Spatial phylogenetic patterns and conservation of threatened woody species in a transition zone of southwest China

Phylogenies are crucial for understanding historical patterns of genetic biodiversity, but very few are incorporated practically into existing conservation programs. Xishuangbanna, a tropical–subtropical forest transition, is a key biodiversity hotspot in Southwest of China; however, gaps between practical protection and national planning need to be bridged, as ongoing, rapid expansion of rubber plantations in the region increasingly threatens local diversity. Here, we used administrative regions as study units to identify spatial patterns for 158 threatened woody species and investigate the ratio of tropical floristic to temperate floristic in the transition zone. We used all-subsets regression analysis to test the impacts of environments (climatic, edaphic, topographic) on biodiversity patterns. Spatial patterns using several conservation metrics gave different results, with species richness, phylogenetic diversity, and evolutionary distinctiveness and global endangerment highly consistent spatially, while either standardized phylogenetic diversity and phylogenetic structure performed differently from others for spatial patterns. The biodiversity patterns of threatened woody species in Xishuangbanna are affected by the combined impact of rubber plantations and abiotic environments, but their evolutionary history is not, with only c. 69% of phylogenetic diversity currently protected by traditional nature reserves. Although the Menglong and Xiangming townships show high conservation values, they are not in the reserves. Eleven threatened woody species were required for ex situ conservation due to threats from clearance for rubber plantations and in all, 21 regionally and internationally important species are currently unprotected. We recommend incorporating the phylogenetic component of biodiversity in improving current and establishing new reserves.