Has the ecological civilization pilot zone policy improved the urban land green use efficiency?-A case study of the Yangtze River Delta urban agglomeration

Urban land greening efficiency is an essential indicator for assessing the balance between regional ecological sustainability and economic development. This study evaluates urban land greening efficiency in China's Yangtze River Delta region from 2007 to 2021 using a Slack-Based Measure (SBM) model that incorporates undesirable outputs. The empirical results indicate that the average urban land greening efficiency significantly increased from 0.345 in 2007 to 0.742 in 2021. Furthermore, the impact of the Ecological Civilization Pilot Zone (ECPZ) policy on urban land greening efficiency was assessed through a Difference-in-Differences (DID) approach. The findings demonstrate that the ECPZ policy contributed to an approximate 13% improvement in urban land greening efficiency. Additionally, an examination of underlying mechanisms reveals that the ECPZ policy enhances urban land greening efficiency primarily by stimulating green technological innovation and optimizing industrial structures in the Yangtze River Delta region.