<i>Rhododendron</i> diversity patterns provide new insights for conserving China's montane flora

Under anthropogenic global change, mountain plants are among the most threatened flora, making it essential to address conservation gaps to achieve the "30 × 30" target outlined in the Convention on Biological Diversity. Focusing on Rhododendron, the emblematic genus of montane ecosystems in Asia, we compiled an updated checklist of 603 Rhododendron species in China and integrated high-resolution distribution, phylogenetic, functional trait, and environmental data to examine spatial diversity patterns, driving factors, and priority conservation areas. Our results indicated that the taxonomic, phylogenetic, and functional dimensions of Rhododendron diversity were highly consistent. The Three-Parallel-Rivers-Region in the Hengduan Mountains emerged as the overarching hotspot for richness, endemism, and uniqueness. These diversity patterns were collectively influenced by temperature seasonality and elevation range, with temperature-related energy factors further contributing to the overall phylogenetic and functional structures. The mechanisms underlying uniqueness exhibited regional divergence: In southwestern China, high uniqueness was attributed to the accumulation of intermediate-aged and younger distinctive lineages, coupled with rapid community differentiation; in southern China, it was mainly associated with strong spatial compositional differentiation among communities; whereas in northeastern China, it largely resulted from the preservation of relict lineages. Under the 10% conservation target, we delineated nine priority conservation units across the southwestern, southern, and northeastern mountainous regions of China. However, when the conservation target was increased to 30%, these priority areas expanded to encompass broader mountain regions, highlighting a greater conservation gap. This study provides innovative insights for incorporating multidimensional diversity into effective conservation efforts for Rhododendron species in China.