基于ENVI的巴里坤草地动态变化信息提取及分析

Information Extraction and Analysis of the Grassland Dynamic Variation in Barkol Based on ENVI

利用250 m的EOS/MODIS数据,结合1:250 000的土地利用分类图,借助ENVI软件对巴里坤草地变化进行研究,制作掩膜,剔除巴里坤的非草地NDVI信息,只保留草地的NDVI信息,提取巴里坤县2003—2012年连续10 a的草地NDVI信息数据,并以2003年巴里坤草地NDVI为本底数据,计算巴里坤草地面积的动态变化。结果表明:巴里坤草地NDVI差值动态变化较大的主要发生在区间[0.001,0.1)与(-0.1,-0.001],两区间面积合计能占到巴里坤草地面积的90%以上;其次位于区间[0.1,0.2)与(-0.2,-0.1],两区间面积合计占比不到巴里坤草地面积的6%。表明其年际间发生的变化是以微幅变动为主,其发生区域主要集中在覆盖度较低的荒漠化草地和低盖度草地;NDVI差值动态变化发生较大范围变化的面积占比并不大,表明当地的草地生态系统具有一定的相对稳定性。草地NDVI的差值动态变化更能体现出局部区域的细微变化。

By using EOS/MODIS data with 250 meter resolution combined with the land type classification map of Barkol on the scale 1：250000. Based on the ENVI software, we studied the grassland variation of a consecutive 10 years from2003 to 2012 in Barkol, calculated the grassland NDVI, extracted the 10 years NDVI information to obtain the 10-year dynamic variation of NDVI, setting the year 2003 as the background to conduct the calculation and statistics for the grassland area. The results show that the major NDVI difference of dynamic variation of grassland occurred in the intervals, [0.001,0.1） and （-0.1,-0.001],which occupied more than 90% of the total grassland area in Barkol, and the secondary intervals, [0.1,0.2） and （-0.2,-0.1],which occupied near 6% of the total grassland area in Barkol. It showed that the interannual characteristics was mainly small changes, which took place mostly in the desertified grassland and low vegetation coverage grassland; there was only small area took place the large-scale NDVI change showing the relative stability of grassland ecosystem in local area. In conclusion, the NDVI difference of dynamic variation of grassland could better show the regionally particular variety.