Impact of establishing urban agglomerations on land use efficiency: a quasi natural experiment based on the approval of national level urban agglomeration planning.

Land use efficiency is an indicator that measures the level of regional land resource allocation and optimization. The influence of policies tends to lead to the restructuring of regional land use and allocation in urban agglomerations, and the degree of optimization in land use efficiency has become a critical component in evaluating policy performance. In light of this, it is particularly necessary to clarify the theoretical relationship between the establishment of urban agglomerations and land use efficiency and to understand their underlying mechanisms. Additionally, it is particularly important to summarize the spatial differentiation of their effects. This study constructed a theoretical analysis framework to investigate the impact of urban agglomeration establishment on land use efficiency, deriving from the policy pathways of establishing urban agglomerations. It also explored the mediating roles of public service supply, industrial agglomeration, and technological innovation, as well as the moderating effects of geographical, institutional, and economic disparities. Building upon this foundation, the approval and implementation of national-level urban agglomeration planning were treated as a quasinatural experiment for further investigation. Based on the panel data of 244 prefecture-level and above cities in China from 2009 to 2020, this study used a staggered difference-in-differences model to empirically test the impact of establishing urban agglomerations on land use efficiency. In addition, the mediating effects were tested based on three types of pathways, and heterogeneity effects were examined using a 'center-periphery' approach with multiple types of spatial distances to analyze the mechanisms of influence. The study findings were as follows: (1) The establishment of urban agglomerations had a significant and positive impact on land use efficiency, and this effect continued and was strengthened after the establishment of national-level urban agglomerations. (2) The impact of establishing national-level urban agglomerations on land use efficiency was mediated by three factors: public service provision, industrial agglomeration, and technological innovation. However, after adjusting for policy timing, only the mediating effects of industrial agglomeration and technological innovation remained, and their effects were consistent with the establishment of national-level urban agglomerations. (3) The promotion of land use efficiency by national-level urban agglomerations exhibited spatial heterogeneity, with the effect being slightly suppressed as geographic and institutional distances increased. After adjusting for policy timing, this promoting effect was shown to exhibit spatial heterogeneity, being slightly suppressed only with increasing economic distances. Based on these findings, policy recommendations are made to further strengthen regional public investment through the allocation of resources in urban clusters, align industrial agglomeration and technological innovation with rational industry layout and division of labor, and enhance regional institutional reforms and integration to achieve regional balance. [ABSTRACT FROM AUTHOR]