How Do National Key Development Zones Affect Land-Use Eco-Efficiency? Evidence from Counties in the Upper Reaches of the Yangtze River

Against the backdrop of coordinated development of national land use and ecological conservation, national key development zones (NKDZs), as the core carriers of China’s main functional zone planning, provide important reference models for regional development through their pathways to improving ecological efficiency of land. A double-difference model (DID) was used to evaluate the effects of the NKDZ policy on the eco-efficiency of land use, utilizing county-level governing bodies of the upper Yangtze River region in China as a sample from 2005 to 2020. The findings indicate that (1) when the NKDZs were established, the counties’ eco-efficiency in land use in the upper reaches of the Yangtze River considerably improved by 2.6%; this conclusion holds after several robustness checks, including counterfactual tests. (2) Mechanistic analysis reveals that NKDZs promote the enhancement of eco-efficiency in land use, mainly through the technical effect, the structural effect, and the “two processes” effect of promoting the coordinated development of industrialization and urbanization. (3) Heterogeneity analysis reveals that the policy effects on land-use eco-efficiency in municipal districts and cities at the county level are much greater than those in regular counties. Concerning subdistricts, the policy significantly promotes Sichuan, Guizhou, and Chongqing, whereas the effect on Yunnan is not significant. In light of the aforementioned findings, this study makes policy recommendations in terms of technological innovation, structural optimization, and differentiated land control to offer a practical foundation and theoretical justification for the effective use of land and ecological pressure alleviation within NKDZs.