Biogeography of 180 uninhabited land-bridge islands near the southwest coast of Korea: evaluating area and distance effects on plant distribution

This study investigates the principles of island biogeography by evaluating vascular plant biodiversity across 180 uninhabited land-bridge islands situated in Shinan Province near the southwest coast of South Korea. Utilizing a comprehensive dataset derived from a governmental ecological survey, this research specifically examines the species-area relationship (SAR), the species-distance relationship (SDR), and the potential impact of habitat diversity within this insular system. The application of partial correlation analysis corroborated the empirical presence of both the SAR and the SDR; however, it failed to provide statistical support for the hypothesized influence of habitat diversity on these small land-bridge islands. Furthermore, analysis utilizing the Mantel test and distance-based redundancy analysis yielded additional evidence demonstrating the SDR when evaluating species composition data. Notably, these fundamental biogeographic patterns remain prominent despite the Shinan islands being characterized by their small spatial extent, close geographic proximity to the mainland, and relatively recent isolation history, having functioned as real islands for only about 8,000 years. Ultimately, this paper emphasizes that young land-bridge islands serve as suitable and effective models for examining a wide array of biogeographic hypotheses, as effectively as other established island types worldwide.