利用MODIS/EVI数据分析干旱对西南地区植被的影响(英文)

2009年9月至2010年3月我国西南地区出现了有气象记录以来最严重的干旱,给当地的自然环境和生产、生活带来严重影响。本文利用多年MODIS/EVI数据求取距平植被指数来反映干旱对西南地区植被的影响。在此基础上,分析了西南地区植被受旱的时空格局及其可能影响因素。结果表明,我国西南地区植被受干旱影响的范围很大,超过地区总面积的50%,植被受旱程度时空差异显著。这种显著的差异除了受降水等气象因素影响外,还与不同植被类型对干旱的响应差异有很大关系。在西南地区三种主要的植被类型中,作物是最易受干旱影响的植被类型,草地次之,林地的抗旱能力最强。此外,植被干旱的空间分布与气象干旱也存在很大的差异,进一步证明了降水以外的其他因素对干旱程度的调节作用。研究证明与气象干旱指数相比,植被指数更能反映干旱的实际情况。但在使用植被指数衡量干旱影响时也要考虑到植被指数本身的局限性。

Detecting Effects of the Recent Drought on Vegetation in Southwestern China

The severest drought on record occurred in southwestern China from September 2009 until March 2010. In order to measure the impact the drought imposed on vegetation, we developed an evaluation indicator called the Vegetation Index Anomaly （VIA） based on MODIS/EVI. The tempo- spatial pattern of this impact was analyzed. Given that this impact may be modulated by many factors, the responses of different vegetation types （woodland, grassland and cropland）, and the spatial pattern of meteorological drought were also analyzed. Results show that more than 50% of vegetation suffered because of this drought event, but there was significant tempo-spatial variability in the range and intensity of impact. This variability may be caused by many factors. Of the three major vegetation types, cropland was the most sensitive to drought, followed by grassland and then woodland. In addition, meteorological factors （precipitation and air temperature） also played a role; however, obvious differences exist between the spatial distribution pattern of drought-stricken vegetation and that of meteorological drought, which further demonstrates the intervention of other factors besides meteorological factors. So compared to meteorological drought, the vegetation index may be more useful for measuring the actual intensity, duration and impact of drought events. The limitations of vegetation indices are also considered.