Research On Soil Physical And Chemical Properties In Typical Karst Cluster-Peak Depression Areas Of Southwest China

China is the world's largest and most widely distributed area of karst. The karst landform of southwest China is one of the most typical concentrated distributions. The recovery and restoration of fragile karst environment have been focused by domestic and abroad scholars. Guohua karst ecological demonstration zone of about1000hectares was established in2000, located in Guohua town, Pingguo county, Baise city, Guangxi. Belonging to typical karst cluster-peak depression areas, Guohua demonstration area is China's and even the world's tropical and subtropical typical karst landforms. After more than ten years of ecological restoration and rocky desertification control, the ecological environment, economic conditions and living standard of Guohua demonstration zone have been greatly improved. While the precision agriculture has become an industry today, recognizing the soil physical and chemical properties is meaningful for accelerating resional soil quality, recovery ecological environment, improve local people's living standard, and so on.Taking Longhe village, Burao village and Longrao village as Guohua study area, by using G1S, RS, and GPS, according to karst environment, the paper located the soil sampling point by GIS, surveyed soil physical and chemical indice of different soil depth, and obtained their spational positions and attribution data. Using geostatistics, the paper obtained the spatial variability characteristics and spatial distribution of soil physical and chemical indice. By using classical statistics from the elevation, slope, theckness of soil, vegetation, land size, rocky desertification, soil erosion and other karst environment factors, the paper analyzed the main influence factors of soil physical and chemical characteristics. The main results are as follows:â‘ Soil physical and chemical indice in different depth showed different spatial correlation which decreased in longer distance. Spatial autocorrelation scales of5cm,10cm,20cm and30cm of soil pH were respectively2200m,1600m,1600m and2000m; Spatial autocorrelation scales of5cm,10cm,20cm and30cm of soil electric conductivity were respectively2200m,2200m,1400m and800m; Spatial autocorrelation scales of5cm,10cm,20cm and30cm of soil Temperature was respectively1800m,1400m,600m and2000m; Spatial autocorrelation scales of5cm,10cn, 20cm and30cm of soil volumetric water content were respectively2400m2400m,2200m and2000m; Spatial autocorrelation scales of soil color and thickness were both2200m. The soil physical and chemical indice in different depth presented obvious cluster characteristics as well as isolated distribution in somewhere.â‘¡The vertical correlation of soil physical and chemical indice in different depth was high. Semi variogram theory models of each soil indice were mainly index models, globular models, and gauss models which could better reflect the spatial distribution and variation characteristics of soil physical and chemical indice in different depth. The minimum space variable ranges of soil pH soil electric conductivity, soil temperature, soil volumetric water content in different depth were respectively650m,750m,1300m,2400m,500m and850m which could be used to define the soil sampling interval.â‘¢Soil pH was mainly affected by vegetation, rock desertification degree, geological background and plot size; Soil electric conductivity was mainly affected by vegetation, geological background, rocky desertification degree and elevation; soil temperature was mainly affected by soil thickness, soil erosion, slope and vegetation; soil water content was mainly affected by rocky desertification, vegetation, soil thickness and height. On the whole, different karst environment had a significant effect in soil physical and chemical indice which showed a certain regularity and particularity in different karst environments.