal species pool) and soils; spontaneous succession from the seed bank is therefore unlikely in degraded areas and only depends on dispersal. Despite soil alteration some campos rupestres species are found scattered on the degraded stony areas, along with some ruderal species. This indicates that soil conditions can limit spontaneous regeneration but is not sufficient in itself to explain the low resilience.

Drivers of plant community recovery

In Chapter 1, we have highlighted that campos rupestres are a mosaic of at least two communities, but more than the detection of these patterns, it is important to understand the rules or constraints that determine these patterns (Weiher & Keddy 1995). In

Chapter 3, we have stressed that these two communities are not resilient to strong disturbance. Understanding why these communities are not resilient and what determines their recovery has helped us to define which factors determine the assembly of campo rupestre communities. According to the filter model, a niche-based concept which provides a framework to understand plant community assembly [START_REF] Keddy | Assembly and responses rules: two goals for predictive community ecology[END_REF][START_REF] Gotelli | Species co-occurence: a meta-analysis of J M Diamond's assembly rules model[END_REF][START_REF] Temperton | The search for ecological assembly rules and its relevance to restoration ecology, in: Assembly rules and restoration ecologybridging the gap between theory and practice[END_REF], Weiher et al. 2011), each community represents a subset of the regional species pool determined by dispersal, environmental and biotic filters.

In addition, neutral processes can occur alongside niche processes: the regional community assembly is then defined by the complementarity between niche-based processes, evolutionary history, habitat choice and diversification of equivalent species with neutral assembly (Ricklef 2008, Weiher et al. 2011). Indeed, both stochastic processes, such as colonization or extinction rate, and deterministic processes associated with niche processes (particularly important in constraint ecosystems like campos rupestres) can be of major importance in structuring natural communities [START_REF] Chase | Disentangling the importance of ecological niches from stochastic processes across scales[END_REF]. These new approaches to community assembly have acknowledged the important role of dispersal in shaping local assemblages (Ricklef 2008[START_REF] Vellend | Conceptual synthesis in community ecology[END_REF], Weiher et al. 2011). As campos rupestres are constraint ecosystems we then focus here on deterministic processes associated with niche processes.

2.3.1.Dispersal filter

Dispersal is a key contributor to the regional species pool [START_REF] Vellend | Conceptual synthesis in community ecology[END_REF]. It is also a barrier to spontaneous recovery in herbaceous systems (Hutchings & Booth 1996 ;Bischoff 2000 ;[START_REF] Kiehl | Species introduction in restoration projects -Evaluation of different techniques for the establishment of semi-natural grasslands in Central and Northwestern Europe[END_REF]Török et al. 2010 ;Piqueray & Mahy 2011). Campos rupestres are complex grasslands [START_REF] Conceição | Delimitação de habitats em campos rupestres na Chapada Diamantina, Bahia: substratos, composição floristica e aspectos estruturais[END_REF], 2007) with a huge biodiversity, representing a large global species pool, including many endemic species [START_REF] Alves | Plant species endemism in savanna vegetation on table mountains (Campo Rupestre) in Brazil[END_REF], Echternacht et al. 2011, Chapter 1). Campos rupestres are known to be a center of biodiversity especially for Velloziaceae, Eriocaulaceae and Xyridaceae [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF][START_REF] Mello-Silva | Aspectos taxonômicos, biogeográficos, morfológicos e biológicos das Velloziaceae de Grão-Mogol, Minas Gerais, Brasil[END_REF], Wanderley 2011). Endemism is usually attributed to the fragmentation of populations, which promotes genetic differentiation, and therefore the evolution of new species, often with a very limited distribution [START_REF] Alves | Plant species endemism in savanna vegetation on table mountains (Campo Rupestre) in Brazil[END_REF], Giulietti et al. 1997[START_REF] Jesus | Local genetic differentiation in Proteopsis argentea (Asteraceae), a perennial herb endemic in Brazil[END_REF], 2009). The large amount of endemic species in campos rupestres implies dispersal limitation since it is a prerequisite for allopatric speciation [START_REF] Coyne | Speciation[END_REF].

We did not study dispersion per se, but according to the literature, anemochory and autochory are the two main seed dispersal syndromes in campos rupestres, followed by zoochory [START_REF] Faria | Recursos florais e sindromes de polinização e dispersão de espécies de campos rupestres no parque estadual da serra dos pireneus[END_REF], Conceição et al. 2007a[START_REF] Dutra | Fenologia reprodutiva, sindromes de polinização e dispersão em espécies de Leguminosae dos campos rupestres do parque estadual do Itacolomi, MInas Gerais, Brasil[END_REF][START_REF] Fonseca | Dispersão de sementes de Melocactus glaucescens e M. paucispinus (Cactaceae), no Município de Morro do Chapéu , Chapada Diamantina -BA[END_REF][START_REF] Lima | Interactions between ants and nonmyrmecochorous fruits in species of Miconia (Melastomataceae) in a Neotropical savanna[END_REF]. However these studies usually inferred seed dispersal modes from morphological traits of the seeds which might be misleading [START_REF] Tackenberg | Assessment of wind dispersal potential in plant species[END_REF]. Indeed many species commonly defined as wind dispersed, have, in fact, low wind dispersal potential [START_REF] Tackenberg | Assessment of wind dispersal potential in plant species[END_REF]. In grasslands, seed release height and vegetation height are more fundamental to determine seed dispersal distances [START_REF] Soons | Determinants of long-distance seed dispersal by wind in grasslands[END_REF][START_REF] Thomson | Seed dispersal distance is more strongly correlated with plant height than with seed mass[END_REF] than seed mass, which has been long considered as an important factor for dispersal over long distances. This is supported by the fact that many campo rupestre species invest in stalk length [START_REF] Bazzaz | Re-productive allocation in plants[END_REF], especially Eriocaulaceae, Xyridaceae, Asteraceae or Amaranthaceae (Le Stradic, unpublished data). Zoochory seems to be the most important dispersal way concerning woody Cerrado species [START_REF] Leal | Interactions between Fungus-Growing Ants (Attini), Fruits and Seeds in Cerrado Vegetation in Southeast Brazil[END_REF][START_REF] Batalha | Reproductive phenology of the cerrado plant community in Emas National Park (central Brazil)[END_REF][START_REF] Arbelaez | Seed dispersal modes of the sandstone plateau vegetation of the middle caqueta river region, Colombian Amazonia[END_REF][START_REF] Lima | Interactions between ants and nonmyrmecochorous fruits in species of Miconia (Melastomataceae) in a Neotropical savanna[END_REF]), so we can hypothesize that zoochory can be an important mode in the rocky outcrops of campos rupestres, but much less in the open areas, such as sandy and stony grasslands. We did not find studies which reported hydrochory, while the importance of water as a dispersal mechanism in campos rupestres should not be underestimated: sandy grasslands are regularly flooded during the rainy season and sedges seeds are known to be buoyant (Leck & Schutz 2005).

Actually, in campos rupestres, the dispersal remains a black box, only few studies dealt with this aspect [START_REF] Fonseca | Dispersão de sementes de Melocactus glaucescens e M. paucispinus (Cactaceae), no Município de Morro do Chapéu , Chapada Diamantina -BA[END_REF][START_REF] Lima | Interactions between ants and nonmyrmecochorous fruits in species of Miconia (Melastomataceae) in a Neotropical savanna[END_REF]; and there is no study about seed rain for example. Restoration ecology can, however, provide some answers.

Indeed, in case of strong degradation the entire seed bank is removed and thus no longer occurs on the degraded areas (Chapter 3). The availability of propagules in the surroundings and their dispersion is therefore the only way to ensure seed supply and initiate vegetation recovery (Bradshaw 1997[START_REF] Campbell | Determining the immigration potential of plants colonizing disturbed environments : the case of milled peatlands in Quebec[END_REF][START_REF] Shu | Natural Colonization of Plants on Five Lead/Zinc Mine Tailings in Southern China[END_REF]). In our case, seed banks did not recompose with campo rupestre target species via dispersion from reference grasslands; seed bank composition in degraded areas is quite different from those encountered in the reference grasslands and mainly composed of ruderal species. One species, Mesosetum loliiforme, largely present on the degraded seed bank is also encountered on reference grasslands. This native grass is found in Brazil on natural pastures and is one of the main forage species [START_REF] Pott | Pastagens das sub-regiões dos paiaguas e da nhecolandia do pantanal Mato-Grossense[END_REF]. This species 1) reproduces every year, while other Poaceae on campos rupestres do not and 2) forms a seed bank on the degraded areas. These two characteristics are favorable to colonize new areas and this species was common on some stony degraded areas. On the other hand, characteristic species of campos rupestres, such as Tatianyx arnacites or Rhynchospora riedeliana for example, are not found in the degraded seed bank while they were found in those of reference grasslands: they are able to form seed bank but probably did not reach to the degraded areas.

Therefore, as no target species was encountered on the degraded seed bank after eight years, we hypothesize that dispersion is the first barrier to the resilience of strongly disturbed campos rupestres. In addition, each degraded area is characterized by its own species composition (Chapter 3), we then supposed that landscape factors, especially the proximity of seed sources, are important factors to determine plant composition at the beginning of the succession (Del Moral et al. 2005) in campo rupestre degraded areas. For example, degraded sites DSt2 and DSt3, which are directly surrounded by pristine campos rupestres, also recorded some campo rupestre species among the spontaneous vegetation. In the same way, we also note that DSa2, DSa3 and DSt1, which are close together, presented some similarities in vegetation composition, mainly ensured by ruderal species, probably because colonization is ensured by the same species source (ruderal species already present on the degraded areas and the along the road).

2.3.2.Environmental filter

Campos rupestres are commonly defined as constraint ecosystems, due to the dry season (water shortage lasts around 5 months), strong wind during the dry season, high daily temperature oscillations, intense irradiation (UV) (Giulietti et al. 1997). Abiotic filter is therefore expected to be a strong constraint structuring campo rupestre communities.

Indeed, chapter 1 stresses the relationship between environmental conditions (i.e. both granulometry and chemical properties of the soil) and vegetation composition: abiotic filter has been shown to play an important role in defining and circumscribing each community, confining some species to one or the other habitat. Both grasslands occurred in the same area, side-by-side, separated by just a few centimeters; at local scale, dispersion alone cannot explain observed patterns. During the rainy season, stony grasslands are drier than sandy grasslands: since they are usually located on slope, water runs off, and they are more impacted by water erosion and never experience temporary flooding [START_REF] Vitta | Composição florística e ecologia de comunidades campestres na Serra do Cipó, Minas Gerais[END_REF]. We also show that soil composition varies between both grasslands, maybe as a consequence of this local topography and drainage.

The importance of abiotic conditions has also been reported in Chapter 3. We have shown that local site characteristics and the type of substrate are important to determine primary succession [START_REF] Rehounkova | Spontaneous vegetation in disused gravel-sand pits: role of local site and landscape factors[END_REF]): the degraded stony substrate seems more appropriate to spontaneous recovery, potentially due to the microsites created by stones. Soil alteration was one of the main consequences of degradation [START_REF] Negreiros | Caracterização fisico-quimica de solos quartziticos degradados e areas adjacentes de campo rupetsre na Serra do Cipo, MG, Brasil[END_REF], when exploitation/road asphalting stopped, soils are not restituted entirely and construction debris may be added resulting in a highly altered soil. Thus, after road building, degraded areas presented several kinds of substrate: degraded sandy substrate, degraded stony substrate or degraded latosol substrate. All degraded soils present lower nitrogen content and tend to be less acidic than reference grasslands.

Areas with degraded stony and sandy substrates tend to have lower phosphorus and organic carbon contents, on the contrary latosol degraded areas have higher phosphorus, higher pH and higher magnesium and calcium contents.

Usually environmental filter leads to a convergence of traits that are required to survive in a particular environment (under-dispersion): even if species composition differs, species that coexist are more similar than expected (Weiher & Keddy 1995, Weiher et al. 2011). This was observed by [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF] in campos rupestres where there is a morphological convergence between species. On the contrary, the biotic filter tends to cause trait over-dispersion in order to limit similarity and avoid niche overlapping (Weiher et al. 2011).

2.3.3.Biotic factors

Biotic filters, such as competition or facilitation are poorly studied in campos rupestres [START_REF] Guilherme | Existe facilitação vegetal em campos rupestres sobre canga no Parque Estadual da Serra do Rola Moça[END_REF]. The competition strategy is unlikely because the habitat is stressful, species are thus preferentially stress tolerant first [START_REF] Grime | Evidence for the Existence of Three Primary Strategies in Plants and its Relevance to Ecological and Evolutionary Theory[END_REF]. On sandy grasslands, where substrate is not partly composed by quartzitic stones, the vegetation is denser; we thus hypothesize more competition on this kind of grasslands. Only one study dealt with facilitation in campos rupestres and it did not highlight this kind of intra-specific interaction despite the fact that campos rupestres are potentially favorable to it [START_REF] Guilherme | Existe facilitação vegetal em campos rupestres sobre canga no Parque Estadual da Serra do Rola Moça[END_REF]).

In addition, despite local differentiation and limited dispersal of many species, generating high endemism in campos rupestres, geographic isolation alone cannot explain population differentiation [START_REF] Jesus | Local genetic differentiation in Proteopsis argentea (Asteraceae), a perennial herb endemic in Brazil[END_REF][START_REF] Jesus | Low genetic diversity but local genetic differentiation in endemic Minasia (Asteraceae) species from Brazil[END_REF], suggesting action of other evolutive forces beyond gene flow, such as localized pollinator behavior for example.

3.Can we restore campos rupestres?

Three kinds of restoration interventions were tested in order to initiate and accelerate the recovery of campo rupestre vegetation in degraded areas (Kielh et al. 2010[START_REF] Godefroid | How successful are plant species reintroductions ?[END_REF], Pywell et al 2011). We used the filter model as a framework to set up restoration experiments and to determine what factors constraint community assembly.

In the first experiment, we manipulated the dispersal filter, bringing campo rupestre seeds into a degraded area. Following our results, we examined the germination behavior of fifteen herbaceous species. In the second experiment, we translocated eight native species in order to overcome the dispersal filter and the germination, a critical phase for establishing in the degraded areas, and in order to improve environmental conditions bringing together soil and translocated plant. Finally, we translocated vegetation turfs: we aimed to bring to the degraded areas i) a pool of target species, ii) soil of the reference ecosystem and iii) possible associated microorganisms [START_REF] Carvalho | The mosaic of habitats in the high-altitude Brazilian rupestrian fields is a hotspot for arbuscular mycorrhizal fungi[END_REF], therefore overcoming the dispersal, the abiotic filters and part of the biotic filter. Assessing the performance of multiple approaches is useful for testing multiple hypotheses, quickly expands the restoration toolbox in case of success, while restoration failure is also very instructive to learn about the inability of some techniques and to adapt new ones [START_REF] Hilderbrand | The Myths of Restoration Ecology[END_REF].

Hay transfer is a useful technique to increase seed supply in grasslands which recorded notable success in Europe in various kinds of habitats [START_REF] Patzelt | Restoration of Wet Fen Meadows by Topsoil Removal : Vegetation Development and Germination Biology of Fen Species[END_REF], Hölzel & Otte 2003[START_REF] Craft | Restoration of Magnesian Limestone Grassland : Optimizing the Time for Seed Collection by Vacuum Harvesting[END_REF][START_REF] Kiehl | Effect of Hay Transfer on Long-Term Establishment of Vegetation and Grasshoppers on Former Arable Fields[END_REF][START_REF] Donath | Large scale application of diaspore transfer with plant material in restoration practice -Impact of seed and microsite limitation[END_REF][START_REF] Edwards | Hay strewing, brush harvesting of seed and soil disturbance as tools for the enhancement of botanical diversity in grasslands[END_REF][START_REF] Klimkowska | Vegetation Re-development After Fen Meadow Restoration by Topsoil Removal and Hay Transfer[END_REF][START_REF] Coiffait-Gombault | Hay Transfer Promotes Establishment of Mediterranean Steppe Vegetation on Soil Disturbed[END_REF], Baasch et al. 2012). In North America, [START_REF] Graf | Techniques for restoring fen vegetation on cut-away peatlands in North America[END_REF] reported that hay transfer was less successful than in Europe probably due to the questionable viability of reintroduced seeds. Similarly, in tropical grasslands, the method failed completely, even if hay contained lots of seeds (Chapter 3). The large majority of observed seedlings emerging in degraded areas are ruderal non-target species which colonized on their own. Failure can be explained by i) failure in seed germination (i.e. seed dormancy, unviable seeds, unfavorable germination conditions) and/or ii) unfavorable site conditions leading to poor seedling establishment. Our regular monitoring of germination has never revealed seedling emergence either on degraded areas or in greenhouse. We therefore hypothesize, like [START_REF] Graf | Techniques for restoring fen vegetation on cut-away peatlands in North America[END_REF], that hay transfer failure is primarily due to germination issues rather than establishment limitation. We then conclude that, although dispersal is a limiting factor for vegetation establishment, poor seed quality and germination are additional ones.

In Hay also contained Xyridaceae but maybe this small seeds were taken away by water runoff or wind, or the hand-vacuum equipment was not an efficient manner to collect large amount of these seeds, or seeds did not manage to germinate. On the other hand, we suppose that Velloziaceae were not present on the hay, because they do not produce lot of fruits and usually irregularly (Chapter 2).

Finding how to break dormancy could be key to extend restoration project and improve vegetation establishment in disturbed areas. Whereas we expected a significant relationship between fire effects and germination, we found little evidence that fire related cues enhance germination of campo rupestre species, whether they have nondormant or dormant seeds, suggesting that germination is not a preferential way to regenerate after fire. However, fire stimulates flowering of some resprouter species in campo rupestre [START_REF] Neves | Revisão sobre os Efeitos do Fogo em Eriocaulaceae como Subsídio para a sua Conservação[END_REF], Conceição & Orr 2012, personal observation), among which Poaceae and Cyperaceae species, which are then able to resprout rapidly and produce seeds with high germination percent. These species were never observed flowering during the two years of the phenological surveys, while they are abundant in General discussion 184 campos rupestres. We therefore suggest that the ultimate goal of producing seeds might be to disperse rather than to recover.

Since dominant campo rupestre species do not produce fruit or have low germinability, we choose to translocate adult species rather than transplant seedlings grown from seeds in greenhouses (Chapter 5). Among the eight species translocated, just one, Paspalum erianthum, survived, grew and reproduced. Reporting failure is rare; reasons for failure are thus poorly discussed. Some studies have reported that species translocation can be hard to achieve for some species [START_REF] Milton | A Protocol for Plant Conservation by Translocation in Threatened Lowland Fynbos[END_REF][START_REF] Menges | Restoration demography and genetics of plants: when is a translocation successful ?[END_REF][START_REF] Godefroid | How successful are plant species reintroductions ?[END_REF]. Paspalum erianthum is a grass widely distributed from North to South America and probably has higher adaptation abilities since common species have lower habitat specialization [START_REF] Farnsworth | Plant life history traits of rare versus frequent plant taxa of sandplains: Implication for research and management trials[END_REF]. On the other hand, the other species have narrower distribution usually restricted to Espinhaço Range, except Homolepis longispicula found all over Brazil [START_REF] Forzza | Lista de Espécies da Flora do Brasil[END_REF], and probably suffer from inadequate habitat. Native species transplantation was already pointed out as an efficient method to re-introduce species in degraded areas [START_REF] Fattorini | Establishment of Transplants on Machine-Graded Ski Runs Above Timberline in the Swiss Alps[END_REF][START_REF] Soliveres | Irrigation, organic fertilization and species successional stage modulate the response of woody seedlings to herbaceous competition in a semi-arid quarry restoration[END_REF], but some other studies underlined the variable success associated with this method especially because success is usually context-dependent (e.g. herbivory, disturbance, competition) [START_REF] Ash | The introduction of native plant species on industrial waste heaps : a test of immigration and other factors affecting succession primary[END_REF][START_REF] Milton | A Protocol for Plant Conservation by Translocation in Threatened Lowland Fynbos[END_REF][START_REF] Menges | Restoration demography and genetics of plants: when is a translocation successful ?[END_REF][START_REF] Godefroid | How successful are plant species reintroductions ?[END_REF]. Maybe it is possible to improve translocation success by placing microclimate shelters to minimize transplanting stress [START_REF] Milton | A Protocol for Plant Conservation by Translocation in Threatened Lowland Fynbos[END_REF]), however we hypothesize that root damage is too great and hampers greatly translocation success, more than environmental constraints. Establishment is a crucial step and stress-tolerant species, such as campo rupestre species, perform badly [START_REF] Pywell | Plant Traits as Predictors of Performance in Ecological Restoration[END_REF]). In future studies, using seedling transplantation (obtained in greenhouse from seeds) can also reduce root damage compared to adult translocation and then improve re-introduction success, but this is currently hampered by limited knowledge about herbaceous species germination.

Finally, we translocated vegetation turfs which allow the reintroduction of numerous species, such as Tatianyx arnacites, Homolepis longispicula, Lagenocarpus rigidus subsp. tenuifolius, dominant and characteristic campo rupestre species, for which the individual translocation failed. Species richness in these turfs decreased greatly just after translocation and was therefore quite lower to that observed in pristine areas on the same surface. Some endemic species, such as Syngonanthus cipoensis, survived and General discussion 185 occurred on translocated turfs more than one year after the transplantation. This method is therefore the most successful we tested: we overcome the risk and uncertainties associated with establishing the vegetation from seeds (hay transfer) and reduce problems related to root damages (except for species located at the turf edges). Despite the presence of a highly invasive species, such as Melinis repens, on the area, this one was not found on turf yet. Long-term monitoring will permit to answer if this method is actually efficient to restore degraded campos rupestres, if turfs are able to sustain on degraded areas; turf translocation is known to help to restore grassland communities on the long-term [START_REF] Pywell | Long-term heathland restoration on former grassland: The results of a 17-year experiment[END_REF]. So far, the vegetation has not spread outside the turfs to fill in adjacent areas, and this might need much more time [START_REF] Kidd | Site Characteristics and Plant Community Development Following Partial Gravel Removal in an Arctic Oilfield[END_REF]. However this technique was also highly destructive and donor grasslands are poorly resilient, that is why turf translocation should be considered only when habitat destruction is unavoidable, as a "rescue" measure. Nevertheless, some private areas of campos rupestres are already threatened to be destroyed by mining or quarrying enterprise and reclamation, rehabilitation or restoration are required by laws. In such cases, we recommend planning turf transfer in order to save a part of campo rupestre species instead of losing them. Soil transfer of the degraded grasslands can also be conceivable in order to improve the edaphic conditions of the degraded areas and then facilitate native plant establishment in association with other restoration methods (seeding / seedling transplantation).

4.From restoration ecology to community ecology

As presented in the introduction, restoration ecology can be useful to answer some theoretical questions in community ecology and improve understanding of community assembly. Several factors are responsible for the low resilience of campos rupestres following strong disturbance. The resilience is first limited by the phenology of some species, inclusive dominant species, which did not produce seeds during the two-year survey (Chapter 2, Figure 45), and thus did not supply the external species pool. We also hypothesize that the dispersal of main species of campos rupestres is limited, because few target species were encountered and only on some degraded areas; moreover no target species were found on the degraded seed bank (Chapter 3, Figure 45). However, while we could have overcome dispersal filter using hay transfer, target species of campos rupestres did not establish in degraded areas, which imply that limited dispersal alone cannot explain why vegetation did not recover on these areas showing that some species did not reproduce regularly and then are absent from the external species pool which can probably colonize degraded areas; 2) Spontaneous succession from the seed bank is unlikely because it was completely removed during the disturbance; 3) Dispersal limitation did not allow the seed bank re-composition; 4) Hay transfer, which allows overcoming the dispersal filter, was not efficient to initiate vegetation establishment on degraded areas; 5) Some species among them Poaceae & Cyperaceae failed to germinate, other germinated well like Xyridaceae or Velloziaceae but were not able to establish on degraded areas, due to unfavorable germination conditions or because hay did not contain these species; 6) Probable root damages impede species establishment, just one species Paspalum erianthum was reintroduce on degraded areas; 7) turf translocation was the most successful restoration method allowing to introduce native species on degraded areas, but it was also the technique which most impacted the reference grasslands.

Main considerations of this thesis

Before presenting possible perspectives, I am going to sum up the main conclusions of this research: a) Concerning community ecology:

-Chapter 1 has confirmed that campos rupestres are species-rich grasslands, composed by different communities due to topography and soil properties;

-Chapter 2 has showed the variety of phenological patterns occurring on campos rupestres and has underlined that some species do not reproduce sexually regularly;

-Chapter 3 has highlighted that campos rupestres are nor resilient to strong anthropogenic disturbance; campo rupestre seed bank is poor in seeds and species, regeneration from seed bank is thus unlikely; dispersal limitation do not allow recomposing the seed bank of degraded areas; -Chapter 3 has showed that dispersal limitation is not the only limiting factor to campo rupestre regeneration;

-Chapter 4 has emphasized that germination behaviors vary among herbaceous species: some of them germinate well, others present dormancy or unviable seeds.

-Chapter 4 has highlighted that fire-related cues do not enhance germination of campo rupestre species, despite the fact that it is a fire-prone environement; -Chapter 5 has confirmed the strong relationship between soil and vegetation in campos rupestres.

b) Concerning restoration ecology

-Chapter 3 has showed that overcoming dispersion technique is not efficient in campo rupestres; highly altered soils and germination limitation seems the most limiting factors (Chapter 4); -Chapter 5 has underlined that species translocation is risky and not successful for the majority of native species; -Chapter 5 has found that the best manner to restore degraded campos rupestres is turf translocation;

-Chapter 5 has confirmed that this technique must be used only when habitat destruction is already planned, as a "rescue" measure due to the low resilience of destructed campos rupestres. c) Concerning ecological restoration -In case of unavoidable degradation, we suggest to proceed with a "rescue" program including translocation of vegetation turf destroyed or at least to concerve topsoil.

-These techniques can be associated with the transplantation of woody species (Le [START_REF] Stradic | Réintroduction et impacts sur leur environnement de plantes indigènes du Cerrado[END_REF].

Perspectives 1.To increase studies at large scale and use functional traits

New species are found regularly on campos rupestres, thus not all the species composing them are known; and this is a barrier for understanding how the system works. However, it seems important to improve research in order to understand processes generating biodiversity, structuring communities and allowing the coexistence of species, especially at large scales (e.g. Echternacht et al. 2011); studies on campos rupestres cannot be limited solely to species lists. McGill et al. (2008) argue that community ecology should be re-built using general traits, overcoming barrier linked to species list [START_REF] Lawton | Are There General Laws in Ecology ?[END_REF][START_REF] Simberloff | Community Ecology : Is It Time to Move On ?[END_REF], and bringing general patterns to community ecology. Indeed the use of functional traits is becoming more and more common in community ecology [START_REF] Cadotte | Beyond species: functional diversity and the maintenance of ecological processes and services[END_REF]. Then developing researches on functional traits at the scale of the Espinhaço Range will allow drawing some general patterns in campos rupestres, because they allow comparisons between different regions and scales [START_REF] Lavorel | Predicting changes in community composition and ecosystem functioning from plant traits: revisiting the holy Grail[END_REF], Westoby & Whright 2006). They are also a useful tool to better define potential ecosystem services associated with campos rupestres [START_REF] Lavorel | Using plant functional traits to understand the landscape distribution of multiple ecosystem services[END_REF]). In addition, other functionnal aspects, such as dormancy, sclerophylly, watereconomy, light harvesting, temperature control, architectural convergence, dispersal (fundamental factor shaping the communities), etc. are poorly known and need more studies. Their long evolutionary history is another aspect which still needs to be investigated.

Here, we have initiated work in order to detect whether some abiotic factors (soil properties) impact community structure. Like [START_REF] Agrawal | Filling key gaps in population and community ecology[END_REF], we argue that increasing the number of quantitative experimental designs is essential to quantify the magnitude of effects of abiotic and biotic factors, such as competition, facilitation or nutrient availability, and in order to define well their relative importance. Currently, researches on biotic interaction are almost nonexistent, especially concerning positive interactions, such as plant-plant facilitation, despite the fact that these interactions can be useful in restoration [START_REF] Padilla | The role of nurse plants in the restoration of degraded environments[END_REF].

2.Effect of fire on reproductive phenology

Although campos rupestres are a fire-prone environment, few studies deal with this subject, partly because legislation complicates the implementation of fire study. We show here that some species, including some dominant Poaceae, did not reproduce sexually during our two-year survey. However, in August 2011, a fire occurred on Serra do Cipó, and just after (some days), some species flowered among which Bulbostylis paradoxa (Figure 46a). A few months after, almost all individuals of species like Tatianyx arnacites or Homolepis longispicula flowered as well (Figure 46b). It was already reported that fire stimulates flowering of campos rupestres species (Munhoz & Felfili 2005[START_REF] Neves | Revisão sobre os Efeitos do Fogo em Eriocaulaceae como Subsídio para a sua Conservação[END_REF][START_REF] Conceição | Post-fire flowering and fruiting in Vellozia sincorana, a caulescent rosette plant endemic to Northeast Brazil[END_REF]. Then it should be interesting to compare phenological patterns before and after fire, to underline whether species are enhanced by fire to produce flower and fruits. This study should also be realized in association with germination studies. We showed in this thesis that some seeds produced just after fire had a high germinability; however more species need to be tested to draw more global patterns. It is also interesting to assess if such seeds with high germinability can be used to restore degraded areas.

3.Understanding regeneration after natural disturbance

Understanding how natural processes operate following natural disturbances allows us to use these processes to restore highly disturbed sites [START_REF] Prach | Spontaneous Succession versus Technical Reclamation in the Restoration of Disturbed Sites[END_REF][START_REF] Polster | Natural processes: the application of natural systems for the reclamation of drastically disturbed sites[END_REF][START_REF] Prach | Four opportunities for studies of ecological succession[END_REF]. In campos rupestres, fire is the most frequent disturbance and some studies have already demonstrated that these grasslands are particularly resilient to fire [START_REF] Neves | Campo rupestre recém-queimado na Chapada Diamantina , Bahia , Brasil : plantas de rebrota e sementes, com espécies endêmicas na rocha[END_REF][START_REF] Hernandez | Étude de l'impact du feu sur la composition et la structure des communautés herbacées des campos rupestres, pelouses tropicales d'altitude[END_REF]. In August 2011, one of our study sites burnt and, five months after fire, vegetation cover and density in both sandy and stony grasslands have quite similar value to those before fire [START_REF] Hernandez | Étude de l'impact du feu sur la composition et la structure des communautés herbacées des campos rupestres, pelouses tropicales d'altitude[END_REF] (Figure 47). In fire-prone environment, species can (1) resist to fire, conserving a part of their aboveground biomass, (2) resprout, recovering after fire via vegetative regeneration and (3) germinate from the seed bank or from newly dispersed seeds (Hoffmann 1998[START_REF] Keeley | The ecology of regeneration in plant communities[END_REF][START_REF] Pausas | Plant Functional Traits in Relation to Fire in Crown-Fire Ecosystems[END_REF][START_REF] Bond | Fire as a global "herbivore": the ecology and evolution of flammable ecosystems[END_REF]. Fire stimulated germination was not encountered in this thesis but we studied few species and therefore other species have to be tested. Moreover, in the Cerrado, in response to fire (one of the most frequent disturbance), vegetative reproduction is a frequent strategy, much more successful than sexual reproduction (Hoffmann 1998). In campos rupestres, hemicryptophyte species are largely dominant, also suggesting a selection pressure by fire in these kinds of tropical grasslands: hemicrytophyte species are able to re-grow from underground buds and organs which remain viable after fire [START_REF] Coutinho | Fire in the ecology of the Brazilian Cerrado[END_REF]).

Germination

We have demonstrated in Chapter 3 & 4 that germination issues limit restoration using simple techniques, such as seeding or hay transfer, mainly because some species produce unviable or dormant seeds. Fire-related cues did not enhance germination and did not break dormancy of dormant seeds. Further studies are therefore needed to understand seed dormancy, how this trait evolved and how it is possible to break dormancy.

Looking for new restoration techniques

As shown in the present thesis, the most successful method to introduce native species on degraded areas was also the most destructive one, which limits its application. In such a context, it is currently important to look for new methods to propagate plants, such as rhizome transplant [START_REF] Cooper | Restoring the Vegetation of Mined Peatlands in the Southern Rocky Mountains of Colorado[END_REF] or tissue culture (Kock 2007). This latter is a costly and difficult propagation method,only used when there are biological barriers to other methods, such as in campos rupestres. This method should be developed for a species in which sexual reproduction issues were identified in the previous studies, since plants produced by tissue culture are often species that invest energy into underground biomass to ensure survival. However the development of tissue culture methods is a very slow process and it can take several years to learn how to produce some species in mass (Kock 2007).

Conclusion

Campos rupestres harbour a great biodiversity and provide valuable services for human well-being including cultural, spiritual and recreational ones. Unfortunately they are extremely threatened by land-use changes, as mining, quarrying, road construction or unplanned development. Our results allow a better understanding of a part of the history of these peculiar grasslands. However, current knowledge did not allow the development Appendix 3: List of species participating or not in the reproductive phenology with their habitat occurrences (Sandy (Sa) or Stony (St) grasslands), the frequency of reproductive events, the timing and the duration of flowering (Fl.), fruiting (Fr.) and dissemination (Diss.). C: continual, SB: sub-annual, A: annual, SP: supra-annual. R: rainy season, RD: transition rainy to dry season, D: dry season, DR: transition dry to rainy season. S: short cycle (< 2 months), L: long cycle (> 2 months). When data are different between both grasslands, values are separated with a "/". [START_REF] Pakeman | The role of the seed bank, seed rain and the timing of disturbance in gap regeneration[END_REF]. In European grasslands, viable seeds of characteristic species are often absent from the seed bank due to their low longevity or because of low seed production (Hutchings & Booth 1996, Bekker et al., 1997;Buisson et al. 2006), as a consequence the natural regeneration of these ecosystems is low. In mountain grasslands in South America, Funes et al (2001) verified that the largest number of seeds, and thus the highest potential for regeneration, was found in wetter sites, but then the number decreased progressively from mesic to xeric habitats.

Campos rupestres, are one of the physiognomies of the Cerrado (Brazilian savanna), representing c.a. 130,000km² (Barbosa 2012) found at altitudes of between 800m and 2000m. They are composed of a mosaic of stony and sandy grasslands, that bogs along the streams and scattered rocky outcrops with sclerophyllous evergreen shrubs and subshrubs (Chapter 1). Campos rupestres are constrained ecosystems with shallow soils, poor in nutrients and highly acidic (Benites et al. 2007, Chapter 1), highly diverse vegetation and one of the highest levels of endemism in Brazil (Giulietti et al. 1997, Echternacht et al. 2011). Campos rupestres are still subjected to damage, in particular with mining, quarrying, and civil engineering activities.

The objectives of this work were to evaluate the natural regeneration of campos rupestres through seed banks, assessing the seasonal variation (rainy and dry season) in seed quantity and species composition, and the similarity between the seed bank from sandy and stony grasslands. We also discussed the seed bank composition with the above-ground composition.

2.Material and methods

Study site

Our study area is located in Brazil, in the southern portion of the Espinhaço Range, in the Environmental Protected Area (Area de Proteção Ambiental in Portuguese) Morro da Pedreira, buffer zone of the Serra do Cipó National Park (State of Minas Gerais). The climate is classified as Cwb according to the Köppen's system with warm temperate dry winter from May to October and warm rainy summer from November to April. The mean annual precipitation is 1622 mm and the annual temperature is 21.2°C (Madeira & Fernandes 1999).

Seed bank analysis

Five sites of the two main grassland-types (i.e. sandy and stony grasslands) were selected, and five 1L soil samples were taken at the end of the rainy season (end of March) and five at the end of the dry season (end of September), which is the peak period of fruit production (n = 5 samples × 10 sites × 2 seasons = 100). Each sample consisted of 10 pooled sub-samples, randomly taken at each site, to overcome seed bank heterogeneity. Samples were washed with water on sieves of 4 mm and 200 µm mesh sizes to remove 1) plant fragments and stones and 2) the finest fraction (clay and silt). The remaining soil containing seeds was spread as a thin layer on trays (25cm x 35cm) on compresses placed over a 3 cm thick layer of vermiculite (neutral substrate).

Control trays (n=3) (made of compresses over vermiculite) and controls of the finest fraction (n=3) (made of the finest fraction spread out on compresses over vermiculite)

were also set in order to 1) make sure that no species could colonize the greenhouse and contaminate samples and 2) make sure that no seed <200 µm may have been lost

to sieving. All trays were kept in a greenhouse, regularly moved and watered. Emerging seedlings were identified weekly and removed or replanted in pots for later identification to avoid competition in the trays and emission of allelopathic substances. After one month without germination, each sample was dried and microplowed before starting a second germination period, as this being known to cause more seeds to germinate (Roberts 1981).

Statistical analysis

To analyse seed bank data, t-tests with separate variance estimates were run to compare mean seed/species number in each sample/site between sandy and stony grasslands during the dry and the rainy season. Then, a dissimilarity matrix using Braycurtis indices, based on species abundance data was calculated, and an ANOSIM was performed.

3.Results

Seed banks of both sandy and stony grasslands are poor in species and seeds. A higher total number of seeds was observed in sandy grasslands seed bank during the rainy season (Table 1). However, neither grassland-types, nor seasons had a significant effect on the mean number of seeds or species in samples or in sites (Table 1). The seed bank compositions between grassland-types and seasons were similar (ANOSIM R=0.018, p=0.068, Table 2). Frequent species occurring in the seed banks were also species normally found in the vegetation, such as Tatianyx arnacites, Lagenocarpus rigidus subsp. tenuifolius, Rhynchospora riedeliana, Rhynchospora consanguinea and Rhynchospora tenuis subsp. austro-brasiliensis (Table 3). However, some species which are common in the campos rupestres (i.e. with a high importance value index) such as

Mesosetum exaratum and Vellozia spp were absent from the seed banks (Table 3).

Table 1: Number of germinated seeds and number of species found in the seed bank of the 5 sandy and 5 stony grasslands (5 samples x 5 site x 2 grassland-types x 2 season, n=100). ns: non significant difference. T-tests with separate variance estimates were run. ns: non significant difference. Table 3: Dominant species in the seed bank from the sandy and stony grasslands and in the established vegetation.

4.Discussion

Although the natural sandy and stony campos rupestres are highly diverse (Chapter 1), their seed banks are poor in seeds and species and do not vary among seasons. Medina and Fernandes (2007) have already pointed out that the seed banks of some herbaceous communities of campos rupestres are species poor in comparison to other physiognomies, such as some nearby gallery forests. Seed bank of the Cerrado and other tropical savannas appear to be richer in seeds than those of campos rupestres (Perez & Santiago 2001, Salazar et al. 2011). We argue that campos rupestres have a weak ability to regenerate from the seed bank due to the absence of transient and/or persistent seed bank [START_REF] Thompson | Seasonal Variation in the Seed Banks of Herbaceous Species in Ten Contrasting Habitats[END_REF], Kalamees & Zobel 2002). The lack of viable seeds of characteristic species in the seed bank, due to their short longevity, has also been demonstrated in European grasslands (Hutchings & Booth 1996, Bekker et al., 1997;Buisson et al. 2006). In consequence, seed bank plays little role in regeneration [START_REF] Edwards | Herbivores , Seed Banks and Seedling Recruitment in Mesic Grassland[END_REF][START_REF] Pakeman | The role of the seed bank, seed rain and the timing of disturbance in gap regeneration[END_REF] and when dispersal is also limited, the natural regeneration of these ecosystems is low.

First, the low density of emergences can reflect the large quantity of dormant seeds reported before for some campo rupestre species (Gomes et al. 2001, Silveira & Fernandes 2006, Garcia et al. 2011, Silveira et al. 2012). Several other hypotheses can explain the low seed density in the seed bank. Indeed, the ability to form a seed bank seems to vary in campos rupestres: while some species appear not to form seed banks (Velten & Garcia 2007), others may form only a small persistent seed bank (Velten & Garcia 2007, Giorni 2009, Silveira 2011). Bossuyt & Honnay (2008) have found that seed density are low in stable communities which is the case of campos rupestres that are supposed to have been stable ecosystems for 20,000 years (Barbosa 2012); indeed it has been suggested that increasing habitat disturbance always selects for increased seed persistence (Hölzel & Otte 2004). Bekker et al. (1997) have noted that species associated with poor nutrient conditions are relatively scarce in the seed bank. Funes et al. (2001) have found that the largest number of seeds is found in wetter sites and although campo rupestres are sometimes flooded in the rainy season, they are subjected to a severe five-month dry season which can lead to unfavorable environmental conditions to seed bank formation (Funes et al. 2001).

In addition, the poverty of the seed bank might also be associated to the low quantity of annuals species (which are obligate seeder) in campos rupestres where perennial species are dominant (Chapter 1), although Hölzel & Otte (2004) have found large proportion of perennial species with a strong tendency to accumulate seeds in the soil, in some European grasslands.

Moreover, in the Cerrado, in response to fire (one of the most frequent disturbance), vegetative reproduction is a frequent strategy, much more successful than sexual reproduction (Hoffmann 1998). Fidelis et al. (2010) have also pointed out the importance of the bud banks in tropical grasslands that are subjected to fire, which would replace the seed bank in such communities. Indeed, Pausas & Verdu (2005) have highlighted that species able to resprout almost never evolved to one with persistent propagules, contrary to species unable to resprout. The most serious implication of a poor seed bank is the low capacity of campos rupestres to regenerate from the seed bank faced to strong disturbances.

We have found little similarities between the standing vegetation and the seed bank, mainly due to the scarcity of species in the seed bank. It is usually accepted that similarity between seed bank and vegetation are low in stable ecosystems (Bossuyt & RESUMO Composição, fenologia e restauração dos campos rupestres -Brasil. As mudanças ambientais globais, principalmente as mudanças de uso da terra, afetam profundamente o funcionamento dos ecossistemas e a biodiversidade e já alteraram muitos serviços ecossistêmicos. Essas perdas enfatizam a necessidade de se preservar ecossistemas intocados; no entanto, quando os programas de conservação não são suficientes, a restauração das áreas que foram destruídas ou perturbadas pode melhorar os esforços de conservação e mitigar os danos. Este trabalho trata dos campos rupestres, campos neotropicais encontrados em altitudes, incluídos no Cerrado, que possuem uma grande biodiversidade com um alto grau de endemismo e, assim como outros ecossistemas de montanhas, fornecem serviços ecossistêmicos valiosos, tais como filtragem da água e áreas de lazer. Eles forame ainda estão sendoimpactados por atividades humanas, tais como obras de engenharia civil, pedreiras e minas. O primeiro objetivo do presente trabalho foi descrever o ecossistema de referência, a fim de definir claramente um objetivo de restauração para monitorar o progresso e o sucesso da restauração. Mostramos que campos rupestres são compostos por pelo menos duas comunidades vegetais distintas (campos arenoso e pedregoso), cada uma com composição e estrutura específicas e apresentando grande biodiversidade. Vários padrões fenológicos ocorrem nas comunidades herbáceas de campos rupestres: a maioria das espécies florescem e frutificam durante a estação chuvosa, quando algumas espécies reproduzem durante a estação seca mas outros padrões podem ser observados. Durante o nosso levantantamento fenológico de 2 anos, algumas espécies dominantes de Poaceae, entre outros, não foram observadas reproduzindo, o que implica possibilidades limitadas de dispersão em áreas degradadas. A vegetação de campos rupestres não é resiliente após um grande distúrbio: vários anos depois do distúrbio, espécies nativas quase não são encontradas em áreas degradadas, os solos estão completamente alterados e os bancos de sementes recompõem apenas espécies ruderais. De acordo com o modelo dos filtros, uma comunidade local é o resultado de um conjunto regional de espécies selecionadas por três filtros: um filtro de dispersão, um filtro abiótico e um filtro biótico. A atuação sobre os diferentes filtros para influenciar a comunidade de plantas foi o núcleo de nossas intervenções de restauração. Aplicamos, então, três protocolos de restauração in-situ (a transferência de feno, a translocação de espécies e translocação do placa de vegetação) para restaurar os dois tipos de campos. A transferência de feno não permite a restauração da vegetação de campos rupestres devido à alteração do solo e, principalmente, por causa da baixa qualidade das sementes. De fato, estudos mostram que algumas Xyridaceae e Velloziaceae têm uma germinação alta, enquanto algumas espécies dominantes, como Poaceae, Cyperaceae ou Asteraceae, têm sementes sem embrião, inviáveis ou dormentes, o que torna a semeadura uma técnica pouca eficiente. Não há evidências de que o fogo aumenta a germinação das espécies de campos rupestres. A translocação de espécies foi bem sucedida para apenas uma espécie, Paspalum erianthum; para as outras, danos nas raizes provavelmente impediram a sobrevivência. A translocação de placa de vegetação finalmente foi o método mais bem sucedido, uma vez que numerosas espécies foram reintroduzidas em áreas degradadas. No entanto, devido à baixa resiliência dos campos rupestres de onde as placas foram retiradas, a translocação de placa de vegetação apenas pode ser considerada no caso de resgate de habitat, em circunstâncias em que a destruição completa do habitat é inevitável. Face à dificuldade de se restaurar os campos rupestres, a proteção e a conservação dos mesmos deve ser uma prioridade.

Palavras-chave : Banco de semente, Campos rupestres, Cerrado, ecologia da restauração, ecologia das communidade, ecossistema neotropical de montanha, germinação, restauração de campos, savannas, transferência de feno, translocação de placa de vegetação, translocação, transplantação.

ABSTRACT

Composition, phenology and restoration of campo rupestre mountain grasslands -Brazil. Global environmental changes, especially land-use changes, have profound effects on both ecosystem functioning and biodiversity, having already altered many ecosystem services. These losses emphasize the need to preserve what remains; however when conservation programs are not sufficient, restoring areas that have been destroyed or disturbed can improve conservation efforts and mitigate damages. This work focuses on campos rupestres, Neotropical grasslands found at altitudes, which are part of the Cerrado (Brazilian savannas). They host a great biodiversity with a high level of endemism and, like other mountain ecosystems, provide valuable ecosystem services, such as water purification and recreational services.

They have been and still are being impacted by human activities, such as civil engineering construction, quarrying or mining. The first objective of this thesis was to describe the reference ecosystem in order to aim for a clear restoration target and to monitor progress and success. We show that campos rupestres are composed of at least two distinct plant communities (i.e. sandy and stony grasslands), each having a specific composition and structure, hosting a great biodiversity. Several phenological patterns occur among the herbaceous communities: the majority of species flowers and fruits appear during the rainy season but other patterns can be observed. During our 2-year survey, some dominant species belonging to Poaceae, among others, were not observed reproducing, which implies limited chances to disperse on degraded areas. Campo rupestre vegetation is not resilient following a strong disturbance: several years after the disturbance, almost no native species are encountered on the degraded areas, soils are completely altered and seed bank recomposes only with non-target ruderal species. According to the filter model, a local community is a subset of the regional species pool determined by a set of dispersal, abiotic and biotic filters.

Acting on the different filters to influence the plant community was the core of our restoration interventions.

We then applied three in-situ restoration protocols (hay transfer, species translocation and turf translocation) to restore both kinds of grassland. Hay transfer does not allow the restoration of campo rupestre vegetation because of soil alteration and mainly because of poor seed quality. Indeed, germination studies show that, while some Xyridaceae and Velloziaceae have a high germinability, some dominant Poaceae, Cyperaceae or Asteraceae species have embryoless, unviable or dormant seeds, which makes seeding less efficient.

There is no evidence that fire-related cues enhance germination in campos rupestres. Species translocation is successful for only one species, Paspalum erianthum; for the others, root damages probably impede survival. Finally, turf translocation is the most successful method, since numerous species are re-introduced on degraded areas. However due to the low resilience of pristine campos rupestres where turfs are taken from, turf translocation can only be considered in the case of habitat rescue, in circumstances when complete habitat destruction is otherwise unavoidable. Face to the difficulty to restore these peculiar grasslands, the protection and the conservation of campos rupestres must be made a high priority.

Keywords: Cerrado, community ecology, germination, grassland restoration, hay transfer, Neotropical mountain ecosystems, restoration ecology, rupestrian fields, rupestrian grasslands, savannas, seed bank, translocation, transplantation, turf transfer.

  e vejo a minha serra, a serra de meu pai e meu avô, de todos os Andrades que passaram e passarão, a serra que não passa. Era coisa dos índios e a tomamos para enfeitar e presidir a vida neste vale soturno onde a riqueza maior é a sua vista a cotemplá-la. De longe nos revela o perfil grave.A cada volta de caminho aponta uma forma de ser, em ferro, eterna,

  for values. ................................ 107 Table 15: Number of germinated seeds and number of species found in the seed banks of the reference grasslands (sandy (Sa) and stony (St) grasslands) and of the three types of degraded areas (with latosol substrate (DL), stony substrate (DSt) and sandy substrate (DSa)) (n= 5 samples x 3 sites x 5 types of areas). Letters indicate significant differences according to the result of the GLM procedures (family: Poisson, link: log). ................................................................................................ 109

  ............................................................................................................................. 161Table 24: Number and percentage of surviving translocated individuals 3 months after the translocation, in June 2011 for individuals translocated in March 2011 and in February 2012 for individuals translocated November 2011. Individuals were translocated to a degraded sandy area (DSa) and to a reference sandy grassland (RSa) without added nutrients. 10 individuals for each species were translocated to DSa in March 2011, and for the other treatments, 5 individuals per species were translocated. To test the effect of the period of transplantation and substrate type GLM procedures were run with a binomial family distribution and logit link function. ns: non significant. ............................................................................................... 162 Table 25: Average number of individuals in 20x20cm and 40x40cm turfs translocated to degraded sandy substrate at T0 and T14 according to plant form: graminoids, forbs and sub-shrubs. Results of the LMER procedures are shown. ............................. 164

Figure 2 :Figure 3 :Figure 4 :Figure 5 :

 2345 Figure 1: The role of biodiversity and restoration activities in global change. Human activities (1) are now causing environmental and ecological changes of global significance (2). Through a variety of mechanisms, these global changes contribute to changing biodiversity (3), and changing biodiversity feeds back on susceptibility to species invasions (4). Changes in biodiversity, can have direct consequences for ecosystem services impacting human economic and social activities (5). In addition, changes in biodiversity can influence ecosystem processes and feedback to further alter biodiversity (6). Altered ecosystem processes can thereby influence the ecosystem services that benefit humanity (7). Global changes may also directly affect ecosystem processes (8). Restoration actions are represented by dashed lines. (Adapted from Chapin et al. 2000, Palmer & Filoso 2012, Le Stradic unpublished)............................................................................................................. 2 Figure 2: General overview of the organization of this thesis highlighting the steps recommended by the SER primer (SER 2004). Pale grey boxes correspond to the different steps developed in the thesis's chapters, dark grey boxes represent the filters structuring the community (see section 4.5 Assembly rules: How do species assemble into communities?). Full black arrows: studies related to the reference ecosystem; full grey arrow: disturbance which destroyed pristine campos rupestres; dashed black arrows: we have assessed if degraded campos rupestres are resilient to strong disturbance from the external or internal species pool; dashed grey arrows: restoration techniques we have tested, act on different filters. .................................. 4Figure 3: Schematic representation of the trajectory of a natural or semi-natural ecosystem over time. Full lines correspond to trajectories resulting from restoration interventions (reference ecosystem trajectory, rehabilitation or failure); dashed lines represent natural processes, or trajectories observed without interventions, and grey lines, the functions evolving in a third dimension, ASS (Alternative stable state). (Modified from Hobbs & Norton 1996, Prach & Hobbs 2008, Buisson 2011). ........... 8 Figure 4: The relationship between ecological theory, restoration ecology, and ecological restoration can be viewed in a hierarchical fashion (Palmer et al. 2006)................. 11 Figure 5: The theory of community ecology (from Vellend 2010) ................................... 13

Figure 7 :Figure 8 :Figure 9 .Figure 10 :Figure 11 :Figure 12 :Figure 14 :Figure 15 :Figure 16 :Figure 17 :Figure 18 :Figure 20 :Figure 21 :Figure 22 :Figure 26 :Figure 27 :Figure 29 :

 7891011121415161718202122262729 Figure 7: Map of the tropical savannas according Bourlière 1983 .................................. 20 Figure 8: The main processes affecting savanna functioning. Grey arrows: factors occurring in all savannas. White arrows: factors occurring in some savannas at particular times (Le Stradic unpublished). ............................................................... 21

Figure 41 :

 41 Figure 41: Average vegetation cover (%) (mean ± standard error) on 40x40cm TSa (black squares with dashed line), on 20x20cm TSa (black squares with solid line) translocated in DSa and on 20x20cm TSt (black triangles and dashed line) and TSa (open squares and solid line) translocated in DSt over time (in months). .............. 163 Figure 42: a) Average number of individuals and b) plant species richness in 40x40cm (dashed lines) or 20x20cm (solid line) translocated turfs in DSa over time (in months). Means within size were significantly different in May 2012 (T 14) (P <0.001) in both number of individuals and species richness. ................................ 164 Figure 43: a) Average number of individuals and b) plant species richness in 20x20cm TSt (dashed lines) and TSa (solid line) translocated in DSt over time (in months). Means within origin of turfs were similar in May 2012 (T 14) (P >0.05) in both number of individuals and species richness. ........................................................ 165 Figure 44: a) Average number of individuals and b) plant species richness in 20x20cm TSa transplanted in DSa (full squares) and in DSt (open squares) over time (in months). Means within each substrate were significantly different in May 2012 (T 14) in number of individuals (P <0.001) but similar in species richness (p=0.6). ......... 167

Figure 1 :

 1 Figure 1: The role of biodiversity and restoration activities in global change. Human activities (1) are now causing environmental and ecological changes of global significance (2). Through a variety of mechanisms, these global changes contribute to changing biodiversity (3), and changing biodiversity feeds back on susceptibility to species invasions (4). Changes in biodiversity, can have direct consequences for ecosystem services impacting human economic and social activities (5). In addition, changes in biodiversity can influence ecosystem processes and feedback to further alter biodiversity (6). Altered ecosystem processes can thereby influence the ecosystem services that benefit humanity (7). Global changes may also directly affect ecosystem processes (8). Restoration actions are represented by dashed lines. (Adapted from Chapin et al. 2000, Palmer & Filoso 2012, Le Stradic unpublished).

Figure 2 :

 2 Figure 2: General overview of the organization of this thesis highlighting the steps recommended by the SER primer (SER 2004). Pale grey boxes correspond to the different steps developed in the thesis's chapters, dark grey boxes represent the filters structuring the community (see section 4.5 Assembly rules: How do species assemble into communities?). Full black arrows: studies related to the reference ecosystem; full grey arrow: disturbance which destroyed pristine campos rupestres; dashed black arrows: we have assessed if degraded campos rupestres are resilient to strong disturbance from the external or internal species pool; dashed grey arrows: restoration techniques we have tested, act on different filters.

Figure 3 :

 3 Figure 3: Schematic representation of the trajectory of a natural or semi-natural ecosystem over time. Full lines correspond to trajectories resulting from restoration interventions (reference ecosystem trajectory, rehabilitation or failure); dashed lines represent natural processes, or trajectories observed without interventions, and grey lines, the functions evolving in a third dimension, ASS (Alternative stable state). (Modified from Hobbs & Norton 1996, Prach & Hobbs 2008, Buisson 2011).

Figure

  Figure 5: The theory of community ecology (from Vellend 2010)

Figure 6 :

 6 Figure6: The main processes / filters that structure a plant community. Each process/filter is represented by a pair of horizontal lines. Solid arrows depict the movement of species through the filters. Grey boxes indicate how ecosystem degradation may affect the different levels (inspired by[START_REF] Lortie | Rethinking plant community theory[END_REF][START_REF] Fattorini | The dynamic environmental filter model: how do filtering effects change in assembling communities after disturbance?[END_REF][START_REF] Belyea | Beyond ecological filters: feedback networks in the assembly and restoration of community structure, in: Assembly rules and restoration ecologybridging the gap between theory and practice[END_REF], Buisson 2011, Le Stradic unpublished).

Figure 7 :

 7 Figure 7: Map of the tropical savannas according Bourlière 1983

Figure 8 :

 8 Figure 8: The main processes affecting savanna functioning. Grey arrows: factors occurring in all savannas. White arrows: factors occurring in some savannas at particular times (Le Stradic unpublished).

Figure 10 :

 10 Figure 10: Simplified structural gradient of Cerrado ecosystems (modified from Coutinho 1978) and representation of the ideology developed by some authors on the concept of Cerrado (Le Stradic unpublished).

  . In 2005, the Espinhaço Range was designated a Biosphere Reserve by UNESCO (UNESCO 2005), and it now includes 16 protected areas (National Parks, State Parks, State Ecological Stations and Municipal Natural Parks) (Figure 12).

Figure 11 :

 11 Figure 11: Campos rupestres considered as a physiognomy of the Cerrado (Le Stradic unpublished)

Figure 12 :

 12 Figure 12: Map of the Espinhaço range showing the protected areas (Unidade de Concervação de Proteção integral). Number 1 is the Serra do Cipó National park where this study was realized Map from Biodiversitas fundation.

Figure 13 :

 13 Figure 13: Map of the 10 study sites on the two main grassland-types of campos rupestres: sites with the sandy substrate located on flatted areas (Sa) and sites with stony substrate on slopes (St). The dashed line represents the highway MG-010. The inset shows a map of the environmental Protected Area (Area de Proteção Ambiental in Portuguese) Morro da Pedreira, which includes the Serra do Cipó National Park. (Map realized using Plano de manejo do PARNA Serra do Cipó (2009), Google Earth image and QGIS).

Figure 15 :

 15 Figure 15: Map of the 9 degraded sites on three kinds of substrate: sites located on degraded latosol substrate (DL), on degraded sandy substrate (DSa) and on degraded stony substrate (DSt). The dashed line represents the highway MG-010. The inset shows a map of the environmental Protected Area (Area de Proteção Ambiental in Portuguese) Morro da Pedreira, including the Serra do Cipó National Park. (Map realized using Plano de manejo do PARNA Serra do Cipó (2009), Google Earth image and QGIS).

Figure 16 :

 16 Figure 16: Degraded areas with a) degraded latosol substrate, b) degraded sandy substrate, c) degraded stony substrate. Photo credit S. Le Stradic.

  , occasionally separated one from another by just a few centimeters (Conceição and Pirani 2005, Alves and Kolbek 2010). Benites et al. (2003) noted a considerable diversity of pedoenvironments associated with the vegetation mosaics of campos rupestres. They commonly occur on Leptosols and Arenosols [respectively Neossolos Litólicos and Neossolo Quartzarênico according to the Brazilian Soil Classification System (Embrapa 1999)]

Figure 17 :

 17 Figure 17: Mean and standard error values of chemical soil parameters, from soils collected in sandy and stony grasslands (3 samples / 5+5 sites / 2 seasons, n=60). Open circles represent dry season and full circles rainy season. SeeTable 2 for twoway ANOVA results.

Figure 18 :Figure 19 :Figure 20 :

 181920 Figure 18: Ward clustering of a matrix of chord distances among sites (species data).

Figure 21 :Figure 22 :

 2122 Figure21: Percentage of species according to plant forms. Sandy grasslands (black columns) and stony grasslands (grey columns) χ 2 =27.3, P<0.001 in sandy grasslands and χ 2 =27.0, P<0.001 in stony grasslands. Lower-case letters indicate differences between forms within sandy grasslands and capital letters between forms within stony grasslands (Multiple comparisons made using the Bonferroni correction).

Figure 23 :Figure 24 :

 2324 Figure 23: Number of species from the most-represented families in sandy grasslands (black columns) and stony grasslands (grey columns). (5 sites of each physiognomy, 15 1 m 2 quadrats in sandy grasslands and 20 1m 2 in stony grasslands).

Chapter 1 -

 1 Campos rupestres communities 64 Note: According to Vitta (2005), Lagenocarpus rigidus (Kunth) Nees subsp. tenuifolius (Boeck.) T. Koyama & Maguire is a synonym of Lagenocarpus tenuifolius.

Figure 26 :

 26 Figure 26: Distribution of mean monthly temperatures (T°C) at 6h00 (open square) and 13h00 (full square), and cumulative rainfall (mm) between November 2009 and October 2011. Temperature data provided by G.A. Sanchez-Azofeifa, Enviro-Net project, University of Alberta. Rainfall data obtained by INMET (2012).

  During two consecutive years (from November 2009 to October 2011), we surveyed ten 1m² quadrats at each site monthly. For each quadrat we recorded the list of species, and for each species we recorded: (1) total number of individuals or clumps (i.e. thick group of the same species, probably clones), (2) number of individuals or clumps with inflorescence, (3) the number of inflorescences, and (4) the number of inflorescence in each phenophase: (i) flower (including flower buds and open flowers), (ii) fruit (including unripe and ripe fruits), and (iii) dissemination (dissemination signs, open fruits). Hereafter, the numbers of inflorescence in flower, in fruit and in dissemination, were designated by number of flowers, number of fruits and number of dissemination, respectively.

  (C): phenophases always present, Sub-annual (SB): irregular multiple phenophases per year, Annual (A): one major phenophase per year, Supra-annual (SP): Multi-year cycles of phenophases, here designated species that flowered/fruited/disseminated only once during our two-year survey. The timing and duration of each A and SP species phenophase (flowering, fruiting and dissemination) was determined; we defined four timing strategies: occurrence of the phenophase during the (i) rainy season (from November to April) (R), (ii) transition between rainy to dry season (from March to June) (RD), (iii) dry season (from May to October) (D), and (iv) transition between dry to rainy season (from September to December) (DR). Duration was separated in two categories:

Figure 27 :

 27 Figure 27: Flowering pattern in sandy (a) and stony (b) grasslands, fruiting pattern in sandy (c) and stony (d) grasslands and dissemination pattern in sandy (e) and stony (f) grasslands. These patterns were defined according to the number of species in each phenophase (based on the peak). Each species occurs only once. Arrows represented µ and the black circle the significant threshold.

Chapter 2 :

 2 Phenology of the campos rupestres 84 have supra-annual phenological patterns that we were not able to observe in such a short study, or because they rarely reproduce. Our results also report the high proportion of perennial species in the campos rupestres (see Warming 1892,Furley & Ratter 1988).Their survival does not rely only on sexual reproduction and seed production. Moreover, it has already been demonstrated that fire induces or increases reproduction in a fireprone habitat, such as the Cerrado[START_REF] Lamont | Fire may stimulate flowering, branching, seed prodiction and seedling establishment in two kangaroo paws (Haemodoraceae)[END_REF][START_REF] Freitas | Pollination Biology in a Tropical High-Altitude Grassland in Brazil : Interactions at the Community Level[END_REF][START_REF] Munhoz | Reproductive phenology of an herbaceous-subshrub layer of a Savannah (Campo Sujo) in the Cerrado Biosphere Reserve I, Brazil[END_REF][START_REF] Neves | Campo rupestre recém-queimado na Chapada Diamantina , Bahia , Brasil : plantas de rebrota e sementes, com espécies endêmicas na rocha[END_REF][START_REF] Lamont | Fire-stimulated flowering among resprouters and geophytes in Australia and South Africa[END_REF][START_REF] Neves | Revisão sobre os Efeitos do Fogo em Eriocaulaceae como Subsídio para a sua Conservação[END_REF][START_REF] Conceição | Post-fire flowering and fruiting in Vellozia sincorana, a caulescent rosette plant endemic to Northeast Brazil[END_REF]. Indeed fire-stimulated flowering species have already been observed in campos rupestres for some species, such as Bulbostylis paradoxa or some Eriocaulaceae, or Velloziaceae[START_REF] Figueira | Dinâmica de populações de Paepalanthus polyanthus (Eriocaulaceae) na Serra do Cipó[END_REF][START_REF] Kolbek | Impacts of Cattle, Fire and Wind in Rocky Savannas , Southeastern Brazil[END_REF][START_REF] Neves | Revisão sobre os Efeitos do Fogo em Eriocaulaceae como Subsídio para a sua Conservação[END_REF][START_REF] Ribeiro | Uma Abordagem Histórica do Fogo no Parque Nacional da Serra do Cipó, Minas Gerais -Brasil[END_REF][START_REF] Conceição | Post-fire flowering and fruiting in Vellozia sincorana, a caulescent rosette plant endemic to Northeast Brazil[END_REF]. Moreover, species such as Tatianyx arnacites, Mesosetum exaratum, Paspalum erianthum or Homolepis longiscapa, abundant Poaceae in sandy and stony grasslands (Chapter 1), recorded few reproductive individuals during these two years, hence suggesting the need for a stimulus to induce flowering and fruiting, which might be fire, among other factors.

  , Bakker & Berendse 1999, Alpert & Maron 2000, Patzelt et al. 2001, Holzel & Otte 2003, Klimkowska & al. 2009, Piqueray & Mahy 2010, Török et al. 2011), or ii) on managing the soil surface (e.g.

  target species appears to be essential to overcome the limited natural regeneration and the dispersal barrier. The main near-natural methods for restoring grassland communities with local target species include (based on the review from[START_REF] Kiehl | Species introduction in restoration projects -Evaluation of different techniques for the establishment of semi-natural grasslands in Central and Northwestern Europe[END_REF] and[START_REF] Török | Grassland restoration on former croplands in Europe: an assessment of applicability of techniques and costs[END_REF] in Europe:1) Seeding of site-specific seed mixture:[START_REF] Cooper | Restoring the Vegetation of Mined Peatlands in the Southern Rocky Mountains of Colorado[END_REF],[START_REF] Lindborg | Recreating grasslands in Swedish rural landscapeseffects of seed sowing and management history[END_REF],Martin & Wisley (2006), Jongepierova et al. (2007), Jaunatre et al. (2012) 2) Transfer of fresh seed-containing hay / vacuum harvesting: Coiffait-Gombault et al. (2011), Jaunatre et al. (2012) (Mediterranean grasslands), Hölzel & Otte (2003), Donath et al. (2007) (species-rich flood meadows), Edwards et al. (2007) (lowland hay meadows/ chalk grasslands), Kiehl & Pfadenhauer (2006), Kiehl & Wagner (2006) (calcareous grassland), Patzelt et al (2001), Klimkowska & al. (2009) (fen meadows) 3) Transfer of turfs or topsoil: Rochefort et al (2003) (peatlands), Cobbaert et al (2004) (fen plant community, after mining), Jaunatre et al. (2012) (Mediterranean grasslands). 4) Transplants of seedlings, rhizomes, willow stem cutting: Cooper & MacDonald (2000) (fen in mountain), Page & Bork (2005) (mountain communities) 5) fire[START_REF] Moyes | Restoration of Native Perennials in a California Annual Grassland after Prescribed Spring Burning and Solarization[END_REF], hydrography(Dijk et al. 2007) or grazing(Martins & Wisley 2006[START_REF] Orrock | Native Consumers and Seed Limitation Constrain the Restoration of a Native Perennial Grass in Exotic Habitats[END_REF][START_REF] Klimkowska | Vegetation Re-development After Fen Meadow Restoration by Topsoil Removal and Hay Transfer[END_REF]) management.

Figure 28 :

 28 Figure28: The first objective of the third chapter is to assess the resilience of the heavily destroyed campos rupestres. The second objective is to test whether hay transfer is an efficient method to overcome the dispersal filter and restore campos rupestres.

  , including such activities as rehabilitation or reclamation (SER 2004). Many countries have already passed laws which require the reclamation, rehabilitation or restoration of quarries and mines once exploitation is over, e.g. the US Surface Mining Control and Reclamation Act of 1977; the Australian National Environment Protection Measures Act; the Canadian Law for environment quality (L.R.Q., c. Q-2, a. 20, 22, 23, 31, 46, 70 & 87); the French Décret n° 77-1133 du 21/09/77 pris pour l'application de la loi n° 76-663 relative aux ICPE; and in Brazil, Law 9605/1998, law 9985 18/07/2000 (linked to the article 225, § 1°, paragraphs I, II, III and VII of the Federal Constitution (1988)), article 19 of Law 4771/65, the technical standard ABNT 13030, SMA 08/2008 legislation

Chapter 3 -

 3 Resilience and restoration of campos rupestres 101 up leaves[START_REF] Coiffait-Gombault | Hay Transfer Promotes Establishment of Mediterranean Steppe Vegetation on Soil Disturbed[END_REF]. Then, the hay was dried and conserved in paper bags.

Figure 29 :

 29 Figure 29: Experimental design of the hay transfer experiment. HSa: hay collected on the two sandy grassland donor sites, HSt: hay collected on the two stony grassland donor sites, h: control without hay, G: with geotextile, w: without geotextile. Each treatment was replicated four times at each site in blocks.

Chapter 3 -

 3 Resilience and restoration of campos rupestres 104 2.4.2

Chapter 3 -

 3 Resilience and restoration of campos rupestres 105

Figure 31 :

 31 Figure 31: Mean and standard error values of chemical soil parameters, from soils collected in 3 sandy grasslands (Sa) and 3 stony grasslands (St), 3 degraded areas with latosol substrate (DL), 3 degraded areas with stony substrate (DSt), 3 degraded areas with sandy substrate (DSa) (3 samples / site / season, n=90). Full circles rainy season.See Table3for one-way nested ANOVA results.

Figure 33 :

 33 Figure33: Correspondence analysis run on the matrix of the species abundance in February 2012 in 40cmx40cm quadrat after hay transfer in reference grasslands: 2 stony (St) and 2 sandy grasslands (Sa) and in degraded areas: 3 with latosol substrate (DL), 3 with sandy substrate (DSa) and 3 with stony substrate (DSt) [232 points x 161 species]. Some quadrats received hay and some not and some had geotextile and some not. Projection of the two first axes, axis 1 (17.2%) and axis 2 (14.2%). Inertia=0.23, p<0.001, Monte-Carlo permutations.

Figure 34 :

 34 Figure 34: Mean number of seedlings occurring per 40cm×40cm quadrat on reference sandy grasslands (Sa) and on the 3 types of degraded areas: with latosol substrate (DL), with sandy substrate (DSa) and with stony sustrate (DSt) and 2 levels of 2 treatments: with hay (HSa) / without hay (h) and with geotextile (in clear grey) / without geotextile (dark grey). Letters indicate significant differences according to the result of the LMER procedures (family: Poisson, link: log), *: indicate difference between with and without geotextile.

Figure 35 :

 35 Figure 35: Mean number of seedlings occurring per 40cmx40cm quadrat on reference areas: sandy grasslands (Sa) and stony grasslands (St) and on degraded areas with stony substrates (DSt) according and 2 or 3 levels of 2 treatments: with hay from sandy grassland (clear grey) / with hay from stony grassland (grey) / without hay (dark grey), and with geotextile (G) / without geotextile (wg). Letters indicate significant differences according to the result of the LMER procedures (family: poisson, link: log), *: indicates difference between with and without geotextile.

  resilient to endogenous disturbance (sensu White & Jentsch 2001), such as fire[START_REF] Neves | Campo rupestre recém-queimado na Chapada Diamantina , Bahia , Brasil : plantas de rebrota e sementes, com espécies endêmicas na rocha[END_REF][START_REF] Hernandez | Étude de l'impact du feu sur la composition et la structure des communautés herbacées des campos rupestres, pelouses tropicales d'altitude[END_REF], we have shown that species-rich campos rupestres present very low resilience to severe anthropogenic degradation (i.e. exogenous disturbance). Indeed, eight years after quarrying, bare ground still dominated the degraded areas and species composition remained very different from reference campos rupestres. Some characteristic campo rupestre species, such as Tatianyx arnacites, Mesosetum exaratum, Homolepis longispicula, Lagenocarpus rigidus subsp.

Chapter 4 -

 4 Germination and dormancy of herbaceous species of campos rupestres 134 Table 20: Germination synchrony (mean and standard error). Low values indicate more synchronized germination and high values indicate asynchronous germination. Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 135

Chapter 4 -Figure 36 :

 436 Figure 36: Germination percentage (%) (a), Mean germination time (b) and synchrony (c) at 25°C, for species which flower immediately after fire and species which flower without fire. Letters indicate significant difference according (a) GLM procedure (quasibinomial error distribution and logit link function) with F=25.43, p<0.001, (b) GLM procedure (Gamma error distribution and inverse link function) with F=52.78, p<0.001, (c) simple ANOVAs, followed by post-hoc tests (Tukey's "Honest Significant Difference") F=31.70, p<0.001).

Figure 37 :

 37 Figure 37: Reconstructed phylogenetic tree of the fifteen species studied, species with dormant seeds are underlined.

Figure 38 :

 38 Figure38: The objective of the fifth chapter is to test whether species and turf translocation are efficient techniques to restore campos rupestres. Both techniques aimed to overcome the dispersal filter. Using species translocation we expected to overcome the critical phase of the establishment in the degraded areas and to improve environmental conditions bringing together soil and translocated plant. Using turf translocation, we aimed to bring to the degraded areas i) a pool of target species, ii) soil of the reference ecosystem and iii) possible associated microorganisms[START_REF] Carvalho | The mosaic of habitats in the high-altitude Brazilian rupestrian fields is a hotspot for arbuscular mycorrhizal fungi[END_REF]; overcoming therefore the environmental filter and a part of the biotic filter.

  On top : turf translocation, at right : Paspalum erianthum translocation Photo credit S. Le Stradic Chapter 5 -Species and turf translocation to restore campos rupestres 151 Chapter 5 -Restoration of campos rupestres: Species and turf translocation as techniques to restore highly degraded areas. Soizig Le Stradic 1,2 , Elise Buisson 1 & G. Wilson Fernandes 2 . 1 -UMR CNRS/IRD 7263/237 IMBE -Institut Méditerranéen de Biodiversité et d'Ecologie -Université d'Avignon et des Pays de Vaucluse, IUT, Agroparc, BP 61207, 84 911 Avignon cedex 9, France. 2 -Ecologia Evolutiva & Biodiversidade / Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 30161-970 Belo Horizonte MG, CP 486, Brazil.

Figure 39 :

 39 Figure 39: Experimental design of species translocation. Experiment 1A was carried out in March 2011 at the end of the rainy season, while Experiment 1B was carried out in November 2011 at the beginning of the rainy season.

  ), turfs from donor reference sandy grasslands (hereafter referred as TSa) were transferred to DSa in March 2011, using two different 10-cm-deep turf sizes: 40x40cm and 20x20cm, each spaced by 20 cm. Four replicates of eight turfs of each size were set up. In the second experiment (Experiment 2B, Figure 40), 10-cm deep 20x20cm turfs were transferred from the donor reference sandy (TSa) and stony (hereafter referred as TSt) grasslands to DSt (receptor site). Four replicates of eight turfs each were set up. Turfs were watered twice per week during the first month.

Figure 40 :

 40 Figure 40: Experimental design of turf translocation carried out in March 2011 at the end of the rainy season. Experiment 2A was carried out in degraded sandy substrate DSa, while Experiment 2B was carried out in degraded stony substrate DSt.

Figure 41 :

 41 Figure 41: Average vegetation cover (%) (mean ± standard error) on 40x40cm TSa (black squares with dashed line), on 20x20cm TSa (black squares with solid line) translocated in DSa and on 20x20cm TSt (black triangles and dashed line) and TSa (open squares and solid line) translocated in DSt over time (in months).

Figure 42

 42 Figure 42: a) Average number of individuals and b) plant species richness in 40x40cm (dashed lines) or 20x20cm (solid line) translocated turfs in DSa over time (in months). Means within size were significantly different in May 2012 (T 14) (P <0.001) in both number of individuals and species richness.

Figure 43

 43 Figure 43: a) Average number of individuals and b) plant species richness in 20x20cm TSt (dashed lines) and TSa (solid line) translocated in DSt over time (in months). Means within origin of turfs were similar in May 2012 (T 14) (P >0.05) in both number of individuals and species richness.

Figure 44

 44 Figure 44: a) Average number of individuals and b) plant species richness in 20x20cm TSa transplanted in DSa (full squares) and in DSt (open squares) over time (in months).Means within each substrate were significantly different in May 2012 (T 14) in number of individuals (P <0.001) but similar in species richness (p=0.6).

Figure 45 :

 45 Figure45). Resilience of campos rupestres after strong disturbance is complex: we obtain the most convincing results, in terms of restoration, using turf translocation, a technique which allows to overcome dispersal filter, to modify the abiotic conditions, to overcome the critical germination step and potentially to bring into the degraded areas associated microorganisms[START_REF] Carvalho | The mosaic of habitats in the high-altitude Brazilian rupestrian fields is a hotspot for arbuscular mycorrhizal fungi[END_REF]) (Chapter 5, Figure45).

  Figure 46: a) Bulbostylis paradoxa flowering a few days after a fire, and b) on sandy grasslands, lot of species flowering after a fire. (Photos S. Le Stradic)

Fidelis

  et al. (2010) pointed out the importance of the bud bank in tropical and subtropical grasslands subjected to fire, which replace the seed bank in such communities. A bud bank study could therefore be the next step to understand how campos rupestres overcome natural disturbances, such as fire, and use this knowledge to restore them. Finally it is important to incorporate the management of natural disturbances, such as fire, as a tool in restoration (Fuhlendorf & Engle 2004) and its potential use (e.g. to enhance sexual or vegetative reproduction of transplanted species) should be assessed. a) b) Figure 47: Resilience of sandy grasslands after a fire a) in September 2011: one week after a fire, and b) in January 2012: four month and a half after a fire.

  of an efficient technique to restore them. In the words of Robert et al. (2009) "our planet's future may depend on the maturation of the young discipline of ecological restoration", nevertheless, for the moment, concerning campos rupestres, the preservation of pristine areas should be emphasize and prioritize due to the difficulty to restore them General view of campos rupestres. Photo credit S. Le Stradic Oliveira P.S. & Marquis R. J. 2002. The Cerrados of Brazil. Ecology and natural history of a neotropical savanna. Columbia University Press, New York. Oliveira-Filho A.T. & Ratter J. 2002 Vegetation physiognomies and woody flora of the Cerrado, in: The Cerrados of Brazil -Ecology and natural history of a neotropical savanna. Oliveira P.S. & Marquis R.J. (eds), pp 91-120. Columbia University Press, New York

Table 2 :

 2 Dissimilarity matrix (Bray-curtis indices) of the seed bank composition between grassland-types (sandy and stony grasslands) and seasons (rainy season and dry season) based on abundance data (n=5 samples x 5 sites x 2 grassland-tyes x 2 seasons). St-R: Stony grassland in rainy season, St-D: Stony grassland in dry season, Sa-R: Sandy grassland in rainy season, Sa-D: Sandy grassland in dry season.

Table 1 :

 1 Geographic coordinates of the 10 reference sites of campos rupestres. Florictic and phenological survey were realized on the 10 sites (Chapter 1 & 2); Sa1, Sa2, Sa3, St1, St2 & St3 were used as the references in the Chapter 3. ........................ 35

Table 2 :

 2 Mean and standard error values of granulometric soil parameters, from soils collected in 5 sandy and 5 stony grasslands (3 samples / site , n=30). T-tests were run using separate variance estimates for the coarse fraction. ns: non-significant difference, *** :significant difference with P<0.001. ................................................. 51

Table 3 :

 3 Results of the two-way ANOVAs performed for chemical soil parameters, from soils collected in 5 sandy and 5 stony grasslands (3 samples / site / season, n=60. ns: non-significant difference, *: significant difference with P<0.05, ***: significant difference with P<0.001. ......................................................................................... 51

Table 4 :

 4 Family and species distribution between sandy (5 sites, 15 quadrats / site, n=75) and stony grasslands (5 sites, 20 quadrats / site, n=100). ns: non significant difference,

*:significant difference with P<0.05. ...................................................... 56

Table 5: Total number of species surveyed in both grassland-types, with number and percentage of perennial and annual species in each one and number and percentage of species participating in the reproductive phenology (flower, fruit and/or dissemination). ............................................................................................ 75 Table 6: Flowering, fruiting and dissemination data of sandy (Sa) and stony (St) plant communities at Serra do Cipó. Circular statistics (µ: mean vector, and r: parameter of concentration, Rao's spacing test: test of unimodality and Rayleigh tests). ........ 76 Table 7 : Number and percentage of species according to the timing of flowering, fruiting and dissemination in sandy (Sa) and stony (St) grasslands. Pearson χ 2 tests were performed, data marked with « ◊ » were not used in tests, species with continuous and sub-annual frequency patterns were not taken into account for the tests. ........ 78

Table 8 :

 8 Number of species and percentage according to the timing of flowering and phenological frequency in sandy (Sa) and stony (St (grasslands). A: annual frequency and SP: supra-annual frequency. Only A and SP species participating in the flowering phenophase were taken into account. ............................................... 79

Table 9 :

 9 Number and percentage of species with long or short flowering (Fl.), fruiting (Fr.) and dissemination (Diss.) duration in sandy (Sa) and stony (St) grasslands.

  ). Kruskal-Wallis test were run for the coarse fraction and one-way nested ANOVA for the fine fraction. NS: non-significant difference, *significant difference with P<0.05,

*** significant difference with P<0.001. ................................................................. 107

Table 18 :

 18 Germination percentage (mean and standard error) for each species, according to each treatment. GLM procedures (with quasibinomial distribution) were performed for Aristida torta, Lessingianthus linearifolius, Vellozia caruncularis, Vellozia epidendroides, Vellozia resinosa, Vellozia variabilis, Xyris obtusiuscula and Xyris pilosa. .......................................................................................................... 132

	al.

rainy season, RD: transition rainy to dry season, D: dry season, DR: transition dry to rainy season. Mean IVI and Mean relative Dominance (Chapter1). ...................... 127 xx

Table 19 :

 19 Mean germination time MGT in days (mean with standard error) for each species according to each treatment. GLM procedures (with Gamma distribution) were performed for Aristida torta, Lessingianthus linearifolius, Vellozia caruncularis, Vellozia epidendroides, Vellozia resinosa, Vellozia variabilis, Xyris obtusiuscula and Xyris pilosa. .......................................................................................................... 133

Table 20 :

 20 Germination synchrony (mean and standard error). Low values indicate more synchronized germination and high values indicate asynchronous germination. .. 134

Table 21 :

 21 Viable, empty and dormant seeds (mean percentage and standard error) for each species. Dormant seeds were calculated as the final germination percentage over the total number of viable seeds. ND: non-dormant seeds. .......................... 138

Table 22 :

 22 Number of individuals translocated in March 2011 (T0) and still surviving 3 months later in June 2011 (

Table 26 :

 26 Average number of individuals in 20x20cm turfs from sandy grasslands (TSa) and stony grasslands (TSt), translocated on degraded stony substrate at T0 and T14 according to plant form: graminoids, forbs and sub-shrubs. Results of the LMER procedures are shown. ....................................................... 165

Table 27 :

 27 Average number of individuals in 20x20cm turfs from sandy grasslands translocated to degraded sandy substrate (DSa) and degraded stony substrate (DSt) at T0 and T14 according to plant form: graminoids, forbs and sub-shrubs. Results of the LMER procedures are shown. ....................................................... 167 xxii

  [288 points x 178 species]. Projection of the two first axes, axis 1 (17.2%) and axis 2 (16.4%). Inertia=0.17, p<0.001, Monte-Carlo permutations. .................................................................... 106 Figure 31: Mean and standard error values of chemical soil parameters, from soils collected in 3 sandy grasslands (Sa) and 3 stony grasslands (St), 3 degraded areas with latosol substrate (DL), 3 degraded areas with stony substrate (DSt), 3 degraded areas with sandy substrate (DSa) (3 samples / site / season, n=90). Full circles rainy season. See Table 3 for one-way nested ANOVA results. ..Germination percentage (%) (a), Mean germination time (b) and synchrony (c) at 25°C, for species which flower immediately after fire and species which flower without fire. Letters indicate significant difference according (a) GLM procedure (quasibinomial error distribution and logit link function) with F=25.43, p<0.001, (b) GLM procedure (Gamma error distribution and inverse link function) with F=52.78, p<0.001, (c) simple ANOVAs, followed by post-hoc tests (Tukey's "Honest Significant Difference") F=31.70, p<0.001). .......................................................... 137 Figure 37: Reconstructed phylogenetic tree of the fifteen species studied, species with dormant seeds are underlined. ............................................................................. 139 Figure 38: The objective of the fifth chapter is to test whether species and turf translocation are efficient techniques to restore campos rupestres. Both techniques aimed to overcome the dispersal filter. Using species translocation we expected to overcome the critical phase of the establishment in the degraded areas and to improve environmental conditions bringing together soil and translocated plant.

	Figure 35: Mean number of seedlings occurring per 40cmx40cm quadrat on reference
	areas: sandy grasslands (Sa) and stony grasslands (St) and on degraded areas with
	stony substrates (DSt) according and 2 or 3 levels of 2 treatments: with hay from
	sandy grassland (clear grey) / with hay from stony grassland (grey) / without hay
	(dark grey), and with geotextile (G) / without geotextile (wg). Letters indicate

.................................. 108 Figure 32: Mean vegetation percent cover per 40cmx40cm quadrat according 5 types of areas: degraded areas with latosol substrate (DL), with sandy substrate (DSa), with stony substrate (DSt), reference sandy grassland (Sa) and reference stony grassland (St), and 2-3 level of 2 treatments: with hay from sandy grassland (HSa) / with hay from stony grassland (HSt) / without hay (h), and with geotextile (clear grey) / without geotextile (dark grey). Letters according the result of one-way nested ANOVAs, followed by Tukey post-hoc tests. ........................................................ 110 Figure 33: Correspondence analysis run on the matrix of the species abundance in February 2012 in 40cmx40cm quadrat after hay transfer in reference grasslands: 2 stony (St) and 2 sandy grasslands (Sa) and in degraded areas: 3 with latosol substrate (DL), 3 with sandy substrate (DSa) and 3 with stony substrate (DSt) [232 points x 161 species]. Some quadrats received hay and some not and some had geotextile and some not. Projection of the two first axes, axis 1 (17.2%) and axis 2 (14.2%). Inertia=0.23, p<0.001, Monte-Carlo permutations. ................................. 111 Figure 34: Mean number of seedlings occurring per 40cm×40cm quadrat on reference sandy grasslands (Sa) and on the 3 types of degraded areas: with latosol substrate (DL), with sandy substrate (DSa) and with stony sustrate (DSt) and 2 levels of 2 treatments: with hay (HSa) / without hay (h) and with geotextile (in clear grey) / without geotextile (dark grey). Letters indicate significant differences according to the result of the LMER procedures (family: Poisson, link: log), *: indicate difference between with and without geotextile. .................................................................... 112 significant differences according to the result of the LMER procedures (family: poisson, link: log), *: indicates difference between with and without geotextile. .... 113 xxvi Figure 36: Using turf translocation, we aimed to bring to the degraded areas i) a pool of target species, ii) soil of the reference ecosystem and iii) possible associated microorganisms (Carvalho et al. 2012); overcoming therefore the environmental filter and a part of the biotic filter........................................................................... 149 Figure 39: Experimental design of species translocation. Experiment 1A was carried out in March 2011 at the end of the rainy season, while Experiment 1B was carried out in November 2011 at the beginning of the rainy season. ...................................... 156 Figure 40: Experimental design of turf translocation carried out in March 2011 at the end of the rainy season. Experiment 2A was carried out in degraded sandy substrate DSa, while Experiment 2B was carried out in degraded stony substrate DSt. ...... 157

  Spontaneous succession from the seed bank is unlikely because it was completely removed during the disturbance; 3) Dispersal limitation did not allow the seed bank re-composition; 4) Hay transfer, which allows overcoming the dispersal filter, was not efficient to initiate vegetation establishment on degraded areas; 5) Some species among them Poaceae & Cyperaceae failed to germinate, other germinated well like Xyridaceae or Velloziaceae but were not able to establish on degraded areas, due to unfavorable germination conditions or because hay did not contain these species; 6) Probable root damages impede species establishment, just one species Paspalum erianthum was reintroduce on degraded areas; 7) turf translocation was the most successful restoration method allowing to introduce native species on degraded areas, but it was also the technique which most impacted the reference grasslands. ............................................................................................................................. 187 Figure 46: a) Bulbostylis paradoxa flowering a few days after a fire, and b) on sandy grasslands, lot of species flowering after a fire. (Photos S. Le Stradic) ................. 190

TSa transplanted in DSa (full squares) and in DSt (open squares) over time (in months). Means within each substrate were significantly different in May 2012 (T 14) in number of individuals (P <0.001) but similar in species richness (p=0.6). ......... 167 Figure 45: Main insights of the thesis. 1) Phenological survey allows showing that some species did not reproduce regularly and then are absent from the external species xxvii pool which can probably colonize degraded areas; 2) Figure 47: Resilience of sandy grasslands after a fire a) in September 2011: one week after a fire, and b) in January 2012: four month and a half after a fire. .................. 191

  ; in France, Décret n° 77-1133 du 21/09/77 pris pour l'application de la loi n° 76-663 relative aux ICPE; and in Brazil, Law 9605/1998, Law 9985 18/07/2000 (linked to article 225, § 1°, paragraphs I, II, III and VII of the Federal Constitution (1988)), article 19 of Law 4771/65, the technical standard ABNT 13030, SMA 08/2008 legislation (Aronson et al. 2011)).

  This particular point is controversial because there is now evidence that savannas are ancient and actually pre-date the earliest human populations.

	General introduction
	4) Human activity: savannas are an anthropogenic artifact created by clearing and
	Climate : -Warm tropics -Seasonnality: alternance DRY/WET season burning forests. Savannas Grazing
	Consumers	Continuous	With a discontinuous
		herbaceous cover	presence of woody
	Fire	species (shrubs, trees, palm trees)
	Man's
	activities
		Soil
			21

Table 1 :

 1 Geographic coordinates of the 10 reference sites of campos rupestres.

	Florictic

Table 2 :

 2 Mean and standard error values of granulometric soil parameters, from soils collected in 5 sandy and 5 stony grasslands (3 samples / site , n=30). T-tests were run using separate variance estimates for the coarse fraction. ns: non-significant difference, *** :significant difference with P<0.001.

			Sandy	Stony
			grasslands	grasslands	t value
	Coarse	soil >1cm (%)	1.79 ± 0.71	27.63 ± 1.18	18.81***
	fraction of soil	soil >2mm (%)	12.98 ± 2.42	60.04 ± 1.89	16.26***
	Fine fraction of soil <2mm	Coarse sand (dag/kg) Fine sand (dag/kg) 46.87 ± 2.04 19.66 ± 2.48 Silt (dag/kg) 29.27 ± 1.94	25.80 ± 2.42 37.33 ± 1.41 31.53 ± 1.49	1.63 ns 4.65*** 0.85 ns
		Clay (dag/kg)	4.20 ± 0.43	5.33 ± 0.47	1.54 ns

Table 3 :

 3

			Two-way ANOVAs
		Season	Grassland type	Interaction
		F	F	F
	N (dag/kg)	1.09 ns	8.69*	1.93 ns
	pH (H 2 O)	41.99***	9.26*	0.17 ns
	P (mg/dm 3 )	188.26***	6.34*	3.49 ns
	K (mg/dm 3 )	2.63 ns	15.04**	1.68 ns
	Ca 2+ (cmolc/dm 3 )	3.09 ns	18.53**	0.63 ns
	Mg 2+ (cmolc/dm 3 )	0.23 ns	19.37**	0.79 ns
	Al 3+ (cmolc/dm 3 )	0.94 ns	0.14 ns	0.82 ns
	Organic carbon (dag/kg)	6.83*	23.18**	4.73***

Results of the two-way ANOVAs performed for chemical soil parameters, from soils collected in 5 sandy and 5 stony grasslands (3 samples / site / season, n=60. ns: non-significant difference, *: significant difference with P<0.05, ***: significant difference with P<0.001.

  Lagenocarpus sp1 (20.7 and 12.8) and Mesosetum exaratum (16.2 and 6.2). These five dominant species represented 56.4% of the vegetation cover and the first 16 dominant species accounted for 80.0% of the vegetation cover (Appendix 1). In the stony grasslands, Mesosetum exaratum (IVI and dominance values of 43.2 and 14.7, respectively), Tatianyx arnacites (28.9 and 12.8), Lagenocarpus tenuifolius (14.9 and 8.9), Homolepis longisticula (14.7 and 4.8) and Xyris minarum (14.3 and 0.8) can be considered the main species based on their IVI values, while Vellozia resinosa and V. caruncularis can be characterized as important, having respective dominance values of 8.8 and 6.1 (Appendix 1). The top five most dominant species represented 51.3% of the vegetation cover and the top 19 dominant species accounted for 80%.

		Sandy	Stony	t-test or
		grasslands	grasslands	Wilcoxon test
	Total number of families	33	34
	Total number of species	158	170
	Total number of dicotyledons 68 (43.1%)	74 (43.5%)
	Total number of monocotyledons 90 (56.9%)	95 (55.9%)
	Total number of pteridophyte	-	1(0.6%)
	Total number of annual plants	7 (4.4%)	3 (1.8%)
	Total number of perennial plants 151 (95.6%)	167 (98.2%)
	Total number of species endemic from the Serra Do Cipó	22 (13.9%)	29 (17.1%)
	Total number of species with an endangered/vulnerable/critical statue	15 (9.5%)	22 (12.9%)
	Number of species / site	81.0 ± 2.7	85.8 ± 2.5	t= 1.28 ns
	Number of species / m 2	26.8 ± 0.6	29.1 ± 0.5	t= 2.93*
	Number of individuals / m 2 578.8 ± 19.6	581.9 ± 17.2 W= 3711.5 ns
	Abundance of forbs / site 642.0 ± 179.9 1207.6 ± 294.9	t= 1.63 ns
	Abundance of graminoids / site 7853.2 ± 643.3 9955.8 ± 677.4	t=2.25 ns
	Abundanceof liana / site	3 ± 1.5	7.8 ± 5.8	t= 0.79 ns
	Abundance of shrub / site	10.8 ± 2.9	91 ± 46.3	W= 1*
	Abundance of sub-shrub / site 188 ± 92.3	371.2 ± 112.4	W= 5 ns
	Abundance of fern / site	0 ± 0	8.8 ± 8.3	-

). According to the IVI and dominance values, the sandy grasslands were characterized by Tatianyx arnacites (with IVI and dominance values of 40.2 and 17.7, respectively), Homolepis longispicula (37.3 and 12.3), Paspalum erianthum (30.0 and 7.3), Table

4

: Family and species distribution between sandy (5 sites, 15 quadrats / site, n=75) and stony grasslands (5 sites, 20 quadrats / site, n=100). ns: non significant difference, *:significant difference with P<0.05.

  The predominance of monocotyledons, which has already been noted in earlier botanical surveys of campos rupestres[START_REF] Meguro | Phytophysiognomy and composition of the vegetation of Serra do Ambrósio, Minas Gerais, Brazil[END_REF]

	Conceição and Pirani 2005, Viana and Lombardi 2007, Borges et al. 2011), indicates
	the presence of limiting ecological factors according to Granville (1984). The marked
	dominance of hemicryptophytes in both grassland types highlights a probable
	selective pressure by fire, which is a frequent endogenous disturbance (sensu White
	and Jentsch 2001) in savannas and tropical grasslands. As hemicrytophytes are
	defined by underground renewing buds, regrowth organs remain viable and allow
	regeneration after fire (Coutinho 1990).
	Apocynaceae	(Minaria,	Hemipigon),	Ericaceae	(Gaylussacia,	Agarista),

They are composed of herbaceous strata dominated primarily by Poaceae (Paspalum, Andropogon) and Cyperaceae (Lagenocarpus, Rhynchospora, Bulbostylis), and combined with Xyridaceae (Xyris), Eriocaulaceae (Paepalanthus, Leiothrix, Syngonanthus), Velloziaceae (Vellozia, Barbacenia) and Iridaceae (Trimezia, Pseudotrimezia).

Some forb and sub-shrub species are also found in these grasslands. They belong to families, such as Asteraceae (Lychnophora, Richterago), Melastomataceae (Lavoisiera, Marcetia), Fabaceae (Chamaecrista), Malpighiaceae (Byrsonima), Euphorbiaceae (Sebastiana), Vochysiaceae (Vochysia), Rubiaceae (Declieuxia),

  Vellozia albiflora in stony grasslands. Therefore, this study further corroborates the hypothesis that campos rupestres are formed by a mosaic of distinct plant communities characterized by their own floristic composition. These findings have important implications for the conservation of these plant communities that must be considered separately. Having laid the necessary ground work, the present study makes it possible, in due course, to consider issues such as remaining surface area and conservation strategy.

The main species, such as Tatianyx arnacites, Mesosetum exaratum and Homolepis longispicula, can be found in both grassland types, but with different importance indices and dominance values. On the other hand, some species are restricted to one or another grassland, conferring a real singularity and a peculiar value to each grassland type, such as Paspalum hyalinum, Xyris asperula and X. insignis in sandy grasslands and Paepalanthus nigrescens, Prestelia eriopus, Marcetia acerosa and

  1,2 , Elise Buisson 1 , G. Wilson Fernandes 2 & L. Patrícia C. Morellato 3

	1 -UMR CNRS/IRD 7263/237 IMBE -Institut Méditerranéen de Biodiversité et d'Ecologie -Université d'Avignon et des Pays de Vaucluse, IUT, Agroparc, BP 61207,
	84 911 Avignon cedex 9, France.
	2 -Ecologia Evolutiva & Biodiversidade / Instituto de Ciências Biológicas, Universidade
	Federal de Minas Gerais, 30161-970 Belo Horizonte MG, CP 486, Brazil.
	3 -Laboratorio de Fenologia, Departamento de Botânica / UNESP -Univ Estadual Paulista , CP. 199, Rio Claro / SP -Brazil
	Abstract:

  Our study area is located in southeastern Brazil, in the southern portion of the Espinhaço Range, the area is within the Environmental Protected Area of Morro da Pedreira, a buffer zone of the Serra do Cipó National Park (state of Minas Gerais). The climate is classified as Cwb according to the Köppen's system with warm temperatures, dry winter and rainy summer. The mean annual precipitation is 1,622mm

	Campos
	rupestres are the main vegetation formation of the Espinhaço mountain range. The main
	herbaceous plant communities, the sandy and stony grasslands (Chapter 1), are
	species-rich grasslands mainly composed of Poaceae (Paspalum, Andropogon) and

Cyperaceae (Lagenocarpus, Rhynchospora, Bulbostylis), with Xyridaceae (Xyris), Eriocaulaceae (Paepalanthus, Leiothrix, Syngonanthus) and Velloziaceae (Vellozia, Barbacenia) and of some forbs and sub-shrub species belonging to Asteraceae (Lychnophora, Richterago) or Melastomataceae (Lavoisiera, Marcetia) among others.

Table 5 :

 5 Total number of species surveyed in both grassland-types, with number and percentage of perennial and annual species in each one and number and percentage of species participating in the reproductive phenology (flower, fruit and/or dissemination).

		Sandy Grasslands	Stony grasslands
		Number of	Number of	Number of	Number of
		species	individuals	species	individuals
	Total	146	29.227	155	31.354
	Perennial species 138 (94.5%)	29.100	151 (97.4%)	31.327
	Annual species	8 (5.5%)	127	4 (2.6%)	27
	Participating in the phenology	107 (73.3%) 2,691 (9.2%)	89 (65.9%)	2,226 (7.1%)
	Not participating in the phenology	39 (26.7%)	26,409 (90.8%)	46 (34.1%)	29,101 (92.9%)

Table 6 :

 6 Flowering, fruiting and dissemination data of sandy (Sa) and stony (St) plant communities at Serra do Cipó. Circular statistics (µ: mean vector, and r: parameter of concentration, Rao's spacing test: test of unimodality and Rayleigh tests).

		Flowering	Fruiting	Dissemination
		Sa	St	Sa	St	Sa	St
	Mean vector µ	68.5°26.5°136.7°342.0°326.4°355.2°L
	ength of mean vector r 0,26 0,19 0,24 0,12 0,08 0,19
	Rao's spacing test <0.001 <0.001 <0.001 <0.001 <0.001 <0.001
	Rayleigh test (Z)	5,53 3,01 4,71 1,07 0,65 3,26
	Rayleigh test (p )	0,004 0,049 0,009 0,342 0,523 0,038
	Since there were no well-defined seasonal patterns for any of the grassland

types, we classified the species according to their flowering, fruiting and dissemination strategies. (i) The sub-annual reproductive phenological frequency (SB), is composed of six species: Asteraceae sp1, Polygala apparicioi, Polygala glochidiata, Polygala paniculata, Sebastiana ditassoides and Thesium brasiliense (Appendix 3). (ii) The continuous reproductive phenological frequency (C), producing and dispersing all year long (which does not exclude the occurrence of production peaks) contained six species in both sandy and stony grasslands: Lagenocarpus rigidus subsp. tenuifolius, Lagenocarpus tenuifolius, Rhynchospora ciliolata, Rhynchospora riedeliana, Rhynchospora pilosa (only on sandy grasslands) and Rhynchospora terminalis (only on stony grasslands) (Appendix 3). In sandy grasslands (iii) 62 species (59.0%) presented an annual reproductive frequency (A), and (iv) 32 species (30.5%) a supra-annual frequency (SP). Similarly, in stony grasslands, 66 species (66.7%) had an annual frequency and 25 species (25.3%) a supra-annual frequency (Appendix 3). In both, sandy and stony grasslands, annual reproductive frequency was the most represented frequency (χ 2 = 1.29, p=0.25).

Table 7 :

 7

Number and percentage of species according to the timing of flowering, fruiting and dissemination in sandy (Sa) and stony (St) grasslands. Pearson χ 2 tests were performed, data marked with « ◊ » were not used in tests, species with continuous and sub-annual frequency patterns were not taken into account for the tests.

Table 8 :

 8 Number of species and percentage according to the timing of flowering and phenological frequency in sandy (Sa) and stony (St (grasslands). A: annual frequency and SP: supra-annual frequency. Only A and SP species participating in the flowering phenophase were taken into account.

			Transition		Transition
		Rainy	Rainy/Dry	Dry	Dry/Rainy
		season	season	season	season	Total
	Sa	A 23 (24.7%) 21 (22.6%) 16 (17.2%) 2 (2.2%)	93 (100%)
		SP 22 (23.7%) 1 (1.1%)	4 (4.3%)	4 (4.3%)
	St	A 34 (39.5%) 17 (19.8%) 8 (9.3%)	5 (5.8%)	86 (100%)
		SP 13 (15.1%) 2 (2.3%)	6 (7.0%)	1 (1.2%)

Table 9 :

 9 Number and percentage of species with long or short flowering (Fl.), fruiting (Fr.) and dissemination (Diss.) duration in sandy (Sa) and stony (St) grasslands. Long cycle is considered with a phenophase duration > 2 months and short cycle with a phenophase duration < or = 2 months. Species with continuous and sub-annual frequency patterns were not taken into account. w indicated that the χ 2 tests were realized without the data from transition season Dry/Rainy due to the low number of species.

*: p-value<0.05 and **: p-value<0.01, ***:p-value <0.001.

  Regardless of the phenophase considered (flowering, fruiting or disseminating), 26 species (83.8%) had the same phenology in sandy and stony grasslands. Only five

species: Lagenocarpus alboniger, Rhynchospora tenuis, Rhynchospora tenuis subsp austro-brasiliensis, Rhynchospora terminalis and Vellozia epidendroides, presented different phenologies between sandy and stony grasslands, considering frequency or timing (duration was similar) of the phenophase. Rhynchospora terminalis had a continuous phenology in stony grasslands and an annual phenological frequency in sandy grasslands; Rhynchospora tenuis was supra-annual in stony grasslands and annual in sandy grasslands (Appendix 3). Individuals of Vellozia epidendroides flowered and fruited during the dry season in sandy grasslands while they did so during the rainy season in stony grasslands. Rhynchospora tenuis subsp austro-brasiliensis disseminated earlier and Lagenocarpus alboniger flowered earlier in the season in stony grasslands.

Fruit production did not vary between stony and sandy grasslands for 11 species (Dioscorea stenophylla, Mesosetum loliiforme, Pseudotrimezia cipoana, Rhynchospora consanguinea, Rhynchospora tenuis subsp austro-brasiliensis, Rhynchospora terminalis, Richterago arenaria, Sisyrinchium vaginatum, Thesium brasiliense, Vochysia pygmaea

Table 11 :

 11 Average fruit production by site and number of fruits per individual for the 31 selected species. z indicates the result of GLM procedures with a quasibinomial error distribution and logit link function. * indicates significant differences with p<0.05. T-tests were performed using numbers of fruits per individual as dependent variables and grassland-types as categorical predictors, * indicates p<0.05.

		Sa	St		Sa	St	t-test
	Dioscorea stenophylla	1 ± 0	1.0 ± 0.5	0	NS 1.0 ± 0.0 0.6 ± 0.2 2,07 NS
	Drosera montana	0.9 ± 0.3	9.5 ± 5.1 5,79 *** 0.3 ± 0.1 0.6 ± 0.1 -1,36 NS
	Lagenocarpus alboniger	2.2 ± 0.7	9.2 ± 2.0	3,9 *** 1.4 ± 0.4 0.9 ± 0.1 1,25 NS
	Lagenocarpus tenuifolius	8.0 ± 1.9 27.6 ± 5.8 8,92 *** 2.2 ± 0.6 1.6 ± 0.5 0,73 NS
	Lagenocarpus rigidus subsp. tenuifolius	147.5 ± 17.7532.3 ± 20.5 -22,53 *** 3.2 ± 0.2 1.5 ± 0.4 3,88 *
	Mesosetum loliiforme	47.8 ± 34.7 4.3 ± 2.4	0	NS 7.9 ± 4.8 2.4 ± 0.9 1,29 NS
	Paepalanthus geniculatus	26.2 ± 11.8 18.2 ± 4.5 -3,77 *** 1.9 ± 0.3 1.8 ± 0.1 0,42 NS
	Panicum cyanescens

  ). Kruskal-Wallis test were run for the coarse fraction and one-way nested ANOVA for the fine fraction. NS: non-significant difference, *significant difference with P<0.05, *** significant difference with P<0.001.

							Kruskal-
					Latosol	Stony	Sandy	Wallis /
			Sandy	Stony	degraded	degraded	degraded	Nested
			grasslands	grasslands	areas	areas	areas	ANOVA
	Coarse fraction of soil	Soil >2mm (%) 10.8 ± 3.3 a 60.5 ± 2.4 b 52.0 ± 4.1 b 46.3 ± 5.3 b 13.5 ± 2.9 a χ 2 =32.0 ***
		Coarse sand (dag/kg)	19.6 ± 2.5 25.8 ± 2.4 12.8 ± 1.8	21.7 ± 2.8	13.4 ± 1.9 F=1.6 NS
	Fine fraction	Fine sand (dag/kg)	46.9 ± 2.0 a 37.3 ± 1.4 b 10.1 ± 0.8 c 33.7 ± 2.7 b 33.6 ± 2.0 b F=19.2 ***
	of soil < 2mm	Silt (dag/kg) 29.3 ± 1.9 a 31.5 ± 1.5 a 43.3 ± 2.1 b 36.1 ± 2.8 ab 48.7 ± 3.3 b F=4.7 *
		Clay (dag/kg) 4.2 ± 0.4 a 5.3 ± 0.5 a 33.7 ± 1.7 b 8.4 ± 1.7 a 4.3 ± 0.7 a F=22.6 ***

Table 14 :

 14

		one-way
		nested
		ANOVA
	N (dag/kg)	F=19.44 ***
	pH (H 2 O)	F=4.0.3 *
	P (mg/dm3)	F=3.53 *
	K (mg/dm3)	F=5.53 *
	Ca 2+ (cmolc/dm3)	F=3.71 *
	Mg 2+ (cmolc/dm3)	F=4.62 *
	Al 3+ (cmolc/dm3)	F=2.70 NS
	Corg (dag/kg)	F=13.68 ***

Result of the one-way nested ANOVAs run on chemical soil parameters, from soils collected in reference grasslands: 3 sandy, and 3 stony grasslands, and in degraded areas: 3 latosol, 3 sandy and 3 stony (3 samples x 3 sites x 5 types of areas: n=45). NS: non-significant difference, * significant difference with P<0.05, *** significant difference with P<0.001. See Figure

4

for values.

  Table 16:). In the degraded areas seed banks were mainly composed of ruderal species such as Aristida setifolia or Andropogon sp. By contrast, in the reference grassland seed banks we recorded species such as Tatianyx arnacites, Rhynchospora consanguinea, Rhynchospora riedeliana or Lagenocarpus rigidus subsp. tenuifolius.

	Chapter 3 -Resilience and restoration of campos rupestres
	p<0.001,
	109

Table 15 :

 15 Number of germinated seeds and number of species found in the seed banks of the reference grasslands (sandy (Sa) and stony (St) grasslands) and of the three types of degraded areas (with latosol substrate (DL), stony substrate (DSt) and sandy substrate (DSa)) (n= 5 samples x 3 sites x 5 types of areas). Letters indicate significant differences according to the result of the GLM procedures (family: Poisson, link: log).

		DL		DSa	DSt	Sa	St	p(>|Chi|)
	Number of germinated seeds from the seed bank	10		318	361	54	50
	Mean number of germinated seeds per sample (1L)	0.67 ± 0.45 a 21.20 ± 5.71 b 24.07 ± 7.42 b 3.60 ± 0.71 c 3.33 ± 1.28 c	***
	Number of species in the seed bank	3		13	20	14	15
	Mean number of species / site 1.33 ± 0.41 a 6.33 ± 3.89 b 8.33 ± 4.32 b 7.33 ± 1.63 b 7.00 ± 3.43 b	***
			St	Sa	DL	DSt
		Sa	0,68
		DL	1	1
		DSt	1	1	0,95
		DSa	1	1	0,93	0,77

Table

16

:: Dissimilarity matrix (Jaccard indices) of the seed bank composition between the degraded areas with latosol substrate (DL), stony substrate (DSt) and sandy substrate (DSa) and reference grasslands: the sandy (Sa) and the stony (St) grasslands based on presence-absence data (n=3 sites x 5 types of areas).

  -Diversity of germination strategies and dormancy of graminoid and forb species of campos rupestres. Soizig Le Stradic 1,2 , Fernando Silveira 3 , Elise Buisson 1 , Kévin Cazelles 4 , Vanessa Carvalho 2 & G. Wilson Fernandes 2 .

	1 -UMR CNRS/IRD 7263/237 IMBE -Institut Méditerranéen de Biodiversité et d'Ecologie -Université d'Avignon et des Pays de Vaucluse, IUT, Agroparc, BP 61207,
	84 911 Avignon cedex 9, France.
	2 -Ecologia Evolutiva & Biodiversidade / Instituto de Ciências Biológicas, Universidade
	Federal de Minas Gerais, 30161-970 Belo Horizonte MG, CP 486, Brazil.
	3 -Departamento de Biologia Vegetal, Instituto de Ciências Biológicas, Universidade
	Federal de Minas Gerais. 20
	4 -AgroParisTech, 16 rue Claude Bernard, F-75231 Paris Cedex 05

Vellozia variabilis. Photo credit S. Le Stradic Chapter 4 -Germination and dormancy of herbaceous species of campos rupestres 122 Chapter 4

  the relative frequency of germination,

			n i is the number of germinated seeds
	on day i and k is final day of observation. Low	E values indicate more synchronized
	germination and high	
		



E values indicate asynchronous germination.

Table 21 :

 21 Viable, empty and dormant seeds (mean percentage and standard error) for each species. Dormant seeds were calculated as the final germination percentage over the total number of viable seeds. ND: non-dormant seeds.

	Viable seeds (%) Empty seeds (%)
	(mean ± se)	(mean ± se)

Table 23 :

 23 Number and percentage survival of translocated individuals in December 2011 (T9) and in March 2011 (T12). Individuals were translocated to a degraded sandy area (DSa), and to a reference sandy grassland (RSa) broken into two groups, one with an added nutrient supply (N) and one without (n). To test the effect of nutrient supply and substrate type, GLM procedures were run on data recorded in March 2012, with a binomial family distribution and logit link function. ns: non significant.

	Time		T9			T12		GLM procedures on T12 data
	Treatment	DSa/N DSa/n RSa/N RSa/n DSa/N DSa/n RSa/N RSa/n Nutrient Substrat Interaction
	Homolepis longispicula	1 (10%)	0 (0%)	0 (0%)	1 (20%)	1 (10%) (0%) 0	0 (0%)	1 (20%)	0.003 ns -0.002 ns 0.004 ns
	Lagenocarpus rigidus	1 (10%)	6 (60%)	0 (0%)	0 (0%) (10%) (60%) (0%) 1 6 0	0 (0%)	2.065 *	-0.004 ns 0.001 ns
	Mesosetum exaratum	0 (0%)	4 (40%)	0 (0%)	0 (0%)	0 (0%) (30%) (0%) 3 0	0 (0%)	0.004 ns	0.001 ns -0.002 ns
	Paspalum erianthum	10 (100%)	10 (100%)	5 (100%)	3 (60%)	10 (100%)	10 (100%)	5 (100%)	3 (60%)	0.001 ns 0.001 ns -0.001 ns
	Rhynchospora riedeliana	1 (10%)	1 (10%)	0 (0%)	0 (0%) (10%) (10%) (0%) 1 1 0	0 (0%)	0.001 ns -0.004 ns -0.001 ns
	Tatianyx arnacites	5 (50%)	6 (60%)	0 (0%)	0 (0%) (50%) (60%) (0%) 5 6 0	0 (0%)	0.290 ns 0.004 ns 0.001 ns
	Vellozia epidendroides	0 (0%)	2 (20%)	1 (20%) (0%) 0	0 (0%) (20%) (20%) (0%) 2 1 0	0.003 ns 0.003 ns -0.004 ns
	Vellozia resinosa	0 (0%)	1 (10%)	0 (0%)	0 (0%)	0 (0%) (10%) (0%) 1 0	0 (0%)	0.002 ns 0.001 ns -0.001 ns
	3.1.2.Effect of the translocation period
	Transplantation at the end of the rainy season (March 2011) tended to be more
	successful than at the beginning (p=0.06), with the exception of Velloziaceae (Table 24),
	whatever the substrate type (p=0.72). When translocation occurred in November 2011,
	Homolepis longispicula, Lagenocarpus rigidus, Mesosetum exaratum, Rhynchospora
	riedeliana and Tatianyx arnacites showed low survival (<40%) (Table 24); on the
	contrary Vellozia epidendroides and Vellozia resinosa, which barely survived on Sa, had
	moderate survival on DSa (Table 24). Finally, only Paspalum erianthum survived as well
	(>80%) as in the first experiment.

Table 24 :

 24 Number and percentage of surviving translocated individuals 3 months after the translocation, in June 2011 for individuals translocated in March 2011 and in February 2012 for individuals translocated November 2011. Individuals were translocated to a degraded sandy area (DSa) and to a reference sandy grassland (RSa) without added nutrients. 10 individuals for each species were translocated to DSa in March 2011, and for the other treatments, 5 individuals per species were translocated.To test the effect of the period of transplantation and substrate type GLM procedures were run with a binomial family distribution and logit link function. ns: non significant.

	Date of transplantation	mars-11	mars-11	11-nov	11-nov	GLM procedures
	Substrate type	DSa	RSa	DSa	RSa	Date	Substrate
	Homolepis longispicula	0 (0%)	2 (40%)	0 (0%)	0 (0%) -0.002 ns -0.001 ns
	Lagenocarpus rigidus	6 (60%)	2 (40%)	0 (0%) 2 (40%) -0.001 ns 0.006 ns
	Mesosetum exaratum	7 (70%)	3 (60%)	0 (0%) 1 (20%) -0.960 ns 0.006 ns
	Paspalum erianthum	10 (100%) 5 (100%) 5 (100%) 4 (80%) -0.002 ns -0.001 ns
	Rhynchospora riedeliana 2 (20%)	2 (40%)	0 (0%)	0 (0%) -0.004 ns 0.001 ns
	Tatianyx arnacites	10 (100%) 5 (100%) 2 (40%) 2 (40%) -0.003 ns 0.001 ns
	Vellozia epidendroides	4 (40%)	0 (0%)	5 (100%) 2 (40%) 0.004 ns 0.001 ns
	Vellozia resinosa	2 (20%)	0 (0%)	3 (60%) 0 (0%) 0.001 ns 0.001 ns
	3.1.3.At the species level: cases of Paspalum erianthum and Tatianyx
	arnacites
	Substrate type and nutrient supply did not have a statistically significant effect on the
	height relative growth rate (RGR) between March 2011 and March 2012 of Paspalum
	erianthum (F=0.64, p= 0.42 for substrate type and F=0.05, p=0.82 for nutrient supply).

Table 25 :

 25 Average number of individuals in 20x20cm and 40x40cm turfs translocated to degraded sandy substrate at T0 and T14 according to plant form: graminoids, forbs and sub-shrubs. Results of the LMER procedures are shown.

		T0		T14
		20x20cm	40x40cm	20x20cm	40x40cm	Size	Time Interaction
	Graminoids	30.6 ± 2.7 101.6 ± 3.9 20.7 ± 2.7 66.8 ± 4.7 32.94 *** -3.43 *** 0.01 ns
	Forbs	1.4 ± 0.6	1.2 ± 0.3	0.6 ± 0.2	0.8 ± 0.3 -0.75 ns -2.26 ** 1.28 ns
	Sub-shrubs	0.4 ± 0.2	0.6 ± 0.1	0.4 ± 0.2	0.4 ± 0.1	1.20 ns 0.30 ns -0.65 ns

Table 26 :

 26 Average number of individuals in 20x20cm turfs from sandy grasslands (TSa) and stony grasslands (TSt), translocated on degraded stony substrate at T0 and T14 according to plant form: graminoids, forbs and sub-shrubs. Results of the LMER procedures are shown.

		T0		T14
		TSa	TSt	TSa	TSt	Origin	Time Interaction
	Graminoids 19.0 ± 1.7 16.1 ± 1.7	11.6 ± 1.1	7.9 ± 0.5	-2.77 ** -7.52 *** -2.22 *
	Forbs	0.5 ± 0.2	6.5 ± 1.3	0.5 ± 0.1	1.1 ± 0.4	9.86 ** 0.001 ns -4.40 ***
	Sub-shrubs 0.1 ± 0.1	0.1 ± 0.1	0.6 ± 0.2	1.0 ± 0.3	0.001 ns 3.02 ** 0.52 ns
		3.2.3.Effects of the substrate of the degraded area.

Table 27 :

 27 Average number of individuals in 20x20cm turfs from sandy grasslands translocated to degraded sandy substrate (DSa) and degraded stony substrate (DSt) at T0 and T14 according to plant form: graminoids, forbs and sub-shrubs. Results of the LMER procedures are shown.

		T0		T14
		DSa	DSt	DSa	DSt	Substrate Time Interaction
	Graminoids 30.6 ± 2.7 19.1 ± 1.7 20.6 ± 2.7 11.6 ± 1.1 -4.32 *** -7.78 *** -1.24 ns
	Forbs	5.5 ± 0.4	4.7 ± 0.3	4.4 ± 0.3	4.4 ± 0.3	-1.68 ns -2.97 ** 1.77 ns
	Sub-shrubs 1.4 ± 0.6	0.5 ± 0.2	0.7 ± 0.2	0.5 ± 0.1	-1.12 ns -0.19 ns 2.74 **
		3.2.4.Reference grassland regeneration
	The regeneration rate of donor grasslands from which turfs were drawn is very low. More
	than one year after turf removal (14 months), only a few individuals recolonized the
	sampled areas. On sandy donor grasslands, 2.78 ± 0.58 seedlings were recorded on
	20x20cm quadrats (representing 1.20% ± 0.34% of the quadrat) and 5.03 ± 0.66
	seedlings on 40x40cm quadrats (representing 1.70% ± 0.44% of the quadrat); vegetation
	percent cover recovery did not vary with turf size (z=-7.80, p>0.05). On stony donor
	grasslands, 1.40 ± 0.22 seedlings were registered on 20x20cm quadrats, which is
	significantly lower than on sandy donor grasslands (z=-1.81, p<0.06). Species that
	recolonized the most significantly are Rhynchospora riedeliana (97 seedlings),

  Xyris obtusiuscula or Xyris pilosa among others. However, each species occurs at various density and/or frequency depending on the grasslands, emphasizing a larger niche in one or the other grassland. On the other hand, some species are restricted to one grassland-type, underlining their narrower niche. We thus argue that

	, while the main species are common to
	both grasslands, such as Tatianyx arnacites, Mesosetum exaratum, Homolepis
	longispicula, Paspalum erianthum, Lagenocarpus rigidus subsp. tenuifolius,
	Rhynchospora consanguinea, Rhynchospora riedeliana, Bulbostylis paradoxa,
	Paepalanthus geniculatus, Syngonanthus cipoensis, Vellozia epidendroides, Xyris
	melanopoda,

species assemblages in campos rupestres are non-random, but constrained by abiotic and/or biotic factors.

  . In our case, we have shown (Chapter 3) that eight years after the disturbance, the degraded areas, despite the fact that they are surrounded by pristine campos rupestres, presented a vegetation composition quite different from those of reference grasslands and a large surface still had bare ground: we can thus assert that campos rupestres are not resilient to strong disturbance. Only some species which occurred on reference grasslands, such as Mesosetum loliiforme, Marcetia taxifolia, Rhynchospora consanguinea, can be found in degraded areas with stony substrates. However, ruderal species, such as Aristida setifolia, Andropogon bicornis or Chamaecrista rotundifolia, are dominant on degraded areas. In addition, the different degraded areas harbor quite different vegetation composition one from another. The forces, which promote divergence in primary

succession, such as proximity, microsites or priority effects, are strong

[START_REF] Temperton | Order of arrival and availability of safe sites: an example of their importance for plant community assembly in stress ecosystems[END_REF], Del Moral et al. 2005[START_REF] Rehounkova | Spontaneous vegetation in disused gravel-sand pits: role of local site and landscape factors[END_REF], Del Moral 2007)

; several alternative communities can thus develop after this kind of intense disturbance, which, in our case, do not carry or carry only few target species.

  order to verify this, we have carried out germination tests on 15 herbaceous native species (Chapter 4). Velloziaceae and Xyridaceae species have high germination, corroborating the results of other studies[START_REF] Abreu | Efeito da luz e da temperatura na germinação de sementes de quatro espécies de Xyris L .(Xyridaceae) ocorrentes na Serra do Cipó, MG, Brasil[END_REF], Garcia et al. 2007). On the contrary, some Cyperaceae, Poaceae and Asteraceae species record extremely low or null germination. Among these species three groups can be distinguished, species

with a lot of embryoless seeds: Richterago arenaria, Rhynchospora ciliolata, Lagenocarpus alboniger, species with many unviable seeds: Echinolaena inflexa for example, and species presenting physiologically dormant seeds: Lagenocarpus rigidus subsp. tenuifolius, Rhynchospora consanguinea or Rhynchospora riedeliana. While collected hay was mainly composed of Cyperaceae and Poaceae seeds, embryoless seeds, low seed viability and dormancy can explain why this restoration technique has failed.

I define the Cerrado as a savanna according toRizzini (1997) and[START_REF] Coutinho | O conceito de bioma[END_REF], but a debate still exists (see the next paragraph and[START_REF] Batalha | O cerrado não é um bioma[END_REF]).

The author defines ecoregions as "relatively large units of land containing a distinct assemblage of natural communities and species, with boundaries that approximate the original extent of natural communities prior to major land-use changes".

The term oreadic refers to a floristic province recognized by[START_REF] Martius | Flora Brasiliensis[END_REF][START_REF] Martius | Flora Brasiliensis[END_REF] in Flora Brasiliensis

Probably much more species occur but no floristic survey was carried out since 1987.

Munhoz C.B.R. & Felfili J.M. 2005. Fenologia do estrato herbáceo-subarbustivo de uma

A.Zanin & Longhi-Wagner

Walker L.R., Walker J. & del Moral R. 2007. Forging a New Alliance Between Succession and restoration, in Linking restoration and ecological succession, Walker L.R., Walker J. & Hobbs R.J. (eds), pp 19-44.New York. Springer. Walker L.R. & del Moral R. 2003. Primary Succession and Ecosystem Rehabilitation, Cambridge University Press Walker L.R. & del Moral R. 2009. Lessons from primary succession for restoration of severely damaged habitats. Applied Vegetation Science 12: 55-67. Walter B.M.T. 2006. Fitofisionomias do bioma Cerrado: síntese terminológica e relações florísticas. Ph.D. Thesis. Universidade the Brasilia Wanderley M.G. 2011. Flora da Serra do Cipó, Minas Gerais: Xyridaceae. Boletim Botanica da Universidade de Sao Paulo 29:69-134. Warming E. 1892. Lagoa Santa: Et bidrag ti1 den Amsterdam. biologiska plantegeografi. Det Kongelige danske Videnskabernes selskabs Skrifter 6:153-488. Warming E. 1899. On the Vegetation of Tropical America. Botanical Gazette 27: 1-18. Weiher E. & Keddy P.A. 1995. Assembly rules, null models, and trait dispersion: new questions from old patterns. Oikos 74: 159-164. Weiher E., Freund D., Bunton T., Stefanski A., Lee T. & Bentivenga S. 2011. Advances, challenges and a developing synthesis of ecological community assembly theory. Philosophical Transactions of the Royal Society B 366: 2403-2413. Werneck F.P., Nogueira C., Colli G.R., Sites Jr J.W. & Costa G.C.2012. Climatic stability in the Brazilian Cerrado: implications for biogeographical connections of South American savannas, species richness and conservation in a biodiversity hotspot. Journal of Biogeography 39: 1695-1706. Westoby M. & Wright I.J. 2006. Land-plant ecology on the basis of functional traits. Evolution 21:261-268. White P.S. & Pickett S.T.A. 1985. Natural disturbance and patch dynamics, an introduction, in: The ecology of natural disturbance and patch dynamics. White P.S. & Pickett S.T.A. (eds), pp 3-13. Academic Press, New York. White P.S. & Jentsch A. 2001. The search for generality in studies of disturbance and ecosystem dynamics. Progress in Botany. 62:399-450. White P.S. & Jentsch A. 2004. Disturbance, Succession, and community assembly in terrestrial plant communities, in: Assembly rules and restoration ecologybridging the gap between theory and practice. Temperton V.M., Hobbs R.J., Nuttle T. & Halle S. (eds), pp 342-366. Island Press, Washington, D.C.

INMET 2012-Instituto Nacional de Meteorologia URL: www.inmet.gov.br (cited 15/10/2012) IUCN 1998. Guidelines for re-introductions. prepared by the IUCN/SSC Re-introduction Specialist Group; IUCN, Gland, Switzerland and Cambridge, UK.

Appendix 1: Plant list. Life forms (Raunkiaer (1904) modified by [START_REF] Mueller-Dombois | Aims and methoods in vegetation ecology[END_REF]): He: Hemicryptophyte, CH: Chamaephyte, NA: Nanophanerophyte, HL: Hemicryptophytic Liana, GE: Geophyte, TH: Therophyte. Plant forms: F: Forbs, G: Graminoids, Ss: Sub-shrub, S: Shrub, L: Liana, Fe: Fern. Habitats in Brazil [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF][START_REF] Forzza | Lista de Espécies da Flora do Brasil[END_REF]): CR: campos rupestres, AG: altitude grassland, Ce: cerrado, Ca: Caatinga, AtR: Atlantic rainforest, AmR: Amazon rainforest, WG: wet grassland. Distribution range [START_REF] Giulietti | Flora da Serra do Cipó: caracterização e lista de espécie[END_REF][START_REF] Forzza | Lista de Espécies da Flora do Brasil[END_REF]

Vochysia pygmaea

Bong.

Vockysiaceae

Xyris longiscapa

Xyris melanopoda

Xyris tortula

Mart.

Xyridaceae

248

Species not participating in phenology

Gomphrena incana

Mart.

Amaranthaceae X X

Apocynaceae sp1

Apocynaceae X

Apocynaceae sp2

Apocynaceae X X

Apocynaceae sp3

Apocynaceae X

Apocynaceae sp4

Apocynaceae X

Oxypetalum cf montanum

Apocynaceae X

Asteraceae sp2

Asteraceae X

Calea tridactylila

Sch.Bip. ex Krasch.

Asteraceae X

Inulopsis scaposa

Lepidaploa sp1

Asteraceae X

Lychnophora joliana

Semir & Leitão (unresolved name)

Asteraceae X

Lychnophora rupestris

Semir & Leitão (unresolved name)

Asteraceae X

Minasia cipoensis

Loeuille (unresolved name) Asteraceae X

Prestelia eriopus

Sch.Bip.

Asteraceae X

Encholirium heloisae

Bromeliaceae X Bulbostylis paradoxa (Spreng.) Lindm.

Cyperaceae X X

Bulbostylis sp1

Cyperaceae X

Cyperaceae sp1

Cyperaceae X

Cyperaceae sp2

Cyperaceae X

Cyperaceae sp3

Cyperaceae X X Cyperaceae X X

Rhynchospora sp2

Cyperaceae X

Agarista duartei

(Sleumer) Judd Ericaceae X X

Gaylussacia riedelii

Meisn.

Ericaceae X

Paepalanthus macrocephalus

Eriocaulaceae X

Paepalanthus pubescens

Koern.

Eriocaulaceae X

Croton timandroides (Didr.) Müll.Arg., Euphorbiaceae X

Trimezia fistulosa var. fistulosa

Foster Iridaceae X

Eriope arenaria

Harley Lamiaceae X X

Hyptis sp2

Lamiaceae X

Spigelia aceifolia

Woodson Loganiaceae X

Diplusodon ciliiflorus

Koehne Lythraceae X

Banisteriopsis campestris

(A.Juss.) Little Malpighiaceae X X

Byrsonima cipoensis

Mamede Malpighiaceae X

Byrsonima cydoniifolia

A. Juss.

Malpighiaceae X

Byrsonima dealbata

Griseb.

Malpighiaceae X

Camarea axillaris

Malpighiaceae X

Microlicia juniperina

A.St.-Hil.

Melastomataceae X

Epistephium sclerophyllum

Lindl.

Orchidaceae X

Andropogon carinatus

Nees Poaceae X

Andropogon cf ingratus

Poaceae X

Anthaenantia lanata

(Kunth) Benth.

Poaceae X X

Apochloa sp1

Poaceae X Poaceae X

Ctenium brevispicatum

J.G. Sm.

Poaceae X X

Paspalum guttatum

Trin.

Poaceae X

Paspalum pectinatum

Nees ex Trin.

Poaceae X X

Paspalum sp1

Poaceae X

Poaceae sp1

Poaceae X

Poaceae sp2

Poaceae X

Poaceae sp3

Poaceae X

Poaceae sp4

Poaceae X X

Poaceae sp5

Poaceae X

Schizachyrium sp1

Poaceae X

Sporobolus sp1

Poaceae X X

Polygala hirsuta

Polygalaceae X

Polygala sp1

Polygalaceae X

Pellaea cymbiformis

251

Vellozia sp1

Velloziaceae X

Lippia florida

Cham.

Verbenaceae X

Stachytarpheta procumbens

Moldenke Verbenaceae X X

Vochysia elliptica var. elliptica

Mart.

Vochysiaceae X

Xyris calostachys

Poulsen Xyridaceae X

Xyris sp3

Xyridaceae X Dicotyledon 1

X

Dicotyledon 2 X Appendix 4: Soil seed bank in mountain Neotropical grasslands: seasonal variations and potential to restore degraded areas.

1.Introduction

Ecological restoration is the process of intentionally assisting the recovery of degraded ecosystems in order to repair ecosystem processes, productivity and services, as well as to re-establish biotic integrity (SER 2004). Before implanting a restoration project, the first step is to assess the resilience of the ecosystem in order to identify whether restoration is necessary and to gather potentially useful information to plan restoration. Natural regeneration of plant communities after a given disturbance is important for their conservation and can be an effective strategy for restoration (Leck et al. 1989, Bakker et al. 1996[START_REF] Aide | Forest Regeneration in a Chronosequence of tropical abandoned pastures: implications for restoration ecology[END_REF][START_REF] Sampaio | Does Restoration Enhance Regeneration of Seasonal Deciduous Forests in Pastures in Central Brazil?[END_REF]. However, the process of natural succession of species-rich grasslands, when highly destroyed, is slow (Bradshaw 1983[START_REF] Davis | Early Seral Communities in a Limestone Quarry: An Experimental Study of Treatment Effects on Cover and Richness of Vegetation[END_REF], Bradshaw 1997), particularly when there is a lack of seed pool from the seed bank (Bakker et al. 1996). Among the restoration techniques aiming to reintroduce target species on degraded areas, topsoil transposition containing nutrients, organic matter and the seed bank was already noted as an effective technique (Reis et al. 2003[START_REF] Vieira | O papel de banco de sementes na restauração de restinga sob talhão de Pinus eliottii Engelm[END_REF][START_REF] Cobbaert | Experimental restoration of a fen plant community after peat mining[END_REF][START_REF] Jakovac | O uso do banco de sementes florestal contido no topsoil como estratégia de recuperação de áreas degradadas[END_REF]. Native seeds from the seed bank are brought through transplanted soil, and edaphic conditions of the degraded area are changed improving environmental condition for plant establishment [START_REF] Potthoff | Soil Biological and Chemical Properties in Restored Perennial Grassland in California[END_REF]. However before planning such restoration experiment, a prerequisite is to assess the composition of the seed bank in reference grasslands.

The term "seed bank" is defined as the reserve of viable seeds present in the soil and on the soil surface (Robert 1981). [START_REF] Thompson | Seasonal Variation in the Seed Banks of Herbaceous Species in Ten Contrasting Habitats[END_REF] highlighted that the transient and/or persistent seed bank confer to the vegetation the potential to regenerate after a disturbance or to colonize new areas. The ability of plant species to produce seeds which remain viable in the soil (i.e. forming the seed bank) allows them to overcome unfavourable environmental conditions to germinate and establish. It was already demonstrated that seed bank has an important functional role in perennial grassland community as a means for population maintenance and regeneration of many species (Kalamees & Zobel 2002[START_REF] Pakeman | The role of the seed bank, seed rain and the timing of disturbance in gap regeneration[END_REF]. Moreover, the seed bank plays an important role on determining the trajectory of secondary succession after disturbances Honnay 2008): without disturbances, germination from the seed bank is not promoted (lack of creation of new microsite). However, if the similarity between seed bank and vegetation decreases with time after the disturbance in forest and wetland ecosystems, this is not always true in grasslands. Indeed, [START_REF] Hopfensperger | A review of similarity between seed bank and standing vegetation across ecosystems[END_REF] has noted that similarity between seed bank and vegetation tends to increase with time since the disturbance in grasslands. Campos rupestres are subjected to regular disturbance (fire), but due to the poverty of the seed bank, we assume that this way is not the preferential manner to regenerate. This could be due to the fact that campos rupestres are nutrient poor ecosystems and stress-tolerant species are often long lived clonal species (Bekker et al. 1997;[START_REF] Chang | Relationship between vegetation and soil seed banks in an arctic coastal marsh[END_REF][START_REF] Matus | Impact of management on vegetation dynamics and seed bank formation of inland dune grassland in Hungary[END_REF].

We thus suggest that using topsoil transfer (Reis et al. 2003) to restore campos rupestres will have a limited effect due to the poverty of the seed bank although soil transfer could improve the edaphic conditions of the degraded areas and then facilitate native plant establishment. Moreover, topsoil transfer leads to the destruction of the vegetation on the donor site. Therefore, it should only be considered in circumstances when complete habitat destruction is otherwise unavoidable and should be associated with other restoration methods. In addition, Bossuyt & Honnay (2008) have already noted that the absence of target species greatly limit the restoration of target plant communities from the seed bank. In such case, the regeneration of grasslands relies mainly on seed dispersal.

Appendix 5: Life-history traits of the four plant species dispersing seeds after a fire in August 2011. Appendix 6: Phylogenetic reconstruction method. To understand the evolution of seed dormancy in the herbaceous flora of the campos rupestres, we built a phylogenetic tree showing relationships among the studied taxa after checking the names against the Missouri Botanical Garden's nomenclatural database (http://www.tropicos.org/Home.aspx). We built a pruned tree with our 15 study species as terminal tips with the aid of Phylomatic: http://www.phylodiversity.net/phylomatic/. Species relationships were improved and polytomies were resolved based on available and published data for the taxa relationships. succès pour une seule espèce, Paspalum erianthum, alors que pour les autres, les dommages causés au niveau des racines lors de la translocation limitent probablement leur survie. Enfin la translocation de plaques de végétation s'avère être la méthode la plus efficace puisque de nombreuses espèces ont ainsi pu être réintroduites en zones dégradées. Cependant, en raison de la faible résilience des campos rupestres dans lesquels les plaques de végétation ont été prélevées, cette méthode ne peut être envisagée que pour sauver des habitats dans le cas extrême où la destruction de l'habitat est inévitable. Face à la difficulté de restaurer les campos rupestres, leur protection et leur conservation doit être une priorité.

Keywords: banque de graines, Cerrado, écologie des communautés, écologie de la restauration, écosystèmes néotropicaux d'altitude, germination, pelouses, restauration de pelouses, savanes, transfert de foin, transfert de plaque de végétation, translocation, transplantation.