全球变化与荒漠化

文章以干旱、半干旱地区沙质荒漠化为例，分析了其成因过程、发展趋势。指出干旱是荒漠化的原因，而频繁、过度的人为活动则更加剧其发展。在中国北方荒漠化土地的成因类型中，有３０．１％是由于过度放牧，２６．９％是由于过度开垦，３２．７％是由于过度樵采，有９．６％是由于水资源利用不当，有０．７％是由于工矿交通建设过程中不重视环境保护而造成的。所以合理利用土地和采取相应的防治措施是防治荒漠化的重要途径

GLOBAL CHANGES AND DESERTIFICATION

Desertification is not only one of the most serious environmental problems in the world but also a main content of global changes. Its importance is affirmed by the international convention to combat desertification signed in 1994. Based on definition given by the convention and on China′s situation, desertification as a process of land degradation is manifested itself by desert like landscape and is triggered by the interaction between irrational human activites and fragile ecosystems. Sandy desertification is one of the main types of desertification in North China, which is indicated by drought, frequent winds, exposed surface and loose sand composition of topsoil. Especially, continual aridization of North China in the recent times is responsible for the development of desertification. The sandy desertification in the arid and semi arid regions is caused mainly by human factors, i.e., 30 1% by overgrazing, 26 9% by over reclamation, 33 7% by excess woodcutting, 9 6% by misuse of water resources and 0 7% by industrial mining and communication activities. Based on aerial photos and landsat in different time, it is shown that desertification trends to spread, for example, the sandy desertified lands have already increased by 17838.3 km 2 from 1975～1987, especially, it is more distinct within the dry farmlands in the sandy steppe region.