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Mediterranean coastal areas have been occupied and developed intensively for a long time facing issues related to agricultural production, urbanization, tourism, preservation of natural resources often linked to salinity. This article explores the relationship between historical land planning and water management, and current soil and water salinity to gain insights into future projections.Soil samples (1185) were collected in a coastal plain of 114 km2 in the south of France and saturated paste extract Electrical Conductivity (ECsp) was deduced from 1:5 dilution. Soil salinity exhibits a wide range of variation (from 0.54 to 113.1 mS cm-1) and spatial patterns. ECsp is significantly different among soil types, higher at depth than at the surface (Kruskal Wallis and Wilcoxon tests) and influenced by the distance to ancient anthropogenic structures (Pettitt test). Surface water and shallow groundwater samples were collected for trace element concentrations and Oxygen (18O/16O) isotope ratio measurements. The geochemical signatures indicate a mixture between surface freshwater and seawater, with the presence of over-salted seawater and a stratification of salinity from the surface to the depth.Results suggest that groundwater is the source of soil salinity, and illustrate the long-term impact of water management and land planning. Less saline soils are found near the freshwater supply channel (constructed from 15th to 18th), while more saline soils are located near drainage channels. The presence of over-salted water reflects temporal evolution of the plain over the last few centuries (initially under seawater, gradually filled in, presence of ponds and salt works that have now disappeared). The current soil salinity patches continue to be a visible reminder of this evolution. The trend towards desalinization of the plain over the last few centuries has been made possible by massive freshwater inflows, which are now under threat due to the general decrease of water resources availability.

Despite the possible mitigation of carbon emissions by favoring carbon transfer to terrestrial carbon sinks, little is knownabout the capacity of different crop genotypes to enhance soil carbon sequestration. We hypothesize that carbon sequestrationpotential linked to old wheat varieties (released before 1960) is higher than the one linked to modern ones while old varietiesare known to develop bigger and deeper root systems. Moreover, modern varieties are often cultivated using syntheticchemical inputs known to modify soil carbon dynamics. We conducted a field experiment by cultivating four modern andfour old wheat varieties, with and without chemical inputs (nitrogen, herbicide and fungicide), in Calcaric Cambisolconditions. After root and soil sampling, root morphology was assessed by image analysis, whereas potential catabolicactivities by soil microbial communities was assessed by MicroResp ™ measurements. Additionally, CO2 emissionsmeasurements were done by incubating soil and roots from each agronomic modality. Results suggest that the genotype (oldversus modern varieties) did not affect root traits nor substrates respiration, but the soil from old variety modalities released6% more CO2 than the one from modern ones. Application of inputs did not affect root traits, but increased soil microbialrespiration by 11%. Inputs also increased the respiration of citric acid by 19.1%, while it decreased respiration of fructose andalanine by 8.84% and 16.79%, respectively. Taken together, our results invalidate the hypothesis that old varieties could bemore performant than modern ones in storing carbon in this specific soil.

National audience; Gérer convenablement les puits de carbone pourrait permettre de compenser les émissions deCO2. Étant donné la superficie des terres arables, les pratiques sur les sols agricoles peuventservir de levier d'action. Dans ce projet de thèse, nous faisons l’hypothèse que la séquestrationdu carbone est modifiée par le développement et la profondeur du système racinaire descultures. À ce titre, les variétés de blé anciennes sont réputées pour leur système racinaire plusprofond que celui des modernes. De plus, l’apport d’intrants chimiques de synthèse, dont lesengrais azotés, pourrait modifier la dynamique du carbone du sol. Dans une étude de terrain,des variétés modernes et anciennes ont été cultivées avec ou sans intrants. La morphologieracinaire, les activités cataboliques potentielles et les émissions de CO2 de sol et racines incubésont été mesurés pour estimer le stockage de carbone. Le génotype et les intrants considérésindépendamment n’ont pas impacté la biomasse, la surface et le diamètre moyen des racines.Toutefois, il existe un effet de l’interaction génotype*intrants : en absence d’intrants, lesvariétés anciennes présentaient une longueur racinaire plus importante que les modernes à laprofondeur 0-15cm. En présence d’intrants, la longueur racinaire et le diamètre moyen desvariétés modernes augmentaient. Les analyses MicroResp ont montré que la présence d’intrantsentrainait une modification de la respiration pour le sol prélevé à 15-30cm. Les incubationsavec suivi de CO2 sont en cours. Une expérience similaire a été mise en place sur trois autressites pour tester la généricité des résultats.

International audience; Les sols et les paysages évo- luent conjointement sous l’effet combiné de facteurs naturels et humains. Cette coévolution se retrouve dans l’analyse des terroirs viticoles, construits et transformés au cours du temps. Ainsi les sols viticoles obser- vés aujourd’hui sont l’héritage d’une construction multiphasée et d’occupations successives qui ont transformé progressi- vement les paysages viticoles. Aussi, la compréhension des sols ne peut être dissociée de celle de la structuration du pay- sage, à un tel point que des dif- férences entre terroirs peuvent s’expliquer, entre autres, par des trajectoires agraires différentes. Les paysages viticoles sont des mosaïques de parcelles, struc- turés par des aménagements dont les fonctions ont été pro- fondément modifiées par les évolutions contemporaines. Ces évolutions sont pour la plupart liées à la transition depuis un espace aux usages multiples vers un espace souvent monocultural pour lequel l’adaptation du par- cellaire s’est faite en relation à la mécanisation et à l’optimisa- tion du temps de travail. Aussi, pour de nombreux paysages viticoles, et donc leurs sols, se pose aujourd’hui la question de la durabilité et de l’adaptabilité du système de production. Après un rappel sur les relations sols/paysages, nous présentons des exemples de transformation et de coévolution entre sols et paysages viticoles au cours du temps. Enfin, nous exposons comment la capitalisation des connaissances dans des outils d’aide à la décision peut per- mettre de mieux appréhender de futurs dimensionnements et la restructuration des vignobles.

Publication de la Chaire UNESCO "Culture et Traditions du Vin" de l'Université de Bourgogne et du Centre Georges Chevrier UMR CNRS/uB 7366.; National audience

International audience; During the last decades, a large number of fires occurred in Portugal due to its large forest area exacerbated by high fire weather index and due to the plantation of fire prone species such as eucalyptus. A large number of studies show that fires lead to accelerated soil erosion and land degradation. Additionally, heavy ploughing was shown to exacerbate erosion in post fire forest areas. We studied the fire of 2011 to calibrate the erosion model LANDSOIL to evaluate the impact of fires in Maciera, part of the Caramulo region in NW Portugal. For that, land use maps from 2000 to nowadays were classified, the DEM was improved with the inclusion of terraces and about 40 extreme rainfall events were selected to feed the model. Once the model was calibrated, we simulated the impact of the 2011 fire on soil erosion and repeat the same method for 2 previous fires. Finally, we created future land use maps based on narrative scenarios that were developed from socio-economic surveys sent to local researchers. Four types of scenarios were applied: business-as-usual, land productivity, environmental protection and sustainable trade-off scenarios. The impact of different land managements and land uses was then assessed on soil erosion.

International audience; Vineyards of southern France are important environments for the quality of agricultural production and for the peculiarity of their landscapes. In a changing world, where these environments are experiencing new challenges, land use (LU) and climate change play a central role in hydrological and soil erosion processes. The study area is a 91ha hilly catchment (Roujan), located in the Occitanie region around 25 kilometres from the southern coast, with an average elevation of 102 meters a.s.l.; in the present land coverage configuration, it contains 62% vineyard land cover. Effect of land use and climate changes were modelled by comparing 2050 to present conditions using LandSoil, a model simulating water and tillage sediment redistribution on fine spatial (1-10 metres) and temporal (rainfall event) scales. We tested the climatic impact, simulating on medium terms with: 1) a 20 years climatic historical series (1992-2012) and, 2) a future climatic scenario (2040-2060), as the result of RCM (ALADIN53) on a RCP4.5 CO2 emission configuration. Land use change is accounted for in considering land cover and soil-water conservations techniques evolutions through four different scenarios developed from socio-economic surveys such as: 1) Business-as-usual, following the last decade's LU trend changes (i.e., decreasing of vineyards surface abandoning and or grouping small fields); 2) Productivist (i.e., introducing grape varieties with high productivity, adopting vineyard irrigation, as well as accepting the use of fungicides and pesticides and reducing the grass strips percentage); 3) Environmental protection (i.e., prohibiting pesticides to protect ground waters, creating additional vegetative strips to decrease the erosion and to increase the local biodiversity); 4) Sustainable (i.e., adapting the productivity to local demand and valorising small quality productions with a balanced land-use pattern and architecture). Results show that even in a monitored catchment, where the landscape architecture is preserved from soil loss, interesting differences are observed when land use changes dramatically, as in the proposed LU scenarios, pushing the soil loss balance to very different equilibrium conditions.

Soil is a rare natural resource and it is at the center of the main issues in agronomy, environment and land use planning. At global level, erosion is one of the major soil degradation processes and it is responsible for the decrease in agronomic potential of soils and in agricultural land surfaces. Water and soil conservation works (WSCW) are built to protect soil from erosion. The financial and environmental cost the WSCW construction is very high. However, the positive impacts of WSCW are not taken into account in Life Cycle Assessment (LCA). The objectives of this study is to intergrate the impact of WSCW on soil quality in LCA. There are different types of WSCW with different functions and they act differently on erosion process. In this study we focussed on contour ridges (CR) because they are associated to crop systems. CR are generally built in upland areas to reduce runoff and erosion, to increase on-site deposition of eroded particles and to increase local water infiltration. They modify water and soil flows at catchment scale, so it is necessary to use a model able to calculate the inventory flow at the catchment and not at the plot level. In this study we present a methodology to integrate the impact of CR on topsoil erosion at the catchment level and to compute characterization factors in presence of such WSCW. The proposed method was applied in a case study in semi-arid context in central Tunisia (Merguellil watershed) which presents the issues of over-exploitation of water resources, accelerated land degradation and a high expansion of conservation works. In order to investigate the impact of WSCW on topsoil erosion, diffrent catchment scenarios (with and without CR) and land use types were tested using soil redistribution model (LandSoil model). For life cycle impact assessment, we focussed on two midpoint impact categories of LANCA soil functions : erosion resistance and mechanical infiltration. The CFs were calculated using the two models : LANCA and LandSoil models. These CFs were then compared. The results showed how contour ridges can modify topsoil erosion process, the erosion impact depend on location of landuse and contour ridges increase mechanical infiltration of soil. However, these impacts were not considered in LANCA model. In conclusion, It is necessary to integrate the positive impacts of contour ridges in life cycle assessment. It will be also neccessary to integrate the impact of the other types of WSCW in topsoil erosion impact modelling.

International audience

International audience; Performing sustainable agricultural production system ought to integrate soil knowledge in order to maintain yield and preserve soil resources. This issue is particularly important for perennial vegetation production as financial investments are often done at least for a 30-year duration. But the main limitation with soil knowledge production is that soil mapping needs a large amount of data that can be expensive and time consuming. In the same time, farmers usually have a good knowledge or perception of their soils, mainly based on pragmatic observations and most of the time not integrated in soil scientist prospections. Therefore, the aim of our work was to develop a methodology in order to integrate winemaker knowledge into soil mapping process, from soil sampling design optimization to soil organization model production. The example we presented is an application of the methodology on two vineyards in Bordeaux area (France): 15 ha in Saint-Emilion and 45 ha in North Médoc. For these vineyards, high-resolution soil survey (descriptions and lab analysis) and soil electrical resistivity surveys were done. Concomitantly, winemaker and vine manager knowledge were collected in order to produce an expert map and a vineyard zoning. The comparison of both soil scientist and expert maps shows that experts correctly visualized main variations of soil properties, among which soil texture (mainly clay fractions). Calcareous nature of soils is also well estimated by farmers on discretized soil map. Although main factor in soil water availability, the soil thickness doesn't really stand out from the expert map. At the end of the day, using empirical knowledge seems a good way to enhance the efficiency of a soil survey and then, the involvement of local experts in soil map building make these maps user-friendly for winemakers.

International audience

International audience; Landscapes are modelled by natural and anthropogenic processes: natural processes are responsible of reshaping through hydrologic and soil erosion processes and they are the result of the interaction of climate, soil physic-chemical characteristics and landscape geometries; anthropic activity is therefore responsible for landscape and ecosystem changes through urbanisation and agricultural practises advent – changes that are even wider than the impact of natural and climatic factors. Soil erosion processes and landscape modifications have been also accelerated during the last centuries due to land use, increasing consumption of natural resources and technologic innovations.The purpose of this section is to stimulate scientists coming from different experiences and disciplines to converge on a modelling approach to study soil erosion and their link with environmental drivers, such as climate and/or land use changes.We’ll approach the study of soil erosion processes, human impact and long term modelling for all terrains in the block (a) and the soil surface processes on karst terrains in the block (b), that represent a specific environment in terms of soil development and distribution, soil hydrological behaviour and associated soil erosion responses.Discussions are expected to focus on analysis and modelling of the processes accounting as priority causality and interaction between the processes. It will be interesting to approach the problem in an evolutionary view, the knowledge of past landscapes is essential to understand the present and predict their future state.

International audience; Erosion and sediment delivery in agricultural landscapes: monitoring, modelling and managementAgricultural landscapes are mainly composed by a mosaic of cultivated fields, uncultivated patches (woodlands, heath land, wetlands), and a network of mostly linear anthropogenic structures (hedgerows, embankments, drainage ditches, grass strips, terraces). In these environments, hydrological connectivity, sediment delivery into streams and at longer time soil cover geometry are closely linked to spatial and temporal dynamics in land use and management.Agricultural landscapes are exposed to fast changes in environmental conditions but agriculture itself dynamically reconfigures our landscapes via changes in land use and management. To understand, analyse and potentially manage future changes in water and sediment fluxes in these landscape it is essential to deal with these interrelationship between different driving forces. This session will present contributions addressing different aspects of hydrologic connectivity and sediment delivery on different spatial and temporal scales, based on experiments and modelling. The session will have a particular focus on landscape and climate changes effects upon connectivity and sediment delivery.