Demographic response of Rana uenoi to land use near breeding sites: A case study from the Gayasan region, South Korea

Amphibians are extremely sensitive to habitat disturbances due to their permeable skin and reliance on both aquatic and terrestrial habitats. To better understand how human-driven land-use changes affect amphibian populations, we examined long-term dynamics of Rana uenoi in the Gayasan region of South Korea, focusing specifically on alterations of breeding habitats. From 2007 to 2023, annual egg mass surveys were conducted at 14 breeding sites, and land-use variables were classified annually using aerial imagery and standardized governmental categories within a consistent 500-meter buffer surrounding each site. This approach provided detailed spatial data on habitat shifts throughout the study period. Several candidate regression models were developed to evaluate the effects of land-use change and climatic variability on egg mass counts. Among the candidate models, the land-use-only model provided the best explanation for variation in egg mass counts. Specifically, breeding habitats (wetlands and rice paddies) and low-quality habitats (cultivated fields and artificial grasslands) exhibited significant positive associations with egg mass production, whereas high-mortality habitats, primarily roads and transportation infrastructure, showed a significant negative relationship. Egg mass counts declined by up to 98.5% during the study period, primarily due to habitat degradation and the expansion of urban and transportation infrastructure. These findings underscore the urgent need for targeted habitat preservation, restoration efforts, and the expansion of protected areas. Long-term monitoring systems and integrated land-use planning will help ensure the persistence of R. uenoi and other amphibians in landscapes increasingly affected by human development.