Effects of grazing and fertilization on community productivity and species richness in eastern alpine meadow of Tibetan plateau

The community productivity,species richness and their interaction response to grazing and fertilization were analyzed in eastern alpine meadow of Tibetan Plateau with four nitrogen fertilizer levels and two grazing levels.Fertilization significantly reduced( P 0. 001) the species richness and inhibited the growth of forbs group but increased the aboveground biomass and promoted the growth of grasses group,while grazing significantly increased( P 0. 001) the species richness and promoted the growth of forbs group but decreased the aboveground biomass and inhibited the growth of grasses group. In the plots with both fertilized and grazed,there was no significant changes for species richness,whereas there were significant reductions( P 0. 001) in the fertilized plots without grazing.These results suggested that grazing was the main factor and the effects of fertilization was covered up by the grazing. There was a negative relationship between species richness and community biomass in the plots two only with grazing or fertilization. The moderate nitrogen fertilization can increase community productivity and the ratio of forage without effects on species richness. This management was optimal for loading more stocks to achieve more profits without degradation of grassland which can be applied in the local grassland. ested that moderate fertilization in the grassland of the study site would increase community productivity and have little effect on species richness. The reasonable solution is suitable for generalization in the local pasture.