干旱区生态环境知识资源中心

Land desertification is one of the most serious environmental and social-economic problems in the North China. The processes of desertification mainly have being controlled by the interaction of human activities and fragile eco-environment, that means the pattern and intension of landuse are major factors for development or reverse of desertification. Because of the increasing pressure of population, the rangeland in the North China has being cultivated decade by decade, which changed landuse from grassing to cropping in a large area and destroyed the natural vegetation cover. The result is to let the wind erosion become easier and the desertification has developed very quickly. According to the statistics of desertified land areas with different landuse purposes, the human impact on the contributing to the desertification in the rangeland region were as 25% of over-cultivation, 28% of over-grassing, 32% of over gathering firewood and 8% of mis-used water resources. The occurrence and development of desertification in the North China is accompanied by human civilization history, especially in recent one hundred years the development of desertification is quickest. Desertification processes aggravate soil wind erosion, deteriorate soil physical and chemical properties, reduce land productivity, cause great economic loss and seriously affect livelihood and living environment. During last 5 decades, desertified land has expanded continually in the North China, which total area has reached over 350,000 km(2) by middle 1990's. Based on the remote sensing monitoring, we found that the growth rate of desertified land has being increased decade by decade like as the annual average spread area has increased 1,560 km(2) of among 1950's and middle 1970's to 2,100 km(2) of between middle 1970's and late 1980's, to 2,460 km(2) of last decade. Accordingly, in-depth study of anthropogenic effects, in particular the effect of over-rangeland use on the desertification development has an important practical significance to elucidate the mechanism of desertification occurrence, enrich the theory of desertification study and formulate the policies and measures to combat desertification. But some successful models of combating desertification have improved that where the reasonable landuse has been adopted over some years, the sandy desertified land has reversed and can be used again for more effective farming or grassing. Desertification is one of the most serious environment and socioeconomic problems in the world today and China is one of the countries suffering from serious desertification, especially in the north China where sandy desertification is developing rapidly over large areas and receiving widespread attention. According to human activity and socioeconomic characteristics and their interactions, through nearly 20 years of theoretical research and practices, we give a conception of sandy desertification: sandy desertification is the process with sand drift activity as main mark occurred in arid, semi-arid and partial sub-humid areas resulting from human irrational economic activities and inharmony between natural resources and environment (Zhu Zhenda, Wang Tao 1993). The occurrence and development of sandy desertification in the north China is accompanied by human civilization history, especially in recent one hundred years the development of sandy desertification is quickest.

Sandy desertification processes aggravate soil wind erosion, deteriorate soil physical and chemical properties, reduce land productivity, cause great economic loss and seriously affect livelihood and living environment of the mixed agropastoral region in the north China. Accordingly, in-depth study of anthropogenic effects, in particular the effect of land use on the sandy desertification development has an important practical significance to elucidate the mechanism of sandy desertification occurrence, enrich the theory of desertification study and formulate the policies and measures to combat sandy desertification.