The dynamic changes of eco-environmental quality in Dongting lake wetland during 1990-2020, China

Dongting Lake is a globally significant wintering ground and one of the 200 most significant ecological areas. However, the eco-environmental quality (EEQ) of Dongting Lake Wetland (DLW) has been largely decreased due to intensive anthropogenic and natural stressors during the past decades. Here, we calculated the remote sensing ecological index (RSEI) and analyzed the spatial autocorrelation of DLW from 1990 to 2020 using Landsat TM/OLI remote sensing data. We also used the Geo-detector model (GDM) to quantitatively reveal the driving factors and their interactions with EEQ. Our results showed that: (1) the RSEI values ranged between 0.45 and 0.55 indicating a medium level of EEQ. The EEQ showed a first decreasing and then fluctuating increasing trend during 1990-2020, and the spatial distribution of EEQ was general higher in the eastern while lower in the western DLW. (2) The spatial distribution of EEQ was positively correlated and exhibited a cluster pattern. The High-High cluster areas were predominantly grassland (RSEI = 0.572), while the Low-Low cluster areas were characterized by phragmites (RSEI = 0.388) and mudflats (RSEI = 0.474). (3) The interactions between internal and external factors showed synergistic effects on EEQ, with vegetation coverage (q = 0.417) and landscape pattern (q = 0.347) were the main external driving factors of EEQ. Our results imply that the priority of improving the EEQ of DLW should focus on the protection and restoration of plants especially for grassland.