Interaction networks

The Camargue (Rhône delta) is a complex social-ecosystem with important issues regarding biodiversity conservation and economic and cultural activities. In a context of global change, anthropogenic (water management in agricultural and natural areas, agricultural practices) and climatic (rainfall, evapotranspiration) drivers affect the hydro-saline balance. This hydro-saline functioning is a central element in the dynamics of the Camargue's habitats and species, and the associated networks of activities and services.

In the face of global change, one of the major challenges for contemporary societies will be the preservation of biodiversity. In this context, it is necessary to identify the most vulnerable areas, especially within drainage basins and their river networks, very sensitive to these pressures. In order to inform public policy and help prioritize decision-making, it has become essential to better understand the consequences of management decisions and climate change scenarios on future biodiversity, which necessitates the study of projections (i.e. simulations) based on species models.

Some of the agricultural contaminants (pesticides, nitrogen) spread on cultivated soils reach the hydrosphere through agricultural drainage (1) with proven consequences on aquatic ecosystems and their functions. Constructed wetlands are designed to break down nitrates and certain pesticides through natural purification features. Nevertheless, they constitute potential reservoirs of contaminants likely to impact the wild species they shelter by acting as ecological traps.

Freshwater, biodiversity hotspots and major supports of ecosystem services, are among the most threatened ecosystems on Earth.

Our landscapes are continually being modified by changes in land use and management practices, leading to a redefinition of the relationship between biodiversity and management practices. However, the levers for action to conserve biodiversity are often conceived at a local scale (site or parcel) by looking for practices that better preserve local biodiversity. This local vision is not adapted to account for the dynamics of biotic and abiotic fluxes and the interactions between the elements of the landscape mosaic that are essential for ecosystem functioning. Despite recent conceptual advances in landscape ecology, the current challenge in terms of conservation is still to move from a "management" vision at the local scale to a "spatial planning" vision at the landscape scale.

Biodiversity is the baseline of all ecosystem services and thus represents an essential supporting service. The lakes and ponds of the Aquitaine coastline are unique ecosystems at both the national and European levels. They host significant biological diversity, especially from a plant perspective, but are currently under severe threat. While the taxonomic diversity of these communities is well-known, the knowledge of their genetic diversity is currently non-existent. Improving this knowledge however appears essential for better management of these ecosystems, particularly for their endangered species.

Hearing the biodiversity of mosaic rural landscapes through passive ecoacoustic sampling

Mixing species is an agroecological practice central to increasing the ecological functioning of agroecosystems (resilience to hazards, stability of performance, efficient use of resources, regulation of pests and diseases) in a context of global change (reduction of inputs, climate change). However, this practice comes with a complexity in the choice and management of crops and requires farmers to have knowledge and tools to help them implement it.

Studying the dynamics of plant biodiversity, from its emergence to its dispersal by water. Agricultural intensification has degraded ecosystems, and it is now necessary to take greater account of the role of biodiversity in agrosystems and its importance for ecosystem services provision. For the past two decades, cultivators in vineyards have been improving their sustainable management practices, developing a vegetation cover inside inter-rows to limit soil erosion, and an extensive management of plot edges and networks of ditches. These practices support the development of a spontaneous vegetation cover, a source of numerous ecosystem services including for example runoff regulation, water erosion mitigation and organic pollutants retention.  This is a major challenge, particularly in Mediterranean vineyards, where climate change is likely to increase the frequency of intense rainfall.

Taking into consideration the environmental continuums, including the interface zones, to study and manage ecosystems is gradually gaining interest in both scientific and operational spheres. In this context, the role of the soil-water continuum in maintaining biodiversity and ecosystem functions and services is increasingly questioned. However, this role is still very little studied, especially because of the compartmentalization of research by type of environment (e.g. soil vs surface water vs sediment) as well as of conceptual and methodological scientific limitations (including in terms of experimental set-ups that integrate terrestrial and aquatic compartments).