关键词: 若尔盖盆地, 草地沙化, 驱动因素, 驱动机制, 主成分分析

Abstract:

As the world's largest alpine mire wetland, Zoige Basin is an important water recharge area of the Yellow River, known as the Yellow River "reservoir ". As ecologically sensitive areas, under the influence of the natural environment and irrational human activities, the Zoige Basin shows a series of serious environmental problems, such as wetlands shrinking, grassland degradation, sandy land increase, and so on. This paper analyzes the current situation and its driving factors of desertification in the Zoige Basin, and then describes and analyzes the driving mechanism of desertification. The results show that widely distributed fossil dune is the sand supply of the modern desertification. Destruction of turf which contained a dense growth of grass and its matted roots resulting of exposure of underlying loose fossil dune sand sediments is the key step in formation of desertification. As a kind of large-bodied underlying-dwelling rodents, the burrows digging behavior of marmots (Marmota himalayana) play a vital role in destroying surface turf. Marmot burrow sites are usually located in open, herb-covered talus slope. The large opening of burrows is easily collapse by rainfall erosion and other biological factors, causing destroying of turf and exposing loose sand. Another important role that can destroy turf is the thaw subsidence and slump effect, which results from permafrost degradation. The subsidence and slump of surface can form pull crack on the turf around the subsidence pit or slump scarp, leading exposedness of loose sand. The exposed loose sand blown out by wind, resulting of wind erosion pit. With the expansion wind erosion pit, aeolian activities intensified, leading the reactivation of fossil dunes. The reactivation of fossil dunes combined with continuous heavy grazing, leads aeolian deposition in leeward and formation desertification. Principal component analysis showed that desertification is the result of human factors and natural factors work together, where the human factors are the main driving factors.

Key words: Zoige Basin, grassland desertification, driving factors, driving mechanism, PCA