Relationships between rocky desertification and spatial pattern of land use in typical karst area, Southwest China

Karst rocky desertification is a typical type of land degradation in the Southwest China. An attempt was made to study quantitatively the relationships between rocky desertification and spatial pattern of land use through applying spatial analysis of Geographical Information System in Nandong underground river system, a typical karst area, Southwest China. The spatial distribution of rocky desertification and spatial pattern of land use were obtained from interpreting Landsat Images in Nandong area in 2007 by supervised classifications, and verified and rectified through field survey. The results indicate that: (1) the total land deserted area covers 378.3 km², or 23.4% of the total area, of which intense, moderate and slight rocky desertification covers 269.46, 54.2, and 54.63 km², respectively, in Nandong area. (2) There is an obvious effect of spatial pattern of land use on rocky desertification. With the increase of elevation and slope, there is a higher occurrence ratio of rocky desertification in the cultivated land and grass land. Also, more than half of total rocky desertification was dominated within the areas of 4 km from the construction land, and 97% of total rocky desertification was dominated within the areas of 10 km from the construction land in Nandong area. And what can be known from the data is that the primary effect distance of human on rocky desertification from the construction land is 4 km, and the farthest effect distance of human on rocky desertification from the construction land is 10 km in Nandong area.