Regional differences and dynamic evolution of urban land green use efficiency within the Yangtze River Delta, China

It is urgent and important to explore the regional differences and dynamic evolution of urban land green use efficiency (ULGUE) in the context of green development. The SBM-Undesirable model was used in this study alongside coefficient of variation and kernel density estimation to analyze the spatial-temporal pattern and dynamic evolution of ULGUE in 25 cities across the Yangtze River Delta, China from 2004 to 2015. Carbon emissions resulting from the urban construction land and happiness index were placed into the ULGUE evaluation index framework. In terms of regional differences, ULGUE in the Yangtze River Delta appears to have trended upward from 2004 to 2015. The undesired output indicators representing average ULGUE were 0.7131 and 0.7323, respectively, while the average values not including the undesired output indicators were 0.7612 and 0.8578. The Yangtze River Delta can be divided into advantaged, flat, and disadvantaged areas. Seven cities belong to the advantaged areas, fourteen cities to the flat areas, and four cities to the disadvantaged areas. The ULGUE of the whole and different types of urban areas in the Yangtze River Delta shows a highly skewed distribution and different degrees of polarization with time. Policy-wise, it is essential to completely consider the country?s resources and environmental conditions, especially in inter-city, urban, and rural-to build a beautiful China and to contribute meaningfully to the protection of the global eco-environment and food security.