Partitioning Net Biodiversity Effects on Ecosystem Resistance and Resilience

ABSTRACT Despite significant advances in recent decades, understanding how biodiversity affects the stability of ecosystems remains topical in ecology. Here we reveal new selection and complementarity effects by which biodiversity affects ecosystem stability. Biodiversity can favour ecosystem resistance by making species less sensitive to perturbations and through a selection effect by which less sensitive species are favoured by ecological assembly. Surprisingly, if ecosystem resilience can be favoured by an increase in species resilience and a selection effect that benefits resilient species, it can also be favoured by another selection effect by which changes in species resistance benefit the least resilient species. To exemplify the mechanisms at play and showcase the clarifying potential of our partitioning, we analyse a mechanistic model of grassland ecosystems subjected to drought. Our partitioning precisely explains how functional complementarity and differences in life‐history strategies can allow more diverse grasslands to resist and swiftly recover from droughts.