Sustainable spatial planning for coastal islands: Integrating ecological resilience and development suitability in China’s county-level island administrative divisions

Owing to the confined area, clear spatial boundaries, and heterogeneous characteristics, islands serve as ideal natural laboratories for developing territorial spatial planning techniques. This study addresses the disconnection between ecosystem-based assessments and practical planning across China's 12 major island counties. We established fine-resolution (100 m × 100 m) models of island ecological resilience and development suitability based on element couplings. Results revealed significant national-scale spatial heterogeneity: ecological resilience is predominantly influenced by human activities, a dominant role demonstrated here for the first time at this scale, while development suitability is primarily controlled by soil, topography, and coastline proximity. These models informed three multi-scenario conservation zonings and five region-specific functional zonings, whose integration generated 15 planning schemes dividing the study area into core conservation, buffer conservation, permanent farmland, urban development, and integrated development zones. Theoretically, we demonstrate that element couplings exhibit systematic spatial heterogeneity and that aggregation scale directly influences planning outcomes, establishing region-specific parameterization as a necessity. Methodologically, the "realism and orientation" principles bridge technical assessment and implementation by embedding feasibility and strategic direction as explicit selection criteria. Guided by these principles, we selected optimal solutions for each county. We further identified four development orientations, namely, nature conservation, agricultural production, urban development, and integrated multifunction, for 209 individual islands and the 12 counties, and proposed management strategies aligned with China's "Three Zones and Three Lines" framework. Beyond China, the study offers three actionable insights for island regions worldwide: regulating human activity intensity as the primary driver of ecological resilience, adopting region-specific planning within national frameworks, and complementing technical zoning with integrated management strategies . The findings validate that multi-scenario and region-specific techniques effectively balance ecological assessments with societal needs, bridging research and practice in spatial planning. This framework is transferable to other archipelagic regions and to any context where spatial heterogeneity of coupling parameters is significant.