With a subtropical climate, Guangxi has a typical karst landscape. Land degradation has become a serious environmental issue due to its high vulnerability caused by the joint effect of natural settings in geology, topography, rainfall, and vegetative cover, as well as human activities such as deforestation. Its eco-environment has deteriorated over recent years while cultivated land is disappearing quickly. This, in turn, has exacerbated the poverty level in rural areas. In this study we monitored the spatial distribution of land degradation and its temporal evolution using Landsat TM/ETM images of the late 1980s, mid-1990s and late 2000 (for simplicity, we identified them as 1985, 1995 and 2000). We also explored the causes of its initiation and expansion. Through constructing regression models using all the relevant variables and considering the lagged effects as well as fixed effects, we quantified the exact role of different factors in causing land degradation in the study area with new findings. Based on these results we further analyzed the hazard of land degradation and proposed a few practical rehabilitation measures, including forestation, infrastructure projects, and ecological projects. The findings in this study are invaluable in preserving, restoring, and reconstructing the degraded environment in Guangxi and other karst areas in Southwest China while alleviating poverty in rural areas.
Urban expansion continues to accelerate and herewith changes profoundly the Earth surface and results in many environmental consequences, such as affecting ecological sustainability in the rapid urbanized area of China. Therefore,it is of significance to map the intensity and spatial pattern of urban expansion and assess its environmental effects. The objectives of this paper are three-folds: (1) using two-period Landsat TM/ETM images from 1988 to 2000, urban
expansion in Mianyang prefecture of China was mapped out. Results showed that urbanization in Mianyang increased dramatically with an expansion rate of 76.8%. Most of the new urban development was done at the cost of arable land. (2) The study found determinants of urban expansion, and concluded that urban expansion was constrained by biophysical as well as social-economic factors. The change of industrial structure in downtown area and the improvement of
transportation were predominant drivers for urban expansion. (3) Combining with statistical environmental-data, the paper analyzed environmental effects of urban expansion in Mianyang, such as urban heat island effect (UHI), water pollution and acid rain.