Abstract: Studying the spatio-temporal evolution process and changing factors of ecological quality in Changshou District of Chongqing is of great significance for the ecological construction and restoration of the Three Gorges Reservoir area. In this study, we utilized Landsat-5 TM images and Landsat-8 OLI images from 2002 to 2021 and constructed the Remote Sensing Ecological Index (RSEI). With the RSEI, we investigated the evolution of ecological quality in Changshou District from both temporal and spatial perspectives. Additionally, we employed the random forest model regression to analyze the correlation between ecological quality and potential driving factors. Our findings revealed the following: 1) The average RSEI in Changshou District declined from 0.642 7 in 2002 to 0.566 5 in 2006. However, since 2010, the average RSEI has exhibited a steady increase, indicating an overall improvement in ecological quality after a previous deterioration. 2) The areas with better ecological quality mainly concentrates in higher elevation regions, whereas the industrial park, chemical industry park, and urban residential areas along the Yangtze River exhibited relatively poorer ecological conditions. 3) Over the period from 2002 to 2021, Changshou District experienced an improved area of 628.838 km², accounting for 44.16% of the total, and a degraded area of 183.269 km², which represented 12.87% of the total. The overall effect of ecological quality improvement was evident. 4) Through random forest regression analysis, we identified elevation and population density as the primary potential driving factors influencing RSEI changes. Moreover, human activities and terrain factors played a dominant role in regional ecological changes. As a result, RSEI and the random forest model can be effectively utilized for evaluating the ecological quality of both Changshou District and similar areas within the Three Gorges Reservoir region.

Key words: ecological quality, RSEI, random forest, space-time variations, driving factors, Three Gorges Reservoir area, Changshou District