We sampled plots in three tropical cloud forests which are located in the west (Bawangling, 21 plots, BWL), the southwest (Jianfengling, 12 plots, JFL), and the central of Hainan Island (Limushan, 15 plots, LMS). We collected species data and functional trait data including plant height, specific leaf area, chlorophyll content, leaf thickness and wood density. We assessed the differences within- and among-community species diversity, functional diversity and phylogenetic diversity in these three tropical cloud forests using the Kruskal-Wallis test.

The tropical cloud forests in JFL had the highest species abundance and richness whereas the lowest in LMS. However, the Bray-Curtis and Jaccard dissimilarity coefficients showed the opposite distribution patterns (i.e. the highest in LMS whereas the lowest in BWL). Distinct distribution patterns in species diversity across the three tropical cloud forests may be explained by the air temperature and relative humidity. The functional evenness (FEve) within communities was the highest while functional richness (FRic), Rao’s quadratic entropy (RaoQ) and the mean pairwise trait distance among communities were the lowest in JFL, indicating that habitat filtering plays an important role in community assembly. BWL had the highest RaoQ and mean pairwise trait distance among communities, and the lowest FEve, which demonstrated that limiting similarity would be prevalent in forest communities assembled. LMS had the highest FRic within communities and mean nearest trait distance among communities, leading to a limiting similarity influencing forest communities. BWL had the highest Faith phylogenetic diversity (PD) within communities and mean nearest phylogenetic distance among communities, reflecting an overdispersed pattern in phylogenetic structures. LMS had the lowest PD and mean pairwise phylogenetic distance within and among communities, suggesting that a clustered pattern in phylogenetic structures. The mean pairwise phylogenetic distance within and across communities were the highest in JFL while the mean nearest phylogenetic distance within communities was the lowest, indicating that phylogenetic clustering and overdispersion patterns co-occur in this forest. We conclude that both plant species interactions and environmental filtering determine the distribution patterns of plant species diversity, functional diversity and phylogenetic diversity both within and among three tropical cloud forests in Hainan Island.