Changes in above-ground biomass and vegetation composition of alpine meadows three years after changing the stocking rate in comparison to the initial stocking rate of 3.55 sheep ha^-1 on an alpine pasture in Tibet (after Zhao and Zhou, 1999)

Above-ground biomass decreased with increasing grazing density. In addition, vegetation composition changed, the proportion of grasses and litter decreased, and forbs increased as the grazing density increased. The forbs, as indicator plants of grassland degradation, are mostly unavailable for sheep and yaks.