Objectives

The aim is to understand how the structure and functioning of grassland agro-ecosystems in upland areas (Massif-central, France) respond to climate change, and how this response depends on changes in practices and biodiversity over time and space.

First, we will analyse the relationships between the functional diversity of plants and the dynamics/stability of plant communities within grassland ecosystems. We propose to mobilise the most recent advances in ecology by studying the different forms of distribution of functional traits in plant communities subjected to contrasting management practices. To do this, we will use data from a long-term observation system (20 years) set up at an altitude of 900 m (ACBB-Anaee-F) on permanent grassland and manipulating the rates of disturbance (mowing, grazing) and fertilisation (N,P,K). By studying the shape of functional distributions, we will be able to highlight the dynamics of species assemblages in plant communities, which are not random but dependent on management practices.

Secondly, we will assess the consequences of farmers' management choices in response to climate change factors on grassland ecosystems within a contrasting geographical area. We will draw on a dataset acquired over 15 years (2008 - 2016 - 2022) on around sixty livestock farms spread across the Massif-central. Characterising changes in climate, biology, soil and management practices will be an important output of this study and will provide a better understanding of ecosystem responses to change and the resulting effects (in terms of vegetation dynamics and ecosystem services). To do this, we used the « space-for-time substitution hypothesis » at the scale of the Massif-Central area, which is topographically and pedologically contrasting. More specifically, the aim will be to compare the response of ecosystems over time and space and to gain a better understanding of the factors potentially involved in this equivalence. We hypothesise that by targeting global correlations between climatic, agronomic, pedological and biodiversity variables we will be able to approach predictions on the functioning of grassland ecosystems and in particular their carbon storage potential within the different pools of soil organic matter.

In addition to the cognitive contributions of this work, we also hope to be able to assess the possible effects of these multiple changes on the stability of grassland agroecosystems and their capacity to maintain ecosystem services at the level expected by farmers and/or society, by identifying and constructing potential scenarios combining climate change, management practices and community assembly.