Effects Of Grazing On Plant And Soil Microbial Community Characteristics In Mountain Meadow On The Northern Slope Of The Tianshan Mountain

Grazing is not only an economical production method of grassland animal husbandry,but reasonable utilization of grazing is also one of the basic approaches to scientific grassland management.Determining the appropriate grazing intensity is of great significance to the sustainable utilization of grassland resources.In this paper,taking the montane meadow in the middle section of the northern slope of the Tianshan Mountains in Xinjiang as the research object,through a combination of field survey and sampling and indoor analysis,the effect of grazing on the plant community characteristics,soil physicochemical properties and soil bacterial and fungal community structure of the montane meadow in the middle section of the northern slope of the Tianshan Mountains was studied.In order to provide an important theoretical support for the rational grazing and stability of the mountain meadow grassland ecosystem.The main results were as follows:(1)There were 31,32 and 29 plant species under ungrazed,lightly and heavily grazing conditions,respectively.Grazing changed the species richness and diversity of plant communities.With the increase of grazing intensity,the species richness,height,coverage and diversity index of plant communities all decreased significantly.The biomass changes of different functional groups were different.The biomass above and below ground of grasses,legumes,sedges and forbs decreased significantly,while the biomass on poisonous grassland increased significantly.The root-shoot ratio was the lowest under light grazing and the highest under heavy grazing;Under heavy grazing conditions,the dominant species of perennial grasses and sedges were gradually replaced by poisonous weeds and weeds.(2)With the increase of grazing intensity,soil organic carbon,soil total nitrogen and total phosphorus all decreased,and under heavy grazing conditions,soil organic carbon decreased by 19.66% compared with no grazing and light grazing conditions and 15.63%,soil p H,total phosphorus and total potassium were not significantly different.(3)Regardless of grazing or grazing,the soil bacteria with the highest relative abundance at the phylum level are Actinobacteria,the class level is Actinobacteria,and the genus level(which can be accurately named)has the highest relative abundance of Rubrobacter;Shannon index of soil bacterial community did not change significantly under different grazing intensities,ACE index and Chao1 index both showed the highest no grazing treatment,ACE index was 7.99% higher than light grazing and heavy grazing,respectively and 6.51%,and the Chao1 index was 8.80% and 6.34% higher than light grazing and heavy grazing,respectively.(4)Under different grazing intensities,the soil fungi with the highest relative abundance at the phylum level are Ascomycota,the class level with the highest relative abundance is Sordariomycetes,and the genus level(which has been clearly named)The highest relative abundance was Mortierella;the fungal OTUs under no-grazing treatment were significantly higher than those under heavy-grazing;under heavy-grazing conditions,the ACE index of soil fungal community was 22.09% lower than that of no-grazing and light-grazing,respectively and 12.13%,Chao1 index also decreased significantly with the increase of grazing intensity,while Shannon index did not change significantly.(5)Through RDA analysis,it was found that soil organic carbon content,total nitrogen content,total phosphorus content,available potassium content,soil water content,vegetation community coverage and height have a greater impact on soil bacterial community;soil fungal community is affected by soil bulk density.,organic carbon content,and vegetation community height and coverage;plant community height,soil available potassium content were significantly positively correlated with soil bacterial diversity index,and plant species richness and soil bulk density were significantly correlated with soil bacterial diversity index.Negative correlation;plant community height and soil available potassium content were significantly positively correlated with soil bacterial diversity index,and plant species richness and soil bulk density were significantly negatively correlated with soil bacterial diversity index.Soil bulk density,organic carbon and total phosphorus were the main driving factors affecting the vegetation characteristics of the community.Based on the above research results,the changes of grazing intensity have a significant impact on the composition of grassland plant species and plant community characteristics.Under heavy grazing conditions,the dominant species of perennial grasses and sedges in the community are gradually replaced by poisonous weeds and weeds;soil Specific physical and chemical indicators have a significant response to grazing;the main groups of soil bacteria and fungi are the same under different grazing intensities,but there are differences in relative abundance;microbial diversity The index decreased significantly under grazing treatment;soil bacterial community was greatly affected by soil organic carbon content,total nitrogen content,total phosphorus content,available potassium content,soil water content,vegetation community coverage and height;soil fungal community was greatly affected by soil bulk density,The organic carbon content has a great influence on the vegetation community height and coverage.