Response of community characteristics to different grazing intensity on salinizationLeymus secalinus grassland in the north region of Shanxi Province

The five grazing levels (i.e. no grazing(CK), grazing light(LG), moderate grazing(MG), heavy grazing(HG) and extreme grazing(EG)) was used to investigate the effect of grazing intensity on community characteristics of Leymus secalinus grassland for determining a reasonable grazing capacity, which further optimize the utilization patterns of grassland. This study showed that the cover and frequency of the dominant species L. secalinus and Potentilla ansrina were maximum in the MG, but the changes of density and height were not significant(P0.05)；the cover of Artemisia lavandulaefolia, Saussurea amara and Taraxacum mongolicum were maximum in the MG. As grazing intensity increased, the dominance of the main species had downward trend in this grassland and the dominance of individual species resistance to grazing and the ability to propagate species increased gradually; the grassland biomass increased with the decrease of grazing intensity, but had increasing trend in the MG. After twotime of grazing, The Margalef species richness index, ShannonWiener diversity index, Simpson dominance index and Pielou uniformity of grassland communities were significantly different (P0.05). In MG, the species richness was maximum. The grassland community had high species richness and dominance, but the uniformity was low in the MG.