Spatial correlation analysis of rocky desertification and soil types in karst area：A case study of Guizhou Province

This paper takes Guizhou Province, a typical representative of karst landforms in southwest China, as the research object. Guizhou Province is located in the southeastern part of southwest China, and the eastern part of Yunnan-Guizhou Plateau. The landform is dominated by plateau mountains, and its topography is high in the west and low in the east. It is inclined from the central to the north ,east and south, and the structure is distributed in three steps distribution. The average elevation is about 1,100 m, the climate is warm and humid. It belongs to the subtropical humid monsoon climate with an average annual temperature of 14-18 ℃and an annual average precipitation of 1，100-1，300 mm.In this paper, by referring to the study of rocky desertification by relevant scholars, the degree of rocky desertification was divided into 5 grades, namely, non-rocky desertification, mild rocky desertification, moderate rocky desertification, severe rocky desertification and extremely severe rocky desertification. Then, the spatial distribution map of rocky desertification in Guizhou in 2010 was obtained. The soil type map of Guizhou soil chronicle was vectorized in ArcGIS, and finally a digital map of soil type distribution was obtained by thematic mapping. The spatial correlation between karst rocky desertification and soil types in Guizhou Province was quantitatively analyzed by using spatial analysis function, combined with the principle of map algebra, and the transformation matrix, combined with slope, elevation and other information, so as to provide scientific basis for the prevention and control of rocky desertification in different soil types.The incidence rate of rocky desertification was used to analyze its occurrence, and it was concluded that the occurrence rate of rocky desertification was the highest in karst area, reaching 46.41%,followed by yellow brown soil of 43.32%.The comprehensive order was, rocky soil > yellow brown soil > mountain meadow soil > brown soil > red soil > coarse bone soil>lime soil>yellow soil>purple soil>paddy soil> fluvo-aquic soil.In order to further analyze the incidence rate of rocky desertification of each grade, the statistical analysis of the incidence rate of various soil types show that the study area is generally dominated by moderate rocky desertification, and the incidence rate of rocky soil is the highest in terms of extremely severe, severe, moderate and mild rocky desertification. Secondly, the incidence rate of calcareous soil of moderate and mild rocky desertification were more than 10%, the limestone soil accounts for the largest area of soil types in the karst area of the study area. According to the analysis of comprehensive area and incidence rate, when discussing the incidence rate, the incidence rate of rocky soil is the highest.at different levels, and the order is, rocky soil > brown soil > lime soil> yellow brown soil > mountain meadow soil > coarse bone soil> yellow soil> paddy soil> purple soil> red soil > fluvo-aquic soil. The incidence rate of rocky desertification of all soil types, except for yellow soil, purple soil, rice soil and tidal soil, was relatively low, while the incidence rate of other soil types was relatively high, and the rocky soil occupied the dominant position.It is conclusion that,(1) The development and distribution of karst rocky desertification in Guizhou is largely controlled by the lime soil with the parent material being carbonate rock. (2) Soil parent rocks, physical and chemical properties, lithological composition factors and other factors have affected the occurrence of rocky desertification to a certain extent. For coarse bone soil areas, more attention should be paid to the prevention of rocky desertification. For areas with high incidence rates such as the brown soil and yellow brown soil ,more attention should be paid to the prevention and treatment of potential rocky desertification area. It is necessary to comprehensively consider that the overall layout of ecological environment governance of rocky desertification.(3) In the future, the protection and control of ecological and environmental problems such as rocky desertification, can be carried out according to different rocky desertification grades and the mutual relations and characteristics between rocky desertification and various natural environment.