General scientific strategy

The study of agroecosystem functioning is the core of our activities,  through consideration of biogeochemical processes, material and energy flows, and the functions of organisms in isolation or interacting with their environment (Fig. 9). Agroecosystems respond to external forcing, which will induce technical actions by the farmer (nitrogen inputs, pesticides,  recycling of organic waste, tillage, choice of varieties/species) to mitigate or circumvent constraints to achieve the objectives of production. Some finalized outputs of our research contribute to the ecosystem services required from agroecosystems. Thus, the concept of services constitutes a conceptual framework for the organization and valuation of our final research, especially for the following services:

• Production of food biomass and renewable carbon (via studying the functioning of plant populations under abiotic and biotic constraints) ("production" service).

• Recovery of organic waste and recycling of the organic matter and nutrients in organic waste (via the management of waste products) ("recycling" service).
• Maintenance of the biodiversity reservoir (via studying the dynamics and effects of living organisms in agrosystems) ("biodiversity" service).
• Regulation of the global climate (via storage of carbon and nitrogen in the soil and greenhouse gas emissions studies) ("climate" service).
• Regulation of the quality of biosphere compartments (via studying the dynamics and ecotoxicological effects of contaminants in agroecosystems) (“filtering” service).

To implement the approach of ecosystem service networks and study more specific environmental issues, ECOSYS mobilizes concepts of functional ecology through, for example, the analysis of flows between biosphere compartments, studying interactions between biological functions and environmental factors, and studying structural and functional plant plasticity. The challenge of ECOSYS was to appropriate concepts and theories from functional ecology to ultimately propose tools and models that can be used for forecasting or evaluation and for decision support.