Ensemble Species Distribution Modeling of Climate Change Impacts on Endangered Amphibians and Reptiles in South Korea

Climate change poses a serious threat to amphibians and reptiles, which are especially vulnerable because of limited thermoregulatory capacity and restricted dispersal. We used an ensemble species distribution modeling framework to assess habitat determinants, niche breadth, and climate-driven distribution changes for eight legally protected endangered amphibian and reptile species in South Korea. Occurrence records collected between 1997 and 2021 were combined with ten bioclimatic, topographic, and hydrological predictors, and 11 species distribution modeling algorithms (SDMs), including Random Forest and MaxEnt, were implemented and combined into weighted ensemble predictions. The weighted ensemble model showed high predictive performance (mean ROC-AUC = 0.897; overall mean across all SDMs = 0.843). Variable-importance analysis revealed clear taxonomic contrasts: reptiles exhibited approximately 1.7-fold greater dependence on temperature variables than amphibians, whereas amphibians were more strongly associated with precipitation and topographic context. Environmental niche-breadth analysis identified <i>Sibynophis chinensis</i>, <i>Hynobius yangi</i>, and <i>Dryophytes suweonensis</i> as narrow- or moderate-niche specialists largely constrained by precipitation of the driest month and a small set of climatic variables. Under moderate (SSP2-4.5) and high (SSP5-8.5) emission scenarios, areas of high species richness are projected to decline by 22% and 45%, respectively, by the 2070s, with distribution centroids shifting northeastward and pronounced habitat loss in western lowland plains. Priority conservation targets include <i>S. chinensis</i>, <i>D. suweonensis</i>, and <i>H. yangi</i>, which combine narrow niches, restricted ranges, and high climate vulnerability. These findings provide a quantitative basis for climate-adaptive conservation planning for threatened herpetofauna in South Korea.