Impact of human activities on land use in Dafang county, Guizhou Province

Under the background of climate change, it has important significance to study the temporal and spatial changes of land use in ecologically vulnerable areas, which also can reveal the regularity of land use change and influence of human activities. Rocky desertification disaster in the main forms of water loss and soil erosion badly threats land ecological security in karst areas of South China. Dafang county is located in the northwest of Guizhou Province, China, which is one of the most serious areas of rocky desertification, whether in total area or degree of rocky desertification. In this study, Dafang county was chosen as the research area. We study temporal and spatial variations of regional land use in order to provide reference for land use structure optimization and land management in karst areas.In this work, the land use classification of TM images in 1988, 2001 and 2009 in Guizhou Province is carried out using the method of partition-layered-individual wavebands. Based on the classification results, we analyze the temporal and spatial variations of images, including spatial changes of land use types and quantity changes and effects of different altitudes and slopes on spatial and temporal variations of land use types. We also discuss the influence of human activities on these variations. The results show that the total area of cultivated land was reduced by 33%, the area of forest land increased by 34%, grassland area decreased by 11%, and the area of construction land increased by 715%, respectively. The elevations of forest land, cultivated land, grassland, construction land sequentially decrease. The influence of altitude on cultivated land and forest land is relatively large. Except for the forest land, the effect of slope on the other three kinds of land use change is relatively little. Overall, human activities are the main factors influencing the change of land use quantity and spatial pattern in Dafang county, and the natural factors such as elevation and slope have significant effects on the expansion and reduction of cultivated land and forest land.