Impact of a stress on the Eukaryots network in soil

The metacommunity concept is a new field of research emerging since 2004’s paper of Leibold et al. It tries to explain the complexity of ecological interactions both between and within patches spatial scales. This goes in a theoretical direction, and currently four models of ecological dynamic (patch-dynamic, species-sorting perspective, mass-effect paradigm and neutral perspective) exist, but few experimental works have to be done to complete this approach.

As this new thinking concerns the phylogenetic, the functional and the taxonomic diversity, it appears to us that comparing how the stress impact communities and how this impact changes in spaces.

My project is included in two ongoing stress experiments. The first one is a punctual stress with a long term return to normality (the decomposition of a pig cadaver), with monitoring of soils parameters and diverse soils taxa until complete resilience of soil community. For this experiment, we will follow testate amoeba, nematode, and mite community together with changes in soil chemistry through time. We will follow how the community pattern changes over time and space. The second experiment is a long term stress, with a standard community of soil organisms (experiment in mesocosms with Sphagnum mosses and microbial community from acid bog lawn) and different variation of water table depth and fluctuations along three years. We will follow testate amoeba and some other soil eukaryots on one hand and the whole metacommunity through a NGS analysis (Illumina sequencing) on the other hand.

Our aims are 1) to show how the pattern of community changes in time, comparatively with control groups; 2) to highlight response pattern to stresses.