Evaluation Of Ecological Environment Quality Based On A New Karst Remote Sensing Ecological Index In Qiannan Prefecture

Ecological environment is the material basis and important guarantee for human survival and development.Karst area topography is broken,shallow soil layer,surface water is easy to drain,the ecological environment is extremely fragile.In recent years,the deepening of human reconstruction of nature and the acceleration of urbanization have caused serious threats to the ecological environment quality in karst areas.It is an important task to systematically monitor and evaluate the ecological environment quality in karst area and explore its change rule in the new era.Remote sensing technology has the advantages of high resolution,wide range and real-time,so it has important practical significance and feasibility to use remote sensing method to monitor ecological environment changes in karst areas.In this study,a typical karst landform gathering area in Qiannan Buyi and Miao Autonomous Prefecture of Guizhou Province(hereinafter referred to as Qiannan)was taken as the research object.Landsat remote sensing image was used as the main data source.Based on principal component analysis,ecological factors such as greenness,humidity,bedrock exposure,driness and heat were coupled.Karst Remote Sensing Ecological Index(KRSEI)was established to monitor and analyze the spatial-temporal variation trend of ecoenvironment quality in Qiannan Prefecture.In addition,combined with land cover data,land cover change monitoring methods and ecological environment statistical analysis methods were used to deeply analyze the ecological effects of land cover change and the driving mechanism of eco-environmental quality change in Qiannan Prefecture.The main contents and conclusions are as follows:(1)From 2000 to 2020,the trend of changes in various ecological factors and KRSEI index was significant.The greenness factor and humidity factor showed an overall downward trend,with a decrease of 40.7% and 42.2% respectively;The exposed rate of bedrock,dryness factor,and heat factor showed an overall upward trend,with increases of 20.7%,120.5%,and50.9%,respectively;The average KRSEI index first slightly increased and then continued to decline,showing an overall downward trend,decreasing by 31.5%.The ecological environment quality in Qiannan Prefecture has significantly decreased,showing an overall deterioration in space.(2)From 2000 to 2020,the surface cover pattern of Qiannan Prefecture underwent significant changes,mainly characterized by the conversion of a large amount of forest land into farmland and construction land,resulting in a significant reduction in forest land area and an increase in farmland and construction land area.Among the main types of surface cover in Qiannan Prefecture,the ecological quality of forest land cover is the best,followed by grassland and farmland,while the ecological quality of construction land is the worst;The significant conversion of forest land into arable land and construction land is an important reason for the decrease in ecological environment quality.(3)The sum of the contribution rates of the first three principal components’ eigenvalues is above 90%,and the contribution rates of the first principal component PCA1’s eigenvalues are all above 70%,indicating that the KRSEI index has high rationality and accuracy.By analyzing the fitting equation parameters between various ecological factors and the karst remote sensing ecological index,the results showed that the greenness factor and humidity factor played a promoting role in the ecological environment quality of Qiannan Prefecture,while the bedrock exposure rate,dryness factor,and heat factor played a restraining role in the ecological environment quality of Qiannan Prefecture;And the greenness factor is the main promoting factor,while the bedrock exposure rate is the main inhibiting factor.(4)The slope of the fitting equation between forest cover area and greenness factor is greater than 0.5,and the correlation coefficient R 2 Both are greater than 0.8,showing a strong linear positive correlation;The slope of the fitting equation between forest cover area and bedrock exposure rate is less than-0.5,R 2 They are also greater than 0.8,showing a strong linear negative correlation;The change in forest cover area causes changes in ecological factors,which in turn affects the ecological environment quality of Qiannan Prefecture.The ecological environment quality of Qiannan Prefecture is largely influenced by changes in surface cover.