Water Availability Rather Than Temperature Control Soil Fauna Community Structure And Prey-Predator Interactions

1. The ongoing climate change may strongly impact soil biodiversity with cascading effects on the processes they drive. Thus, it is of prime interest to improve our knowledge about responses by soil organisms such as collembolans to expected shifts in environmental conditions by considering communities comprising both detritivores and predators.2. The aim of the present study was to evaluate how simulated climate change and predation under laboratory conditions alter a collembolan community.3. To infer the impact of climate change, we applied a decreased level of soil moisture (60% vs. 30% soil water holding capacity) and an increasing air temperature (15 degrees C vs. 25 degrees C) to a collembolan community constituted by four species (Folsomia candida, Protaphorura fimata, Proisotoma minuta and Mesaphorura macrochaeta) exhibiting distinct functional traits, for example, body size and furca presence, in the presence or absence of a predatory gamasid Acari Stratiolaelaps scimitus during 2 months in a microcosm experiment.4. We observed that decreasing soil moisture altered the collembolan community with species-specific responses. Interaction between soil moisture, temperature and predation indicates that low soil moisture reduced total collembolan abundance especially (a) by suppressing the positive effect of increasing temperature and (b) by increasing the predatory control on collembolan abundance.5. These results highlight that soil moisture is the major driver of Collembola community and by consequence, a shift in climatic parameters with the ongoing climate change should strongly modify the Collembola community structure and the predator-prey interaction. Our findings are highly important since a strengthening of predation impact on Collembola prey could have major consequences on the whole soil food web being able to lead to a slowdown of key ecosystem processes they drive (e.g. litter decomposition and nutrient recycling). Finally, our study promotes the need to study more complex systems considering distinct soil-dwelling species, their functional traits and their trophic interactions to better predict the ecosystem responses to the ongoing climate change.