利用卫星遥感数据TERRA/MODIS,以2004、2005年5—10月的月度变化为例,分析了北疆试验区高寒草甸、高寒草原、温性草原化荒漠、人工草地和沼泽5种草地类型植被指数(MODIs—EVI、NDVI)在各个生长阶段的变化,从而反映5种草地类型生长状况及其特性。研究结果表明,5种草地类型增强型植被指数(EVI)均比归一化植被指数(NDVI)小,两者月度变化趋势基本一致,但EVI变化幅度比NDVI小。在高寒草原、高寒草句、温性草原化荒漠草地类型上EVI比NDVI更稳定,但在沼泽多水的自然环境和人工草地上,EVI波动幅度大于NDVI。
Taking monthly change from May to October in 2004 and 2005 as an example, the NDV! (Normalized Difference Vegetation Index) and EVI (Enhanced Vegetation Index) for five typical grasslands of alpine steppe, alpine meadow, temperate desert steppe, artificial grassland and swamp were analyzed in different growth stages by use of new remote sensing data of MODIS (Moderate Res- olution Imaging Spectroradiometer), which reflected its growth status and characteristics. The results indicated that the EVI values were lower than the NDVI values, and there existed a similar monthly change trend, but the magnitude of EVI was lower than the NDVI. EVI was steadier than NDVI in alpine steppe, alpine meadow and temperature desert steppe, but the stabilization of NDVI was better than EVI in artificial grassland and swamp.