近20年来祁连山区植被变化特征分析

利用1982-2003年8 km分辨率的 NDVI数据集,分析了祁连山区植被覆盖的年、年际、年代变化特征.结果表明:祁连山区植被覆盖总体上自东向西递减,其年变化NDVIm都为单峰型;祁连山区各段植被覆盖的年际NDVIy、年代变化NDVIn趋势有所不同:祁连山西中段植被的NDVIy 变化趋势基本相似,20世纪80年代变化较平稳,90年代变化幅度最大,1995年以后植被明显开始增加,祁连山东段植被的 NDVIy 从1982年开始呈增加趋势,直到1997年以后下降;祁连山西中段1982-1985,1986-1990,1991-1995,1996-2000,2001-2003年5个阶段植被的 NDVIn最大值出现在2001-2003年,最小值出现在1991-1995年,而祁连山东段最大值出现在1996-2000年,最小值出现在1982-1985年;祁连山各段5～9月植物生长期植被的NDVIpy,NDVIpn变化与年的NDVIy,NDVIn变化相似.

Analysis on the Vegetation Change in the Qilian Mountains since Recent 22 Years

In this paper,the annual and interannual change of vegetation in the Qilian Mountains is analyzed using GIMMS(Global Inventory Modeling and Mapping Studies)/NDVIdata set with spatial resolution of 8 km,which was collected every 15 days during the period from January 1982 to December 2003.The results show that the vegetation coverage in the Qilian Mountains decreases from the east to the west,and the annual change curves of NDVIvalues in the study area are all unimodal.The annual and decadal change trends of NDVIyand NDVInof vegetation in the Qialian Mountains are different: the change trend of NDVIyof vegetation in the western and central parts of the Qilian Mountains are basically similar,it was stable in the 1980s,its change extent was the highest in the 1990s,and the vegetation coverage has been obviously increased since 1995;the NDVIyof vegetation in the eastern part of the Qilian Mountains was in increase trend from 1982 but in decrease trend after 1997;the maximum and minimum of NDVInof vegetation in the western part of the Qilian Mountains occurred during the periods of 2001-2003 and 1991-1995 respectively among the five periods of 1982-1985,1986-1990,1991-1995,1996-2000 and 2001-2003,whereas they in the eastern part occurred during the periods of 1996-2000 and 1982-1985 respectively.The change of NDVIpyand NDVIpnof vegetation in the Qilian Mountains in growth season during the period from May to September is similar to the annual change of NDVIyand NDVIn.