Different trends in phylogenetic and functional structure of plant communities along an elevation gradient

Abstract The study of diversity gradients due to elevation dates back to the foundation of biogeography and ecology. Although elevation‐driven patterns of plant diversity have been reported for centuries, uncertainty still exists about the assembly rules that drive these patterns. In this study, we revealed the causal factor of community assemblies for the diversity of tree and herb species along an elevation. To this end, we applied an integrated method using both functional traits and phylogeny, called the mean pairwise functional‐phylogenetic distance, to understand the assembly rules for woody and herbaceous species communities along an elevation gradient. At higher elevation sites, woody and herbaceous communities were comprised of species having similar traits. The phylogenetic trends for woody species were consistent with the functional trends; closely related species co‐occurred more frequently than expected at higher elevations. Phylogenetic trends for herb species were opposite to the functional trends; species with similar traits but having a random phylogenetic distribution co‐occurred at higher elevations. We suggest that the community assembly rules for woody and herb species vary with elevation; and functional constraints due to environmental filtering at higher elevation act as assembly rules along gradients in both woody and herbaceous communities, even though their phylogenetic backgrounds differ.