Untangling the Complex Relationships Governing Trait-Mediated Litter Decomposition by Detritivores and Cascading...

AbstractSoil organisms play a crucial role in essential ecosystem functions, such as leaf litter decomposition. Our study builds on the positive biodiversity-ecosystem functioning relationship to understand how different soil fauna species affect litter decomposition via variation in their consumption rate, leaf litter selectivity, and cascading effects on soil abiotic and biotic properties. This mechanistic approach requires focusing on identity effects, which are pivotal in understanding biodiversity effects. Results were obtained from monocultures of seven detritivore species from three functional groups (isopods, snails, and earthworms) feeding on two leaf litter species. We found that decomposability is not solely a litter-specific trait. Instead, decomposition is better understood in the context of trait-mediated detritivore-litter interactions. Accordingly, we demonstrate that detritivore species (in part even within functional groups) have distinct litter selectivity and varying impacts on soil physicochemical parameters and belowground microbial communities. Our experimental approach allows us to quantify the relevant traits at multiple trophic levels, thus making a significant step toward understanding the complexity of soil ecosystems and better predicting their functioning in a changing world.