In the next decades, grasslands as important ecosystems and basis of dairy and meat production are likely to experience damages and subsequent production losses due to changing climate. Recent events (e.g. severe drought in Western Europe in 2003) highlighted an insufficient capacity in local populations of grassland species to cope with unusual climatic events. However, most grassland species show a large ecotypic diversity over wide environmental ranges. We consider that this large ecotypic diversity could be used to recombine natural climatic adaptations and value for services to create improved populations of grassland species adapted to the foreseen future regional climates. To implement this strategy, it is necessary to have extended knowledge of the adaptive diversity existing in grassland species. With this aim, we intend to use an innovative methodological frame (landscape genomics) to screen the natural diversity of a grassland species (perennial ryegrass) in order to discover genetic variability involved in environmental adaptation, and more specifically in climatic adaptation. The landscape genomics approach is based on the combined use of methods correlating genomic polymorphisms and environmental variations at sites of origin of genotypes and of tests of signature of selection. To implement this frame, we will use a genotyping method based on massively parallel sequencing technology applied to 550 populations of perennial ryegrass sampled across the whole area of primary expansion of this species (Europe, Northern Africa and Near East). These populations will be taken out from genebanks of plant breeding institutes or collected in situ across Europe. Our genotyping protocol is expected to deliver several tens thousands of polymorphisms sites along perennial ryegrass genome. We will furthermore phenotype these populations in fields and in controlled environment to record agronomic and eco-physiological traits. Association models between genomic polymorphisms and environmental variations will be used to map the spatial distribution of genomic markers linked to adaptive diversity in present climatic conditions and to foresee possible shifts in the spatial range fitting these markers in the context of several climate change scenarios based on the four Representative Concentration Pathways of IPCC AR5. Based on these results, we will define allelic profiles of perennial ryegrass expected to provide climatic adaptation at regional scale over Europe under the future climatic conditions foreseen by climate models. We will consider combining climatic adaptation and value for services by genetic recombination. We will finally design a number of genetic pools mixing different natural populations. These genetic pools will be the basis to initiate breeding programmes aiming to deliver improved populations adapted to future regional climates. These improved populations will enable to restore grasslands degraded by future climatic disruptions.

The effects of increasing global temperatures on soil biodiversity and the resulting effects on the coupling/decoupling of biogeochemical C, N, P cycles are poorly understood. This project attempt to assess the biodiversity and functional composition of soil microbial communities, including soil fauna (earthworms) and plant-soil interactions responses to soil warming using three whole soil warming experiments established in France, USA and China. We will focus our study on whole soil profiles, as in particular subsoil horizons may have a large temperature response to warming and could release carbon to the atmosphere as positive feedback mechanism. The information obtained through the data generated by our project will be used to benchmark an existing simulation model, which includes representation of soil depth, transport, and microbial physiology of functional guilds. The simulations outcomes can then support the formulation of policies to promote adaptation and mitigation strategy.

Soils, as reservoirs for the green water, are essential in agricultural ecosystem services. Their hydric functioning in water balance model is described by their Available Water Content AWC, i.e. the maximum quantity of water available for plant growth. No consensus exists about neither its definition nor its real value, whereas it is a widely used concept, known by farmers and scientists as well. AWC is estimated on soil by soil scientists, using laboratory measurements, field monitoring, or calculation by pedotransfer functions using soil databases. Ecophysiologists and agronomists estimate AWC from in-situ monitoring of plant development, or inverse modelling of crop models. The RUEdesSOLS project then aims at developing, evaluating, benchmarking and coupling references methods in a synergistic and interdisciplinary scheme, to propose a methodology for the AWC estimation that could be used in a large range of pedoclimatic conditions at plot and territory scales. It also consists in analysing the impact of uncertainty associated to these AWC estimates. To reach these objectives, the RUEdesSOLS consortium gathers scientists from the field of soil science, ecophysiology, agronomy, remote sensing and modelling. It is a mixed consortium with partners involved in basic research (INRA, CNRS, CNES, University of Toulouse) and other involved in applied research (ARVALIS, CETIOM). It is organized in 6 workpackages dedicated to i) the management of the project, the sharing of data and the dissemination [WP1], ii) the comparison and fusion of soil-based and plant-based approaches [WP2], iii) the measurement of soil/plant parameters and the collection of legacy data [WP3], iv) the soil-based estimation of AWC [WP4], v) the plant-based estimation of AWC [WP5], and iv) the impact analysis of the AWC estimations on two applied study-cases in relation with the estimation of ecosystem services, say the sunflower yield and the maize irrigation. The transfer of the RUEdesSOLS project toward end-users is assured by the three UMTs (Unité Mixte Technologique) CAPTE, EAU and TOURNESOL, whose assignment is to transfer scientific results from basic research into applied contexts, and by the RMT (Réseau Mixte Technologique) Sols & Territoires, that intends to increase and enhance soil knowledge, from the farm scale to rural territories.