Ecosystem multifunctionality increases with beta diversity in restored prairies.

The loss of biodiversity at local and larger scales has potentially dramatic effects on ecosystem functioning. Many studies have shown that ecosystem functioning depends on biodiversity, but the role of beta diversity, spatial variation in community composition, is less clear than that of local-scale (alpha) diversity. To test the hypothesis that beta diversity would increase ecosystem multifunctionality through variation in species functional traits, we gathered data on plant community composition, plant functional traits, and seven ecosystem functions across 29 restored prairies. We found that averaged multifunctionality (mean of seven ecosystem functions) increased with both taxonomic beta diversity and functional beta diversity. The abundance of the dominant species, big bluestem, played a more minor role, suggesting a limited role for the selection effect. Neither taxonomic nor functional alpha richness was associated with multifunctionality, though this finding may be sensitive to the identity of the functions included because alpha diversity was associated with some individual functions in opposing directions. These findings suggest that in systems structured largely by natural processes, beta diversity (a patchwork of functionally different plant communities) and dominant species abundance may be more important than alpha diversity in fostering ecosystem multifunctionality. These findings suggest the need for an increased focus on community heterogeneity to reestablish functional ecosystems during restoration.