Effects of functional diversity and phylogenetic diversity on the tropical cloud forest community assembly

Abstract

Aims Phylogenetic and functional diversity are important components of species biodiversity, and are thought to play key roles in the mechanisms of community assembly. In this study, we explore the mechanisms of community assembly in tropical cloud forest plant community in Hainan Island, in southern China, using phylogenetic and functional diversity based methods. Methods We constructed a species pool of 186 woody plant species from three tropical cloud forest sites in Hainan Island. For these species, we measured 13 functional traits and assessed their phylogenetic signals. In addition, we measured seven environmental factors and assessed their relationships using Principal component analysis (PCA). Then we chose Rao’s quadratic entropy (RaoQ) and mean pairwise distance (MPD) indices to examine the effects of functional diversity and phylogenetic diversity on tropical cloud forest community assembly. To do this we compared these indices to expectations under null models that assume neutral community assembly. We used standard effect sizes to evaluate the influence of environmental factors on community assembly. Important findings Canopy openness, soil total phosphorus content and slope were significant environmental predictors in tropical cloud forest. The phylogenetic signals of most functional traits were very low and not significant, indicating that the phylogenetic relationship and functional traits were not consistent with the change of historical process. The observed values of RaoQ and MPD were significantly lower than expected, and their standard effect sizes were significantly correlated with soil phosphorus content, which suggested that habitat filtering driven by soil phosphorus was the key factor driving the community assembly in tropical cloud forest.