The area of desertified land has increased by 27.3% from 1987 to 2000 in Maduo County,northeastern Qinghai-Tibet Plateau.Driving forces of land degradation has been extensively studied in the region.Using Factor Analysis (FA),we evaluate contribution of human activity and natural environmental change to land degradation.Four common factors were extracted in this study.The result shows that climate related other than human-related factors,are the major inducing factors of land degradation in Maduo County.Climate change and consequent change of permafrost account for 70% to the land degradation.Increasing evaporation and declining precipitation in the beginning of the growing season hamper seedling establishment.Decreasing frozen days and rising active layer lower bound make surface soil loose and less soil moisture available for plant.
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