Abstract:In order to understand the effects of phylogenetic diversity and phylogenetic structure on decisionmaking of island plant diversity conservation, the relationship among species richness, phylogenetic diversity and phylogenetic structure in angiosperm communities in Wuzhizhou Island, Hainan, China were studied. The results showed that there were 10 formations of vegetation in Wuzhizhou Island. Species richness was positively correlated with phylogenetic diversity in 22 plots, but the order of conservation priority indicated by phylogenetic diversity and species richness were not completely consistent. Species richness and phylogenetic diversity of forest communities were greater than those of shrub and herb communities. Four plots are phylogenetically overdispersed and three are phylogenetically clustered in forest communities. Pandanus tectorius bushland showed the highest phylogenetic diversity in shrub communities, while did Scaevola sericea bushland in herb communities. Shrub and herb communities were mostly phylogenetically clustered. Communities near to the sea or to the anthropic zones were likely to be structured by habitat filtering, which far from the sea and the anthropic zones were likely to be structured by competitive exclusion. Therefore, species and phylogenetic demensionality, together with environmental factors, succession stages and island exploitation modes, should be considered in conservation of island plant diversity.