GISbased classification of grassland types in Qinghai

The data of ＞0 ℃ annual accumulation temperature (AAT), the annual precipitation (AP), altitude and latitude of 50 meteorological stations from 1971 to 2006 in Qinghai were analyzed and the model for estimating AAT and AP was established. Based on the model and altitude data, the AAT and AP values were obtained by interpolating under the GIS environment, and the resolution was 4 km 4 km. The moisture index of each grid was calculated. And then, the grassland type of every grid was determined by the Integrated Orderly Classification System of Grassland (IOCSG). The results showed that there were 18 classes. In which, the area of frigid perhumid rain tundra and alpine meadow was the most and accounted almost half of the total area of grassland in Qinghai.