Abstract
The protected area network (PAN) is a vital strategy for enhancing ecological integrity and connectivity. However, its contributions to the Kunming-Montreal Global Biodiversity Framework (GBF) 2030 Targets and Sustainable Development Goals (SDGs) remain understudied due to limited indicator assessments and regional case comparisons. This study applied circuit theory to construct and optimize a PAN in China's coastal region. First, resistance surfaces were mapped, connectivity corridors identified, and network key points determined. Second, the network structure was analyzed to classify source areas and corridors by importance and to identify potential conservation zones. Finally, the PAN's contributions to GBF Targets 2 and 3, SDG 15 indicators, and related synergistic benefits were quantified using coverage-based performance metrics and spatial analysis. The results show that the PAN raises protected-area coverage to 33.3%, meeting the GBF 30 × 30 target, boosts SDG 15 terrestrial protection by 50% above the regional average, and supports other SDGs. Key connectivity points align along the coastal belt, with eight regions exhibiting both pinch points and barriers, underscoring the complexity of coastal-terrestrial ecotones. This study highlights the unique role of coastal PANs in global conservation and recommends refined assessment frameworks and collaborative planning to enhance their international applicability.