艾比湖保护区荒漠植被时空过程变化及其植被指数影响因素分析

利用1990-2011年Landsat数据,结合了4个气象站点的年降水量、年均温数据,基于垂直地带性特征和荒漠植被指数对艾比湖保护区的遥感图像进行了专家知识决策树分类。研究了典型绿洲-荒漠交错带的荒漠草地等地物近20年的面积变化、NDVI及其与气候因子的关系。结果表明,1)近20年间植被类型的NDVI值大致呈山前荒漠荒漠草原盐生草甸草本沼泽荒漠的规律。2)近20年降水量与温度都呈上升趋势,植被NDVI和气温主体呈不显著负相关,与降水主体呈显著正相关。3)研究区在保护区建立前,荒漠植被退化十分严重,荒漠植被面积大量减小,大多向不可用地类转化,保护区建立后的生态环境有了很大改善。可见政府的政策导向对荒漠生态环境具有重要作用。

Vegetation index feature change and its influencing factors and spatial-temporal process analysis of desert grassland in the Ebinur Lake Nature Reserve,Xinjiang

This research investigated the vegetation of the Ebinur Lake Nature Reserve, Xinjiang, a typical desert-oasis ecotonein northen China. After radiometric and geometric correction, Landsat remote sensing images from 1990, 1998 and 2011 were used for the study. The classification of land cover based on a decision tree approach was implemented using the normalized difference vegetation index (NDVI) and the vertical zonal vegetation distribution. Annual rainfall and the average annual temperature data of four meteorological stations were utilized. The NDVI was generally highest in the piedmont desert grass and lowest in desert areas; piedmont desert grass>desert steppe>saline meadow>herbaceous swamp>desert. The area of land influenced by salinization appeared to be increasing. Over the 20 year period mean temperatures showed an increasing trend, consistent with the global warming trend. Temperature did not influence NDVI but rainfall was positively correlated with NDVI. It was concluded that the establishment of the Ebinur Lake Nature Reserve has significantly reduced land degradation and that government policy plays a significant role in the protection of desert environments.