中国北方农牧交错区土地荒漠化的环境脆弱性机制分析

在综合分析中国北方农牧交错区自然 、经济和社会环境的基础上，概括出导致该地带土地 荒漠化的生态环境脆弱性机制：①脆弱的自然条件奠定了特殊的地貌格局和脆弱的地表物质基础，受东亚季风影响的气候条件是土地荒漠化的自然驱动力。②人类不合理的经济活动是土地荒漠化的直接推动力。③不利的社会因素加快了土地荒漠化的进程。

ANALYSIS ON THE ECO-ENVIRONMENTAL VULNERABLE MECHANISMS OF LAND DESERTIFICATI ON IN THE FARMING-PASTORAL ECOTONE IN NORTH CHINA

Since the current monsoon formed in mid Pleistocene, a vast transitional zone from the semi arid area to arid area, i.e. a farming pastoral ecotone, has formed from Hulunbeir on the western slope or Daxinganling in the north, and extended southwestward through southeast Mongolia, north Heibei and north Shanxi to north Shaanxi and Erduosi Prairie in north China. Its agricultural and pastoral areas lay in spatial distribution and shift in temporal sequence. Located in a vulnerable ecological environment zone, the farming pastoral ecotone in north China is charaterized by the serious ecological environment vulnerability, poor carrying capacity, obvious degeneration and frequent occurrence of natural disasters. Based on the synthetic analysis on the ecological environment in the farming pastoral ecotone, in this paper, the eco environmental vulnerable mechanisms of land desertification are discussed. The results are as follows: (1) The peculiar geomorphic pattern and the surface substance base for desertification are steeled by the vulnerable natural conditions, and the land desertification in the farming pastoral ecotone is driven by the climatic conditions which is influenced by east Asian monsoon; (2)The irrational human activities are the direct motive forces for the land desertification; (3)The process of land desertification is sped up by the disadvantageous social factors. Land dertification is a synthetic effect of the vulnerable natural conditions and the irrational economic and social factors on the vulnerable ecological environment.