Spatial Assessment of the IUCN Red List Ecosystems in Limestone Areas: Focusing on Gangwon and Chungcheongbuk Provinces

The International Union for Conservation of Nature (IUCN) red list of ecosystems (RLE) has been adopted as a headline indicator for the Kunming-Montreal global biodiversity framework, highlighting its global significance. Limestone areas in South Korean are biodiversity hotspots with a high proportion of rare and endemic species due to their unique environmental conditions; however, they face severe threats from continuous limestone mining. This study assessed the collapse risk of limestone vegetation ecosystems in Korea using the IUCN RLE spatial criteria (criterion B). Based on digital geological maps, we mapped the distribution of major limestone areas, focusing on Gangwon-do and Chungcheongbuk-do. We calculated the extent of occurrence (EOO; criterion B1) and area of occupancy (AOO; criterion B2). To enhance precision, the AOO assessment incorporated grid uncertainty analysis and the 1% threshold rule. The results showed that the total area of limestone regions was approximately 2,760.8 km<sup>2</sup>. The EOO was calculated as 11,030.36 km<sup>2</sup>, classifying the ecosystem as endangered (EN). Conversely, the AOO assessment resulted in 76 grids (7,600 km<sup>2</sup>) even under the most conservative scenario (considering uncertainty and the 1% rule), classifying it as least concern. Following IUCN guidelines to adopt the highest risk category, the final status of the limestone ecosystem was determined as EN. This restricted geographic distribution implies high vulnerability to external threats. These findings provide essential scientific evidence for establishing national conservation strategies and achieving the 30×30 protected area target.