基于NDVI的黄土高原植被覆盖变化特征分析

黄土高原是我国生态环境最为脆弱的地区之一。探讨黄土高原地区植被覆盖动态变化对于区域植被恢复和生态系统重建具有积极意义。利用空间数据分析软件GeoDa和ArcGIS地统计分析模块，采用1998、2003、2008和2012年8月21日的SPOT—VGTNDVI数据代表黄土高原地区相应年份植被覆盖最大的时期，对黄土高原植被覆盖随时间的演变特征进行分析。结果表明，1998--2012年，黄土高原植被覆盖经历了先降低后增加的过程，且1998、2003、2008和2012年的归一化植被指数（NDVI）数值均有明显的空间自相关关系，NDVI值冷点区的位置和范围均较为稳定，热点区变化较大，主要分布在陕西和山西境内。

Detecting the dynamic changes of vegetation coverage in the Loess Plateau of China using NDVI data

The Loess Plateau is one of the most environmentally vulnerable regions in China. Detecting the dynamic changes of vegetation coverage in the Loess Plateau will benefit the regional vegetation restoration and ecosystem rehabilitation. Based on the spatial data analysis software GeoDa and statistical analysis module of ArcGIS, the SPOT-VGT NDVI （normalized difference vegetation index） data on August 21 of 1998, 2003, 2008, and 2012 were used to represent the annual maximum vegetation coverage, and the dynamic changes of vegetation coverage over time were detected. The results showed that, vegetation coverage in the Loess Plateau decreased from 1998 to 2003 but increased afterwards from 2003 to 2012; NDVI showed a significant spatial autoeorrelation; the location and extent of the cold spots of NDVI were relatively stable, while the location and scope of the hotspots changed obviously, and were mainly distributed in Shaanxi and Shanxi provinces.