Pierre-Yves Hardy

Anne Dray
email: anne.dray@usys.ethz.ch

Tina Cornioley
email: tina.cornioley@usys.ethz.ch

Maia David
email: maia.david@agroparistech.fr

Rodolphe Sabatier
email: rodolphe.sabatier@inra.fr

Eric Kernes
email: eric.kerneis@inra.fr

Véronique Souchère
email: veronique.souchere@inra.fr

Assessing the potential of new collective Agri-Environmental Schemes in the Marais Poitevin wetland region using a participatory approach

Keywords: cooperation, agriculture, wetlands, role-playing game, biodiversity, trade-off, public policy, Agri-Environmental Schemes

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

INTRODUCTION

The intensification and homogenization of agricultural practices in Europe over the last decades has driven substantial landscape changes with direct negative effects on biodiversity [START_REF] Tscharntke | Landscape perspectives on agricultural intensification and biodiversity -ecosystem service management[END_REF]. Farmland birds species have been particularly affected [START_REF] Donald | Agricultural intensification and the collapse of Europe's farmland bird populations[END_REF], especially in areas where mechanization, intensification and land consolidation triggered habitat degradation and/or loss [START_REF] Vickery | The management of lowland neutral grasslands in Britain: effects of agricultural practices on birds and their food resources[END_REF]. However, in the specific context of grasslands, agricultural activities such as extensive grazing and occasional mowing are essential for the maintenance of suitable bird habitat [START_REF] Donald | The Common Agricultural Policy, EU enlargement and the conservation of Europe's farmland birds[END_REF][START_REF] Sabatier | Heterogeneity and the trade-off between ecological and productive functions of agro-landscapes: A model of cattle-bird interactions in a grassland agroecosystem[END_REF]. In such cases both management intensification and abandoning management (desertification) can lead to biodiversity loss [START_REF] Simons | Contrasting effects of grassland management modes on species-abundance distributions of multiple groups[END_REF]. This also applies to wetlands where interdependencies between cropping areas, pastures, water levels and bird species richness are creating a complex landscape of competing uses and synergies.

In France, wetlands were the first habitats targeted by environment schemes during the early 90's [START_REF] Sabatier | Action versus Result-Oriented Schemes in a Grassland Agroecosystem: A Dynamic Modelling Approach[END_REF]. Those public policies, known as "action-based" Agri-Environment Schemes (AES), aim at engaging farmers in more sustainable practices to protect biodiversity. They focus on the delivery of land management practices and not on the provision of outcomes [START_REF] Burton | Result-oriented agri-environmental schemes in Europe and their potential for promoting behavioural change[END_REF]. They have been implemented as a mechanism to financially compensate farmers for the loss of income associated with less intensive forms of grassland management [START_REF] Batáry | The role of agri-environment schemes in conservation and environmental management[END_REF]. Those incentives reward sustainable practices such as fertilizer reduction, cattle density limitations, and mowing period restrictions.

However, 15 years after implementation, the effectiveness of AES is still under debate [START_REF] Kleijn | Mixed biodiversity benefits of agri-environment schemes in five European countries[END_REF][START_REF] Riley | Will farmers work together for conservation? The potential limits of farmers' cooperation in agri-environment measures[END_REF]. In their review, [START_REF] Kleijn | How effective are European agri-environment schemes in conserving and promoting biodiversity?[END_REF] concluded that about half of the schemes did not increase species richness. One of the reasons is that farmers' participation, which is key to ensure success, remains very often too low to achieve tangible biodiversity results [START_REF] Lastra-Bravo | What drives farmers' participation in EU agri-environmental schemes?: Results from a qualitative metaanalysis[END_REF][START_REF] Kuhfuss | Nudging farmers to enrol land into agrienvironmental schemes: The role of a collective bonus[END_REF][START_REF] Mckenzie | FORUM: landscapescale conservation: Collaborative agri-environment schemes could benefit both biodiversity and ecosystem services, but will farmers be willing to participate?[END_REF].

Those measures are now being criticized for reinforcing rather than cancelling the opposition between agricultural production and environmental protection [START_REF] De Krom | Farmer participation in agri-environmental schemes: Regionalisation and the role of bridging social capital[END_REF]. Indeed, in the Marais Poitevin, in France, the current AES reduce the sets of practices and induce economic limitations; farmers lose money when committing in AES [START_REF] Schwarz | An analysis of the potential effectiveness of a payment-by-results approach to the delivery of environmental public goods and services supplied by Agri-Environment Schemes[END_REF].

An alternative to current AES would be the implementation of result-oriented AES payments, where the payments are conditional on positive biodiversity conservation outcomes, independently of farmers management practices [START_REF] Sabatier | Action versus Result-Oriented Schemes in a Grassland Agroecosystem: A Dynamic Modelling Approach[END_REF]. Such schemes have been widely tested but are still at the experimental stages or implemented on too restrictive spatial or temporal scales to allow for a proper valuation of their effects [START_REF] Schwarz | An analysis of the potential effectiveness of a payment-by-results approach to the delivery of environmental public goods and services supplied by Agri-Environment Schemes[END_REF].

In their study, Le [START_REF] Coent | Why pay for nothing? An experiment on a conditional subsidy scheme in a threshold public good game[END_REF] used an experimental economics framework to compare an action-based subsidy (unconditional subsidy) with a result-based subsidy (conditional subsidy) and showed that the second mechanism is more efficient and effective. In their experiment, conditionality for payment was linked to an aggregated contribution at a collective level. However, this study was decontextualized, as participants were students and not real stakeholders. Moreover, the experimental economics framework depicted in the study, where all parameters are strictly controlled, leaves little room for innovation and creativity from participants to invent alternative scenarios.

More recently, [START_REF] Groeneveld | Effects on participation and biodiversity of reforming the implementation of agrienvironmental schemes in the Netherlands[END_REF] explores the impact on biodiversity when switching from individual to collective application of AES using mathematical modelling. They highlight that the land use system is less resilient under the collective scheme, but warn against generalization as their model is based on a small sample of farmers and rely on strong hypothesis behind their decision-making process. Moreover, these authors mention the fact that, since the change in paradigm from individual to collective AES is rather new, scientific data to analyze it is not yet widely available.

Today, scientific and political arenas question not only the choice of an action-based subsidy but also at a higher level the effectiveness of the top-down approach to AES and their prescriptive nature that hinders long-term behavioral change [START_REF] Arnott | What can management option uptake tell us about ecosystem services delivery through agri-environment schemes?[END_REF]. There is a new call for innovative agri-environmental provision (de Krom, 2017) where the focus is placed at regional levels instead of top-down imposed [START_REF] Böcher | Regional Governance and Rural Development in Germany: the Implementation of LEADER+[END_REF][START_REF] Kneafsey | The region in food--important or irrelevant?[END_REF]. As [START_REF] Winter | New Policies and New Skills: Agricultural Change and Technology Transfer[END_REF] as already pointed out: "For too long the policy debate has been conducted with little reference to farmers or to their view of the world". Scientists are increasingly aware of the importance of farmers' participation in AES design. They acknowledge the existence of different sources of expertise and of representation of the environment [START_REF] Mathieu | Conceptions des agriculteurs et modèles agronomiques. Le pâturage des vaches laitières dans le Jura[END_REF][START_REF] Mathieu | Qu'est-ce que la prise en compte des conceptions des acteurs peut changer dans les pratiques des aménageurs, des conseillers, et des chercheurs?[END_REF], and many advocate for more proximal methods, based on local contexts.

The importance of understanding stakeholders' mental models -their conceptual representation of the world based on their experience, perception, and knowledge -for natural resource management is not new (see the review by [START_REF] Jones | Mental Models: An Interdisciplinary Synthesis of Theory and Methods[END_REF]. Mental models are the basis on which individuals make decisions and take actions, and thus affect the way individuals interact with their environment. Eliciting the mental models of the multiple stakeholders involved may improve collaboration and management planning by a) strengthening communication and mutual understanding, b) integrating multiple sources of knowledge, and c) contributing to creating shared ownership, and d) identifying common ground and disagreements [START_REF] Biggs | The implementation crisis in conservation planning: could "mental models" help?[END_REF]. In sum, by enabling stakeholders to communicate their mental model with each other, social learning can occur and lead to a shared mental model providing a common framework of understanding and basis for actions [START_REF] Mathevet | Water Management in the Camargue Biosphere Reserve: Insights from Comparative Mental Models Analysis[END_REF][START_REF] Schusler | Social learning for collaborative natural resource management[END_REF].

ComMod is a community-based scientific approach that emerged in the 1990s to facilitate collective action (Étienne, 2014). Using Multi-Agent Systems (MAS) and role-playing games, the aim is to facilitate dialogue between the different stakeholders and promote shared learning on environmental issues [START_REF] Bousquet | An environmental modelling approach: the use of multi-agent simulations[END_REF]. This approach has been implemented for various agri-environmental issues and in a wide variety of contexts: groundwater management in the low-lying atoll of Tarawa [START_REF] Dray | The atollgame experience: From knowledge engineering to a computer-assisted role playing game[END_REF]; Watershed Management in Mountainous northern Thailand [START_REF] Barnaud | An Evolving Simulation and Gaming Process to Facilitate Adaptive Watershed Management in Mountainous Northern Thailand[END_REF] ; forest management planning in the Causse du Larzac [START_REF] Simon | A companion modelling approach applied to forest management planning[END_REF] ; erosive runoff in the Seine Maritime [START_REF] Souchère | Coconstructing with stakeholders a role-playing game to initiate collective management of erosive runoff risks at the watershed scale[END_REF] ; game hunting management in Cameroon (Le [START_REF] Page | Interactive Simulations with a Stylized Scale Model to Codesign with Villagers an Agent-Based Model of Bushmeat Hunting in the Periphery of Korup National Park (Cameroon)[END_REF] ; impacts of farming practices on trade-offs among ecosystem services in the Mont Lozère [START_REF] Moreau | Conciliate agriculture with landscape and biodiversity conservation: a roleplaying game to explore trade-offs among ecosystem services through social learning[END_REF]. This approach is a powerful method to elicit and share mental models between multiple stakeholders [START_REF] Mathevet | Water Management in the Camargue Biosphere Reserve: Insights from Comparative Mental Models Analysis[END_REF]. It offers an arena to test new public policies acceptability and explore prospective scenarios in a virtual world mimickingto some extent -their realities.

Here, we propose to use a ComMod approach, coupled with ethnographic fieldwork [START_REF] De Sardan | portant classement du parc naturel régional du Marais poitevin (régions Pays de la Loire et Poitou-Charentes)[END_REF], to explore in situ, new policy instruments with farmers in a biodiversity-rich wetland context, and track changes in mental models. In our study, we focused on the Marais Poitevin wetlands, a highly anthropized environment, combining cropping and pasture systems, where conservation of farmland bird biodiversity is at high stake. The observation of the players constitutes the core of this study.

Our objective with these combined approaches is to test actors' choices when facing two policy options (individual action-based VS result-based) in a role-playing game experiment.

We explore the effects of these policy alternatives on the behaviors of the actors, including the setting-up of collective action and their semantic and mental models.

MATERIAL AND METHODS

Description of the case study

The study site is located on the French Atlantic coast and focuses on the Marais Poitevin wetlands (46°22′N, 1°25′W), the second biggest wetland of France and of major importance for biodiversity conservation [START_REF] Pinton | La construction du réseau Natura 2000 en France -Une politique européenne de conservation de la biodiversité à l'épreuve du terrain[END_REF]. This agro-ecosystem is dominated by a mosaic of cropping and grassland areas in two distinctive zones of wet and dry marshlands (Figure 1). It hosts more than 330 migratory and non-migratory bird species, many of which are dependent on very specific intensity of farming practices for the maintenance of suitable habitats. The main stakeholders and organizations in the area are:

the farmers and their professional organizations, -the nature conservationist with the Bird Protection League and the Wildlife and Hunting National Office managing the natural reserves the wetlands association ("Association de Syndicat de Marais") in charge of controlling water levels through sluice gates.

All of the above are coordinated on a regional level by the government-owned corporation ("Etablissement Public du Marais Poitevin") and the regional park who supervises the application of the AES in the region. Figure 1: The Marais Poitevin region: in green the wet marshland, in pale pink, the dry marshland and in blue the salt meadow. The studied area is represented by a grey rectangle in the center of the dry marshland. The selected area for the study (grey rectangle on Figure 1) is situated in the middle of several biological reserves ("Conservatoire du littoral" zone in the south, "Reserve de Saint Denis du Payré", one of the first bird reserve in France in the West and "Grand site de France" in the most humid part of the wetland in the East). This central zone presents the most illustrative situation in terms of bird conservation. Preliminary discussions with the regional park manager, the water management association and diverse NGOs and agriculture chambers active in the region helped gaining a first understanding of the local context and the farmers' organization. Based on those meetings, we identified this representative area of 15km x 10km surrounded by the abovementioned biological reserves.

After a historical period of livestock breeding dominance [START_REF] Derex | Pour une histoire des zones humides en France (xviie-xixe siècle)[END_REF], the mechanization of agriculture in the last century allowed the progressive implementation of crop rotation (wheat, corn, sunflower), leading to an increase in the number of pastures being tilled. The resulting rapid decline in grassland areas [START_REF] Duncan | Long-term changes in agricultural practices and wildfowling in an internationally important wetland, and their effects on the guild of wintering ducks[END_REF] together with an overall intensification of farming practices led to a severe degradation of the environment [START_REF] Billaud | L'État nécessaire? Aménagement et corporatisme dans le marais poitevin[END_REF]. In an effort to protect the ecosystem, the region was labelled "natural regional park" ("Parc Naturel Régional du Marais Poitevin") in 1979, but lost its designation in 1996 following the sharp decline in grassland areas [START_REF] Charles | Les Communaux du Marais Poitevin : géohistoire et construction collective d'un projet global[END_REF]

A ComMod approach including an ethnographic study

At the beginning of 2012, we proposed to local stakeholders in the Marais Poitevin area to think about the reconciliation of agricultural production and biodiversity conservation objectives at the scale of farms and agricultural territories using a Companion Modelling (ComMod) approach. ComMod is a community-based scientific approach that emerged in the 1990s to facilitate collective action [START_REF] Etienne | Companion modelling : a participatory approach to support sustainable development[END_REF]. Using Multi-Agent Systems (MAS) and role-playing games (RPG), the aim is to facilitate dialogue between multiple stakeholders and promote shared learning on environmental issues [START_REF] Bousquet | An environmental modelling approach: the use of multi-agent simulations[END_REF]. This can be achieved through the collective construction of a common artificial world leading to the emergence of a shared representation of the complex system and problem in order to test new public policies acceptance and explore prospective scenarios. 21 people from different institutions (Associations for the protection of the environment, Farmers' association, regional and local authorities, Regional and Natural Park of the Marais Poitevin, and wetland associations,) were invited by the scientists to several participatory workshops. Just over 50% of those invited did participate in at least one of the workshops and worked together for five years. Figure 1 shows the main stages in the study that are based on back and forth steps between the model and the field.

Figure 2: Step and timeline of the ComMod process

During the first half-day workshop in January 2012, three salient points were raised. Firstly, the local stakeholders strongly insisted that the question around the reconciliation of agriculture and biodiversity would encompass the issues on water levels' management, which are directly related to the availability and quality of the birds habitats. Second, they opted to focus the study on the dry marshland given the extent of its surface (almost 50% of the marsh surfaces). Furthermore, they considered that it would be easier to take better account of conflicts over water levels between different farmers (breeder vs cereal producer) while also

showing that the preservation of biodiversity is not only the prerogative of breeders. Third, they discussed the type of tool (role-playing game or simulation model) that should be developed following the various workshops. The final choice led to favoring the role-playing game option for its very interactive aspect, allowing collective thinking to emerge while integrating the requirements of each other. At the end of this first workshop, the question chosen to guide the development of the conceptual model of the future role-play was: how to reconcile agriculture, bird biodiversity and water level management in dry marshland? Then, during three other one-day workshops in March, April and June 2012, we worked with the group to build the conceptual model of the role-playing game based on the ARDI method [START_REF] Etienne | ARDI: a co-construction method for participatory modelling in natural resources management[END_REF]. Our objective was to collectively identify the main stakeholders concerns with the issue of agriculture, bird biodiversity and water levels, the entities they manage and the main dynamics and interactions at play according to different temporal and spatial scales. At the end of these workshops, we had gathered all the elements needed to begin implementing the role-playing game called ''BotNidVeau''. Between November 2012

and March 2016, we alternated phases of RPG development, periods of inventory and clarification of knowledge available via surveys and literature reviews, and meetings and crash tests to validate the tool.

In parallel, we conducted an ethnographic study to get an in-depth understanding of the perception of AES by the Marais Poitevin farming community. We documented farmers behavior, social interactions and perceptions 1) in situ (which we hereafter refer to as the ethnographic fieldwork), and 2) during game sessions where the farmers played a role-playing game simulating their agroecosystem (which we hereafter refer to as the ComMod approach).

The ethnographic fieldwork was conducted by the first author in autumn 2015 and spring 2016. He immersed himself in the life of seven farmers living in the zonation depicted in the Figure 1 who were already involved in the ComMod process described in the previous paragraph. He spent altogether 33 days in the field, with the shortest stay being 1 day, and the longest stay being 10 days with the same farmer. He documented community members' actions, words, and environment through observations and (conversational) interviews to understand how the community makes sense of a given situation [START_REF] Merriam | Introduction to qualitative research[END_REF][START_REF] Okely | Anthropological practice : fieldwork and the ethnographic method[END_REF]. The researcher introduced himself to the farmers as anthropologist working on the question of livestock breeding practices and its socio-economic consequences. During his immersion stays, he assisted the farmers with their daily activities. Farmers did not change their habits, nor their duties. They carried on with their usual activities, including feeding animals, repairing fences, and cleaning the stabling with the help of the researcher.

Conversations arose naturally and farmers spoke freely on the topics of nature, birds, water, agricultural practices and public policies. He recorded his observations and impressions in a field diary. Particularly, he documented each farmer's relationship with other community members, his political reactions and feedback on AES, and his ecological knowledge. He evaluated the relationships between farmers based on what farmers said about each other, and the ecological knowledge of a farmer based on the farmer's understanding of birds (including the role of birds in the ecosystem, their seasonality, their feeding behavior, and the precise locations where they have been spotted)

Game Design

The game board and game mechanisms

The game board (Figure 3) represents an archetypal dry marshland divided into two wetlands associations. Each association is divided in four pools that communicate by sluice gates.

Within each pool, grassland or cropland plots are attributed to players. The virtual landscape interlinks the dynamics of agricultural production, water management and farmland bird abundance. Water levels are collectively managed at the scale of wetland associations.

Roles and players' actions

The game is tailored for eight roles that can be played individually or in team of two:

five mixed farmers (with both crops and cattle) one head of a wetland association ("Association de Syndicat de Marais"), who is also a crop farmer one head of a wetland association ("Association de Syndicat de Marais"), who is also a cattle farmer one nature conservationist in charge of a natural reserve.

One round in the game corresponds to a one-month period in reality. The game session simulates a three-year period. Players take active decisions for the spring season, namely the months of April, May and June. The computer simulates the rest of the months, using the inputs from the players during the above-mentioned spring season. During a round, players can perform a set of actions depending on their roles: -Farmers can make decisions regarding the rotation of their crops (if any), the size and allocation of plot to cattle (if any), and the mowing date for their grassland (if any).

-

Wetland association presidents can decide on water levels in the various marshland compartments -

The nature conservationist cannot perform any action on the board. He/she manages the natural reserve and promotes suitable conditions for nesting and breeding. He/she has to convince the farmers to allocate cattle to graze in the reserve to maintain grass height and to protect nests in their fields. He/she also needs to persuade the wetland associations' presidents to increase water level whenever necessary. Figure 3: The game board around which players interact. The yellow areas represent the agricultural plots while the green ones represent the grassland plots (the darker the green the higher the grass height). The two zones delimited by white dotted line correspond to the two wetland' associations. Players decide individually or collectively about the number of cows and mowing machines per plot, the type of cultivated crops, the water levels settled by the wetland association presidents and the number of cows allowed by the nature conservationist to populate the grasslands of the nature reserve. The birds are also present and take the form of little figurines.

Players' targets

Players in the farmer' roles have to secure sufficient incomes at the end of the session. They start the game with a given amount of money based on their farming system and size, ranging from 5 to 80 money units (we used an imaginary currency called "mailles", calibrated against real figures). Players are provided with an information sheet along with economic data on the potential yield per crop and market prices. The economic data were derived from the ethnographic survey. The agent-based model compiles the economic outcomes of the players.

The nature conservationist aims for the highest possible bird populations. The wetland association presidents have no specific targets since they are driven by the targets of the other players and their own farmers' roles.

The AES in the game

The game can be played with one of two scenarios: individual action-based VS collective result-based AES.

During the morning session, the individual action-based AES was proposed (hereafter referred to as the classical scenario). Farmers can contract a "classical" individual actionbased AES with special constraints on mowing dates and trampling restrictions through limited livestock units. No matter the results in terms of bird survival, if these conditions are fulfilled players get a fixed financial compensation of 3 money units.

In the afternoon session, we proposed two new public policies, with both a collective dimension and a result-based implication 1 : a "bonus AES" and a "free-form AES" (hereafter referred to as the alternative scenario). The "bonus AES" has been designed as a collective, action-oriented and result-based AES that aims to link player decisions to their effects on biodiversity indicators (in the game the birds). The collective action is here defined as a group arrangement of practices to achieve a common objective, i.e. a biodiversity result. If successful, the financial retribution is of 7 money units. The eligible condition for the extra payment is 1) to apply the constraints of the "classical" AES, 2) to work with a minimum number of three neighboring farmers, and 3) to reach a target of 20% fledging success. A group of three corresponds to more than one third of the total number of players and can lead to an observable consequence of collective action on the biodiversity indicators within the game.

As the "bonus AES" still maintains the "classical" constraints (namely lid mowing date and reduced unit livestock density), we also proposed another collective result-based AES ("freeform AES") with no action constraints at all to allow farmers to look for adaptation of 1 Two collective AES have been proposed to the players, but as described in section 4.2.2, only the "free-form AES" was chosen. Therefore, only this latter policy could be fully explored in the role-playing game.

practices [START_REF] Burton | Creating culturally sustainable agri-environmental schemes[END_REF]. On the one hand, the "bonus AES" gives a caveat to proceed a familiar system of constraints as a working base. On the other hand, the "free-form AES" does not accompany the farmers with a set of practices. It gives a large space to cope with an environmental aim but can potentially restrain farmers who may have problems proceeding from a blank page.

Table 1 summarizes the specificities of the three public policies available in the game.

Running the game and data collection

The game sessions took place in March 2015 and lasted one full day. During the morning session, eight participants -the seven farmers who participated in the ethnographic study, and a nature conservationist, played the classical scenario. In the afternoon, the alternative scenario was played with one fewer player as one farmer had to leave for unexpected personal reasons. Participants were assigned a role corresponding to their role in real life. Table 2 introduces participants' role in the game, their profile/farming system in real life and their "type" as determined during the ethnographic fieldwork (inclination towards science, politics and/or environmental conservation). We documented players' behavior and equipped players with microphones to record their narrative during the two game sessions and the debriefing.

Players ID

Role in the game Role and farming system in real life

Quantitative data analyses

To support the qualitative data collected during this study, we also performed quantitative data analyses on the participants' narrative of the two game sessions. We perform a content analysis [START_REF] Carley | Extracting, representing, and analyzing mental models[END_REF], i.e. we examine the use of language of the farmers and of the nature conservationist in their daily-life as well as during a role-playing game session, and categorize words and phrases into key concepts, to elicit mental models. We chose this method over influence diagram, arguably the most common approach [START_REF] Abel | Mental models in rangeland research, communication and management[END_REF][START_REF] Dray | The atollgame experience: From knowledge engineering to a computer-assisted role playing game[END_REF][START_REF] Mathevet | Water Management in the Camargue Biosphere Reserve: Insights from Comparative Mental Models Analysis[END_REF][START_REF] Prager | Using mental models to understand soil management[END_REF], because of its non-intrusive nature, thereby allowing uninterrupted game session.

The analyses were conducted with IRAMUTEQ, a linguistic software based on R and Python [START_REF] Ratinaud | Iramuteq: Interface de R pour les Analyses Multidimensionnelles de Textes et de Questionnaires[END_REF]. Prior to performing analyses, the words of the transcript of the audio recording of the two game sessions were lemmatized (i.e. inflected forms of words were grouped together so that for example "had" and "has" were converted to "to have"). The text was sectioned into text segments based on a size criterion and punctuation (see Loubère and

Ratinaud, 2014 for a full description). Only content words (nouns, verbs, adjectives and certain adverbs) were included. Function words, such as pronouns and articles, were not considered.

We performed a similarity analysis to identify potential semantic changes. A similarity analysis is a method based on graph theory that represents the connectivity between nods (or in our case, words) [START_REF] Degenne | Introduction à l'analyse de similitude[END_REF][START_REF] Marchand | L'analyse de similitude appliquée aux corpus textuels: les primaires socialistes pour l'élection présidentielle française (septembre-octobre 2011)[END_REF]. The strength of the connectivity between two words was determined by the frequency of the co-occurrence of these words in text segments. The weakest links are removed from the graph to create a "maximum tree" (sensus [START_REF] Rosenstiehl | L'arbre minimum d'un graphe[END_REF], an acycle connected graph [START_REF] Degenne | Introduction à l'analyse de similitude[END_REF]. The similarity analysis of IRAMUTEQ is based on the R-package proxy (Meyer and Buchta, 2019)2 .

RESULTS

We first present the behavior of the players while playing the classical scenario (section 3.1.1), and the alternative scenario (section 3.1.2). We then present the results of the semantic analysis in section 3.2. From the narrative of the farmers during the ethnographic fieldwork and during the games, we identified three critical notions: management, birds and the commons (see section 3.2.1). We further detected a shift towards a common semantic amongst the players between the first and the second game sessions (see section 3.2.2). We also found that the interactions between the players increased during the second game session (see section 3.2.3).

Behaviours in the game

Classical scenario

All players contracted the action-oriented AES during the classical scenario session. At the end of the game, before the financial retribution from the action-oriented AES, three players made a loss, and four made a profit -among those four, three started the game with more crop fields than the others. They confirmed that their return in the game was equivalent to the ones they face in real life. After receiving the income from the AES, all players had positive return.

Players commented that the income from AES was not perceived as a compensation for ecological services but as a meat production support. They considered it a salary that helps them to cope with financial difficulties.

During fieldwork as well as in the game session, farmers stated that they were increasingly driven to think in strict economic terms in real life; reducing costs, spending less time with animals, using second-hand equipment, and rarely meeting with colleagues. They deplored it and specified that one third of the time was allocated to the crop while it provides more than two third of the profit. Many farmers wished they could have more cropland. They regretted not to have ploughed their pasture before the ban was enforced. Some farmers argued about the necessity to fertilize and to mow early in the year in order to get better economic performance.

Alternative scenario

During the alternative scenario session, players could chose to implement "free-form AES" or "bonus AES". After a short discussion, farmers agreed to implement a "free-form AES", and created two groups of three (three being the minimum group size requirement). They all concurred that the current AES constraints induced an economic loss and an economic uncertainty due to payment delay and risk of reimbursement in case of contract statement violation. Therefore, the farmers preferred to start from scratch rather than the "bonus AES".

In this form, each farmer received a payment depending on the collective performance of his group, and risked receiving no reward for his effort if the strategy was unsuccessful. Very interestingly, to mitigate the risk for the players with fewer crop fields, the players with the most crop field offered to financially support the former in case of AES failure. It is the collective insurance that brought farmers into a collective strategy. Despite the risk, they stated that the potential extra income was a strong motivation to work together. They also recognized that they were more willing to implement AES in the absence of constraints. For those skeptical about the "free-form AES", the risk sharing was preferable to an individual offset of current AES difficulties. The two groups of players, instead of collaborating to enhance the total number of birds, competed with each other. They elaborated their spatial strategical management at the level of the "water association" (water basin) and not at the whole landscape level. Players of one group tended to destroy favorable bird habitat in the other group; farmers with plots in both water associations allocated most of their cattle in tiles of the other group to maintain their production level, thereby destroying nests of the other group.

Despite the competition, the economic performances at the end of the alternative scenario session differed drastically from the classical scenario. Before AES income, all farmers ended with positive return. Their collective strategy generated more income compared to the individualist strategy from the classical scenario session (cf. Table 1).

However, the farmers acknowledge that such a mechanism is unlikely to be implemented in reality. They recognized their coordination limits -coordination being understood as "working towards the same objectives but in isolation" (Prager, 2015). They stand that a collective insurance fund is impossible on a water association level. They expressed regret regarding the first AES which were implemented twenty years ago, which was considered more flexible. The game helped them realize the consequences of their actions and the importance of the interaction, which might be a first step to the elaboration of a collective AES that could be applied in reality.

Semantic

Participants semantic across three critical notions: management, birds and the commons

The participants' narratives during the ethnographic fieldwork highlighted their respective semantic fields and the game was insightful to foster reciprocal influences and narratives changes. Changes in narratives between the classical and alternative scenarios are reflected in the word connectivity graph (Figure 4).

We identified three domains of semantic change related to three critical notions: management, bird, and commons. We focused on farmers semantic as they embodied the main actors of the AES implementation. The denomination 'farmers' refers here to the mixed farmers (not to the crop farmer, i.e. player #1).

Critical notion 1: Management

During the game session, farmers had very little use of the verb "gérer" ('to manage'). They used the verb "produire" ('to produce') to refer to meat production. Farmers did not speak about complexity, nor did they replace complexity by another word or expression. For farmers, their production system remained complicated, not complex, "we are tired of hearing that we belong to a complex system". They thus handled a production system with its inner complications. Farmers had an intensive use of the words related to production ("do we produce or do we provide a service?", "I don't raise cattle for tourists"). In comparison, the nature conservationists used the French verb 'gérer' and talked about habitat maintenance during the field interviews.

We recorded many expressions related to the economic uncertainty ("how much income?", "does it pay") stemming from the AES implementation in the game. In the course of the session with the classical scenario, the farmers' expressed concerns about the structure of the public policy, and not about its ecological impact; "will the funding be limited?", "will the eligibility criteria be flexible enough?", "when will the funding be provided?". In the alternative scenario where the collective result-based with no more constraints ("free-form AES") was proposed, all the farmers had similar narratives; "no more direct constraints", even though some farmers had difficulties to think in non-constraint terms. Indeed, we recorded many sentences such as "no, you forgot, there is no more constraints". The implementation of this "free-form AES" has progressively transformed constraint-driven operations to more bird dynamics concerns. Before the new AES implementation in the alternative scenario session, the uncertainty was almost entirely articulated around the public policy and not the environment consequences of their actions while during the collective result-based AES implementation, questions focused on birds and the environment.

Critical notion 2: Bird

During the ethnographic fieldwork, we observed that farmers had some knowledge on birds' season of arrival and feeding habits, but not so much on habitat requirement for breeding in terms of grass composition and size. They use the French term "piaf" (quite pejorative word, meaning a bunch of bird or one bird). These findings were confirmed by the players' discourses during the game.

Figure 4: The two word connectivity graphs from the similarity analysis, with the narratives from the classical scenario on the left and from the alternative scenario on the right. Words size is proportional to their frequency, and branches thickness is proportional to the strength of the connection between two words. The blue circles are centered around the word "oiseaux" ("bird"), which in the alternative scenario is closed to the words "vache", "ble" and "oiseau", respectively "cow", "wheat" and "bird".

During the classical scenario session, farmers spoke about "bestiole" and "piaf" (quite pejorative words for "animal" and "bird" respectively) rather than "oiseaux" literally translated by "birds". They did not mention the birds' conservation effort but for the "bestiole"/"piaf" presence's accountability, they did acknowledge a fauna presence. In the word connectivity graph of the classical scenario, the word "oiseaux" (bird), is anecdotal, and distantly located from the words "vache" (cow) and "blé" (wheat), while in the graph of the alternative scenario, it is predominant and closely associated to the words "vache" and "blé".

In the meantime, farmers did not speak about habitats nor environments, rather "cultivated fields", "grasslands plots", "ridges" and "canals". During the classical scenario session, the reference to "bestiole"/"piaf" contrasted with the nature conservationists who referred regularly to "species" and especially to "habitats". However, during the alternative scenario session, no such word came out. The farmers and the nature conservationist spoke about "birds" and met in a common semantic field. Moreover, the notion of cattle and wheat came regularly with the notion of bird as depicted in the Figure 4, revealing a cause-consequence link. During the alternative scenario, farmers asked many questions to the nature conservationist regarding bird ecology.

The nature conservationist faced the problem of the operational ecological knowledge; the nature conservationist had to translate his own expertise in terms of production, "produce birds". The nature conservationist made a translation during the alternative scenario session, answering in farmers' words to farmers asking how to produce more birds in the game. He did so by explaining how the relationship between grass height and water level in the game can trigger birds' presence on specific fields. The farmers and the nature conservationist have thus used a production semantic while speaking about birds avoiding any management narratives. In doing so, they linked the conservation's narratives with the production semantic, involving a new conservation's production discourse, "We are doing badly for the birds, we need to improve our business".

Critical notion 3: Commons

During the ethnographic fieldwork, farmers' narrative was rather oriented on individual concerns while avoiding the subject of the collective dimension in their socio-economic life.

They stated acting in an individualist way with some mutual help when needed after unexpected gear problems or complicated maintenance. This contrasted with the semantic of the nature conservationist who talked about collective effort and need for cooperation in order to provide a good ecological state at a regional scale. The individualistic semantic of the farmers was reflected in the game. During the classical scenario session, no collective semantic such as "together", "common", "with others", etc. emerged. The word connectivity graph of this scenario is star-shaped with multiple branches centered on one word (Figure 3, left). This shape suggests an absence of a common semantic between the players and is consistent with a lack of collaboration, as described by the players during the debriefing session.

The farmers' narratives corresponding to the collective dimension appeared only during the alternative scenario session. The shape of the corresponding graph (Figure 3 right) is more linear, with a large lateral branch and a second thinner one. This shape suggests that players adopted a collective semantic. It is also in this scenario that the words "to share" and "group"

were mentioned. This pattern can be expected to emerge from the implementation of collaborative strategies. Indeed, during the debriefing, players explained that they worked in groups to be able to meet bird targets to receive compensation.

The semantic shift

In the second session, the farmers changed their semantic using a bird semantic while thinking more broadly in terms of animal production. Moreover, they acted with a more collective perspective, from individual dynamics to hybrid ones with collective and individual dynamics. Conversely, the nature conservationist adapted his semantic from "species" to "bird", from "habitat" to "birds" and "grassland" and "cattle", and from collective to collective and individual. The cognitive shift is schematized in Figure 5. The central cell,

where the farmers and the nature conservationist met at the end of the game sessions, reflects the semantic convergence. The nature conservationist adopted a 'bird production' metaphor to meet with the farmers' original semantic focused on meat production. Note that the semantic of both parties do not overlap fully as representation divergences remained. This cell can be characterized as a collective and multi-issues space of discussion. It is a condition for the new AES success since stakeholders brainstormed all together in new modalities. It provided an opportunity to exchange about divergence and agreement while converging to decision and collective action.

Figure 5: The graph qualifies the cognitive state in the classical scenario for farmers (in square) and the nature conservationist (in circle), as well as the common domain in the center of the table from the alternative scenario. The gradient between individual and collective induce a twofold semantic with both individual and collective references.

Interactions amongst participants through semantic analysis

The ethnographic fieldwork revealed that in reality, each participant interacts with at most three other participants, and three participants do not regularly interact with the others (Figure 6). The farmers all work on their own and believe they are too different one from another to be able to work effectively in cooperation. Few participants are politically active or involved in a union movement and few have responsibilities in local networks. On a social dimension perspective, farmers do not interact very often; they meet during water management meetings or technical training groups and have almost no discussion opportunities. They stated that collective action is limited because of divergent personal projects and views. Moreover, sharing farm equipment is made virtually impossible because of the very narrow mowing period allowed by AES.

From the transcript of the recording of the game sessions, we could determine the interactions between players and their intensity (low/high) on the topics of birds and crop/grassland.

During the game, many more interactions took place than in reality. More interactions happened during the alternative scenario session than during the classical scenario session, and interactions were more intense on the topic of crop/grassland than on birds.

During the classical scenario session, farmers interacted mostly with each other (#3-6) and the water association presidents (#1 and #7). One of the water association presidents (#1) had to make the link between farmers and the nature conservationist (#8) to discuss crop and pasture management. On the contrary, during the alternative scenario session, both water association presidents (#1 and #7) had almost nothing to do since the farmers interacted directly with the nature conservationist. They were no longer acting as intermediaries nor interpreters. Due to unforeseen personal reasons, players #2 had to quit the game during the alternative scenario session and is therefore not positioned in the scheme.

Results from the ethnographic work

Players' relations

Results from the game session

Players' interactions…

DISCUSSION AND CONCLUSION

Our work explores public policies to conciliate agricultural production, biodiversity conservation and water management in wet grasslands, with the case study of the Marais Poitevin wetland located in France. We examine the current individual action-based policy as well as collective result-based alternatives. We use a two-fold methodology combining an ethnographic fieldwork and a role-playing game experiment. In addition, in both approaches we lead a semantic analysis in order to complete our work with a language-based interpretation eliciting subjacent mental models.

The ethnographic fieldwork allows us to study the actor's relationships, which is useful in understanding collective policies. It is also helpful to create trusting relationships and legitimacy between the scientific team and farmers to allow involvement in the role-playing game.

In the role-playing game, players explore three public policy tools. The first one is the existing policy, namely an action-based individual AES. Two alternatives are offered to the players, namely a result-based but action-constrained collective AES and a free-form resultbased collective AES. Only the free-form AES was chosen by the players and tested during the game session. This choice is a result per se, which we discuss below.

Our work contributes to the literature as it provides a rare example of a collective result-based AES experiment while this form of AES is less common than action-based ones and is promising (Le [START_REF] Coent | Why pay for nothing? An experiment on a conditional subsidy scheme in a threshold public good game[END_REF][START_REF] Schwarz | An analysis of the potential effectiveness of a payment-by-results approach to the delivery of environmental public goods and services supplied by Agri-Environment Schemes[END_REF]. This innovative form of AES also presents the interest of being a bottom-up approach rather than top-down as farmers choose themselves which actions to implement to reach a given objective. Another contribution lies in the fact that the role-playing game has an educational function; it helps actors understand the consequences of their actions and the benefits of their interaction. It thus represents a first step in the implementation of collective result-based AES.

Our main results are the following.

First, farmers all chose the free-form AES in the game when presented with the opportunity to select either a free-form or a constrained AES. It is a strong result given that there is a double uncertainty for farmers when choosing the free-form AES. The first source of uncertainty is due to the collective characteristic of the AES making the payment depend on a collective result and thus on the behavior of the other farmers, contrarily to an individual AES. The second uncertainty comes from the result-based form of the AES making the payment less predictable as the result (bird abundance) depends on random factors that are independent from farmers' efforts. Despite these uncertainties, farmers unanimously chose this free-form and built a collective insurance -some farmers offered to support other farmers in case of AES failure -to mitigate these risks. Farmers prefer to quit the constrained system (late mowing date and reduced trampling) to favor a blank page strategy, working together on a new set of constraints. Such AES modalities reveal farmers' need for flexibility and recognition as pointed by [START_REF] Emery | The potential for collaborative agri-environment schemes in England: Can a well-designed collaborative approach address farmers' concerns with current schemes?[END_REF].

Second, we observed that in the free-form AES, competition appeared between the two groups of collective AES with some farmers trying to sabotage the other group's conservation effort. This questions whether this adverse effect of free-form AES could appear in real-world implementations. The problems induced by the 'bird production' implementation and the risk of 'a race for bird' with detrimental effects thus call for the necessity to address the result of the collective result oriented AES through a participatory process [START_REF] Lardon | Recherches participatives sur les exploitations agricoles et les territoires: des démarches innovantes[END_REF] and a landscape approach [START_REF] Sayer | Ten principles for a landscape approach to reconciling agriculture, conservation, and other competing land uses[END_REF] where system boundaries are clearly defined. In our case, the two groups implemented a spatial planning at the scale of the water association, not the whole landscape.

Third, the economic performances before the AES payment were improved in the collective result-based AES compared to the individual action-based one. This finding supports the implementation of collaborative result-based over individual action-based AES. The literature tends to support the cost effectiveness of the result-based approach [START_REF] Reed | Improving the link between payments and the provision of ecosystem services in agri-environment schemes[END_REF], as well as its ecological benefits [START_REF] Musters | Breeding Birds as a Farm Product[END_REF]. However, as modelled by [START_REF] Groeneveld | Effects on participation and biodiversity of reforming the implementation of agrienvironmental schemes in the Netherlands[END_REF], adverse effects can also arise under the collective scenario, even if the economic incentives seem higher. How farmers weight biodiversity plays a key role in ensuring participation in collective scheme and long-term commitment.

Last, the semantic analysis demonstrated the existence of three critical topics in the language used by the actors: management, birds and the commons. Moreover, we noted a shift towards a common semantic and towards increased interactions between the first and second game session. In other words, the level of interaction between the farmers but also between the farmers and the nature conservationist were higher when they played the alternative scenario.

As in this scenario farmers have to collaborate, it is trivial that they interact more with each other. Likewise, as the reception of the financial retribution is condition upon biodiversity outcome, it is not surprising that they exchange more with the bird conservationist to ask him about the conditions favorable to biodiversity. The implementation of a collaborative approach to AES could likely increases social interactions between the stakeholders, something that the cattle farmers and the nature conservationist stated during the ethnographic fieldwork they would welcome. The increase in social interaction can be beneficial beyond the simple exchange of information. Under a collective dynamic, farmers are in a better psychosocial condition to perform AES's measures [START_REF] Van Dijk | Factors underlying farmers' intentions to perform unsubsidised agri-environmental measures[END_REF].

Our work presents some limits and several of our results can be discussed. The fact that participants achieve a common semantic and increased interactions in the second game session compared to the first one may be a normal evolution with time and players' experience, rather than due to the collective form of the policy. Other game experiments should be implemented to elucidate this point. Also, we compare two AES for which two

  Agricultural dynamics are managed by individual farmers. The biophysical processes represented in the game are water flow, grass growth, birds nesting and reproducing. Their specific dynamics, affected by climatic factors (rainfall) and players' decisions, are computed and updated in an associated agent-based model. Three bird species are included in the game to represent bird abundance and its interaction with farming practices: two grassland species, the Northern Lapwing (Vanellus vanellus) and the Common Redshank (Tringa totanus), and one cropland species, the Montagu Harrier (Circus pygargus). Their dynamics depend on direct cattle and/or mowing disturbances as well as habitat quality in terms of water and grass levels.

  Figure 6: The different types of interactions are depicted in the different sub figures. The top row illustrates the relationship before the game (extracted from the ethnographic fieldwork), the dotted arrow qualify a rather conflictual relationship between the two water associations' presidents (#1 and #7) while the other arrows show good relationships. The other sub figures illustrate the levels of interactions during the game session. Each arrow's width corresponds to the discussion intensity about the subject related by each line (birds or crop/grassland).Due to unforeseen personal reasons, players #2 had to quit the game during the alternative scenario session and is therefore not positioned in the scheme.

  parameters differ: the individual vs collective form and the action vs result-based form. It would have been interesting to change one parameter at a time and test a collective actionbased AES and an individual result-based AES as well 3 . This opens scope for further research. ACKNOWLEDGEMENT This work was carried out with the financial support of the «ANR-Agence Nationale de la Recherche -The French National Research Agency» under the «Programme SYSTERRA», project «FARMBIRD» and with the financial support of the BASC Labex. The authors wish to acknowledge the stakeholders who participated in the joint construction of the RPG and in the RPG sessions. The authors wish also to thank Cécile Helan, Marion Sorrieul, Patricia Grené, and Brigitte Rémy for their involvement in the development and the implementation of this methodology. Finally, we thank the editor and two anonymous reviewers for their constructive comments on an earlier version of the manuscript.

Table 1 :

 1 Comparative table across four dimensions (involvement, constraints, environmental objectives and financial retributions) of the three proposed AES in the game.

		Classical scenario	Alternative scenario
		Action-oriented AES	Bonus AES	Free-form AES
	Players' involvement	Individual	Collective (at least 3	Collective (at least 3
			farmers)	farmers)
	Constraints	Mowing date	Mowing date	none
		Trampling restrictions	Trampling restrictions
	Environmental objectives	none	+20% fledging success	+20% fledging success
	Financial retributions	+3 money units	+7 money units conditional	+7 money units conditional
		irrespective of env.	upon achieving env.	upon achieving env.
		objectives.	objectives.	objectives.

Table 2 :

 2

Participants' profile with their role in the game and their farming system/activity in real life *This player could only attend the game during which the classical scenario was played.

As IRAMUTEQ is based R, analyses ran in IRAMUTEQ can build on the large collection of functions and data sets developed freely by the R-community provided in the form of R-packages. In this case, we indirectly used the package proxy that computed the similarity matrix.

However, relevant result-based AES are generally collective as the interesting results for biodiversity conservation usually call for the simultaneous effort of several actors. That is the reason why we directly tested a collective result-based approach.