基于MODIS/NDVI的新疆伊犁河谷植被变化

利用2000-2010年16 d合成的MODIS/[NDVI]数据，结合植被异常指数、趋势线分析和Hurst指数等分析方法，对新疆伊犁河谷植被覆盖的时空变化特征进行了分析。结果表明：（1） 伊犁河谷内植被覆盖随海拔增高而先增加后减小，最高植被覆盖区位于2 000～2 500 m的高程带；2000-2010年伊犁河谷各高程带内植被覆盖整体下降趋势明显，但海拔低于1 000 m的高程带除外。（2）受干湿环境影响，伊犁河谷全区平均被植异常指数最高值出现在降水最多的2002年，最低值出现在降水最少的2008年，但不同区域植被异常指数的变化存在较大差异。（3）伊犁河谷内植被覆盖增加和减小的区域分别占总面积的4.09%和19.34%，增加区域主要位于伊犁河两岸的平原区，减小区域主要位于乌孙山两端以及伊犁河谷周围海拔2 000 m左右的低山区域；变标度极差分析结果表明，伊犁河谷内植被覆盖年际变化呈现很强的持续性，未来一定时间内将保持现有变化趋势不变。

Vegetation dynamics in Ili River valley of Xinjiang based on MODIS/NDVI

16-day composite data set of normalized difference vegetation index （NDVI） from an moderate-resolution imaging spectroradiometer（MODIS） was used to capture essential feature of temporal and spatial vegetation variability in Ili River valley of Xinjiang during the 2000-2010 period. Various statistical analyses involving vegetation anomaly index, linear regression analysis and Hurst index were applied. Examination shows as follows：（1）Vegetation cover of Ili River Valley increases firstly and then decreases as altitude increases，with highest vegetation cover located in the area with the altitude from 2 000 to 2 500 m. Generally，vegetation cover of different elevation zones of Ili River valley followed a decreasing trend during the period of 2000-2010，not including the areas located below 1 000 m above the sea level. （2）As vegetation anomaly index is subject to humidity of the air，so the highest spatially averaged vegetation anomaly index value was observed in the wettest year of 2000，and the lowest value in the driest year of 2008, and changes of vegetation anomaly index of different area exhibit varied patterns. （3）The areas with increasing or decreasing of vegetation cover account for 4.09% and 19.34% of the study region’s total area，respectively. The increasing area’s regions are mainly located at the plains of both banks of the Ili River. The decreasing area’s regions are mainly located at the both ends of the Wusun Mountains and the low mountain areas surrounding the study region with the altitude of 2 000 m. Rescaled range analysis shows that changes of vegetation cover in the Ili River valley exhibits strong sustainability，which means that the change of vegetation cover will follow the same variation trend in the future some period in the Ili River valley