20年间艾比湖流域植被覆盖度景观格局变化

选取艾比湖流域1990年、2001年、2011年同期（9月）3期I．and．satTM遥感影像，基于归一化植被指数NDVI，提取植被覆盖等级图，利用ArcGIS9．3和Fragstas3．3对该流域植被景观的变化进行了分析研究。结果表明：1990—2011年，该流域植被覆盖度变化明显，低植被覆盖区和较低植被覆盖区都有所减少，分别由1990年的34．05％和32．94％减少到2011年的32．8％和24．06％；较高植被覆盖区和高植被覆盖区有所增加，分别由8．49％和5．20％增长到15．13％和9．83％，但水域面积退化明显，由1990年的525．9765km2缩小至494．9876km2，减少了30．9889km2，退缩幅度达O．4％；最大斑块指数（LPI）由17．04上升到21．10，香农多样性指数（SHDI）和香农均势度指数（SHEI）分别由1．5387和0．8588增长到1．6395和0．9150。表明艾比湖流域景观格局混杂程度愈来愈高，空间异质性在逐年加强，总体空间格局向破碎化趋势发展。

Landscape Pattern Change of Vegetation Coverage in Ebinur Lake over the Past 20 Years

The variation of vegetation landscape of Ebinur Lake in 1990, 2001 and 2011（Sep. ） was studied, which based on the normalized differential vegetation index（NDVI）, the multi - level map and Landsat TM, by using AreGIS 9.3 and Fragstas 3.3. The result shows that the vegetation coverage decreased obviously. From 1990 to 2011, the low and low- mid vegetation coverage decreased respectively from 34.05 % and 32.94 % to 32.8 % and 24.06 %, the mid - high and high vegetation coverage increased respectively from 8.49% and 5.20% to 15.13% and 9.83%. The water area deceased also obviously and the area decreased 30.988 9 km2 （from 525.976 5 km2 in 1990 to 494.987 6 km2 in 2011 ）, the withdrawal rate reach 0.4%. The largest patih index （LPI） increased from 17.04 to 21.10, shannon diversity index（SHDI） and shannon equihbrium degree（SHEI） increased respectively from 1.538 7 and 0.858 8 to 1.639 5 and 0.915 0, this indicated that the landscape pattern of Ebinur lake became more and more complex, the spatial heterogeneity rose by years, and the trend of spatial pattern develop to fragmentation.