Does urban cluster promote the increase of urban eco-efficiency? Evidence from Chinese cities

In this paper, we first explore the spatial distribution of 273 cities with the index of urban clustering and measure the urban eco-efficiency employing the data envelopment analysis in China from 2003 to 2015. We then comparatively analyze the impacts and mechanisms of urban cluster on urban eco-efficiency under a multidimensional framework. The results demonstrate that the degree of urban clustering and the urban eco-efficiency in China have generally improved, and the improvement of urban cluster is conducive to enhancing urban eco-efficiency. There is a “core-periphery” spatial structure in the process of urban cluster development, and the impact of urban clustering on the eco-efficiency in core cities is stronger than in the periphery cities. Urban cluster benefits urban eco-efficiency through the decentralization effect and structural optimization effect. The decentralization effect is heterogeneous: urban cluster effectively decentralizes the diseconomy of large cities but not small- and medium-sized cities. Similarly, the structural optimization effect is not uniform. For large cities, this effect mainly improves the eco-efficiency by affecting tertiary industry, whereas for small- and medium-sized cities, it mainly improves the eco-efficiency by affecting the secondary industry.