An Analysis of Temporal-spatial Dynamics of Grazing Pressure on Grassland in Three Rivers Headwater Region

Temporal-spatial dynamics of grazing pressure on grassland in Three Rivers headwater region in 1988-2005 were analyzed.The results showed that grassland was overgrazed averagely by 1.5 times,and even 2 times in winter-spring pasture in last 18 years.Meanwhile grazing pressure was steadily relieved,especially in winter-autumn pasture,which showed that grassland in Three Rivers headwater region has been utilized reasonably year by year.It is considered that overgrazing is one of the main factors resulting in grassland ecosystem degradation.Thus livestock number should be reduced further to a suitable level in order to restore degraded grassland and protect important functions of ecosystem based on the state ecologic strategy in the region.