Abstract:

Based on meteorological, hydrological, forest, and grassland data collected by location observation,remote sensing,field surveys and relevant literature during 1956 to 2009, the ecological environment change in northern slope of the Qilianshan Mountains was analyzed synthetically using regression and correlation analyses.The results showed that the temperature had an annual variation rate of 0.0334 ℃·a^-1 in northern slope of the Qilianshan Mountains since 1960,and exhibited a raising trend, especially since 1987.The annual variation rate of annual precipitation was 0.5702 mm·a^-1,indicating that the precipitation tended to increase. The climate had changed from arid to humid in this region since 1976.From 1956 to 2006,the glacier area of six inland river basin(Shiyanghe river,Heihe river,Beidahe river,Shulehe river,Danghe river and Halternhe river)and Datonghe river basin in northern slope of Qilianshan mountains decreased by 17.7%.Thickness of the glacier reduced about 5~20 m,and the snow line rose about 100~140 m.The Glacier ice reserves in inland river basin of Hexi decreased by 11.4%. From 1972 to 2007,27 glaciers in the eastern section of the Qilianshan Mountains disappeared.From 1956 to 2009,the runoff change in the northern slope of the Qilianshan Mountains was different in different regions. The runoff was reduced significantly in Shiyanghe river basin, increased slightly in Heihe river basin,and increased obviously in Shulehe river basin.From 1958 to 1988,the area of the deforest and farming was more than 10.0 million hm²,and the forest area was reduced 0.6 million hm².Since the Qilianshan Mountain Nature Reserve was established in 1989,the forest was restoring gradually because of continual protection and cultivating,and the forest area was increased 9.4 million hm² grom 1989 to 2008.Due to human interference,especially over-grazing impact,the quality of the wood-land,shrub-land and grass-land in northern slope of the Qilianshan Mountains were in a degraded condition,which resulted in serious harm of forest pests,decrease of shrubbery snow and water-retention capacity and exacerbation of soil erosion.The ecological environment in northern slope of the Qilianshan Mountains was improved in certain regions,but deteriorated in overall region, and the protection and management are needed to be strengthen.

Key words: the northern slope of Qilianshan Mountains, ecological environment, changing trend, countermeasures