Unraveling the Effects of Climate Change and Human Activity on Potential Habitat Range Shifts in Four Symplocos Species in China

Climate change and human activities profoundly impact forest biodiversity, with effects projected to intensify. The <i>Symplocos</i> genus, a diverse assemblage of flowering plants prevalent in the subtropical and tropical forests of the Yangtze River in China, holds substantial economic and medicinal value. However, the impacts of climate change and human activities on the habitat ranges of <i>Symplocos</i> species in China remain unclear. This study employed an optimized Maxent model to predict potential habitats for four key <i>Symplocos</i> species-<i>Symplocos setchuensis</i>, <i>Symplocos chinensis</i>, <i>Symplocos groffii</i>, and <i>Symplocos sumuntia</i> under current and multiple future climate scenarios (SSP1-2.6 and SSP5-8.5 during the 2070s and 2090s). Moreover, we assessed the relative importance of various predictors, including climatic, topographic, soil, and anthropogenic factors, in shaping their habitat range patterns. Currently, the habitat ranges of the four <i>Symplocos</i> species are mainly concentrated in southern China, exhibiting notable differences in areas of high habitat suitability. Furthermore, the habitat ranges of <i>S. setchuensis</i>, <i>S. chinensis</i>, <i>S. groffii</i>, and <i>S. sumuntia</i> were primarily influenced by the mean temperature of the driest quarter (bio9), the minimum temperature of the coldest month (bio6), the temperature annual range (bio7), and precipitation seasonality (bio15), respectively. Notably, the habitat suitability of <i>S. setchuensis</i>, and <i>S. sumuntia</i> increased at a progressively slower rate with human footprint. Under future climate scenarios, <i>S. groffii</i> and <i>S. sumuntia</i> are projected to expand their ranges significantly northward, while <i>S. chinensis</i> is expected to maintain stable habitat, and <i>S. setchuensis</i> may face considerable contractions. Our results underscore the importance of climate and human activities in shaping the habitat ranges of <i>Symplocos</i> species, revealing distinct adaptive responses among the four species under future climate change.