Spatial patterns and future potential of tree species richness and structural diversity in China's forests

Two fundamental aspects that characterize the diversity of natural forests are species richness and structural diversity. Our understanding of the fine-grained patterns and drivers of tree species richness and structural diversity in many regions has been limited by lack of spatially representative vegetation-plot data. Here we use data on 314,613 trees from 3,396 plots to elucidate spatial patterns, determinants and future potential of tree species richness and structural diversity in natural forests across China. We find that the patterns and their dominant drivers differed between tree species richness and structural diversity. Precipitation seasonality is the foremost predictor of species richness, whereas forest age is the leading predictor of structural diversity. Projections based on future climate scenarios SSP126 and SSP245 highlight the potential for substantial increases in fine-grained species richness (~36%) and structural diversity (~27%) by 2100. While this increase in diversity could enhance carbon sequestration, it may also pose threats to endangered species due to intensified competition for limited ecological niches.