Regional biodiversity patterns are often similar across taxa, but it is unclear whether these similarities reflect shared responses to climate and environmental gradients, or if they are facilitated by cross-taxon biotic associations. Parsing these drivers is critical to understanding the processes underlying species assembly and generating predictions of biodiversity across taxonomic groups and for novel sites, but requires data that connect cross-taxon local-scale assemblages across regional environmental gradients. We used species inventories of vascular plants, birds, and small mammals collected by the U.S. National Ecological Observatory Network (NEON) at 38 terrestrial field sites, to investigate the dimensions and drivers of taxonomic, functional, and phylogenetic alpha and beta diversity. By parsing the abiotic and biotic predictors of biodiversity across taxonomic groups, we tested whether cross-taxon associations provide additional predictive power after accounting for shared environmental responses.
Results/Conclusions
We found that phylogenetic and functional, but not taxonomic, alpha diversity were strongly correlated with one another in plants and birds, indicating phylogenetic diversity is a better proxy for functional diversity than is species richness. While the abiotic environment was generally the strongest predictor of biodiversity across taxa, the biodiversity of co-occurring taxonomic groups also emerged as a strong predictor of taxonomic and phylogenetic diversity (alpha diversity) and turnover (beta diversity). This pattern of the biodiversity of one taxon predicting that of another, even when environment is accounted for, suggests that we can and should address the influence of species' biotic environment—other co-occurring clades—in predictions of biodiversity and community assembly.