Species richness, endemism, and conservation of wild Rhododendron in China

This study aimed to identify the main factors driving species richness and endemism patterns of Chinese wild Rhododendron as well as to assess the hotspots of species diversity and their conservation status. We initially mapped the species richness and endemism (expressed by weighted endemism) patterns of 546 wild Rhododendron in China in 100 × 100 km grids using 13,969 occurrence records. Subsequently, the effects of environmental variables on species richness and endemism patterns were assessed using regression models, and hotspots were identified based on the areas overlapping in 10% of the grids with the highest species richness and endemism. Finally, the conservation status of the hotspots was evaluated via gap analysis. The key environmental variables affecting species richness and endemism patterns differed. Species richness patterns were significantly influenced by moisture index, whereas endemism patterns were significantly influenced by elevation range. Moreover, the following five species diversity hotspots were identified: southern Xizang, Hengduan Mountains, south-central Sichuan, eastern Yungui Plateau, and central Gansu; however, these hotspots are not fully covered by the existing nature reserves. Our results indicate that the establishment of nature reserves should be actively promoted to effectively protect wild Rhododendron in hotspots with a conservation gap.