Towards ecological integration in city clusters: A case study of Guangdong-Hong Kong-Macao Greater Bay Area

Rapid urbanization in the Guangdong-Hong Kong-Macao Greater Bay Area has intensified ecological degradation, underscoring the urgent need for integrated spatial planning informed by ecosystem services (ES) assessment. This study developed a dynamic assessment framework to quantify and map five key ES—water conservation, soil retention, stormwater regulation, grain production, and carbon sequestration—from 2000 to 2015. Using the Getis-Ord Gi* spatial statistic, we identified ES hotspots and coldspots and delineated functional zones based on service importance. The results reveal a notable spatial mismatch between ES supply and administrative boundaries, with high-value clusters concentrated in the northern and peripheral regions, while the central urban basin functions as an area of low ES values. Multi-service co-protection zones were identified, particularly in Zhaoqing and eastern Huizhou, which should be prioritized in ecological protection redline delineation. This study demonstrates that ES-based spatial zoning can effectively bridge ecological science and spatial governance, offering a replicable decision-support tool for cross-jurisdictional coordination and sustainable planning in complex urban agglomerations.