The impact of port production on mangrove ecological vulnerability: Evidence from mainland China

Rapid port expansion has reshaped coastal socioeconomic systems while intensifying pressures on mangrove ecosystems, and the mechanisms through which port activities influence mangrove ecological vulnerability (MEV) remain insufficiently understood. Using panel data from 25 port cities in mainland China from 2003 to 2023, this study integrates the Intergovernmental Panel on Climate Change (IPCC) vulnerability framework with the Sensitivity-Resilience-Pressure (SRP) model to construct a multidimensional MEV index, and applies XGBoost-SHAP to identify dominant port-production drivers, nonlinear thresholds, and interaction effects. Against the background of continued port-production expansion, mangrove area increased by approximately 43% and overall MEV declined by 7.9%. However, this overall improvement did not eliminate high-vulnerability clusters in port-production-intensive regions, particularly west coast of the Pearl River Delta and southern Fujian. SHAP analysis identifies the number of port enterprises (16.97%) and berth capacity (13.55%) as the primary port-related drivers. When port-enterprise number falls below 0.163, its interaction with population density significantly amplifies vulnerability, revealing a pronounced nonlinear threshold effect. These findings illuminate the complex coupling between port-production activities and mangrove ecosystems, supporting green port transitions and blue carbon governance under increasing coastal development pressures.