Predicting differential habitat suitability of Rhodomyrtus tomentosa under current and future climate scenarios in China

Rhodomyrtus tomentosa, with edible and medicinal values, is a key shrub species in south China's forest under story. It maintains ecological balance, soil and water conservation, and biodiversity in the widely degraded mountain ecosystems. The distribution and population of R. tomentosa have shrunk recently due to anthropogenic impacts. At present, wild communities of R. tomentosa are rare in China's low-altitude areas. A comprehensive understanding of its current and future spatial patterns vis-`a-vis changing climatic conditions can inform co-management for economic use and conservation. Based on 213 validated distribution records and nine selected environmental variables, the potential biogeographical range of R. tomentosa in China was predicted by Maxent and QGIS modeling under current and three future climate-change scenarios. The limiting factors for distribution were evaluated by Jackknife, per cent contribution and permutation importance. We found that the present actual biogeographical range was concentrated in tropical and south-subtropical China with some extensions to mid-subtropical east and southwest China, with the main occurrence in the core range of Guangdong, Guangxi, and Hainan provinces. The modeling results indicated temperature as the clinching determinant of distribution patterns, including the minimum temperature of coldest month, mean temperature of warmest quarter, and temperature seasonality. Moisture was a necessary but not critical secondary factor. Under future climate-change scenarios, habitats with excellent suitability index will expand and shift towards southwest China and high-altitude areas. The findings provide science-based evidence to adjust management and conservation plans in response to climate change protect and use R. tomentosa in suitability habitats.