The Effects of Different Grazing Pressures on the Plant Community Characteristics and Plant Life Forms of Mountain Meadows in the Middle Section of the Northern Slope of Tianshan Mountains
[Objective]In order to investigate the changes in plant community characteristics of mountain meadows in the middle section of the northern slope of the Tianshan Mountains under different grazing pressure conditions,and to provide theoretical basis for establishing a reasonable grazing and utilization system in the studied area.[Methods]By conducting a survey on the actual grazing intensity and vegetation status of the summer and winter pastures in Solbastao of Miaoergou Township,representative areas of heavy grazing(HG),moderate grazing(MG),and light grazing(LG) were selected. Three monitoring points of different grazing pressures were set up,with three replicates for each monitoring point.[Results]Firstly,under different grazing pressure conditions,the dominant species of plant communities were slightly different,and the number of community species decreased with increasing grazing intensity. With the increase of grazing pressure,the important values of excellent grasses in the Poaceae and Leguminosae families decreased,while those of forbs and Achnatherum inebrians increased. Secondly,grazing pressure had the greatest impact on vegetation biomass,followed by vegetation coverage and height,which affected the frequency slightly,and the average height,total coverage and biomass of vegetation showed a decreasing trend with the increasing of grazing intensity. Thirdly,the dominant species and plant life forms of mountain meadow vegetation were obviously affected by different grazing periods. Dasiphora fruticose,plants of which were small and had low importance values in summer pastures,showed tall plants with extremely high importance values in winter pastures.[Conclusion]Under different grazing pressure conditions,the species composition of the plant community varied. The number of species in pastures of HG、MG、LG were 26,22 and 33,respectively,with obvious difference. Heavy grazing reduced the height,coverage,and aboveground biomass of the plant community,and increased the advantages of forbs and Achnatherum inebrians. The life form and importance value of plants changed along with the increasing of grazing intensity,which was also a strategy for plants to adapt to environmental changes during their growth process.
middle section of the northern slope of the Tianshan Mountainsdifferent grazing pressuresmountainous meadowplant community characteristic
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