Assessment on ecosystem fragility of karst mountain areas based on synthetic method— A case study in Puding Country, Guizhou Province

Based on principle component analysis and taken 13 villages in Puding Country, Guizhou Province as the example, the authors analyze 9 variables influencing ecologic al frangibility, and calculate the fragility with Euclidean distance formula. The results show that the cultivated area is the most import ant factor in determining the ecological vulnerable degree and its weighted value is up to 0.189, and the average gradient is the second factor. Among the 13 villages, there are 7 villages falling into severely or extremely fragile areas. Especially in Pianpo village whose vulnerable degree is maximum both in potential fragility and stress fragility. The study area evaluated as a whole is classified as severely fragile areas with an ecological fragile degree of 0.653. According to the standard of estimation grade, the authors find the Puding Country belongs to moderately fragile degree and we must take measures to recovery the ecoenvironment by controlling the land use for agricultural.