Do national key ecological function areas promote sustainable regional development? -evidence from 271 prefecture-level cities in China

The National Key Ecological Function Areas (NKEFA) represent a critical spatial planning policy for China's sustainable development, yet their ecological-economic synergy and implementation efficacy remain underexplored. Based on the panel data of 271 prefecture-level cities in China from 2006 to 2015, this paper constructs a continuous difference-in-differences (DID) method, and systematically evaluates the impact of the NKEFA on the coupled coordination degree of "environmental quality-urbanization" (EU-CCD).The results show that NKEFA significantly improves EU-CCD in prefecture-level cities, and is driven by two paths: promoting industrial structure transformation and upgrading, and increasing government attention. The study further reveals the heterogeneity of policy effects: the policy effect of the NKEFA is significant only in the prefecture-level units where the area's basis is poorer, the infrastructure development is more backward, and the regional green ecological construction is poorer. The results verify that the path of territorial spatial planning to force green transformation through institutional constraints, providing replicable theoretical support and policy insights for developing countries to coordinate ecological protection with urbanization processes and achieve sustainable development.