Functional diversity of macroinvertebrates as a tool to evaluate wetland restoration.
Ecological restoration of aquatic ecosystems has become widespread in recent decades. Although the recovery of biodiversity in restored wetlands has been studied from a taxonomic perspective, our knowledge of how functional biodiversity recovers remains poorly understood. We studied the functional diversity of macroinvertebrate communities in 32 Mediterranean temporary ponds 6-7 years after their creation during a restoration in South-West Spain, and compared them with 10 natural reference sites during two consecutive hydroperiods. We compared alpha functional diversity indices, and the individual contributions of new ponds and reference sites to the regional functional beta diversity, as well as to its turnover and nestedness components. We also investigated the influence of environmental and spatial variables on the dissimilarities of functional beta diversity and its components between new ponds and reference sites. Alpha functional diversity in new ponds was lower than in reference sites. Although the contribution of new ponds to the regional functional beta diversity was similar to that of reference sites, the latter contributed more to functional turnover while new ponds contributed more to functional nestedness. Dispersal limitation coupled with environmental filtering structured the functional variation in communities between new ponds and reference sites, but their relative importance differed between beta components. New ponds can hold species with unique functional compositions, but their contribution to the regional functional beta diversity was mostly due to trait losses with respect to reference sites. Synthesis and applications. Considering different aspects of functional diversity of invertebrate communities can help elucidate the processes and mechanisms through which ecosystems recover following restoration. We encourage the use of trait-based approaches to identify trends in processes and patterns that can guide future wetland restoration projects.