Interaction networks

PARMENIDE shows that the degree of naturalness of a landscape promotes acoustic diversity. In particular, landscape mosaics that are not highly fragmented and contain a high proportion of permanent grassland, as well as landscapes where management practices are becoming more extensive (particularly organic farming), very clearly promote biophony.

The model of the Camargue delta’s functioning (MAELIA-Delta), developed in this thesis and tested under various scenarios, demonstrates the central role of water management in balancing agricultural activities, soil salinization, and the preservation of natural habitats in the Camargue. It provides a body of knowledge that stakeholders can use to design a more integrated management approach for the delta, aimed at reconciling agriculture and ecosystem conservation.

SYNBIOTOX, through ecological and ecotoxicological monitoring of a pilot constructed wetland (CW) located in Seine-et-Marne, demonstrates that the risk posed by agricultural contaminant flows within the CW is significant for amphibians, and that negative behavioural and ecological effects are exerted on aquatic fauna. This thesis provides a better understanding of the potential impacts of agricultural contaminant flows on aquatic fauna in constructed wetlands.

The isoetid communities of the oligotrophic coastal lakes of Aquitaine, ecosystems unique in Europe, are under serious threat. The microsatellite markers developed by ISOTEIDES to characterize genetic diversity and analyze the relative contribution of spatial and environmental processes to the structuring of taxonomic and genetic diversity lead to recommendations for the conservation management of these lakes at both the local and regional levels.

SEINARIOS sheds light on the role of connectivity in the composition of river fish communities, as well as on the influence of management and climate change on future river ecosystems. It provides practical guidance for future management and new methodologies for assessing connectivity within river networks and integrating it into modelling approaches for the distribution of river fish, whilst evaluating the significance of climate change and land-use management on the conservation of fish species.

C-DIVERS demonstrates the complex effects of crop diversity and hedgerows, at both the local and landscape scales, which do not, on their own, facilitate all the outcomes required for the development of multifunctional agroecosystems. However, the presence of a hedgerow at the edge of a plot does promote certain ecological (pollination) or agronomic (agricultural production) outcomes. In the long term (15 years), plant diversification becomes a key factor in pest management, reducing the use of chemical inputs and improving livestock feed.

LANDEV has shown that, thanks to their flexibility, environmental easements appear to be a suitable tool for protecting land whilst maintaining agricultural activity in the long term. However, most of the operators surveyed consider that the ecological benefit of compensatory OREs is low. This study highlights the current limitations of OREs, but also shows that they contribute to the diversification of responsibilities and stakeholders, to cooperation and to the development of expertise

The MODIMIV project aims to model the relationships between microbial and plant diversity in multi-species agroecosystems, particularly grasslands, in order to improve the simulation of carbon (C) and nitrogen (N) flows and better synchronise nutrient supply and demand. The initial objective was to overcome the limitations of existing models, which often incorporate biodiversity in an implicit or simplified manner, by developing explicit and dynamic simulators capable of representing biotic interactions.

ECART has tested a system for measuring microclimatic variables and a tool for collecting spores in the canopy. These data have been used to investigate the factors influencing the distribution of this biodiversity within trees. Initial results show distinct associations of bryophyte species between the upper trunk, the base of the trunk and the rest of the crown, as well as a negative effect of tree decline on bryophyte richness in the upper part of the tree

A meta-ecosystem model has been developed to study nitrogen fluxes in agroforestry systems (AFS). Its application at the DIAMS experimental site has shown that the spatial organisation of the AFS, in interaction with agricultural practices, strongly structures the distribution of nitrogen stocks and fluxes between landscape sub-units, with consequences for crop production and the system’s ability to limit nitrogen losses through leaching.