Effects of habitat fragmentation on mammalian species richness in the Republic of Korea

Abstract Road networks cause habitat fragmentation by reducing the patch size and connectivity, threatening wildlife. We assessed the effects of road-induced habitat fragmentation and proximity to roads on mammalian species richness in the Republic of Korea. Habitat patches were delineated to minimize road impact, and patch size and connectivity were quantified. The mammalian species richness was based on nationwide occurrence records. We compared species richness across three consecutive 1-km buffers extending from the roads to evaluate edge effects. In total, 6176 patches were identified, with over 66% being smaller than 1 km 2 . Species richness increased significantly with patch size and connectivity, with patch size exerting the strongest effect. Species richness was nearly twice as high in highly connected patches exceeding the connectivity threshold, particularly in landscapes with higher forest cover and lower agricultural land cover. Species richness increased with increasing distance from roads, being lowest at 0–1 km and highest at 2–3 km. These findings indicated that mammalian species richness is highly sensitive to habitat fragmentation and that structurally favorable patches with higher natural cover support substantially greater biodiversity. Pronounced declines in species richness near roads highlight strong edge effects on mammalian species richness in the Republic of Korea.