Changes of above-ground biomass,species population and biotope in grazed and ungrazed grassland in Qinghai Gong-he Basin

The changes of above-ground biomass,species population and biotope in the grazed and ungrazed grassland in Qinghai Gong-he Basin were studied. The results indicate that the above-ground biomass and height of plant in ungrazed grassland are higher than those in the grazed grassland,and the degeneration intensity of grassland is medium a nd sever according to the ratio of biomasses between the ungrazed and grazed gra sslands in Gong-he;the desert vegetations invade and gradually become the dominant or secondary dominant species,the biomass of predominant species is decreased,so according to the ratio of biomasses between other species and domi nant species,＜0.1 is a slight degeneration,0.1～0.5 is a light degeneration, 0.5～1.0 is a medium degeneration,1.0～5.0 is a sever degeneration,and＞5.0 is a very sever degeneration,and Jijicao grassland is of a medium and sever degene ration,stipa grassland is of a sever and very sever degeneration at present;there are two directional restorations（former grassland and other degraded grasslan d）in ungrazed grassland of Qinghai Gong-he Basin,but a single directional degeneration to desert,so it makes the Gong-he Ba sin biotope and desertification poorer.