1981-2001年西北地区植被变化特征分析

Analysis of Vegetation Variation and its Effect Factors in Northwestern China during 1981-2001

植被是西北地区维持陆地生态环境的重要组成部分,受气候因子的影响显著,通过监测植被的动态变化可以在一定程度上反映气候变化的趋势。本文利用1981-2001年的NDVI数据和同期相应的气温、降水资料,分析了西北地区植被覆盖的时空变化特征及其与气候变化的相互关系。结果表明:西北地区的植被覆盖呈现明显的季相变化特征,在夏季尤其是7-8月,随着气温升高和降水增加,植被覆盖达到最大值;从年际变化来看,春、夏两季的干、湿年份对比中,干旱年份植被生长比湿润年份差,并且夏季的差异比春季更明显,此外西北地区的植被覆盖在研究期内的1981-1995年总体向改善的趋势发展,1996-2001年有退化的现象。

The vegetation is important to maintain the ecological environment in northwest region,and it is affected by climate factors significantly.Dynamic monitoring of the vegetation variation could reflect the trend of climate change to some extent.In this paper,NDVI data and the corresponding temperature and precipitation data during 1981-2001 were used to analyze the temporal and spatial changes in vegetation coverage and the corresponding factors.The results showed that vegetation coverage in the Northwest region appeared a clear seasonal variation.The vegetation coverage reached its maximum in July and August with the rising temperature and increasing precipitation.From the inter-annual change in point of view,the growth of vegetation was also significantly different in dry years and wet years.It was poorer in dry year than that in wet year,and the difference in summer was larger than that in spring.Meanwhile,from 1981 to 1995 the vegetation coverage appeared improvement as a whole area but degeneration in some local areas from 1996 to 2001.