Huanxian County of Gansu Province

located in the south part of farming-pastural ecotone

was selected as a study site

aiming to quantitative analyze the natural and anthropogenic factors of desertification inthis region.Principal component analysis was conducted on 16sets of data from 1949to 2009.The resultshowed that during the process of desertification

the contribution rate of combined natural and anthropogenic factors could be account for up to 49.64%

natural factors only contributed 21.79%

and anthropogenicfactors accounted for 10.89%

respectively.This demonstrated that natural and anthropogenic factors weredominating factors of desertification in Huanxian County.In addition

human activities played a decisive rolein desertification although climate condition also imposed substantial impacts.The effects of natural factors

including rising temperature

less rainfall

lower humidity

and higher evaporation potential restricted theplant growth and decreased vegetation coverage as well as the soil erosion resistance ability.In the otherhand

stronger winds and torrential rains could accelerate soil erosion.Anthropogenic factors including rapidly increased total population

oversized agricultural population

and subsequent excessive developing andgrazing are the direct factors of desertification in the study site.