What determines local phylogenetic and functional beta diversity in temperate forests?
Although trait information has been widely used to explore underlying mechanisms of forest community structure, most studies have focused on local patterns of phylogenetic or functional alpha diversity. Investigations of functional beta diversity, on the other hand, have not been conducted at local scales in a spatially explicit way. In this study, we provide a powerful methodology based on recent advances in spatial point pattern analysis using fully mapped data of large and small trees in two large temperate forest plots. This approach discriminates the relative importance of different ecological processes and mechanisms such as habitat filtering, dispersal limitation and species interactions, for explaining patterns of local phylogenetic and functional beta diversity.
Our results showed clearly that both habitat filtering and dispersal limitation influenced the observed patterns in phylogenetic and functional beta diversity for both small and large trees, but that habitat filtering contributed more than dispersal limitation. This result contrasts with a previous study from the same forests showing that dispersal limitation had a stronger effect than habitat filtering on the observed species beta diversity. In addition, species interactions were unimportant for predicting phylogenetic and functional beta diversity. Our analysis suggests that phylogenetic and functional beta diversity provide insights into the mechanisms of local community assembly that are missed by studies focusing exclusively on species beta diversity