Hugo Fernandez Mena
email: hugo.fernandez-mena@supagro.fr

Hélène Frey

Florian Celette

Léo Garcia

Karim Barkaoui

Laure Hossard

Audrey Naulleau

Raphaël Métral

Christian Gary

Aurélie Metay
email: aurelie.metay@supagro.fr

Hugo Fernández-Mena

Spatial and temporal diversity of service plant management strategies across vineyards in the south of France. Analysis through the Coverage Index

Keywords: cover crop, service plant, intercropping, spontaneous vegetation, survey. Highlights

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

Introduction

Mediterranean regions present a high risk of soil erosion [START_REF] Cerdan | Rates and spatial variations of soil erosion in Europe: a study based on erosion plot data[END_REF][START_REF] García-Ruiz | The effects of land uses on soil erosion in Spain: a review[END_REF][START_REF] González-Hidalgo | A review of daily soil erosion in Western Mediterranean areas[END_REF]. These lands are prone to soil erosion partially because of climatic conditions, with a high occurrence of extreme weather events [START_REF] Reiser | Rainfall uncertainty in the Mediterranean: time series, uncertainty, and extreme events[END_REF], but also because of soils with low soil organic matter content and soil stability [START_REF] Marzaioli | Soil quality in a Mediterranean area of Southern Italy as related to different land use types[END_REF][START_REF] Romanyà | An appraisal of soil organic C content in Mediterranean agricultural soils[END_REF][START_REF] Sinoga | Variability of relationships between soil organic carbon and some soil properties in Mediterranean rangelands under different climatic conditions (South of Spain)[END_REF]. Land-use in the Mediterranean is often devoted to farming [START_REF] Francaviglia | Influence of land use on soil quality and stratification ratios under agro-silvo-pastoral Mediterranean management systems[END_REF][START_REF] Mohawesh | Effects of land use changes and soil conservation intervention on soil properties as indicators for land degradation under a Mediterranean climate[END_REF] and vineyards are one of the main farming activities [START_REF] Dougherty | The geography of wine: regions, terroir and techniques[END_REF]. Aggravated by climate change, farming systems in the Mediterranean can easily lead to degradation, especially in vineyard areas where, generally, the soil covering rate is low [START_REF] García-Orenes | Soil structural stability and erosion rates influenced by agricultural management practices in a semi-arid Mediterranean agro-ecosystem[END_REF][START_REF] Muñoz-Rojas | Impact of land use and land cover changes on organic carbon stocks in Mediterranean soils (1956-2007)[END_REF][START_REF] Zdruli | Land resources of the Mediterranean: status, pressures, trends and impacts on future regional development[END_REF]. Soil management in vineyards is usually achieved through destruction of grass vegetation using soil tillage or by the application of herbicides (Lieskovský and Kenderessy, 2014;Pateiro-Moure et al., 2013). However, soil tillage in vineyards increases the risk of soil erosion, in particular, due to the high level of runoff especially during intense rainfall events [START_REF] García-Díaz | Nitrogen losses in vineyards under different types of soil groundcover. A field runoff simulator approach in central Spain[END_REF][START_REF] Comino | Soil erosion processes in European vineyards: a qualitative comparison of rainfall simulation measurements in Germany, Spain and France[END_REF]. The impact of soil erosion in Mediterranean vineyards has been estimated at 9.3 Mg of soil loss per hectare and year [START_REF] Prosdocimi | Soil water erosion on Mediterranean vineyards: A review[END_REF]. Preventing soil degradation in vineyards is essential, in particular considering the grapevine permanent crop status and their frequent location on terraced or steep slopes [START_REF] Tarolli | Vineyards in terraced landscapes: new opportunities from lidar data[END_REF]. Thus, a more sustainable soil management strategy for vineyards is needed to preserve the soil and to associate ecosystem services [START_REF] Winter | Effects of vegetation management intensity on biodiversity and ecosystem services in vineyards: A meta-analysis[END_REF].

What are service plants and why are they important?

Service plants are spontaneous vegetation (weeds) and sown plant species associated with a perennial crop in the rows or inter-rows with a high potential to provide ecosystem functions and services. In the literature, these plants are often named 'vegetation cover' but without linking their activity to the ecosystem services provided [START_REF] Hall | Vegetation management intensity and landscape diversity alter plant species richness, functional traits and community composition across European vineyards[END_REF][START_REF] Winter | Effects of vegetation management intensity on biodiversity and ecosystem services in vineyards: A meta-analysis[END_REF]; 'cover crops' referring to sown plant species [START_REF] Ripoche | Modeling spatial partitioning of light and nitrogen resources in banana cover-cropping systems[END_REF][START_REF] Samedani | Effect of cover crops on weed community and oil palm yield[END_REF] but sometimes referring also to spontaneous vegetation [START_REF] Schütte | The attitudes of French and Spanish winegrowers towards the use of cover crops in vineyards[END_REF] and also 'service crops' [START_REF] Garcia | Management of service plants for the provision of ecosystem services in vineyards: A review[END_REF] to emphasize their management needs similar to crops. As stated previously, some of the most significant services provided by service plants in vineyards are linked to soil support and regulation [START_REF] Daane | Native grass ground covers provide multiple ecosystem services in Californian vineyards[END_REF]. More generally, service plants present beneficial effects on soil quality compared to bare soils [START_REF] Biarnès | Unexpected predominance of wine grower location over soil trafficability for vine management in southern France[END_REF][START_REF] Guzmán | A field evaluation of the impact of temporary cover crops on soil properties and vegetation communities in southern Spain vineyards[END_REF][START_REF] Salomé | The soil quality concept as a framework to assess management practices in vulnerable agroecosystems: A case study in Mediterranean vineyards[END_REF]. They help to prevent nutrient loss due to reduction of runoff [START_REF] García-Díaz | Nitrogen losses in vineyards under different types of soil groundcover. A field runoff simulator approach in central Spain[END_REF], and through N catch crops when seeding legume species [START_REF] Novara | Managing soil nitrate with cover crops and buffer strips in Sicilian vineyards[END_REF]. Service plants can also play a role in mitigating climate change in vineyards since they can contribute to carbon sequestration by increasing soil organic matter content and soil stability at the same time [START_REF] Novara | Real cover crops contribution to soil organic carbon sequestration in sloping vineyard[END_REF][START_REF] Wolff | Minimum tillage of a cover crop lowers net GWP and sequesters soil carbon in a California vineyard[END_REF]. Service plants can help to provide a habitat for natural enemies of grapevine pests [START_REF] Danne | Effects of native grass cover crops on beneficial and pest invertebrates in Australian vineyards[END_REF]. In addition, they can improve vineyard aesthetics [START_REF] Kazakou | A plant trait-based response-andeffect framework to assess vineyard inter-row soil management[END_REF][START_REF] Winkler | Assessing ecosystem services and multifunctionality for vineyard systems[END_REF] and also reduce on and off-site costs [START_REF] Schütte | Profitability of erosion control with cover crops in European vineyards under consideration of environmental costs[END_REF]. On the flip side, certain plant species associated with grapevines can occasionally induce competition for resources. Water stress is thought to be the most limiting resource to consider for plant association with grapevines in Mediterranean conditions, followed by nutrient competition [START_REF] Celette | WaLIS-A simple model to simulate water partitioning in a crop association: The example of an intercropped vineyard[END_REF][START_REF] Celette | Dynamics of water and nitrogen stress along the grapevine cycle as affected by cover cropping[END_REF][START_REF] Lopes | Combining cover cropping with deficit irrigation in a Mediterranean low vigor vineyard[END_REF][START_REF] Monteiro | Influence of cover crop on water use and performance of vineyard in Mediterranean Portugal[END_REF]. Furthermore, associated plants can eventually host vine pests [START_REF] Muscas | Effects of vineyard floor cover crops on grapevine vigor, yield, and fruit quality, and the development of the vine mealybug under a Mediterranean climate[END_REF][START_REF] Rusch | Grape moth density in Bordeaux vineyards depends on local habitat management despite effects of landscape heterogeneity on their biological control[END_REF][START_REF] Wilson | Review of ecologically-based pest management in California vineyards[END_REF]. Finding suitable trade-offs through careful management of the vineyard cropping system will enhance target services and reduce undesirable disservices [START_REF] Rapidel | Analysis of ecosystem services trade-offs to design agroecosystems with perennial crops[END_REF].

What are the management strategies of winegrowers?

Different strategies can be used to manage spontaneous vegetation or sown species, depending on the composition and diversity of plant species, the surface area of the service plants, the type of vegetation control and the date of destruction [START_REF] Garcia | Management of service plants for the provision of ecosystem services in vineyards: A review[END_REF]. Spontaneous vegetation is frequently chosen as the basic service plant option by winegrowers thanks to its easiness and lower management costs [START_REF] Metay | Spontaneous cover-crop characterization is relevant to define a sustainable soil management strategy in vineyard[END_REF]. Instead, sown service crops, sometimes named intercrops [START_REF] Ripoche | Design of intercrop management plans to fulfil production and environmental objectives in vineyards[END_REF], can be useful for providing additional services compared to the spontaneous vegetation, such as greater biomass production, N fixation, lower water demand or pest repellency [START_REF] Donkó | Comparison of species-rich cover crop mixtures in the Tokaj wine region (Hungary)[END_REF][START_REF] Irvin | The effect of an irrigated buckwheat cover crop on grape vine productivity, and beneficial insect and grape pest abundance in southern California[END_REF][START_REF] Mercenaro | Sustainable management of an intercropped Mediterranean vineyard[END_REF][START_REF] Miglécz | Establishment of three cover crop mixtures in vineyards[END_REF][START_REF] Tomaz | Influence of cover cropping on water uptake dynamics in an irrigated Mediterranean vineyard[END_REF]. Compared to sown plant species, spontaneous service plants have been shown to produce greater [START_REF] Bordelon | Preplant cover crops affect weed and vine growth in first-year vineyards[END_REF][START_REF] Guzmán | A field evaluation of the impact of temporary cover crops on soil properties and vegetation communities in southern Spain vineyards[END_REF] or lower biomass [START_REF] Kazakou | A plant trait-based response-andeffect framework to assess vineyard inter-row soil management[END_REF]. In the Mediterranean context, spontaneous cover treatment can be chosen as a costless trade-off for the winegrowers between improving soil properties, limiting mechanical work and maintaining vine production [START_REF] Kazakou | A plant trait-based response-andeffect framework to assess vineyard inter-row soil management[END_REF]. Additionally, some spontaneous species having different traits and using resources differently can also complete their cycle (e.g., early flowering weed species able to produce seeds before the closure of the canopy of the cover crop) [START_REF] Kazakou | A plant trait-based response-andeffect framework to assess vineyard inter-row soil management[END_REF]. Finally, winegrowers' management can modulate weed richness and abundance presenting interesting functional traits [START_REF] Fried | Relative importance of environmental factors and farming practices in shaping weed communities structure and composition in French vineyards[END_REF].

The management of service plants to avoid grapevine water stress in Mediterranean regions is crucial, especially during the grapevine vegetative period, between budburst and flowering [START_REF] De Cortazar Atauri | Grapevine phenology in France: from past observations to future evolutions in the context of climate change[END_REF][START_REF] Vasconcelos | The flowering process of Vitis vinifera: a review[END_REF]. The spatial and temporal strategy to avoid grapevine water stress has to be flexible enough to adapt to and plot conditions and inter-annual climate variability [START_REF] Ripoche | Design of intercrop management plans to fulfil production and environmental objectives in vineyards[END_REF]. In this sense, the adaptation of service plant coverage to different soil depths is necessary to prevent early water stress in grapevines, but sometimes includes important trade-offs between grape yield and protecting soil from erosion [START_REF] Delpuech | Adapting cover crop soil coverage to soil depth to limit competition for water in a Mediterranean vineyard[END_REF]. In the case of arable cropping systems, the date of destruction is a crucial leverage that farmers have to manage [START_REF] Alonso-Ayuso | The cover crop termination choice to designing sustainable cropping systems[END_REF]. After destruction, service plant residues left in the vineyard provide several agroecological services for the vineyard such as the supply of nutrients and the preservation of soil humidity [START_REF] Ranaivoson | Agro-ecological functions of crop residues under conservation agriculture[END_REF]. Although these residues can be used as a natural mulch preventing the growth of spontaneous vegetation [START_REF] Steinmaus | Mulched cover crops as an alternative to conventional weed management systems in vineyards[END_REF], mulches can be created using pruning wastes [START_REF] López-Urrea | Effect of using pruning waste as an organic mulching on a drip-irrigated vineyard evapotranspiration under a semi-arid climate[END_REF], bringing in biomass, plastics, fibers and/or bioplastics [START_REF] Gastaldi | Agronomic performances of biodegradable films as an alternative to polyethylene mulches in vineyards[END_REF].

Surface area and time of year dictate the number of management operations in the row, the inter-row or both, such as the use of herbicides or mechanical tillage for weeding and the control of plant growth by mowing or rolling. Furthermore, the winegrowers preference for a service plant strategy is also related to grape yield objectives (according to wine label regulations); to the level of technical knowledge [START_REF] Marques | Analysing perceptions attitudes and responses of winegrowers about sustainable land management in Central Spain[END_REF] ; to the use of inputs such as pesticides [START_REF] Mailly | Quantifying the impact of crop protection practices on pesticide use in wine-growing systems[END_REF], fertilizers, water, fuel and labortime [START_REF] Borsato | Use of multiple indicators to compare sustainability performance of organic vs conventional vineyard management[END_REF]; and to the associated services targeted by the winegrower [START_REF] Mercenaro | Sustainable management of an intercropped Mediterranean vineyard[END_REF].

How can we study service plant management strategies at the regional scale?

Although the scientific literature provides detailed information on trials of service plant management strategies at the plot and the farm scale, we know little about how and why winegrowers implement these strategies at farm and regional scales, including the vineyard surface area covered by the service plant, the growth control practices and the dates of destruction. Only a few studies have analyzed the implementation of service plants by winegrowers at the regional scale. [START_REF] Marques | Analysing perceptions attitudes and responses of winegrowers about sustainable land management in Central Spain[END_REF] evidenced that strategies were linked to vineyard climatic conditions, the knowledge of winegrowers and the type of business structures. [START_REF] Schütte | The attitudes of French and Spanish winegrowers towards the use of cover crops in vineyards[END_REF] showed that winegrowers doing direct sales of high quality wine pay more attention to the environment and consequently use service plants more often than winegrowers selling their grapes to winemaking cooperatives. [START_REF] Hall | Vegetation management intensity and landscape diversity alter plant species richness, functional traits and community composition across European vineyards[END_REF] demonstrated that an increase in management operations on service plants (i.e., tillage, chemical weeding, mowing, mulch, etc.) resulted in lower species richness, functional diversity and vegetation cover, although vineyard structural characteristics and winegrower motivations were not taken into account.

In France, the agricultural census [START_REF] Agreste | Pratiques culturales en viticulture pour la Campagne[END_REF] provides a brief classification of service plants in vineyards in 2013. This classification includes the type of weed control (chemical, mechanical or mixed), and just three options of the temporality of weed destruction (completely bare soil; temporary cover crop; and permanent cover crop). The same classification degree was used in several European regions by [START_REF] Hall | Vegetation management intensity and landscape diversity alter plant species richness, functional traits and community composition across European vineyards[END_REF]. However, these classification methods could be improved in terms of temporality and spatial surface covered, in relation to the grapevine cycle, and the objectives of the service plant strategy. Therefore, we believe that further analysis of the diversity of service plant management strategies across vineyards at a regional scale will help to better understand the assets and constraints to the implementation of service plants in vineyards in the Mediterranean region. We hypothesize that an intensive use of service plants (higher surface covered, longer duration, selected plant material, etc.) could be linked to less constrained vineyard conditions concerning soils, water access and climate. Likewise, we expect that this degree of intensity could be linked to vineyards producing wine with high added value and lower target yields.

In the present work, we conducted a survey among winegrowers in the Languedoc-Roussillon region (south of France), enquiring about the practices involved in the management of service plants and the services expected. We built a theoretical spatial and temporal typology, described in section 2.2, and a Coverage Index (CI), described in section 2.3, that were applied to the service plant management strategies found in the survey. Then, we tested if the service plant management strategies depend on: (i) the conditions, in this case, the economic and physical characteristics of the vineyards; and (ii) the desired services, by analyzing target services and disservices highlighted by the winegrowers in the survey.

Materials and Methods

Survey and study area description

We conducted a survey across vineyards of the former Languedoc Roussillon region in 2016 (Fig. 1). The survey aimed to better understand the management strategies of service plants in vineyards during the previous grapevine season, i.e., starting in fall 2014 and harvested in fall 2015. For the survey, about 3000 winegrowers were contacted by email through public and private extension services of the region in agronomy and viticulture (Chambres d'Agriculture, Civam, Sudvinbio, etc.), targeting as many winegrowers as possible without seeking a specific profile. Organic viticulture consultants in the region, Sudvinbio and Civam Languedoc Roussillon who have a specific interest in understanding service plant strategies, helped to elaborate the questionnaire. In total, 334 winegrowers answered the survey, representing around 3% of the current winegrowing population in Languedoc-Roussillon and representing slightly more than 10% of the winegrowers contacted. The questionnaire and the answers are available online in an opensource dataset [START_REF] Fernandez-Mena | Service plant Survey across vineyards of the South of France in[END_REF]. The questionnaire was composed of 101 questions with semi-open and multiple-choice answers divided into four sections:

(i)
the vineyard characteristics (size, labels, irrigation, soil features) (ii) soil management practices (tillage, mowing, herbicide use, compost) (iii) the typical (or most frequent) service plant management strategy at the vineyard scale, defined by the spatial design and its duration, plus the use of sown crops or spontaneous vegetation (iv) their objectives, such as target yield, target services and constraints to the adoption of service plants

Although some vineyards have differentiated management according to plots, most of the questions relating to service plants concern the main management service plant strategy, i.e. applied to the larger part of the vineyard. We considered this to be their main management strategy in the whole vineyard. In Languedoc Roussillon region (Fig. 1), winemaking accounts for around 18000 independent cellars with 228000 hectares of vineyards, representing 30% of the vineyard surface area in France (Agreste, 2013).

The elevation of the region ranges from sea level to 1567 m, although vineyards are usually located below 900 m [START_REF] Fanet | La restructuration des vignobles du Languedoc-Roussillon[END_REF]. Across the landscape of the region, flat vineyards with deep soils are usually located in lowland plains close to the Mediterranean coast while vineyards with steep slopes and shallow soils are in higher altitudes inland. Soils present a high variability in the stoniness, and are mostly calcaric luvisols, lixisols and cambisols [START_REF] Coll | Qualité des sols viticoles en Languedoc Roussillon: effets des pratiques[END_REF]IUSS Working Group WRB, 2015). The climate of the Languedoc Roussillon region is characterized by high temperatures and low rainfall during the summer, with high variability and torrential rain events. Both rainfall and temperatures of the fall 2014 and the winter, spring and summer 2015, obtained from the weather stations in the region (Fig. 2), were similar to the average weather conditions in the region. There is a spatial variability within the region for rainfall and maximum temperatures (Meteo France and ADEME, 2015), usually inland vineyards in high areas present significantly higher rainfall and lower average temperatures.

Typology of service plant management strategies according to temporal and spatial dimensions

According to the literature [START_REF] Celette | Dynamics of water and nitrogen stress along the grapevine cycle as affected by cover cropping[END_REF][START_REF] Garcia | Management of service plants for the provision of ecosystem services in vineyards: A review[END_REF][START_REF] Ripoche | Design of intercrop management plans to fulfil production and environmental objectives in vineyards[END_REF] and after discussing service plant multiple patterns in Languedoc Roussillon (Fig. 3) with agricultural extension services, we proposed a theoretical double typology to examine the strategies announced in the survey through temporal and spatial dimensions. The temporal typology was classified in 4 main strategies:

1. The 'Bare soil' strategy, is generally practiced by winegrowers weeding (chemically or mechanically) the whole year and continuously destroying the soil cover. With this strategy, it is possible to avoid any possible interaction between the service plant and the grapevines. The choice of this strategy could be linked to the apprehension of resource competition with grapevines or to vineyard aesthetics (clean ground). 2. The 'Winter cover' strategy; lies on the practice of leaving a spontaneous service plant or choosing to sow a chosen service plant during winter only, from grape harvest until grapevine budburst. By using this strategy, resource competition during grapevine vegetative period is very limited. Also, the soil is protected when most rainfall occurs. Compared to the previous strategy, they reduce labor and machinery costs of weeding during winter, when the grapevine is dormant, principally making use of spontaneous vegetation in the service plant. 3. The 'Semi-permanent cover' strategy, is followed by winegrowers destroying their service plant during the spring period, generally around grapevine flowering. As highlighted by our surveys (section 3.3), winegrowers using this strategy aim to avoid competition for resources after the grapevine has flowered, while profiting from target services of the service plant during most of the year. Less weeding than the previous strategy is required, and therefore costs are reduced. 4. The 'Permanent cover' strategy, is practiced by winegrowers leaving service plants all through the year. By using this strategy, winegrowers can target positive interactions between service plants and vineyards that endure until grapevine harvest. This strategy englobes permanent partial surfaces, e.g. covering only the row all year, helping to reduce cover crop destruction costs. As regards the spatial design, we identified several configurations depending on the number of rows and inter-rows where service plant destruction can be achieved through tillage or herbicide use. A full cover (row and inter-row) is generally employed to reduce costs, especially in periods of water abundance. The vegetation of the inter-row can be destroyed using herbicides or soil tillage. Vegetation in rows can be eliminated using herbicides or specific equipment such as under-vine foot blades. Different combinations of inter-row cover and bare soil exist, for instance, one-every-two inter-rows or bare soil in one-every-three inter-rows, with or without a covered row. Some growth control operations can also be applied to previous configurations, such as rolling the inter-row or mowing it. Mechanical mowing operations during winter can be associated with grapevine shoot grinding and during summer it helps to create mulch in the row (Fig. 4). Analyzing either the spatial or the temporal dimension alone does not provide complete information on service plant management. Some permanent covers can cover a reduced surface and, on the contrary, full covers are sometimes destroyed early. In many cases, the service plant is partially destroyed at several points in the season, often by reducing the covered surface area. Consequently, an integrated indicator considering both temporal and spatial strategy is needed to better characterize service plant management at the yearly scale, such as the CI explained as follows.

Coverage Index (CI) of service plants

We propose an indicator to measure the coverage rate of a service plant called Coverage Index (CI). This indicator is calculated as the surface covered by the service plant, divided by the total vineyard surface during a specific period 'p' (Eq. 1).

Eq. 1

𝑪𝑰 𝒑 = 𝒔𝒖𝒓𝒇𝒂𝒄𝒆 𝒄𝒐𝒗𝒆𝒓𝒆𝒅 𝒃𝒚 𝒕𝒉𝒆 𝒔𝒆𝒓𝒗𝒊𝒄𝒆 𝒑𝒍𝒂𝒏𝒕 (𝒉𝒂) 𝒕𝒐𝒕𝒂𝒍 𝒗𝒊𝒏𝒆𝒚𝒂𝒓𝒅 𝒔𝒖𝒓𝒇𝒂𝒄𝒆 (𝒉𝒂)
As soil and climate conditions vary according to vineyard and year, service plant adaptation strategies to climatic and soil conditions across vineyards are diverse. To consider the temporal dimension, we split the year into 3 periods corresponding to the main development periods of grapevines and we calculated a specific CI for each of these periods: (i) a vegetative period starting at budburst in April; (ii) a reproductive period starting at flowering; and (iii) a dormancy period considered as starting after harvest and slightly before the beginning of leaf senescence. Therefore, the CI index can be calculated separately for each of the three key periods of grapevine phenology: the dormancy of the grapevine, the vegetative period of the grapevine, and the reproductive period of grapevine. Then, an annual value of the Coverage Index (CI -Annual) can be calculated by adding all the CI periods, weighted by the duration of the period out of a year (Eq. 2).

Eq. 2 𝑪𝑰 𝒂 = (𝑪𝑰 𝒅 * 𝑫 𝒅 ) + (𝑪𝑰 𝒗 * 𝑫 𝒗 ) + (𝑪𝑰 𝒓 * 𝑫 𝒓 )

𝑫 𝒅 + 𝑫 𝒗 + 𝑫 𝒓 = 1 (year)
𝐶𝐼 𝑎 : Coverage Index -Annual is the ratio covered by the service plant, established annually. 𝐶𝐼 𝑑 : Coverage Index -Dormancy is the ratio covered by the service plant during winter and grapevine dormancy.

𝐷 𝑑 : Duration ratio of the dormancy period, that in our case included the period between harvest and leaf senescence as well.

𝐶𝐼 𝑣 : Coverage Index -Vegetative is the ratio covered by the service plant during the grapevine vegetative period.

𝐷 𝑣 : Duration ratio of the grapevine vegetative period, between grapevine budburst and flowering. 𝐶𝐼 𝑟 : Coverage Index -Reproductive is the ratio covered by the service plant during the grapevine reproductive period. 𝐷 𝑟 : Duration ratio of the grapevine reproductive period, between flowering and grape harvest.

In the survey, winegrowers specified how row and inter-row surfaces were managed. In this region and depending on the machinery used, grapevine rows are separated by a distance between 2-2.5 meters large (inter-row coverage), and row width between 0.6-0.8 meters (row coverage), as described in [START_REF] Roby | Références vigne: références technico-économiques de systèmes de conduite de la vigne[END_REF]. For the calculation of the CI, we assumed that inter-rows are equivalent to two-thirds of the total surface, and grapevine rows to one-third of it.

In the Languedoc-Roussillon region, the main grapevine development stages are generally observed in early April for budburst, early-June for flowering and late September or in October for maturity and the beginning of leaf fall [START_REF] Fraga | Modelling climate change impacts on viticultural yield, phenology and stress conditions in Europe[END_REF][START_REF] De Cortazar Atauri | Grapevine phenology in France: from past observations to future evolutions in the context of climate change[END_REF]. Thus, we considered the vegetative period to be equivalent to approximately two months out of 12, 𝐷 𝑣 = 0.166, the reproductive period equivalent to approximately four months out of 12, 𝐷 𝑟 = 0.333 and the dormancy period equivalent to six months out of twelve, 𝐷 𝑑 = 0.5. Therefore, a vineyard presenting a service plant in all inter-rows during dormancy, changing at grapevine budburst to half of the inter-rows and destroying them at grapevine flowering, will have an CI-Annual = 0.388 (Fig. 5).

Data analysis

Firstly, the service plant management strategies founded in the survey have been classified by temporal and spatial design at the identified grapevine periods by calculating the percentage of winegrowers choosing to implement that strategy. Then, both dimensions were integrated into CI calculations for each winegrower, as well as their corresponding CI category. The CI calculations were categorized as a factor by distributing them into 5 Categories: CI= 0; 0>CI<0.25; 0.25>CI<0.5; 0.5>CI<0.75; CI>0.75. The categories were defined by equal intervals, except the 0 category, being the category having the highest frequency among all the CI values together. These categories enabled us to compare the Coverage Index with different vineyard categorical factors, announced as follows.

Secondly, to create a typology of service plant strategies, we used a combination of multiple correspondence analyses (MCA) and ascendant hierarchical classification (AHC), as other studies of farm typologies have done (Aouadi et al., 2015;Deheuvels et al., 2012). Two MCA were performed to observe the link between qualitative factors pointed out by the winegrowers (vineyard structure, soil-climate conditions) and the CI categories. A first MCA was performed using vineyard structural and activity variables such as: vineyard size; winemaking (cooperative; independent); winegrower (full-time; part-time); quality label (PGI; PDO; none); crop protection (organic; conventional); irrigation (yes/no); target yield interval (<40 hl/ha; 40-55 hl/ha; 55-80 hl/ha; >80 hl/ha) and if target yield is achieved or not. A second MCA was performed using pedoclimatic conditions of the vineyards as active variables. They included average rainfall at the closest weather station and main soil conditions in the vineyard: soil texture and depth categories; carbonates in the soil; average stoniness and the degree of slope. Significant MCA dimensions were selected to analyze their variables with the higher contribution by using linear models. The significance of variables with a contribution higher than two times the average of the contributions to these dimensions [START_REF] Cibois | Les pièges de l'analyse des correspondances[END_REF] was tested using linear modeling ('lm' R function). In addition, clusters of the MCA were performed using AHC Ward method [START_REF] Ward | Hierarchical grouping to optimize an objective function[END_REF]). Tukey's range test was used to compare the quantitative CI distribution of the clusters.

Thirdly, the fifth top target services announced by winegrowers and the CI categories of the winegrowers targeting those services were analyzed according to their corresponding and relevant coverage period. The CI-Annual was used to analyze the 'biodiversity' [START_REF] Winter | Effects of vegetation management intensity on biodiversity and ecosystem services in vineyards: A meta-analysis[END_REF] and the 'soil organic matter' [START_REF] Muñoz-Rojas | Impact of land use and land cover changes on organic carbon stocks in Mediterranean soils (1956-2007)[END_REF] services; the CI Dormancy was used to analyze the 'soil erosion' (Rodrigo [START_REF] Comino | Soil erosion processes in European vineyards: a qualitative comparison of rainfall simulation measurements in Germany, Spain and France[END_REF] service and the CI during dormancy plus vegetative periods was used to understand the 'soil bearing capacity' [START_REF] Novara | Real cover crops contribution to soil organic carbon sequestration in sloping vineyard[END_REF] and ' green manure' [START_REF] Novara | Managing soil nitrate with cover crops and buffer strips in Sicilian vineyards[END_REF] services. Finally, the two first disservices highlighted by our survey sample, namely competition for water resources and lowering of grapevine yields, were contrasted with the individual and the categorized CI of the vineyards. Individual CI were confronted with irrigation capacity and rainfall of key periods. In addition, CI categories were confronted with irrigation capacity and target services using chi-squared test test.

Statistical analysis was performed using 'R software' (R Core Team, 2014) and using 'car' R package [START_REF] Fox | An R Companion to Applied Regression[END_REF]. Multiple correspondence analysis and hierarchical clustering on principal components were performed using 'FactomineR' R package [START_REF] Lê | FactoMineR: an R package for multivariate analysis[END_REF]. Plots were done using 'dplyr' R package [START_REF] Wickham | dplyr: A Grammar of Data Manipulation. R package version[END_REF], 'explor' R package [START_REF] Barnier | R CRAN package "explor": Interactive Interfaces for Results Exploration[END_REF], and 'ggplot2' R package [START_REF] Wickham | ggplot2: Elegant Graphics for Data Analysis[END_REF].

Results

Description of service plant management strategies: temporal and surface dimensions

All the temporal strategies previously defined in section 2.2 (Fig. 6) were observed in our survey sample.

The winter cover strategy was the most popular (41.3 %). It is used by winegrowers tolerating vegetation only during winter and aiming to avoid competition between grapevines and the service plant, when grapevine vegetation starts, in particular concerning water resources. Winegrowers with bare soil strategy (23.3 %) decided to destroy their service plant earlier, during grapevine dormancy, probably concerned about a reduction in the soil water stock available at grapevine budburst. Destroying the service plant at grapevine flowering through a semi-permanent strategy (8.4%) is chosen to facilitate fruit filling, especially in seasons marked by water scarcity. Finally, a permanent strategy, was still popular among the winegrowers consulted (27.3 %) choosing to keep a surface portion of the service plant coverage the whole year, probably looking for specific services as developed further in this section. According to our survey, the decision making of the service plant destruction date depended on several indicators: weather conditions; labor (and machinery) availability; grapevine phenology; grapevine stress and grass phenology (SI -Fig. 2). Concerning the spatial design, all of the predefined spatial strategies (Fig. 4) appear in our surveys (Table 1). Very often, winegrowers chose to reduce the surface area with a cover crop during grapevine growth.

During the grapevine dormancy period, 64.4 % of the winegrowers having a service plant (therefore excluding bare soil strategies) used a full surface coverage strategy. The others either chose an inter-row coverage or a row coverage and, a minority of 0.6 %, used a permanent plastic mulch on the row. After grapevine budburst, the range of spatial design implemented by permanent and semi-permanent temporal strategies increased. During these periods, our survey sample chose predominantly, 40.3% and 38.2 % respectively, to cover half of the inter-rows. Since we considered row width and inter-row spaces to be homogeneous for CI calculation in the present study, calculated values of CI periods appeared at specific ratios, such as 0; 0.33; 0.5; 0.66 and 1. However, their combination in the CI-Annual created a higher diversity of values (SI-Fig. 1A). Although various strategies can obtain a similar value of CI-Annual, we observed that, generally, permanent and semipermanent strategies present a higher CI-Annual (SI -Fig. 1B). From dormancy to reproductive periods, we observed that CI decreased and so did the CI categories (Fig. 7). During the dormancy period, most of the winegrowers in the sample (75 %) covered all or part of the vineyard surface and almost half of them (48 %) chose a high surface coverage strategy (CI > 0.75). After budburst (vegetative period), there is a drastic reduction of the CI, with around two-thirds of the survey sample (64,3 %) destroying the service plants and those keeping some coverage did so only partially (CI < 0.5). Finally, no significant differences are observed in the CI from vegetative to reproductive periods.

Winegrower and Vineyard characteristics according to CI categories

With our survey, we obtained a representative sample of vineyard and winegrowers characteristics. We found a wide diversity of vineyard total size, from small (<10ha) to big (>40ha) surfaces. Most were fulltime winegrowers (81.7%) and performed their winemaking in a cooperative winery (60.2%). Around 38% of the them are labelled organic, slightly more than the actual population in the region where 32% of vineyards are labelled organic (Agence Bio, 2017). The two most important wine quality labels in the region are PGI (Protected Geographical Indication -Indication Géographique Protégée) and PDO (Protected Designation of Origin -Appellation d'Origine Protégée) labels of the European framework. In our survey, PGI labels appear in 83% and PDO in 60% of the vineyards consulted. Actually, both labels are slightly over represented in our survey sample, since actual PGI are found in 64% and PDO in 38% of the total viticultural surfaces (Agreste, 2013).

Among farming practices linked to soil management covered in the survey, we highlight that more than one-third of the survey sample did composting, most of them having an organic label (Table 2b). Irrigation systems were present in almost one-third of the vineyards, being overrepresented compared to the 15% in the current census [START_REF] Agreste | Analyse et études Occitanie -Numéro 5 -Janvier 2018[END_REF]. All winegrowers in our sample using herbicides for service plant destruction combined this with tillage. In fact, those combining herbicides and tillage for destruction did not significantly reduce soil tillage (4,31 tillage operations per year) compared to those not using herbicides (4,57 tillage operations per year), yet, those not using herbicides presented higher CI categories. Only winegrowers with the top CI category (> 0.75), substantially reduced soil tillage (1,3 tillage operations per year). Among the control operations, mowing, that included indirect mows while vine shoot grinding, is relatively widespread (60.7%) and is almost always performed in vineyards with high CI categories (0.5-0.75 and >0.75). In contrast, rolling operations were only applied by 4.7% of the sample. The date of mowing varies depending on the temporal management strategy, but they were performed all along the season (SI -Fig 3 ), mainly guided by grass height (SI -Fig. 4).

The spontaneous service plant strategies are predominant in the survey (91.1% of the answers). Only 30 winegrowers had sown specific plant species, especially in their inter-rows. The species sown were mostly grasses (43 %), legumes (39%), and crucifers (16 %) and some flowers (2%). The analysis of the link between farm characteristics and service plant practices was facilitated by MCA, where the first two dimensions explained around one-third of the variability (Fig. 8). Although no clusters were defined for their CI-Dormancy and the service plant destruction method, 3 clusters were defined by the AHC highest inertia gain corresponding to different CI levels for their CI-Annual (SI -Fig. 5). The three clusters are distributed in a parabolic shape, known as the Guttman effect [START_REF] Cibois | Les méthodes d'analyse d'enquêtes[END_REF], where (i) the 1 st cluster corresponds to individuals represented in the negative second dimension and associated with low CI-Annual (0; 0.25-0.5);

(ii) the 2 nd cluster to those in the negative first dimension and associated with intermediate CI-Annual (0.25-0.5); and, (iii) the 3 rd cluster correspond to those represented positively in the two dimensions and associated with high CI-Annual (>0.5; >0.75). According to Tukey's range test, CI Annual, CI Dormancy, CI Reproductive and CI Vegetative of cluster 3 are significantly different from the other 2 clusters (SI -Fig. 6). The first cluster includes 51 vineyards (15.2%), corresponding to small irrigated vineyards (0-10 ha), seeking to obtain the highest yields yet often unsuccessful at achieving them (Table 3). They had the lowest CI-Annual by practicing a bare soil strategy, through both intensive tillage and herbicide use. The second cluster includes 119 vineyards (35.6%) corresponding to vineyards with a PGI label, high target yield and achieved yields, a relatively big size (20-40 ha), equipped irrigation systems and winemaking in cooperatives. They present an intermediate CI-Annual (0.25-0.5) managed by a high number of soil tillage operations, mostly leaving service plants during the Dormancy period. The third cluster includes 164 vineyards (49.1%) and corresponds to vineyards with Organic and PDO labelling (or both), frequently middle sized (10-20 ha), without irrigation systems, a moderate target yield and independent winemaking. They present a high CI-Annual (>0.5; >0.75) and make use of sown plant species. When a service plant is destroyed, they apply a few soil tillage operations (<4). The illustration of active variable ellipses and individuals are presented in SI - Among MCA dimensions, only the 1 st MCA dimension was significant (p-value < 0.05) and included the following variables: presence or absence of an AOP label (AOP) or an IGP label (IGP); the type of crop protection (Crop_Prot); the target yield (Target_Yield) and the real yield (Real_Yield) ranged in hl/ha (<40; 40-55; 55-85; >85) and the type of winemaking: cooperative (Wine_Coop) or independent (Wine_Indep). Among these variables, the significant variables for estimating the different CI periods were: for CI Annual the type of crop protection (Crop_Prot) and the target yield (Target_Yield) ranged in hl/ha (<40; 40-55; 55-85; >85); for CI Dormancy the type of crop protection (Crop_Prot) and the real yield (Real_Yield); for the CI Vegetative and for the CI Reproductive the target yield (Target_Yield) and the presence or absence of an AOP label (AOP).

Target yield appeared as the most influential variable over the different CI. Generally, we observed that winegrowers targeting low yields (<40 hl/ha), presented higher CI (Fig. 9). The unachieved yield situations represent only 5.3% of the total survey sample but most of them correspond to high target yields and therefore lower CI. Dimensions of soil and climate characteristics MCA (soil depth, carbonates degree, stoniness, slope degree, soil texture and rainfall) were not significant to explain any of the CI periods. Although an important soil variability appeared in our surveys, we only observed a small link between higher CI in deep soils (>1m) and lower soil tillage on steep and stony soils (SI -Fig. 9).

Concerning water stress conditions, we evidenced that irrigated and non-irrigated vineyards did not show different CI categories (SI -Fig 10). Furthermore, the dispersion of the CI during dormancy and vegetative and reproductive periods, versus the rainfall of each of those periods did not reveal a correlation between CI and rainfall level in the corresponding period (SI -Fig 11).

Target services and disservices by the use of service plants

In our survey, the winegrowers selected one or several target services that motivate their implementation of service plants in their vineyards (SI -Fig. 12). The most chosen services in the survey list were, in order of importance, 'enhance biodiversity'; 'increase soil organic matter; 'decrease soil erosion'; 'increase soil bearing capacity'; 'green manure'; 'cost reduction'; 'vineyard aesthetics' and 'limit nitrate leaching'; with at least 30 responses. However, there was no correlation between vineyard structural characteristics (Table 2a) and services targeted in the survey.

The CI period calculation of the corresponding service targeted was explained in section 2.4. If we compare the top 5 services among them, the higher CI was found in vineyards where winegrowers have targeted to 'decrease soil erosion', followed by 'increase soil bearing capacity' (Fig. 10). In addition, there was considerable consistency, i.e., winegrowers that have independently selected each of the top 5 target services presented a significantly higher CI by chi-squared test (p-value < 0.05) in the corresponding period, than the winegrowers who did not select the same target services. In contrast, winegrowers who did not choose to maintain any service plant were asked about the reasons for not using any service plants. The most important potential disservices of service plants announced were: (i) competition for resources with grapevine and (ii) risk of lowering yields (SI -Fig. 13). Soil constraints, increasing costs, missing equipment and lack of technical knowledge were other important constraints that were cited.

Discussion

A diversity of service plant strategies observed

Our approach was a first attempt to characterize the spatial and temporal dimensions of service plant strategies at the regional scale using a large survey sample of winegrowers (n=331). Our service plant classification based on both temporal and spatial criteria went further than the classification applied to France by [START_REF] Mailly | Quantifying the impact of crop protection practices on pesticide use in wine-growing systems[END_REF] and to European regions by [START_REF] Hall | Vegetation management intensity and landscape diversity alter plant species richness, functional traits and community composition across European vineyards[END_REF]. The implementation of temporal and spatial hypothetical designs proposed was verified by the survey answers. During the dormancy period, three out of four winegrowers (75 %) covered all or some vineyard surface and almost half of them (48 %) chose a high surface coverage strategy (CI > 0.75), probably explained by lower weeding costs and no risk of competition with grapevines. However, still one fourth of winegrowers did not cover the soil during this period, increasing the risk of soil erosion [START_REF] Guzmán | A field evaluation of the impact of temporary cover crops on soil properties and vegetation communities in southern Spain vineyards[END_REF]. The analysis of spatial designs evidenced that the size of the surface area covered decreased significantly between dormancy and vegetative periods, probably influenced by a risk of competition for resources, as explained by [START_REF] Celette | Dynamics of water and nitrogen stress along the grapevine cycle as affected by cover cropping[END_REF]. During the grapevine vegetative and reproductive periods, the diversity of surface coverage strategies was remarkable, both at the spatial and temporal levels. The surface covered decreased significantly from dormancy to vegetative periods and the spatial design chosen was one-every-two inter rows for almost half of the winegrowers.

The service plant spatial design also depends on the farming machinery available [START_REF] Cloutier | Mechanical weed management[END_REF][START_REF] Ingels | Cover cropping in vineyards: a grower's handbook[END_REF][START_REF] Merot | Converting to organic viticulture increases cropping system structure and management complexity[END_REF]. To till the inter-rows, a wide range of equipment exists, namely cultivators, harrows, etc. Row destruction and inter-row cover were quite widespread, frequently chosen by winegrowers using herbicides on the row. When converted to organic, the mechanical destruction of the row can be performed using specific under-vine weeding machines [START_REF] Merot | Diversity of conversion strategies for organic vineyards[END_REF]. Although these specific types of machines need a considerable economic investment, winegrowers generally acquire them since they prefer not to use service plants on the row, assuming the balance between services and disservices will be less attractive. However, in wetter years, service plants in the rows may be a competitive alternative to herbicides [START_REF] Karl | Impact of undervine management on vine growth, yield, fruit composition, and wine sensory analyses in Cabernet franc[END_REF] that may help to reduce excessive vigor [START_REF] Chou | Annual Under-Vine Cover Crops Mitigate Vine Vigor in a Mature and Vigorous Cabernet franc Vineyard[END_REF].

We observed a large majority of spontaneous vegetation use in the strategies. Despite the fact that spontaneous vegetation may present a lower biomass production and slower soil coverage than sown species [START_REF] Pardini | Cover crop species and their management in vineyards and olive groves[END_REF][START_REF] Ruiz-Colmenero | Soil and water conservation dilemmas associated with the use of green cover in steep vineyards[END_REF][START_REF] Steenwerth | A vineyard agroecosystem: disturbance and precipitation affect soil respiration under Mediterranean conditions[END_REF], it is frequently chosen since it embodies a cheaper intercropping option [START_REF] Kazakou | A plant trait-based response-andeffect framework to assess vineyard inter-row soil management[END_REF] without the need of specific seeds or technical knowledge. The predominance of spontaneous vegetation strategies seen in our sample confirmed the need for developing an analysis of the surface and temporality of each strategy through the Coverage Index (CI).

Usefulness of the Coverage Index for characterizing, analyzing and managing service plant strategies

The measurement of service plant practices through the Coverage Index (CI) was useful to understand the degree of service plant implementation among diversified management practices of a large sample. It helped us to compare the service plant strategies with the structural characteristics, with soil and water variables and with the services targeted by winegrowers. Nevertheless, the CI presents some limitations since it does not take into consideration: (i) the degree of crop growth after control operations (mowing and rolling); or (ii) the type and physiological state of plant species (often senescent after high summer temperatures). The CI merely provides information about the fact that the spontaneous or sown vegetation has not been destroyed by soil tillage or herbicide use. Therefore, the CI suggests that there is good reason note if there is some kind of vegetation rather than a bare soil, since some support services are provided [START_REF] Steenwerth | A vineyard agroecosystem: disturbance and precipitation affect soil respiration under Mediterranean conditions[END_REF] and vegetation growth can easily be revived.

In future studies, the calculation of the CI can help to develop agri-environmental assessments of the use of service plants at the regional scale. In the same way as the Treatment Frequency Index (TFI) measures phytosanitary product use in agriculture, the CI enables standardization of service plant strategies and their comparison along different key periods. The consistency of the farming practices for achieving a specific service can be assessed, for instance, by analyzing the CI during rainfall periods to avoid soil erosion in the region. Besides, label certifiers and public policy makers may be interested in CI as a measurement for scoring the degree of service plants used among a panel of producers, either for winegrowers or farmers with other perennial crops.

Wine labelling and lower target yields drive the CI

As developed by [START_REF] Ripoche | Design of intercrop management plans to fulfil production and environmental objectives in vineyards[END_REF][START_REF] Ripoche | Changing the soil surface management in vineyards: immediate and delayed effects on the growth and yield of grapevine[END_REF], service plant strategies are chosen through a complex integration of winegrower target services, soil resources, label constraints, climatic conditions, material and labor availability. Contrary to our hypothesis based on the analysis of the literature (Fourie et al., 2007;Gaudin and Gary, 2012;[START_REF] Salomé | The soil quality concept as a framework to assess management practices in vulnerable agroecosystems: A case study in Mediterranean vineyards[END_REF], soil features and water resources (irrigation and rainfall) did not seem to influence the service plant strategies measured through the CI. These results support the analysis done by [START_REF] Winter | Effects of vegetation management intensity on biodiversity and ecosystem services in vineyards: A meta-analysis[END_REF] showing that rainfed vineyards presented a significantly higher use of service plants. In our study, most of the irrigated vineyards also corresponded to vineyards with high production objectives limiting the risk of yield losses.

Our results pointed out a greater use of service plants and a corresponding higher CI in Organic and PDO labelled vineyards targeting low wine yields. These results confirmed the importance of the added value of producing high quality wine, and environmental concerns of winegrowers to conceive and implement service plant strategies, as other studies evidenced [START_REF] Marques | Analysing perceptions attitudes and responses of winegrowers about sustainable land management in Central Spain[END_REF][START_REF] Schütte | The attitudes of French and Spanish winegrowers towards the use of cover crops in vineyards[END_REF]. Correlation between PDO and lower yields is not surprising since most PDO in Languedoc-Roussillon restrict wine yield to 50 hl/ha, compared to 70-90 hl/ha in PGI labels [START_REF]Cahier de charges de l'Indication Géographique Protégée[END_REF], 2014). Higher CI in organic vineyards, where herbicides are not allowed, could be linked to the higher cost of mechanical destruction. In addition, the risk of yield losses appeared to be more critical for conventional, irrigated, PGI vineyards targeting high yields and therefore choosing a bare soil. However, some studies do not show the expected decline in grape yields (e.g., [START_REF] Ruiz-Colmenero | Soil and water conservation dilemmas associated with the use of green cover in steep vineyards[END_REF][START_REF] Tesic | Influence of vineyard floor management practices on grapevine vegetative growth, yield, and fruit composition[END_REF] but similar or even higher yields in vineyards with service plants in the inter-rows [START_REF] Mercenaro | Sustainable management of an intercropped Mediterranean vineyard[END_REF][START_REF] Sweet | Alleyway cover crops have little influence on Pinot noir grapevines (Vitis vinifera L.) in two western Oregon vineyards[END_REF]. Independently from yield and growth reduction due to service plant use, some vineyards may present overall profitability by reducing soil tillage costs and associated operations like fruit thinning and leaf pulling [START_REF] Guerra | Influence of floor management technique on grapevine growth, disease pressure, and juice and wine composition: a review[END_REF].

Our results highlight the consistency of the strategies measured by the CI with the target services during dormancy and vegetative periods, in particular for enhancing biodiversity and preserving soil from erosion. Winegrowers aiming to increase soil bearing capacity were numerous, mainly motivated for preventing soil compaction caused by engines performing phytosanitary treatments in spring [START_REF] Biarnès | Analyzing the determinants of spatial distribution of weed control practices in a Languedoc vineyard catchment[END_REF][START_REF] Bogunovic | Soil compaction under different management practices in a Croatian vineyard[END_REF][START_REF] De Combret-Champart | Determinants of the degradation of soil structure in vineyards with a view to conversion to organic farming[END_REF]. Several services are compatible and therefore were targeted at the same service plant period. However, a destruction of the service plant is necessary when using a green manure strategy for nutrient release and a mulch effect for soil evaporation mitigation when enough biomass is produced [START_REF] Ranaivoson | Agro-ecological functions of crop residues under conservation agriculture[END_REF]. In addition, the maximization of services performed annually (i.e., enhance biodiversity; increase soil organic matter) may be harder to ensure due to possible disservices between the service plant and grapevines during water stress periods.

Strengths and limitations of such a regional analysis

As other studies showed [START_REF] Goulet | The use of surveys among wine growers in vineyards of the middle-Loire Valley (France), in relation to terroir studies[END_REF], the use of surveys has been proved to be a relevant tool to perform a regional study of service plant strategies. The survey sample was representative of the current winegrower population in Languedoc Roussillon, despite a slight over-representation of high-quality PDO labels and irrigated vineyards. Our questionnaire addressed a large number of issues, including vineyard structure; soil conditions; compost practices; service plant spatial design, service plant management practices and indicators guiding decision-making. However, several other issues could have been addressed by the questionnaire, such as the plantation framework for improving CI calculation, as alley width can play an important role in the weed control choices [START_REF] Biarnès | Identifying indicators of the spatial variation of agricultural practices by a tree partitioning method: The case of weed control practices in a vine growing catchment[END_REF]. A better characterization of the service plant strategy by group of similar plots instead of the whole vineyard will help to understand the trade-off between services and disservices for more precise water and soil conditions. Similarly to what [START_REF] Neethling | Assessing local climate vulnerability and winegrowers' adaptive processes in the context of climate change[END_REF] revealed, most strategies of vineyard adaptation to climate effects are primarily reactive or anticipatory to short-term climate conditions.

Besides, enquiring about the level of knowhow and the material and labor availability could help to better understand winegrower's decision-making to choose certain control and destruction methods. Most questions of the online survey were closed, increasing the participation rate but possibly creating a bias when options were not specific enough [START_REF] Zhou | Who tends to answer open-ended questions in an e-service survey? The contribution of closed-ended answers[END_REF]. This is particularly the case for the most common target service ('enhance biodiversity') hinting at different scales, namely the soil, the plant, the plot, the vineyard and the landscape biodiversity.

In our survey, we did not consider the winegrower's application for public subsidies supporting the use of service plants. In France, service plant support is provided through subsidies obtained from AECM ('Agri-Environment-Climate Measures') of the European Common Agricultural Policy [START_REF] Draaf Occitanie | Notice MAEC Narbonnaise et basse vallée de l'Aude[END_REF]. Considering AECM applications by each winegrower will be useful to understand how this financial support modifies their service plant strategies. [START_REF] Garini | Drivers of adoption of agroecological practices for winegrowers and influence from policies in the province of Trento, Italy[END_REF] showed that winegrowers adopt agroecological practices mainly because of autonomous choices rather than monetary coercion, encouraging policy-makers to promote autonomy-supportive policies that foster farmers' motivations. Allocating public or private coercing measures to foster service plant strategies targeting multiple services and minimizing most disservices seems possible, especially by promoting winter and semi-permanent strategies with full or partial coverage. In addition, these subsidies can be adapted according to the temporality and the spatial coverage using the CI.

Conclusion

Our study confirmed the existence of a substantial margin of maneuver for the development of different service plant strategies within a region. Spontaneous service plant strategies presented a high spatial and temporal diversity. Overall, the spectrum of the strategies found ranged from a "basic" use of spontaneous vegetation in winter to a complex use of sown plant species for targeted services such as nutrient fixation, increasing soil organic matter or pest repellence. These strategies can be measured by calculating the Coverage Index (CI) for each vineyard. We found that higher CI was linked to quality labels, organic crop protection and low target yields. In contrast, no link was found between CI and water and soil resources in vineyards. We also verified that target services by winegrowers are consistent with the CI of the strategy chosen. This study presented and described a Coverage Index in vineyards that can be useful for agronomic advisors, providing a crucial piece in the puzzle of innovative cropping system design in perennial crops. Furthermore, we evidenced how the calculation of the Coverage Index can help the monitoring of service plant implementation at a regional scale and provided some insights for the assessment of the service plant strategies and its eventual integration in agroecological policies and labels.

  Figure 1. (A) The Languedoc Roussillon region in the South of France shown within official French regional borders which changed in 2015 (Wikialine, 2009). (B) the location of the winegrowers that answered the survey is represented in green circles and weather stations in orange stars.

Figure 2 .

 2 Figure 2. Climatic variables during season 2014-2015 obtained as an average of weather stations (n=17) in the Languedoc Roussillon region (Météo France and CLIMATIK data). Average monthly rainfall (mm) is represented in blue bars. The average monthly temperature (Celsius degrees) corresponds to the solid red line and average monthly Penman potential evapotranspiration (PET) to the yellow dashed line.

Figure 4 .

 4 Figure 4. Service plant management examples in Languedoc Roussillon: a. Spontaneous vegetation in the row during winter, predominance of Taraxacum officinale, © Yvan Bouisson; b. Barley sown in the inter-row and mechanical weeding in the row, in spring, © Yvan Bouisson; c. Faba bean in the inter-row and soil tillage in the row during autumn, © Yvan Bouisson; d. Perennial service plants on the grapevine row by testing different Thymus species (Thymus pseudolanuginosus and Thymus serpyllum), © Hugo Fernandez-Mena.

Figure 4 .

 4 Figure 4. The spatial design of some service plant management strategies. The letters correspond to: 'a' full cover; 'b' row cover; 'c' inter-row cover; 'd' one-every-two inter-rows cover; 'e' row and one-every-two interrows cover; 'f' one-every-three inter-rows cover; 'g' rolled inter-rows; 'h' mowed inter-rows (green squares) and plastic mulch in the rows (yellow stripes).

Figure 5 .

 5 Figure 5. Example of Coverage Index calculation for service plant management in Languedoc Roussillon vineyards. Grapevine phenological periods appear in dark red. Coverage Index in the different grapevine periods are: 𝑪𝑰 𝒅 for the dormancy period; 𝑪𝑰 𝒗 for the vegetative period; 𝑪𝑰 𝒓 for the reproductive period. Similarly, the duration of the periods is: 𝑫 𝒅 for dormancy; 𝑫 𝒅 for the beginning of the grapevine vegetative period and 𝑫 𝒓 : Duration ratio of the grapevine reproductive period.

Figure 6 .

 6 Figure 6. Temporal typology of the service plant strategies. On the left, the timeline presents the main grapevine vegetative periods. Temporal categories according to the date of service plant destruction (symbolized by a black cross) are shown with their percentages for winegrowers having a service plant during that period.

Figure 7 .

 7 Figure 7. Percentages of the Coverage Index (CI) categories on each CI Period. The CI categories correspond to: 0 CI in cream-colored; CI between 0 and 0.25 in very light green; CI between 0.25 and 0.5 in light green;

Figure 8 .

 8 Figure 8. Multiple correspondence analysis (MCA) of the structural characteristics of the vineyards in our survey. Active variables building MCA appear in circles, with a size proportional to their contribution (Contrib) for the first two axes. Variable names stand for: Crop Protection (Crop_Prot); full-time or part-time winegrower job (Job); presence of AOP label (Label_AOP), IGP label (Label_IGP) or no label (Wine_No_Q_label) at least in some vineyard plots; vineyard size (UAA_vineyard); winemaking in a cooperative (Wine_Coop) or independent (Wine_Indep); categories of real (Real_Yield) and target yield (Target_Yield) in hl/ha; yield achieved or not (Yield_Achieved). Supplementary variables displayed are CI Annual Categories (CI_Annual_Cat) in blue crosses.

  Fig 7 and SI -Fig. 8.

Figure 9 .

 9 Figure 9. Percentage of CI-Annual categories of the different target wine yield ranges announced by the winegrowers consulted in the survey.

Figure 10 .

 10 Figure 10. CI categories of the top 5 target services selected by the winegrowers for the purpose of service plants. The CI periods aggregated for each service are presented on the top based on the literature (cf. section 2.4). The percentage of winegrowers targeting the services out of the total survey sample appears below each service.

Table 1 . Percentage of service plant spatial designs out of the total survey sample using service plants (not destroyed in the period) during each of the three key grapevine phenology stages. The most frequent spatial design for each period is underlined. Letters (a, b, c, d, e, f g, h) correspond to spatial designs illustrated in Figure 3.

 1

	Spatial design	Dormancy period	Vegetative period	Reproductive period
	a. full cover	64.4 %	10.3 %	11.1 %
	b. row cover	15.3 %	12.5 %	10.2 %
	c and g. inter-row cover	19.7 %	26.4 %	26.9 %
	d. one-every-two (half) inter-rows cover	-	40.3 %	38.2 %
	e. row and one-every-two inter-rows cover	-	8.9 %	9.3 %
	f. one-every-three inter-rows cover	-	-	2.3 %
	h. mowed inter-row and plastic mulch in rows	0.6 %	1.6 %	2 %

Table 2 . Summary of the survey sample (number of winegrowers) classified by the Annual Coverage Index (CI-Annual) category. At the top, chart 'a' shows vineyard structural characteristics and labels. At the bottom, chart 'b' shows climate and soil characteristics and associated farming practices. Percentages are calculated with the vineyards presenting the characteristic out of the total. Quality labels stand for PGI: Protected Geographical Indication and PDO: Protected Designation of Origin.

 2

	a.
	Vineyard Surface
	CI-Annual
	Category

CI-Annual Category Average rainfall in closest weather station (mm) Soil depth >1m Irrigation Farming practices Total Average number of tillages Control strategy (mowing. rolling and mulching) Sowing Compost

	0	675.3	12	24	4.6	23	0	26	78
	0-2.5	681	10	12	4.3	30	2	18	50
	2.5-0.5	667.8	10	13	5.1	22	4	12	26
	0.5-0.75	689.2	46	49	4.34	120	22	67	165
	>0.75	658.3	4	3	1.3	15	2	4	15
	Total / Average* (Percentage)	682*	82 (24.6%)	101 (30.3%)	4.32* (SD=2.02)	210 (62.8%)	30 (8.9%)	127 (38%)	N=334

Table 3 . Clusters of winegrowers resulting from analyzing vineyard characteristics and service plant practices through Multiple Component Analysis (MCA) and Ascendant Hierarchical Classification (AHC).

 3

	Cluster name and number of vineyards	Vineyards structural characteristics	Service plant management practices
	Cluster 1	No wine label
	51 vineyards	Target yield >85 hl/ha
		Target yield not achieved
		Conventional crop protection
		Winemaking in cooperative
		Most irrigate
		0-10 ha

Acknowledgments

We thank Elaine Bonnier (Montpellier SupAgro) for improving the English writing of the manuscript and Yvan Bouisson for his pictures.

Supplementary Information

A.

B.


Eliana Satiko Mano

Laurent Caner

Sabine Petit

Arthur Pinto Chaves

MINERALOGICAL CHARACTERIZATION OF Cu-LATERITIC ORE FROM THE FURNAS DEPOSIT -CARAJÁS, BRAZIL

Keywords: Carajás, Furnas deposit, mineral characterization; Cu-bearing minerals, clay minerals

Furnas is a small and not well-known copper sulfide deposit in the northern Carajás mineral province (Pará State, Brazil). Mineralogical and geochemical studies were performed on three weathered samples in order to verify the presence of copper in the lateritic minerals. According to these Cu-bearing minerals, the weathered ore can be exploited. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Transformed Infrared (FTIR) spectroscopy analyses have shown that the copper is mainly associated to cryptomelane and to clay minerals and, although goethite composes from 40 to 50% of the samples (weight %), less than 0.1% of the total Cu is associated to it. Based on the results, the weathering sequence could be established; the alteration processes were responsible for the dissolution of the copper primary sulfides; the Cu released by these sulfides is, afterwards, incorporated in biotites and vermiculites, following the gneiss schistosity. Afterwards, the biotites altered to an interstratified 10-14 Å and subsequently to an Al-Fe-Cu smectite; finally, smectite was altered to kaolinite and the Cu was leached.

INTRODUCTION

The mineral province of Carajás is considered one of the most important iron oxide copper gold ore provinces (IOCG) in the world [START_REF] Teixeira | Depósitos de óxidos de ferrocobre-ouro de Carajás[END_REF][START_REF] Groves | Iron Oxide Copper-Gold (IOCG) Deposits through Earth History: Implications for Origin, Lithospheric Setting, and Distinction from Other Epigenetic Iron Oxide Deposits[END_REF], often compared to the Olympic Dam in Australia [START_REF] Tallarico | Geology and SHRIMP U-Pb Geochronology of the Igarapé Bahia Deposit, Carajás Copper-Gold Belt, Brazil: An Archean (2.57 Ga) Example of Iron-Oxide Cu-Au-(U-REE) Mineralization[END_REF]; it is located in the eastern part of the Amazon craton in northwestern Brazil. The estimated Cu resource for all of the Carajás province is around 2 billion metric tons (Bt), with an average 1.4 wt % of Cu and 0.28 to 0.86 g/t of Au [START_REF] Moreto | Neoarchean and Paleoproterozoic Iron Oxide-Copper-Gold Events at the Sossego Deposit, Carajás Province, Brazil: Re-Os and U-Pb Geochronological Evidence[END_REF], for the sulfide ore.

The Carajás province is formed by two tectonic domains: Carajás and Rio Maria, limited by a regional E-W discontinuity [START_REF] Monteiro | Metalogênese das províncias tectônicas brasileiras[END_REF]. The Rio Maria domain comprehends greenstone belts of the metavolcanic sediments type and mesoarchean magmatism (granites and granodiorites). In addition, the Carajás domain is formed by mesoarchean magmatism, especially granites, gneisses and metavolcanic sediments, without greenstone belt evidences. The Archean basement is covered by Igarapé Salobo-Pojuca and Grão Pará group sediments (amphibolites, quartzites and banded iron formations -BIFs). Finally, marine and fluvial clastic sediments of the Águas Claras Formation are discordantly deposited above it [START_REF] Schwarz | Depósito de Cu-Zn Pojuca Corpo Quatro: IOCG ou VMS?[END_REF][START_REF] Moreto | Neoarchean and Paleoproterozoic Iron Oxide-Copper-Gold Events at the Sossego Deposit, Carajás Province, Brazil: Re-Os and U-Pb Geochronological Evidence[END_REF]. Lately, intrusions of mafic, ultramafic rocks and granites followed by tectonic events reactivated old faults resulting in low-grade metamorphism (greenschist facies) and metasomatism/hydrothermalism events. These hydrothermal events led to the formation of the primary Cu-sulfide mineralizations. Weathering and hydrothermal alterations of these sulfides lead to the Cu-bearing lateritic minerals formation.

Based on the studies by [START_REF] Oliveira | The role of residual 2:1 phyllosilicates in lateritic metallogenesis: Ni and Cu deposits in Serra dos Carajás, Brazilian Amazonia[END_REF][START_REF] Toledo-Groke | Comportamento do cobre durante o intemperismo das rochas xistosas cupríferas do Salobo 3, Serra dos Carajás[END_REF] and [START_REF] Veiga | Relationship of copper with hydrous ferric oxides: Salobo, Carajás, PA, Brazil[END_REF], which described malachite, cryptomelane, goethite and clay minerals as the main Cu-bearing lateritic minerals in the Salobo deposit, a detailed mineralogical study was conducted on the lateritic samples from the Furnas deposit. According to the results, the lateritic ore from Furnas could also be exploited together with the sulfide ore in order to increase the Cu recoveries.

MATERIALS AND METHODS

Three samples of different Cu contents were provided by the Vale mining company from the Furnas deposit, a small Cu target, located in the northern Carajás province (Pará, Brazil).

The sampling was performed by Vale and, according to the chemical compositions (table 1) they refer to the different horizons in the weathered profile.

The chemical composition for the three samples was determined by X-ray fluorescence (XRF) on powered bulk samples with Axios Advanced (PANalytical). Loss on ignition (LOI) values of the bulk samples were obtained from 1g of bulk samples dried at 100C and heated at 1020C for two hours; afterwards, the samples were left in a desiccator to cool and later weighed [START_REF] Dean | Determination of carbonate and organic matter in calcareous sediments and sedimentary rocks by loss on ignition: comparison with other methods[END_REF]. Three samples were separated according to their Cu grades: C1 -Low Cu content (<1% of CuO), C2 -intermediate Cu amount (1-1.5% of CuO) and C3 -high Cu grade (>1.5% of CuO).

The samples were treated with a solution of dithionite, tricitrate and sodium bicarbonate (DCB) at 80C for 45 min. to solubilize the Fe oxi-hydroxides [START_REF] Mehra | Iron oxide removal from soils and clays by a dithionite-citrate system buffered with sodium bicarbonate[END_REF]. The Cu in solution was determined by ICP to estimate the Cu associated to the Fe oxi-hydroxides, such as goethite.

The mineralogical assemblage in the bulk samples was identified by randomly oriented X-ray powder diffraction. X-ray diffraction (XRD) patterns were recorded on a Bruker D8 Advance diffractometer (Cu Kα radiation -40 kV, 40 mA-Lynx eye detector) from 2 to 65° 2θ with steps of 0.025° 2θ and a counting time per step of 115s (converted from scanning mode).

The clay minerals of the samples were studied after the extraction of the <2μm fractions. Initially, the samples were dispersed into distilled water and wet sieved at 50m. The coarse material (>50μm) was discarded and the fine fractions (<50μm) were saturated with NaCl 1 mol. L -1 to deflocculate the particles [START_REF] Moore | X-ray diffraction and the identification and analysis of clay minerals[END_REF]. The clay fractions (<2μm) were separated by centrifugation and studied [START_REF] Mano | Metodology for laterítics Cu-bearing clay minerals characterization[END_REF]. Afterwards, the <2μm fraction was separated into five sub-fractions: <0.05μm, 0.05 to 0.1μm, 0.1 to 0.2μm, 0.2-1μm and 1-2μm; each size fraction was studied in detail. The different sub-fractions were separated by successive centrifugation cycles at different relative centrifugal forces [START_REF] Laird | Chemistry of smectitic and illitic phases in inter-stratified soil smectite[END_REF]. The bulk <2μm and the sub-micrometric fractions were flocculated, saturated with CaCl2 0.5 mol. L -1 and washed with distilled water by dialysis to remove the excess of salts. XRD patterns were obtained from oriented Ca-saturated clay dried at room temperature (AD) and after ethylene glycol (EG) saturation, from 2 to 50° 2θ with steps of 0.025° 2θ and a counting time per step of 192 s (converted from scanning mode).

Fourier transformed infrared (FTIR) spectroscopy was used to specify the crystal chemistry of the Cu-bearing clay minerals. Mid infrared analyses (MIR) were performed in transmission mode using a Nicolet Magna-IR 760 spectrometer in the 400-4000 cm -1 range with a 2 cm -1 resolution. The spectra were obtained from pressed KBr pellets, prepared by mixing 1 mg of sample with 150 mg of KBr and pressing at 10 t cm -2 and drying overnight at 110 º C. The infra-red spectra were analyzed using the Omnic software.

The <2µm sub-fractions were mounted in polished section slides, coated with metallic carbon to be analyzed in a scanning electron microscopy (SEM) coupled to EDX (energy dispersive X-ray spectroscopy). The EDX microanalyses were performed both to distinguish the clay minerals composition and to quantify the Cu contents associated to them. The microanalyses were performed on an INCA Energy 300 device from Oxford Instruments, with a Si(Li) detector coupled to a SEM LEO 440 -Leica installed at the Instituto de Geociências at the Universidade de São Paulo -Brazil.

RESULTS

Samples composition

According to the XRD and XRF analyses (Table 1), all the three samples exhibited similar mineralogy, essentially composed of quartz, clay minerals and Fe and Mn oxide/hydroxide (goethite and cryptomelane). Sample C1 exhibited larger amounts of quartz than the other samples (30wt%) whereas its contents of goethite and cryptomelane were the lowest (<45% and <3% respectively). Sample C3, on the other hand, exhibited high contents of Fe and Mn oxides/hydroxides (<55% and 10%) and low amounts of quartz (<15%). Sample C2 exhibited an intermediate composition, with nearly 20% of quartz, 50% of goethite and <5% of cryptomelane. For all the samples, the clay mineral contents represented between 20 to 30% (wt%). In the Furnas deposit, the goethite contents vary between 40 and 55% of the bulk samples. Manganese and copper contents showed the same behavior, suggesting that part of the Cu was associated to Mn as cryptomelane.

Clay minerals study

The XRD patterns of the <2µm Ca-saturated fractions of the three samples (Figure 1), exhibited peaks at d001AD= 7.1Å and d002AD= 3.6Å which did not swell after EG treatment, being attributed to kaolinite. Peaks at d001AD= 10.0Å, d002AD= 5.0Å and d003AD= 3.4Å, which did not shift after EG treatment indicated the presence of mica-illite. Finally, a peak at d001AD= 14.4Å, which displaced to d001EG= 15.6 to 16.5Å after EG treatment, revealed the presence of swelling clay minerals such as smectite. Figure 1B detailedly showed a low-angle shoulder at d001EG= 11.6Å, particularly for sample C3, highlighted after the EG solvatation. This reflection is attributed to an interstratified clay mineral containing mica and an expandable layer (10Å-14Å). A small amount of vermiculite was also observed in sample C3, thanks to the reflection at 14.6Å (Figure 1B), which did not shift after EG treatment.

The finest fractions (<0.05 and 0.05-0.1m), which represent from 15 to 20% (wt%) of the samples, concentrated smectite; while the coarsest fractions (0.1-2µm), which vary from 5 to 10 wt% of the samples, concentrated mica, kaolinite and mixed layers (Figure 2). Samples C1 and C2, in the fractions between 1 and 2 µm, exhibited a d001 at 12.4 Å that displaced to 12.9 Å after EG solvatation (Figure 2D), indicating an interstratification of mica and an expandable layer. This mixed layer is almost absent in sample C3, as noticed in Figure 2D.

Scanning electron microscopy and X-ray dispersion energy analyses

EDX microanalyses for the <2 m size fractions of samples C1, C2 and C3 confirmed the presence of clay minerals with a composition varying between biotite and smectite, as shown in the ternary diagram Al2O3/K2O/Fe2O3+CuO+MgO (Figure 3). The microanalyses data plotted in a ternary diagram of MgO/Al2O3/Fe2O3 confirmed that smectites in the <0.05µm size fractions have a composition close to nontronite (Figure 3B). [START_REF] Petit | Crystallochemical study of a population of particles in smectites from a lateritic weathering profile[END_REF]

Mid infrared results

Kaolinite was easily identified in the MIR spectra of all size fractions (Figure 4), especially for the 0.1 -2 m size fractions through its characteristic AlAlOH stretching bands (AlAlOH) at 3695 cm - 1 , 3669 cm -1 , 3653 cm -1 and 3620 cm -1 [START_REF] Farmer | Infrared spectra of minerals[END_REF][START_REF] Madejová | Application of vibrational spectroscopy to the characterization of phyllosilicates and other industrial minerals[END_REF]. Moreover, the band at 3596 cm -1 , attributed to AlFe 3+ OH in kaolinite [START_REF] Petit | Hydrothermal (200C) synthesis and crystal chemistry of iron-rich kaolinites[END_REF][START_REF] Iriarte | Synthesis of kaolinite with a high level of Fe 3+ for Al substitution[END_REF], showed that kaolinite contains structural iron.

The broad absorption band centered at 3420 cm -1 , due to water, revealed the presence of smectites. This band is more intense for the <0.05 m fractions. The observed band at about 3570 cm -1 in the OH stretching region at 820 and 876 cm -1 in the OH bending region allowed characterizing iron rich-smectite and, more precisely, Al-nontronite [START_REF] Petit | Hydrothermal synthesis of dioctahedral smectites: The Al-Fe 3+ chemical series. Part II: Crystal-chemistry[END_REF]. There are three possibilities for copper occupation in smectites: i) in vacant sites of octahedral sheets; ii) in hexagonal cavities of the tetrahedral sheets; iii) as exchangeable Cu 2+ ion in interlayer sheets. [START_REF] Madejová | FTIR spectroscopic characterization of thermally treated Cu 2+ , Cd 2+ , and Li + montmorillonites[END_REF] and [START_REF] Seiffarth | Structural characterization of (Cu 2+ , Na + ) and (Cu 2+ , NH 4+ ) exchanged bentonites upon thermal treatment[END_REF] described some changes in Si-O vibrations in the MIR region induced by Cu migration in smectites structures. [START_REF] Seiffarth | Structural characterization of (Cu 2+ , Na + ) and (Cu 2+ , NH 4+ ) exchanged bentonites upon thermal treatment[END_REF] observed a shift from 1050 to 1058 cm -1 of Si-OH stretching band resulting from the Cu migration from the interlayer to the hexagonal cavities of the tetrahedral sheet or to octahedral sites. [START_REF] Petit | Hydrothermal synthesis (250C) of copper-substituted kaolinites[END_REF] demonstrated that the presence of copper induced changes in absorption bands, such as broadening and loss of resolution of the 3668 cm -1 , for synthetic kaolinites, containing from 0.1 to 7% of Cu. In these synthetic samples, copper was suspected to be in the trioctahedral distribution.

The FTIR spectra of the three samples did not show any evidence of the presence of Cu in either the smectite or the kaolinite structure. These features might be due to the too low Cu amounts in the clay minerals to be detected. The results revealed that Cu contents are higher in the coarsest size fractions (Table 2), composed mainly of biotite as compared to the finest fractions composed especially of smectite.

Unfortunately, the amounts of 0.05 to 1µm fractions for samples C2 and C3 were not sufficient to perform the ICP analysis.

DISCUSSION

In oxidized ores, Cu is frequently associated to goethite [START_REF] Oliveira | The role of residual 2:1 phyllosilicates in lateritic metallogenesis: Ni and Cu deposits in Serra dos Carajás, Brazilian Amazonia[END_REF][START_REF] Veiga | Relationship of copper with hydrous ferric oxides: Salobo, Carajás, PA, Brazil[END_REF][START_REF] Gerth | Unit-cell dimensions of pure and trace metal-associated goethites[END_REF][START_REF] Toledo-Groke | Comportamento do cobre durante o intemperismo das rochas xistosas cupríferas do Salobo 3, Serra dos Carajás[END_REF][START_REF] Ildefonse | Hydroxy-Cu-vermiculite formed by the weathering of Fe-biotites at Salobo, Carajás, Brazil[END_REF]; however, in the Furnas deposit, this element is preferentially associated to cryptomelane, as observed by [START_REF] Mosser | The mineralogy and geochemistry of two copper-rich weathering profiles in Burkina Faso, West Africa[END_REF] in Burkina Faso (Africa) and [START_REF] Traina | Co, Cu, Ni, and Ca sorption by a mixed suspension of smectite and hydrous manganese dioxide[END_REF]. The chemical analyses (Table 1) performed in this study also confirmed this assumption. Even though Fe-oxides/hydroxides represented from 40 to 55% (mass) of the samples, less than 0.1% of Cu is associated to them, according to the ICP analyses of the solutions from the DCB treatment. In fact, in the Furnas deposit, Cu is approximately partitioned as 50% in cryptomelane and 50% in the clay minerals. Concerning the clay minerals, biotite followed by mixed layers biotite/vermiculite or biotite/smectite exhibited the highest contents of Cu. Smectite (mainly nontronite) revealed the lowest Cu content (Table 2). FTIR from the clay fraction showed that copper is not associated to smectite as structural cation or as interlayer cation, since only 0.01 wt% of Cu is exchangeable, as also registered by [START_REF] Toledo-Groke | Comportamento do cobre durante o intemperismo das rochas xistosas cupríferas do Salobo 3, Serra dos Carajás[END_REF]. [START_REF] Petit | Crystallochemical study of a population of particles in smectites from a lateritic weathering profile[END_REF] showed that smectites from the Salobo deposit exhibited a nontronite composition. Furnas profile is a typical weathering profile found in the Carajás Province, similar to the Salobo deposit [START_REF] Ildefonse | Hydroxy-Cu-vermiculite formed by the weathering of Fe-biotites at Salobo, Carajás, Brazil[END_REF][START_REF] Toledo-Groke | Comportamento do cobre durante o intemperismo das rochas xistosas cupríferas do Salobo 3, Serra dos Carajás[END_REF][START_REF] Veiga | Relationship of copper with hydrous ferric oxides: Salobo, Carajás, PA, Brazil[END_REF] and also resembling the Burkina Faso deposit (Africa) described by [START_REF] Mosser | The mineralogy and geochemistry of two copper-rich weathering profiles in Burkina Faso, West Africa[END_REF]. The alteration processes were responsible for the dissolution of primary sulphides. The Cu released by sulfide dissolution is afterwards incorporated by biotites and vermiculites from the gneisses, according their schistosity [START_REF] Toledo-Groke | Comportamento do cobre durante o intemperismo das rochas xistosas cupríferas do Salobo 3, Serra dos Carajás[END_REF]. The Cu-rich biotites altered to an interlayered clay mineral of 10-14 Å (biotite-smectite-vermiculite) and subsequently to an Al-Fe-Cu smectite (nontronite); finally, smectite was transformed into a kaolinite depleted in Cu.

CONCLUSIONS

In the Furnas deposit, as well as in the Burkina Faso deposit, Cu is mainly assigned to cryptomelane instead of goethite, as observed at the Salobo deposit. Expressive Cu amounts were determined in interlayered clay minerals, possibly a biotite-vermiculite type. Unfortunately, the copper associated to clay minerals is not easy to recover, even in an acid leaching route; therefore, copper behavior in the weathering environment demands more studies in order to completely understand the geochemical fixing process in the lateritic minerals.

Figure 1 -

 1 Figure 1 -X-ray diffraction patterns for the blended samples saturated with Ca and after ethylene glycol (EG) solvatation. Sample C3 is shown in detail -B

Figure 3 -

 3 Figure 3 -Ternary diagram for clay mineral particles <2 m for all samples (A). The theoretical compositions for biotite, nontronite, kaolinite and vermiculite have also been plotted. B -Ternary diagram of <0.05 m size fraction for all samples. Their composition is close to a Fe-rich dioctahedral smectite[START_REF] Petit | Crystallochemical study of a population of particles in smectites from a lateritic weathering profile[END_REF]

Figure 4 -

 4 Figure 4 -MIR spectra for all samples

Table 1 -

 1 Chemical composition of the samples (oxides weight %).

	Samples	C1	C2	C3
	MgO	1.93	1.60	1.36
	Al2O3	9.04	8.68	8.73
	SiO2	37.0	28.6	24.0
	K2O	3.12	2.90	2.11
	MnO	0.52	1.06	2.22
	Fe2O3	37.8	45.8	47.3
	CuO	0.79	1.30	1.69
	LOI	8.84	9.50	11.69
	total	99.0	99.4	99.1

Table 2 -

 2 Chemical analyses by ICP for sample C1 (weight %). ns -no sample

	Sample	Cu (wt%)	Sample	Cu (wt%)	Sample	Cu (wt%)
	C1 <2 µm	0.623	C2 <2 µm	0.78	C3 <2 µm	1.09
	C1 <1 µm	0.471	C2 <1 µm	ns	C3 <1 µm	ns
	C1 <0.2 µm	0.447	C2 <0.2 µm	ns	C3 <0.2 µm	ns
	C1 <0.1 µm	0.265	C2 <0.1 µm	ns	C3 <0.1 µm	ns
	C1 <0.05 µm	0.129	C2 <0.05 µm	0.71	C3 <0.05 µm	0.81

ACKNOWLEDGMENTS

This study has been supported by CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) -Project Ciências Sem Fronteiras: 249132/2013-3 and ITV -Instituto Tecnológico Vale. The authors also thank Elisabeth Fonseca and Antonio Clareti, geologist and engineer, respectively, from VALE. One of the authors, E. Mano acknowledges The Mineralogical Society of Great Britain and Ireland (Clay Minerals Group) for a student travel grant, which allowed her to present these results at the 16 th International Clay Conference, held in Granada -Spain in July, 2017.