Effects of species abundance and size classes on assessing community phylogenetic structure: a case study in Jianfengling tropical montane rainforest

Studying community phylogenetic diversity within forest stands of different diameter classes (i.e. size classes) is helpful for understanding relationships among species at different ages while at the same time community phylogenetic structure. However, little research has been focused on the influence of species abundance on phylogenetic structure of community. This study was conducted in the Jianfengling tropical montane rainforest on Hainan Island. First, we assessed the impact of species abundance on four widely used phylogenetic diversity indices at different size classes. Next, two of the indices (i.e. net relatedness index, •研究报告• 618 生 物 多 样 性 Biodiversity Science 第 24 卷 NRI and nearest taxon index, NTI) were standardized and used to quantify phylogenetic relatedness of woody plants at different size classes across a series of local habitat types. The results showed that: (1) The unweighted MPD (mean pairwise distance) index significantly overestimated phylogenetic diversity relative to MPD weighted according to species abundance. This overestimation when using unweighted MPD was greatest for small trees and shrubs (1 cm≤DBH 0). However, this pattern continued to show overdispersion within communities made up of large trees (DBH≥15 cm) (NTI