Mapping Endangered Plant Distributions, Species Richness, and Climate Refugia Under SSP Climate Scenarios in South Korea

Climate change significantly threatens the survival and distribution of endangered plants. This study quantified current and future patterns of habitat suitability and species richness for legally protected vascular plants in South Korea under two SSP climate scenarios. We modeled the distributions of 69 species designated as Class I or Class II endangered wild plants and evaluated in the Korean National Red List using IUCN criteria. Random Forest (RF) species distribution models were fitted with environmental predictors derived from 1 km² national climate data for a 2010 baseline and SSP2-4.5 and SSP5-8.5 projections for the 2030s-2090s. Cross-validation indicated high model performance (mean AUC = 0.913; TSS = 0.818; Kappa = 0.605), and 61 species (88.4%) achieved an AUC ≥ 0.80. Current richness ranges from 0-40 species per municipality and peaks along the Baekdudaegan mountain range and on Jeju Island, whereas many lowland agricultural basins support few or no endangered plants. Under future climates, richness classes shift systematically: municipalities in low-richness classes expand, while high-richness classes contract, with stronger losses in southern lowlands and relative retention in northern and high-elevation areas, especially under SSP5-8.5. The resulting municipality- and national-park-level richness maps provide a quantitative basis for identifying potential climate refugia and prioritizing vulnerable regions and species.