Effects Of Different Grazing Intensities On Community And Plant Functional Traits In Xilingol Mesdow Steppe

To explore the effects of grazing intensity on grassland plant community characteristics,diversity,productivity,soil physical properties and functional traits of dominant species,four different grazing intensities,no grazing,light grazing,moderate grazing,and heavy grazing were selected in the Xilingol meadow steppe on 2017.We aimed to determine the reasonable grazing intensity,and further to provide a theoretical basis of sustainable utilization for the Xilingol meadow steppe.Results showed that:(1)Grazing intensity enhanced,the height of plant community decreased,the density and coverage increased foregoing then decreased in this three years experiment.Under moderate grazing the community density was the highest of the four treatments,the increase rate was more than 10%compared with the control group.The community coverage was the highest under light grazing.(2)The number of plant genera in the community was the largest under moderate grazing intensity,all of them increased by more than 3 species compared with the control.The number of plant families was the least under heavy grazing,all of which were 10 species.With the increase of grazing intensity,the proportion of important value of grasses first increased and then decreased,and the proportion of important value of sedges and other miscellany grasses increased.Moderate grazing intensity increased species richness,diversity,dominance and evenness in the community.(3)The total aboveground biomass of the community showed a parabolic change with the increase of grazing intensity,and the highest aboveground biomass was found under light or moderate grazing.With the increase of grazing years,the total underground biomass of plant community increased year by year.In the same year,it showed an"N"shaped curve with the increase of grazing intensity.(4)As a whole,soil bulk density increased year by year,and the response to grazing disturbance was mainly in the shallow soil layer of 0-20cm.Grazing increased soil bulk density,but the soil moisture content showed an opposite law.(5)Under different grazing intensities,individual traits of Leymus chinensis,Achnatherum sibiricum and Cleistogenes squarrosa showed a trade-off relationship,and the functional traits were significantly correlated with each other.Heavy grazing would make the plants tend to dwarf,the plant height of the three plants under heavy grazing was significantly decreased compared with that under no-grazing control(P<0.05).(6)In Xilingol meadow grassland,the grazing rate was between light and moderate(1.48 sheep units/(hm~2)·Growing season)～2.46 sheep units/(hm~2·Growing season))is a reasonable grazing intensity.