Evidence of functional species sorting by rainfall and biotic interactions: A community monolith experimental approach

1. Understanding the mechanisms that underlie species assembly is a central concern in community ecology. Abiotic and biotic filters are probabilistic ‘sieves’ that allow species with certain functional traits to become part of the community, or not. We manipulated natural plant assemblieses in order to identify variations in the timings of biotic and abiotic filters that determine community trait assemblies. 2. We extracted soil portions when the investigated annual plant community was in its seed phase (‘community monolith’), thereby maintaining the structure and similar soil characteristics to the field conditions. Community monoliths were subjected to experimental manipulation in terms of the rainfall timing and amount, and perturbations of the biological soil crust (BSC; intact vs. perturbed). We surveyed the experimental community assembly over time based on the functional diversity by considering important functional traits in different life stages. 3. We found that autumn drough...