My PhD

Effects of temporal and spatial variations of the constraints on ecological systems

Key-word

Global change, constraints, community, indicator, numerical model, resources, interactions, dispersion.

Origin of the PhD

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ANDRA (National Agency for Radioactive Waste Management) asked at the CERSP laboratory to make a model to simulate the state of biodiversity in tens of thousands of years on a putative site of radioactive waste.
This PhD directed by the joint direction of Denis Couvet and Alexandre Robert aims to develop a numerical approach particularly suited to the simulation of the biodiversity dynamics in the context of anthropic constraints.

Abstract

Projection models aiming to understand the effects of global change on biodiversity suffer from a lack of robust theoretical framework. Such a framework should provide answers about the modes of action of the constraints associated with global change those influence biological communities at different scales of time and space, and relevant tools (indicators) to identify the state of the studied systems. My approach is based on the analysis of three models.
In a first simulation-based theoretical model, we focused on the use of abiotic and biotic resources in a community of competition species imposing different types of constraints on the system at equilibrium. This model has led to reflect on the Neutral Theory of Biodiversity and allowed to propose a new theoretical framework for the study of global change integrating different constraints: directional or stochastic, specific or global, direct or indirect.
The second theoretical model simulates the behaviour of a food web in which individual consumers can adjust their feeding strategy according to the availability of biotic resources. This analysis allowed us to highlight that food webs are sensitive to species diversity of primary producers above all other parameters.
The third model is coupling a spatialized individual-based module and a set of standardized plant inventory data. It has to integrate the effect of the variability in landscape quality on the structure of meta-communities in urban areas and to propose new methods for measuring habitat connectivity.

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