Analysis of species and phylogenetic β diversity drivers in the Masson pine forests in Suichang, Zhejiang Province

Abstract

Habitat filtering and dispersal limitation are the main ecological processes affecting species composition variation (β diversity) in forest communities, but their relative importance in subtropical Masson pine (Pinus massoniana) forests remains unclear. Jointly analysis of how phylogenetic and species β diversity varies with habitat factors and geographic distance is critical to understand the roles played by historical and current ecological processes in shaping the regional biodiversity. In this study, 37 Masson pine forest plots in Suichang County, Zhejiang Province were selected to analyze the species and phylogenetic β diversities, and the main ecological mechanisms driving the differences of species composition among communities were explored. Species β diversity index (Bray-Curtis) and phylogenetic β diversity index (the mean phylogenetic dissimilarity, Dnn; the mean nearest taxon distance, Dpw) were calculated, and their correlation with habitat factors including soil and topography, as well as geographical distance were analyzed. The relative importance of habitat factors and geographical distance on species and phylogenetic β diversity was analyzed by variance partitioning. In addition, two life stages (divided by diameter class) and growth form were for the same analyses. The results were as follows: (1) Bray-Curtis index significantly correlated with soil factors, topographic factors and geographical distance. Dnn correlated with geographical distance only. Dpw correlated with soil factors and geographical distance. (2) The explanatory degree of habitat factors to Bray-Curtis and Dpw was higher than that of geographical distance. (3) For species diversity, habitat factors could better explain Bray-Curtis of both life stages than geographical distance. For phylogenetic diversity, geographical distance could better explain Dnn and Dpw of sapling stage, while habitat factors were more likely to explain Dpw of adult stage. To conclude, The results show that habitat filtering is the main ecological mechanism driving species and phylogenetic β diversity of Masson pine forests in this region. Dispersal limitation plays a dominant role in the β diversity of Masson pine forests only at the sapling stage. The most important finding of this research is that the main mechanism drives for species and phylogenetic β diversity in Masson pine forests are different, which highlights the necessity of joint analysis of species and phylogenetic β diversity. This research also suggests that the main ecological mechanism drives β diversity may change as plants shift across different growth stages.

Keywords

• masson pine forest
• dispersal limitation
• beta diversity
• phylogenetic structure
• species composition