Sown forage mixtures have shown advantages compared to monocultures in terms of goods and services. Among the most relevant benefits researchers have tested are: high productivity and quality forage, enhanced yield stability, lower susceptibility to pests and diseases, reduced nitrogen need, decreased greenhouse gas emissions (GHG). As major outcome, mixtures were shown to increase soil fertility, and water and nutrient use efficiency, and therefore are expected to have positive effects on soil biodiversity and function. However, a better understanding under extreme conditions and drought is still needed in vulnerable climates including the Mediterranean. This is particularly important as, despite the known benefits of forage mixtures, there is a trend in loss of mixtures in favour of grass monocultures in all Mediterranean areas. Furthermore, there is a lack of information about the effects of grazing on soil carbon and fertility conservation in mixed polycropping-livestock systems, yet grazing systems are key in many Mediterranean countries. Here, they are expected to provide numerous ecosystem services and high biodiversity to human livelihoods in rural areas, sometimes remote. Nonetheless, despite known productive and environmental advantages, there might be barriers to the implementation and spread of sown mixtures, and those could range from management difficulties over seed availability to market demands. To this purpose, SUSFORAGE asks the following questions: a) Are sown mixtures advantageous in dry Mediterranean areas in terms of yield productivity, quality, resilience and stability, moreover for soil fertility, health and carbon sequestration? b) Do sown mixtures combining different plant traits ameliorate soil function and microbial processes to deliver mixture benefits? c) Do the benefits of sown mixtures hold under grazing conditions in water-limited areas? d) What are the most important perceived benefits and constraints of sown forage mixtures by local growers? To answer those questions, SUSFORAGE proposes the establishment of 5 Case-Study Regions across a climatic gradient, where socio-ecological surveys will be carried out and 4 experimental forage swards will be established. The swards will include a range of sown proportions and monocultures of the most commonly used local forage species to develop models of optimal adaptive mixture proportions under given climatic conditions. Several ecological indicators will be measured at all sites during the development of the systems: yield; forage quality; water and nitrogen use efficiency by chemical and isotopic techniques; soil fertility; GHG fluxes; soil organic carbon storage; soil microbial activity, diversity and function by phospholipid fatty acids (PLFAs), exoenzymes and metagenomics; system stability by comparing benefits throughout time. Simultaneously, surveys and socio-ecological multi-actor workshops will be carried out with stakeholders to determine local perceptions on sown mixtures. Overall the SUSFORAGE project will contribute to enlarge the information of the benefits of sown mixtures, particularly in Mediterranean dry areas and under grazed conditions, in a vulnerable region with climate extremes. We will provide a model to determine the optimal proportions of different functional types of forage species locally adapted to the specific climate scenarios. In addition, we will elaborate a socio-ecological model including perceived benefits and constraints by local populations, and design with multi-actor stakeholders how to implement the tested sown systems at large scales in the Case-Study regions. We will derive general recommendations applicable to wider regions in the Mediterranean. Combining innovative methodologies, we will demonstrate if sown mixtures are indeed a solution for mitigation and adaptation to climate change in Mediterranean areas as expected, and the limits and constraints to their widespread distribution.

Land-use changes, habitat destruction and habitat fragmentation are among the most important drivers of the current biodiversity crisis. While species-centred approaches have helped develop potential remediation strategies against the decline of endangered species, they are clearly insufficient given the complexity of ecological interactions and the potential for these interactions to amplify or attenuate anthropogenic ecological damage. The general goal of the WINE project is to understand how spatial connectivity affects ecological interactions in meta-ecosystems by altering the movement of organisms and their resources, and, conversely, how ecological interactions affect effective spatial connectivity within landscapes by altering the space use of organisms and their associated impact on their resources. These feedbacks between spatial connectivity and ecological interactions are likely to take place at different spatial and temporal scales, and determine the properties of ecosystems. To achieve a better understanding of these processes, we propose to conduct both theoretical and empirical research by developing predictive models, using microcosm experiments, and analysing large existing datasets on spatial food webs. This integrated approach should enhance our understanding of the mechanisms at work in the functioning of spatial food webs. The WINE project brings together six laboratories with complementary expertise, enabling the research proposed for these three lines of inquiry to be carried out. We will start the modelling activities by developing a meta-food web model to understand how the structure of the underlying spatial web affects the properties of local food webs. We will then extend this model by considering the evolutionary dynamics of food webs in response to the spatial network and environmental heterogeneity, notably via the size and dispersal abilities of species. Finally, we will distinguish between foraging and dispersal movements to better understand the consequences of different types of movement for the connectivity of meta-ecosystems and their dynamics. Experiments on protists in microcosms will allow us to test some of the model predictions. First, we will measure effective connectivity as a function of the complexity of the food webs used. Then, we will explore the link between spatial network complexity and local food web properties. We will combine this with a gradient of environmental heterogeneity. Finally, we will study the evolution of the manipulated species to understand how the spatial network affects their dispersal abilities. The study of existing datasets on food webs in rivers, lakes, coral reefs, and agricultural landscapes will allow us to explore some of the predictions of the developed models. A first step will be to complete the datasets, mainly through the acquisition of the spatial networks involved. These data sets will first be explored to analyse how spatial structure and environmental heterogeneity affect local food webs. In a second step, we will focus on the link between spatial network and meta-network properties and explicitly compare the effects observed between dendritic (river-like) and planar (grassland-like) networks. Armed with such fundamental knowledge, we believe that the management and restoration of ecosystems in response to human impacts will better handle the complexity of species interactions.

Forest and grassland are the two main terrestrial ecosystems able to mitigate global warming thanks to their high capability to store carbon. Ascendant (xylem) and descendant (phloem) sap flows play a key role in this storage by routing the water necessary for the oxygenic photosynthesis and then transporting the assimilated carbon into the carbon sinks, e.g. wood, roots or soil. In the current context of global warming, a better understanding of these transport mechanisms is key to ensure these ecosystems can continue to play their carbon sink role. Unfortunately, no sensor allowing studying these mechanisms directly in the plant and in its natural ecosystem exists yet. In this project, we will set and validate a new versatile MRI instrument to measure locally and non-invasively water content and flow rate outside the laboratory (in situ). This approach allows exploiting the unique and advantageous features of MRI: it is non-invasive, can measure water quantities and flow rates and is spatially selective, i.e. measurements can be performed in well-defined plant areas. The aim of this project will be to validate this instrument as a new tool to study both forest and grassland agro-ecosystems. For each of them, we will demonstrate the advantages of this new sensor relatively to the in-situ reference methods (such as lysimeters, sap flow sensors, gravimetric methods …). This instrument will be evaluated in regards of its capabilities to: (1) give localized information (specificity), especially to measure both xylem and phloem sap flows as they do not go through the same cells in plants and, to discriminate the root heterogeneity directly in the soil; (2) perform measurements under several environmental conditions (sensibility). We will focus on the hydric stress in order to detect cavitation in trees and recovery of grasses (3) evaluate the carbon storage by the ecosystems thanks to sugar concentration measurements by the in-situ MRI instrument. To maximize the success rate of this project, a multi-disciplinary team has been gathered. The skills of the scientists involved are going from vegetal physiology to applied mathematics through ecosystem modelling. Furthermore, Carel Windt, an internationally renowned scientist for his skill to develop in-situ MRI sensor, will follow the project and bring his expertise to the scientific discussions and choices. At the end of this project, the interest of this new sensor will have been demonstrated and its deployment at larger scale, to have a better understanding of the carbon storage mechanisms, will be possible. The following step would be to create a network of in-situ MRI instruments. Thus, measurements at the individual level would bring more knowledge on the plant itself while exploiting the network data would lead to a better understanding of the whole plant community as an ecosystem. Furthermore, new applications could be tested, especially in microfluidic sciences or in bio-based industries, two fields having currently a high gross rate. To disseminate as widely as possible our results, we will communicate to several scientific communities which could be interested by our results (MRI, functional ecology), to the public thanks to vulgarization (scientific days, articles in scientific magazine). Furthermore, we will make available the instrument to the scientific community through dedicated networks like AnaEE.

Agricultural soils are depleted in organic carbon (OC) and have the potential to sequester substantial amounts of C, contributing to climate change mitigation. An increase in soil organic carbon (SOC) has additional bene?ts, including improvements in soil fertility, water retention and texture, which supports crop productivity and biodiversity. Restoring and maintaining SOC can be achieved by adopting management practices which increase C sequestration and stabilize C in the soil matrix. Common management practices for increasing SOC include the use of external or internally recycled OC inputs (e.g., organic amendments/fertilizers, biochar, plant litter, residues), alternative cropping options (e.g., continuous green cover, cover crops) or measures that reduce OC losses (e.g., reduced tillage, adapted grazing). Conversely, these management practices have the potential to increase greenhouse gas (GHG) emissions by stimulating decomposition of previously sequestered C and N increasing CO2 and N2O emissions. Mechanisms and drivers behind increased GHG emissions and their interactions with OC sequestration under di?erent soil and climatic conditions are not well constrained, partly because little is known about how abiotic and biotic factors control the extent to which soils can store OC. Quantifying negative side-e?ects of increased soil C sequestration on GHG emissions is necessary to develop appropriate management options that reduce GHGs while increasing soil C stocks. The main goal of TRUESOIL is to assess how GHG emissions from agricultural production systems are in?uenced by varying OC inputs for contrasting soil types and climates (i.e. boreal, temperate, Mediterranean and semi-oceanic). We will elucidate the roles of di?erent abiotic and biotic factors in OC storage and the extent to which these factors impact on GHG emissions, in particular N2O, given its high warming potential and large uncertainty in ?ux estimates. Many C-augmenting management interventions are known, or have the potential, to modify soil N cycling leading to enhanced N2O emissions. To understand potential trade-o?s between OC storage and GHG emissions, we combine intensive measurements of GHG ?uxes with carbon-nitrogen cycling studies and microbiological analyses. Comparison of soils that are SOC saturated with those that continue to accumulate SOC will aid in the identi?cation of the major drivers. Using rainfall exclusion experiments, we will also examine the future impact of reductions in precipitation on interactions between SOC accumulation and GHG emissions. TRUESOIL will establish a data repository of past and ongoing research on management-climate interrelationships between GHG emissions and soil SOC sequestration; it will also provide information on the factors likely to in?uence trade-o?s between SOC sequestration and GHG ?uxes, including pedoclimatic conditions, management interventions, soil microbial community composition and C/N budgets (WP1). The repository will serve as basis for overall project activities; examine the impacts of rainfall exclusion on SOC sequestration and GHG emissions (WP2); investigate the role of microbial communities in SOC sequestration and N2O emissions (WP3); and use modelling studies to examine C-N interactions and tradeo?s to identify management options that can maximize SOC sequestration whilst minimizing impacts on soil GHG emissions (WP4). TRUESOIL will then synthesize the scienti?c outcomes and translate them to climate-smart management practices (WP5) which will be disseminated and communicated among the scienti?c community, stakeholders and the general public (WP6). This project will lead to an increased understanding of how environmental factors and management control OC sequestration, SOC persistence and stabilization and how this is linked to GHG emissions, opening up new possibilities for soil-speci?c and climate mitigation strategies.

Natural grasslands and cereal fields play fundamental role in supporting biodiversity conservation and sustainable food production. Natural grasslands (including grasslands within a protected area and unprotected grasslands) and cereal fields provide multiple ecosystem services, but also involve significant trade-offs (e.g., food production vs. soil carbon sequestration). Yet, unlike aboveground plants and animals, the capacity of European protected areas to conserve plant and soil microbial diversity and ecosystem services in natural grasslands under global environmental changes is virtually unknown. Moreover, we know very little about how cereal fields will respond to multiple co-occurring global change stressors, such as drought, pesticides and over-fertilization, which are threatening the conservation of soil biodiversity and function as well as food production. Objectives 1 & 2 will evaluate whether protected areas promote soil biodiversity and multiple ecosystem services in European natural grasslands, and will monitor the microbial diversity and function in cereal fields. To such an end, we will conduct a European-level survey across grasslands’ triplets with different land use intensities (from protected and unprotected natural grasslands to maize and wheat fields). The sampling in cereal fields will support the monitoring that the Crop Microbiome Initiative started in these sites 3-5 years ago. In Objectives 3 & 4, GRASS4FUN will further investigate whether multiple global change stressors impact the microbiome and function of European natural grasslands and cereal fields. To do so, we will use combine the modelling and mapping of soil biodiversity and function across climate and land cover change scenarios with a manipulative study using microcosms subjected to multiple global change stressors. GRASS4FUN will be performed in close collaboration with a stakeholder advisory board to facilitate engagement and uptake by end-users, policy makers and society with the fundamental goal of providing ground-breaking knowledge to increase the resilience of grasslands to global stresses and protect European biodiversity, including organisms living in soils. GRASS4FUN will provide critical knowledge for the long-term economic benefits of the EU, and it is in line with multiple European-level programs such as Farm to Fork Strategy, EJP Soil and European Green Deal.