基于NDVI的内蒙古植被动态变化分析

NDVI-based Analysis on the Vegetation Change Trend in Inner Mongolia,China

植被对于生态环境变化的反应是较为敏感的,研究植被动态变化对生态环境的保护和生态预警有很大的意义.基于SPOT/VEGETATION NDVI数据,该文获得了内蒙古的空间NDVI分布,分析了自1998年至2008年之间NDVI的变化趋势.并由最大值合成法(MVC),Mann-Kendall检验和Rescaled范围(R/S)分析计算出NDVI时间序列的赫斯特指数.此外,通过叠加分析对研究区域NDVI的未来变化趋势进行判断.主要的研究结果包括:第一,1998年到2008年间,内蒙古的植被变化总体上是稳定的,但数据显示10.16%的植被有显著减少的趋势,它们属于脆弱的草原植被;其次,在空间分布方面,NDVI时间序列存在一定规律,赫斯特指数在西部高,东部低;第三,在低植被覆盖区存在植被减少的现象.其中9.58%的土地开始衰退,这些土壤急切的需要植被的保护和综合的管理.没有人类的干预,这些土地将会出现荒漠化.

Vegetation is sensitive to the change of ecological environment,so the study on vegetation dynamics is significant to the protection of ecological environment and to an early ecological warning.Based on the time series of the SPOT/VEGETATION NDVI dataset,this paper has obtained the spatial distribution of NDVI in Inner Mongolia,analyzed the characteristics of NDVI change trend in the period of 1998-2008,and calculated the Hurst exponents of the NDVI time series by Maximum Value Composites（MVC）,Mann-Kendall Test and Rescaled Range（R/S） Analysis respectively.Furthermore,the judgment for the future change trend of NDVI time series in the study area has been made by an overlay analysis.The main findings are as follows.（1） In the years of 1998-2008,the vegetation variation in Inner Mongolia was stable on the whole,with 10.16% of the vegetation there tending to remarkably decrease,which was typical of steppe vegetation in the fragile ecological environment.（2） In terms of the spatial distribution,NDVI time series in most areas of Inner Mongolia is characterized by the high Hurst exponent in the west and the low one in the east;moreover,there is a negative correlation between the Hurst exponent and NDVI.（3） There exists the vegetation degradation in the low vegetation-covered regions,in which 9.58% of the total land tends to be degrading.These areas need an urgent vegetation protection and the ecological environmental management;otherwise,an irreversible desertification will occur to them without human intervention.