I am interested in the stability of plant communities in arid ecosystems in a context of increasing aridification and grazing pressure. During this phd, under the supervision of Sonia Kéfi and Sophie Donnet, I seek to understand the links between types of plant interactions (facilitation, competition), plant community structure and stability of these communities under increasing pressures. To do so, I develop and analyze mathematical models and assemble plant association networks available at the global scale.