Predicting potential distributions of dominant species and assessing future afforestation risks in Guangdong limestone regions under climate change.

Climate change is reshaping species distributions across karst landscapes, yet large-scale ecological restoration in southern China remains hampered by species and site mismatch, rooted in inadequate macro-scale assessment of climate-vegetation equilibrium. Existing species distribution model (SDM) studies in karst regions are dominated by single-species, locally calibrated analyses. Here we assembled occurrence records spanning the full Chinese range of 12 dominant tree species (1,376 records) and combined them with bioclimatic, soil, and topographic predictors. We built optimized MaxEnt models and projected suitable habitat for the northern Guangdong limestone region under the SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios for 2061-2080. We then integrated these projections into a bivariate spatial framework that couples current species richness with net richness change (ΔS) to delineate climate trajectory zones. Models performed well (AUC 0.907-0.984; TSS 0.749-0.933). Annual precipitation (BIO12), precipitation of the driest month (BIO14), and mean temperature of the warmest quarter (BIO10) were the most pervasive drivers across the assemblage. Total suitable area changed by less than 10% across all scenarios. Highly suitable habitat, however, often contracted even where total area held steady, identifying habitat-quality erosion rather than extent loss as the principal threat. Under SSP1-2.6 it shrank for 11 of 12 species, most in