基于SPOT VEGETATION数据的中国西北植被覆盖变化分析

Study on Vegetation Cover Change in Northwest China Based on SPOT VEGETATION Data

基于遥感和地理信息系统的技术,利用SPOT-VEGETATION NDVI(Normalized Difference VegetationIndex)数据对我国西部地区植被覆盖的情况进行了动态监测。采用MVC(Maximum Value Composites)、一元线性回归趋势分析和变化幅度百分比等方法分析西部地区植被变化特征,并结合西北五省土地利用类型图,分析不同植被类型的年最大化NDVI(MNDVI)变化趋势及特点。其结果是:近7 a来植被覆盖存在普遍退化的趋势,且2000-2001与2001-2002年度的变化幅度较大。在局部区域植被有改善的趋势,但总的改善幅度小于退化幅度。分析结果表明,植被改善的区域主要分布在陕西和宁夏的大部分地区以及新疆西北部和西南部地区。大部分地区植被退化。而且不同植被的MNDVI在相同的年份表现出相似的变化特点和趋势。

A time series of SPOT-VEGETATION Normalized Difference Vegetation Index （NDVI） data with 1 km×1 km spatial resolution were used to monitor the vegetation cover change during the period of 1998 to 2004 in Northwest China. The MVC （Maximum Value Composites） method and the linear regression were used to characterize the trends in vegetation cover change. And the landuse map of Northwest China was used to analysis the NDVI variety of different landuse types. During the last 7 years, the vegetation degradation was popular in most regions of Northwest China. However, there were some regions where vegetation cover was increasing, but the increasing range was smaller than the decreasing range on the whole. The results indicated that the improved regions of vegetation cover mainly appeared in the major part of Shaanxi and Ningxia province and in the northwest and southeast parts of Xinjiang. But in the most part of Northwest China, the NDVI was reducing. However in the same particular year, the patterns of NDVI variety of different vegetations were in the similar tendency.