The total land surface of China is 9.6 million km2, of which 4.0 million km2 (more than 40%) are grasslands, and of these 3.3 million km2 lie in the northern temperate zone. A survey of China's grasslands, begun in the early 1970s, seeks to establish the types and grades of grasslands as well as their distribution, productivity, diversity, and the carrying capacities of natural and degraded areas (Keyan chengguo huibian  3:1).
Because most of China's grasslands are located in frontier and mountainous regions where public transportation and communication are poorly developed, remote sensing technology has proved particularly useful. Since the early 1980s, large-scale surveys of grassland areas have identified vegetation types, soil types, topography, climate, and water systems on the basis of color, grain, and other features of remotely sensed imagery obtained from a Multispectral Scanner (MSS) or other remote-sensing device (Wu, 1988). Similarly, the distribution and aboveground biomass of some species can be estimated from reflection patterns on remote satellite photographs. Recently, remote sensing technology has been used to monitor trends over an area of 280,000 km2 in 18 counties of Inner Mongolia, Hebei, and Beijing. Results of this survey show that each year about 4.7 million hectares of grasslands in the northern temperate steppe region have deteriorated, while the numbers of livestock have exceeded carrying capacities in many regions (Li Bo, 1990).
Accurate information on current herbage resources is essential for any program of restoring and managing grazing lands. As a result of overgrazing, the grasslands of Inner Mongolia have been seriously degraded and the primary production of most areas is well below their potential (Jiang, 1988; Liu, 1990). Methods of grassland restoration and management include reducing stocking rates and introducing improved breeds of forage species. First, however, information on current herbage resources is needed. The earliest studies of wild forage species in Inner Mongolia were conducted by Wang (1955) of Nanjing Agriculture University. Beginning in 1952, Wang investigated economic and biological characteristics of 12 wild forage species in Xilingele League. In 1962, Professor Xu Linren of the Mongolia College of Agriculture and Animal Husbandry described the classification, distribution, and biological, ecological and economic characteristics of 23 major forage species (Xu, 1962). Between 1973 and 1983, the Grassland Research Institute conducted similar investigations in Xilingele League, the Xinjiang Autonomous Region, and Guizhou and Hainan provinces (Chen et al., 1985).
These studies have provided useful information on the introduction and domestication of wild species. For example, four years of data on 20 wild