Study On The Grassland Productivity Based On 3S Technology In Xianghuang County, Inner Mongolia

According to the characteristics of the grassland distribution of Xianghuang County, the investigation spots were selected on the remote sensing image, and aboveground biomass was measured in each spot investigation. Meanwhile, the vegetation index is educed from Landsat TM image and MODIS image respectively, which are rectified by ground control points. An optical model used for grassland assessment is established based on the relationship between vegetation index and aboveground biomass.By the correlation analysis, linear correlation was found out between the field aboveground grassland biomass and the vegetation indices derived from TM image or MODIS image in the spots. Two kinds of linear models used for assessing the grassland productivity are built at different scale. The model are built at the diflFerent grassland formations based on TM image and at the different grassland types based on MODIS image, then the models were used to compute the grassland productivity map. It is found that the accuracy of TM based model is a little higher than MODIS based model. Although the MODIS based model should be as the main method for grassland productivity assessment and grassland monitoring at large spatial scale, and in order to improve the accuracy of assessment, the TM based model is a useful assistant method.By the overlay analysis between TM image and MODIS image, grassland productivity of the same region can be contrasted through years, from which the trend of ecological condition and grassland resources can be monitored and the problems can be found in grassland protection and grassland sustainable development project in time.It is concluded that the method for assessing grassland productivity by using TM image and MODIS image is feasible and will play an important role in grassland monitoring and investigation all over China.