MODIS-based remote sensing monitoring of grass production in China

Monitoring grassland production is of great importance for utilizing and administering grassland, developing pasturage and improving the ecological environment. Using Moderate Resolution Imaging Spectroradiometer (MODIS) data and ground truth data for the six grassland regions of China, regional models were established to estimate the grassland production in 2005. The Normalized Difference Vegetation Index (NDVI) was first computed from the MODIS data. Ground truth data were obtained from a large-scale field investigation in 2005. The following results were obtained: (1) total hay output from the grassland in China was 294214 thousand tons in 2005, with an average yield of 830 kg/ha. (2) There were three regions with high grass productivity in 2005: the grassland covering Hulunbuir, Xilinhaote and the western Daxing'anling; the region including eastern Qinghai, northwestern Sichuan and mid-southern Gansu; and the northwestern Xinjiang region. (3) Grassland production for the whole of China in August 2005 remained at the same level as that in August 2004. However, the situation in the major grassland provinces was different: grass production in 2005 in both Qinghai and Gansu increased by 9% and 4%, respectively, when compared with that in 2004. Grass production in Inner Mongolia decreased by 3%, while the production in Liaoning, Xinjiang and Sichuan remained unchanged in comparison to that in 2004. (4) The models based on the six regions are the most suitable for monitoring grass production in China and can meet the need of estimating of grass productivity. The results are very important for grassland administration, pasture grazing and grassland ecosystem studies in China.