Functional diversity: a tool for answering challenging ecological questions

Abstract Functional trait diversity provides a powerful means of addressing ecology's persistent questions, through its dual role as an indicator of mechanisms driving differences in species composition between communities and as a predictor of ecosystem‐level processes. Functional traits provide a means of testing mechanisms behind species turnover between communities because environmental heterogeneity, competition and disturbance influence species fitness via their traits. Functional traits also provide a link between species and multiple ecosystem‐level processes, such as primary productivity, nutrient fluxes and resilience, since species influence these processes via their traits. This special issue demonstrates that functional diversity offers a practical means of investigating ecology's persistent questions.