The coordinated relationship and interactive response between urban quality of life and eco-efficiency in China

It is crucial to clarify the interaction mechanism between quality of life (QOL) and eco-efficiency (EE) to achieve high-quality urban development. This study investigated the complex and dynamic interaction and coupling process between QOL and EE. By constructing two evaluation index systems, this study obtained the values of QOL and EE levels in 282 cities from 2008 to 2020. Then, the interactive relationship between QOL and EE was investigated from two perspectives: static coupling and dynamic coupling. The different development types were classified according to the regional differences between them. The results show that: (1) From 2008 to 2020, the value of QOL gradually increased, while the EE exhibited a "V-shaped" change. Medium to high levels of QOL were located in cities in the eastern coastal area, while low levels were distributed in the western, central and northeastern regions. Furthermore, medium to high levels of EE were distributed in cities in the eastern coastal and southwestern regions, whereas low levels were found in the central and northwestern regions; (2) Overall, the coupled coordination of QOL and EE got better from 2008 to 2020, showing that the relationship between them was close and that the coordination gradually got better. Consequently, the spatial change of the coupled coordination was more pronounced, the number of mildly uncoordinated cities was gradually decreasing, urban development was shifting from uncoordinated to coordinated, and the clustering characteristics of the coupled coordination degree were consistent with the spatial change characteristics; (3) Moreover, there was a Granger causality relationship between QOL and EE. This means that the degree of their mutual influence increased over time, while their development became less dependent on inertia, with obvious interaction characteristics; and (4) The values of integrated QOL and EE were separately clustered and combined with the type of coupled and coordinated urban development based on their development stage. Therefore, the research area was divided into three types: "optimization and upgrading," "continuous improvement," and "cultivating development."