Pathways to High Urban Ecological Environmental Quality in Rapidly Urbanizing Regions: Evidence From the Yangtze River Delta

Urbanization profoundly shapes ecological environmental quality (EQI) in China. This study analyzes 41 cities in the Yangtze River Delta using the Pressure–State–Response (PSR) framework integrated with Necessary Condition Analysis (NCA) and fuzzy-set Qualitative Comparative Analysis (fsQCA). No single factor is necessary for high EQI, while four sufficient pathways—governance–response, structural–optimization, population–synergy, and state–dominant—reveal multiple routes to ecological improvement. Non-high EQI mainly results from poor air quality and weak enforcement, highlighting nonlinear and asymmetric relationships across PSR dimensions. The study suggests differentiated strategies: fiscal–enforcement synergy for resource-rich cities, industrial upgrading with air-quality improvement for industrial cities, and air-quality–focused governance for resource-limited areas. Findings deepen understanding of urban environmental governance and support region-specific sustainability policies.