Abstract
<title>Abstract</title> <p>Island forests provide biodiversity, hazard mitigation, water regulation, cultural benefits, and livelihood support, but agencies often lack comparable baseline information for screening many islands under limited data and budget conditions. This study develops a grid-based ecosystem service assessment and screening framework for prioritizing forest management across inhabited and uninhabited islands. Applied to 492 inhabited and 444 uninhabited South Korean islands, the framework integrated six ecosystem service categories with socioeconomic and ecological sustainability dimensions using expert-derived weights, grid-based scoring, clustering, and sensitivity analysis. Expert-derived weights differed by island type: water regulation and disaster prevention were prioritized for inhabited islands, whereas supporting services and disaster prevention were prioritized for uninhabited islands. Correlations among ecosystem service categories were generally positive, but relationships between ecosystem service and sustainability scores were weak, mostly between − 0.2 and 0.2; supporting services and socioeconomic sustainability on uninhabited islands showed a negative correlation (-0.387). These results support a sequential assessment logic in which ecosystem service scores characterize current forest conditions and sustainability scores refine screening-level priorities within restoration, improvement, and maintenance types. The framework identified restoration needs for the lowest-performing inhabited island cluster, improvement needs for intermediate inhabited and lowest-performing uninhabited clusters, and maintenance priorities for higher-performing clusters. By separating current ecosystem service performance from long-term sustainability potential, the framework offers a transferable assessment-and-screening approach for island-rich countries seeking to compare island forest conditions, support monitoring design, and prioritize forest interventions under data constraints.</p>