The unsung heroes: Soil protists diversity as a driver of plant performance under global changes

Summary

In this thesis I aimed at decipher how soil biodiversity impacts plant performance (mainly growth of the plant) and how this relationship is affected by global change drivers (such as drought or pathogen infection). Due to the vast diversity of species coexisiting in soils, I decided to use protists as models. I wanted to answer the following question: Is the more biodiversity the better? I tried to answer that question through both approaches: experimentally (3 chapters) and theoretically (1 chapter). I discovered that biodiversity indeed matters, but it is not always in a positive way. The effect of an increasing soil biodiversity on plant performance is dependent on the global change factors, ranging from positive, to neural to negative effects. This thesis emphasizes how microbes affect ecosystem functions, how the biodiversity of those microbes is important, and more especially, how global changes are affecting and changing the positive effect of soil biodiversity on ecosystem functions.