Spatio-temporal characteristics and mechanism of ecological degradation in a hilly southern area—a case study of Dongting Lake Basin

Understanding the spatio-temporal characteristics of ecological degradation and its mechanism is the key to implementing national land space ecological restoration. Currently, there is a lack of knowledge about identifying ecologically degraded areas from a structure–function angle. This paper used the Dongting Lake Basin (DLB) as the research area, with the landscape pattern index and InVest model utilized to analyze the landscape distribution characteristics and ecosystem service functions in 2000 and 2018. Based on this, a fuzzy inference approach and geographic detectors were used to explore the characteristics and driving mechanism of ecological degradation in the DLB from 2000 to 2018. The results found are the following: (1) The overall landscape of the DLB was fragmented, the landscape shape tended to be complex, the degree of aggregation declined, and the landscape types were more discrete than before. In terms of the landscape-level index, the overall indicators of the landscape pattern in the DLB showed little change from 2000 to 2018, and the overall landscape pattern change was reasonably stable. (2) The three ecological services exhibited prominent spatial distribution features during the study period. In particular, food supply services showed a steady upward trend, while habitat quality and carbon storage services generally declined. (3) The ecological degradation in the DLB demonstrated striking spatial and temporal differences during the study period, and the ecological situation improved. The ecological degradation areas were mainly distributed in urban areas with denser populations and a higher level of urbanization, while the ecological restoration areas were mainly in the mountainous and hilly areas far away from the urban centers. (4) Among the influential factors, the production potential of urban land and farmland is the main factor that affects the ecological environment degradation and spatial distribution difference in the DLB. The interactive detection results indicate that the driving mechanism exhibits a two-factor enhancement or nonlinear increase.