Estimation of Grassland Aboveground Biomass Using Landsat 8 OLI Satellite Image in the Northern Hillside of Tianshan Mountain

The Landsat 8 OLI remote sensing data was used to obtain six kinds of commonly vegetation indices including NDVI，RVI，DVI，EVI，GNDVI and SAVI.Meanwhile，combining with the measured data of grassland in the research area，the research area was divided into two kinds of shady and sunny slope according to the slope.Then the biomass remote sensing estimation models of shady and sunny slope in Ziniquan Ranch were created by Statistical analysis method and biomass space inversion and verification was implemented.The results of correlation analysis showed that the selected vegetation indices were significantly correlated with pasture biomass and there was a significant difference between the correlation of the classified data and the non classified data by slope，in which NDVI was the highest and EVI was the lowest.The optimal inversion model of Ziniquan Ranch biomass was based on the two order polynomial model of SAVI with the accuracy 80%.By using this model reversion，the grassland average yield of Ziniquan Ranch in 2015 was 113 g/m²，which equaled to dry grass yield 41.85 g/m².The research shows that the slope direction is an important factor affecting the distribution of biomass.Using remote sensing data and ground measured biomass data and combining with the characteristics of the topography of shady and sunny slope of the research area，the biomass estimation model has higher accuracy，which could provide scientific basis for the reasonable estimation of grassland biomass and management of grassland grazing in the pastoral area.