1976—2007年青海省刚察县土地沙漠化驱动力分析

Driving Forces of Land Aeolian Desertification in Gangcha County of Qinghai Province,China,during 1976-2007

土地沙漠化是青海湖沿岸地区最严重的生态环境问题之一。本文选取青海湖北岸的刚察气象站1958—2007年的气象数据和刚察县1976—2007年的社会经济资料,对近30年来刚察县土地沙漠化的驱动力进行主成分分析。结果表明,1976—2007年,刚察县沙漠化土地面积的增加是自然因素和人为因素综合作用的结果,尤以年平均风速和耕地面积变量的贡献率最大。刚察县沙漠化土地的扩张在不同时间段的影响因素不同。1976—1987年,沙漠化面积的扩张是气温逐渐回暖、降水回升的过程中人为因素影响的结果;1987—1995年,沙漠化土地增加了17.28km2,沙漠化土地的扩张是自然因素和人为因素叠加的结果,以自然因素为主导,人为因素起加剧的效果;1995—2007年,在暖湿、风速降低的气候环境下,沙漠化土地的扩张是人为因素作用的的结果。沙漠化扩张过程是高寒脆弱不稳定的生态系统在气候干湿波动、人类活动与沙漠化土地之间复杂的相互反馈作用下形成的。

Aeolian desertification is one of the most severe eco-environmental issues in the area around the Qinghai Lake. By using meteorological data during 1958--2007 collected from Gangcha Meteorological Station on the shore of Qinghai Lake and social-economic data of Gangcha County during 1976--2007, we analyzed the driving forces of aeolian desertification there in recent 30 years through Principal Component Analysis. Results showed that from 1976 to 2007, both natural and human factors contributed to the variation of aeolian desertification area, while contribution rates of annual average wind speed change and arable land change were the primate driving factors of aeolian desertification varied at different stages during 1976-- 2007： （1） The expansion of aeolian desertification area in 1976--1987 was induced by human activities when temperature and precipitation increased; （2） increase of aeolian desertification area by 17.28 km2 from 1987 to 1995 was caused by the interaction of natural and human factors, in which natural factors played a dominant role while human factors intensified the role; and （3） during 1995--2007, human factors hastened the increase of aeolian desertification area when climate was warm-humid and wind speed decreased. In conclusion, the expansion of aeolian desertification area in Gangcha County was the result of mutual interaction among the dry-wet fluctuation, the human activities and aeolian desertified land in the frail alpine ecosystem.