Impacts of land use and land cover changes upon organic productivity values in Karst ecosystems: a case study of Northwest Guangxi, China

Karst areas are one of the most fragile regions in the world. The Karst environment is very common in southwest China with severe poverty and environmental degradation. Therefore, it is necessary to monitor the Karst ecosystem and its ability to provide goods and services for society. In this paper, we analyzed the spatial distribution of organic productivity values (OPV) in Northwest Guangxi, China in 1985, 1990, 2000, and 2005 using remote sensing and geographic information system techniques. OPV showed a decreasing trend in the last 20 years though there were fluctuations. OPV was 184.85, 117.53, 163.66 and 177.25 million Yuan in 1985, 1990, 2000 and 2005, respectively. Woodland and shrub were the two largest contributors to total OPV. They accounted for 70.51%, 69.13%, 73.92% and 66.23%, respectively, in those four years. Conversely, OPVof residential and barren rock was low with a percentage of 0.70%, 0.56%, 0.57% and 0.90%, respectively. Spatially, OPVis higher in the west than in the east. However, OPV increased in typical Karst areas but decreased in non-Karst areas. Our study indicates that ecosystem conditions in Karst areas had improved because of the application of rocky desertification control policies.