Abstract:

According to the latest national investigation in 1999, the area of desertification in China is 267.4×10 4km 2, accounting for 27.3%of the whole territory. In China, the interlock area of farming and pasturing in Semi-arid region is the main region which is affected by desertification seriously. In this paper, in order to analysis the intensity of natural and human activity in desertification process, the Yijinhuoluo County which was located in the interlock area of farming and pasturing was selected as a case study area. On the basis of abundant data from 1959 to 1999, the population quantity, population density, population natural growth rate, agriculture and non-husbandry population, non-agriculture and non-husbandry population, livestock quantity, cultivated land, irrigated land, grain planting land, forest land, afforestation land, total production value of agriculture and husbandry, annual precipitation, annual mean temperature, annual relative humidity, the day of gale, the days of velocity above 5m·s^-1, the days of sandstorm and annual mean wind speed were choosen and the principal component analysis method was used to measure the intensity of nature and human activity factors quantificationally. The results showed that in the process of the desertification process, 53.8% was caused by anthropogenic activity, 10.0% was caused by nature factors, and 23.4% was caused by anthropogenic activity combined with nature factors in Yijinhuoluo County. In the study area, the main anthropogenic factors included population(number, increasing rate), forest land and planting land area, the nature factors were annual preicipitation, annual mean temperature, the day of gale and the days of velocity above 5m·s^-1. Comparing the anthropogenic factors and land sandy desertification, it was found that the anthropogenic factors had two effects in the process of desertification, in which it can accelerate the desertification process in some times, but in another period it can restrain the desertification process. By reducing the population natural growth rate, enlarging the area of irrigated land and forestry land, and increasing the meliorated and artificial grassland, the desertification can be controlled easily.

Key words: Sandy desertification, Nature factors, anthropogenic factors, Quantitative analysis, Ordos Plateau, Yijinhuoluo County