SINO-AUSTRALIAN WORKSHOP
The effect of overgrazing on alpine grassland degradation in Qinghai-Tibetan Plateau
by Dr Long Ruijun, Gansu Agricultural University, Chinese Academy of Sciences
The cause of the alpine grassland degradation is complex. However, our studies showed that the degraded alpine grassland, particular the ‘Black soil patch’ alpine grassland in Qinghai-Tibetan Plateau was caused by over grazing mainly, and rats damaging, climate change as well as glacier decreasing were also important. Effect of grazing intensity on biomass and vegetation structure in summer alpine meadow showed that ratio of favorable forage has been impacted remarkably by intensity of grazing, the ratio of Gramineae forage increased by 20.5 per cent, 6.5 per cent and 13.5 per cent in treatments of light-grazing, medium-grazing and heavy grazing respectively. Ratio of Cyperaceae forage increased by 20.3 per cent, 10.4 per cent in light-grazing, medium-grazing, and decreased by 7.7 per cent in heavy grazing treatment; forbs decreased by 20.5 per cent, 6.5 per cent in light and medium treatments, increased by 13.5 per cent in heavy grazing treatment. Vegetation coverage of Gramineae and Cyoeraceae increased by 1.4 per cent in light grazing treatment and decreased by 2.2 per cent and 6.4 per cent in medium grazing and heavy grazing treatment respectively. Vegetation coverage of forbs decreased by 21.3 per cent and 7.2 per cent in light and medium grazing, and increased by about 13.2 per cent in heavy grazing. Stocking rate had notable effects on yak growth and composition of forage. With the lightening of stocking rates, ratio of high quality herbage (grass + sedge) increased, ratio of weeds (palatable weed + toxic weed) decreased. Within trial period of two years, total average gain of yaks of three treatments whose grazing ratio are 30 per cent, 50 per cent and 70 per cent had notable deviation among three treatments. The ecological restoration degraded alpine grassland not only rely on grassland building, but also manage and plan to grassland resources reasonably. There were guaranties for developing our alpine grassland animal husbandry healthily, that are strengthen investment for pasture region’ education, practicing long-term contracting for grassland, strengthen building for the grassland law, etc.
