Background Karst areas with thin soil are ecologically fragile and highly susceptible to rocky desertification, leading to soil erosion and posing a great challenge to production, life and social-economic development. Therefore, it is necessary to accurately and timely monitor the status of ecological environment changes and influencing factors in karst areas. Guilin belongs to a typical karst area with fragile regional ecological environment, and systematic monitoring and analysis of the changes in ecological environment quality and its influencing factors in Guilin is of great significance to the study of the changes in ecological environment quality in typical karst areas.
Methods The study takes Guilin city, a typical region of karst landscape, as an example. In order to quantitatively analyze the changes of ecological environment quality in Guilin city, we combined the Landsat images (2000, 2005, 2010, 2015 and 2021) and Principal Component Analysis (PCA) to construct karst remote sensing ecological index (KRSEI) for evaluation and analyzing the ecological change and driver factors in Guilin karst region in last decade, combining with the slope, bedrock exposure rate and traditional vegetation cover, dryness, heat and humidity.
Results 1) The sum of the contributions of the eigenvalues of the first three principal components of the KRSEI exceeds 80%, which contains most of the effective information and significantly improves the processing efficiency of remote sensing information. 2) From 2000 to 2021, the ecological grade of forest land cover in Guilin city is the best, followed by grassland, then arable land, and the ecological environment quality of construction land is the worst, and the change of land cover is an important reason for the change of ecological environment quality in Guilin city. The ecological environment quality shows the trend of “rising-declining-rising”, and the overall rising trend, which is caused by the effective control of the expansion trend of building land and the yearly increase of the greening rate in urban and rural areas. 3) Greenness, humidity, and topography indicators can improve the ecological environment, and the increase of greenness and humidity is the primary reason for the improvement of the overall ecological environment quality in Guilin; dryness, heat, and stony desertification indicators negatively affect the ecological environment, and the increase of dryness and stony desertification is the main reason for the decrease of the ecological environment quality locally.
Conclusions The study reveals that in soil and water conservation and ecosystem restoration in karst areas, we need to focus on increasing vegetation cover, reducing the expansion of building land and the degree of stony desertification to improve the overall quality of the ecosystem.
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