Coupling and Coordinated Development of Urbanization and Ecological Environment in China and Its Spatio-Temporal Characteristics

The stability and health of the ecological environment are the premise of urbanization development, and promoting their coordinated advancement constitutes the goal of sustainable social development. This research employs panel data from 30 Chinese provinces and provincial-level municipalities over the period 2011–2023 to construct a comprehensive evaluation index system for urbanization and ecological environment (U-EE). The coupling coordination degree (CCD) model is used to evaluate the coordinated development level of U-EE. Combining the Dagum–Gini index and decomposition (DGID), the spatial autocorrelation model (SAM) and trend surface analysis (TSA), the evolution characteristics and changing trends of the U-EE coordination degree (D-UEE) in both time and space are explored. It is found that, first of all, the CCD model results show that D-UEE is not high overall, yet exhibits a consistent year-on-year upward trend. Secondly, the DGID results show that the intra-group differences among the four regions—namely, the eastern, central, western and northeastern regions—are decreasing year by year, among which the eastern region has the largest difference and the northeastern region has the smallest difference. In terms of inter-group differences, the east–west disparity is the largest, whereas the central–northeast difference is the smallest. Thirdly, the global Moran’s index (GMI) results show that D-UEE presents significant spatial aggregation distribution characteristics and there is a positive correlation phenomenon. Fourthly, from the perspective of the local Moran’s index (LMI), most of the regions are concentrated in the first and third quadrants, corresponding to HH and LL types, exhibiting significant positive spatial autocorrelation and clustering patterns characterized by spatial homogeneity. Fifthly, the results of TSA show that the spatial distribution of D-UEE is high in the eastern and low in the western regions, and high in the southern and low in the northern regions. Through analysis of the results, it is evident that the intra-regional gap in the country is narrowing, but the east–west gap is still the most important reason for spatial differentiation. There are still some incoordination issues between the U-EE systems, but they are continuously improving and moving in a positive direction.