Spatial spillover effects of urban forest policy on urban green production efficiency: evidence from China’s National Forest City Construction

Abstract

As environmental constraints tighten and urban green transformation continues, whether National Forest City Construction (NFCC) can improve urban green production efficiency (GPE) and generate cross-regional spillovers remains an important theoretical and policy question. Using panel data for 277 cities at the prefecture level or above in China from 2006 to 2024, this study applies a spatial Durbin difference-in-differences (SDM-DID) model to estimate the effect of NFCC on GPE. The results indicate that NFCC significantly increases GPE, and this finding remains unchanged across a range of robustness checks. Spatial effect decomposition yields direct, indirect, and total effects of approximately 1.28%, 3.33%, and 4.61%, respectively. These estimates indicate that NFCC improves GPE in designated cities and generates positive spillovers to spatially connected cities through ecological externalities, diffusion of green governance practices, and regional factor interactions. The moderating effect analysis further shows that higher levels of green technological innovation (GTI) and industrial structure upgrading (IND) strengthen the local effect of NFCC on GPE, suggesting that stronger innovation capacity and a more advanced industrial structure enhance the effectiveness of NFCC implementation. The heterogeneity results show that both the local policy coefficient and the spatial policy coefficient are positive and significant for inland cities, whereas only the spatial policy coefficient is significant for coastal cities. These patterns suggest that policy responses differ across locations. Overall, this study reveals the local effects, spatial spillovers, and enabling conditions of NFCC, providing empirical evidence for forest city development and coordinated regional ecological governance.