摘要
额济纳绿洲是发育在黑河下游内陆河三角洲上著名的天然绿洲。 2 0世纪 5 0年代以来 ,额济纳绿洲现代荒漠化过程加剧 ,绿洲萎缩 ,生态恶化。绿洲现代荒漠化过程是由水环境恶化过程、土壤干燥化过程、植被退化与生物多样性衰减过程、土地沙漠化过程和土壤盐碱化过程构成的地表动力学过程。导致额济纳绿洲荒漠化的驱动力是区域气候暖干化、强盛的风蚀侵蚀力、上中游过度开发水土资源的人为活动和额济纳绿洲内的“三滥”活动等。荒漠化驱动力的第一主成分与第二主成分的贡献率分别为 5 9.2 76 %和 2 8.0 83% ,反映出绿洲荒漠化驱动因子的多面性和综合性 ,绿洲内外过度的人为活动是其主导驱动因素。内在、外在驱动力在时间与空间上的耦合性是绿洲荒漠化的区域机制 ,驱动力因子团的互动激发作用形成荒漠化的动力机制 ,驱动力与荒漠化土地间的响应形成正反馈机制 ,三种作用机制组合成绿洲现代荒漠化过程的复杂的驱动机制。
The Ejina Oasis is a famous natural oasis that develops on inland river delta of the lower reaches of the Heihe River. Since the 1950s, its rapid desertification causes a decrease in the oasis area and degradation in ecological environment. The present desertification as a complicated dynamic process of the earth surface is characterized by the several degradation processes such as in water, vegetation, soil and biodiversity. In the process of desertification, the Ejina natural oasis has degraded systematically in the surface features, vegetation and the land biological productivity, and the area of the Ejina natural oasis has decreased to 3070 km^2 from 3908 km^2 in the 1960s, reduced by 21.44%. The reason for these is that many variables play a comprehensive role in the desertification of the Ejina Oasis, which include a warming and drying tendency in climate, strong erosion force, irrational utilization of water and land resources in the middle and upper reaches, and the three popular typical human activities of over cultivation, overgrazing and overhacking in the oasis. Based on the method of rotated PCA, the first tow factors respectively account for 59.276% and 28.083%, which implies that the modern desertification is due to many factors, but the factor of human activities in and outside the oasis leads the first. The warming and drying tendency in regional climate and the strong erosion force are the internal driving forces, but the excessive human activities in and outside the oasis is the external driving force. From analysis above, the paper finally come to a conclusion that the modern desertification mechanism is made of three ones: regional mechanism results from coupling of human and natural factors in temporal and spatial, which controls the changes of ecological environment and the humanitic and historical changes in the Ejina Oasis; dynamic mechanism from mutual interaction among driving factors, which is in chain reactions and becomes the direct driving force of the desertification; and the positive and negative feedback, which be of vicious circle, focus on the relation between the driving forces and the desertification.
出处
《地理科学》
CSCD
北大核心
2004年第1期61-67,共7页
Scientia Geographica Sinica
基金
国家重大基础研究规划项目"西北干旱区生态环境演变与调控"第二课题 (编号 :G19990 43 5 0 2 )。
关键词
黑河
额济纳绿洲
荒漠化过程
驱动力
驱动机制
Heihe River
Ejina Oasis
desertification process
driving force
dynamic mechanism
