Researchers used satellite data and field surveys to estimate the amount of grass in Gannan Prefecture from 2006 to 2008. They found that the grassland biomass decreased over those years, with the most grass found at altitudes between 3,000 and 4,000 meters. The study also showed that the grassland biomass was higher in the western part of the region compared to the east. The results suggest that noise contamination affects the accuracy of the data, and the grass biomass decreased by an average of 97.91 grams per square meter each year.