Monitoring aboveground biomass in semiarid grasslands using MODIS images

摘要

In the present study, we calculated seven vegetation indices (simple ratio [SR.], normalized difference vegetation index [NDVI], enhanced vegetation index [EVI], soil-adjusted vegetation index [SA-VI], optimized soil-adjusted vegetation index [OSAVI],land surface water index [LSWI], and greenery ratio [GR]) based on MODIS surface reflectance data and analyzed the relationships between these indices and the aboveground biomass in semiarid grasslands in Mongolia. The measured values of the biomass forthe study area ranged from 7.5 to 137.0 g dry weight (dw) m"2. The results revealed that NDVI, SR, and OSAVI were strongly correlated with the biomass. Among these, NDVI showed the best performance as a proxy of the plant biomass of Mongolian grasslands. The relationships of NDVI and OSAVI with the temporal variation and spatial pattern of biomass were statistically similar, suggesting that a single linear equation was appropriate to derive aboveground biomass values from NDVI or OSAVI.