Effects Of Different Restoration Methods On Soil Microbial Community Under Different Meadow Use Types

Alpine meadow is one of the main pastoral areas in China,can maintain the global ecosystem stability,but long-term unreasonable use of the meadow vegetation degradation,nutrient loss,low productivity,restore degraded grassland ecosystem is imminent,study the different recovery way of Tibetan plateau meadow vegetation,soil characteristics and microbial function community structure changes,clear the driving factors of soil microbial community structure and function.In this study,alpine meadow with different restoration methods（undisturbed meadow,Fenced+reseeded meadow,Fenced meadow and Grazed meadow）,revealed the influence of soil microbial community structure（diversity,community composition,interaction network,and interaction structure）,and clarified,in order to clarify the recovery and reconstruction of alpine meadow.（1）FM significantly improved the plant diversity index,underground biomass and above-ground biomass,and increased the diversity and richness of grasses and legume species;compared with grazing meadows,organic carbon and total nitrogen content of no grazing meadows increased by 1.32 to 1.38 and 1.71～1.86 times,sticky grain and particle volume fraction increased by 61%～91.1%and 43.5%～80.1%;soil multicultural dimension is higher than grazing meadow.It shows that the ban on grazing can increase soil nutrients,promote the growth of vegetation,make the soil particle size distribution more heterogeneity,conducive to the accumulation of fine particles,can improve the soil texture,affect the soil structure,is a scientific meadow restoration method.（2）FM improved the bacterial Shannon index,Chao1 index,bacterial abundance,and fungal Chao1 index.The dominant bacterial communities under different recovery modes are Proteobacteria and Actinobacteria.Soil fungi concentrate at the phylum level in Ascomycota and Basidiomycota;compared with grazing meadows,grazing meadows significantly increase the number of positive and negative connections and enhance the synergistic and antagonistic effects between macrobiotic.The four meadows had higher positive interactions within the soil boundary than negative interactions and a higher number of bacteria-fungus negative connections than positive connections.Meadows can transform bacteria and fungi from competition to cooperation after banning grazing.（3）Compared with grazing meadow,the contents of microbial biomass carbon（MBC）,microbial biomass nitrogen（MBN）and microbial biomass phosphorus（MBP）in no-grazing meadow were increased by 59.93%,115.80%and 115.76%,respectively.Increasedβ-1,4-glucosidase（BG）activity by 38.15%;32.89%alkaline phosphatase（AP）activity and 51.22%β-N-acetaminoglycosidase（NAG）+leucine aminopeptidase（LAP）activity,indicating that prohibition of grazing can significantly improve soil microbial extracellular enzyme activity,which is a scientific restoration method of degraded meadow.The emission of N2O in the forbidden meadow decreased significantly,but there was still a certain gap compared with that in the undisturbed meadow.The abundance of nitrification（AOA-amo A,AOB-amo A）and denitrification（nir S,nir K and nos Z）genes in grazed meadow were higher than those in grazed and grazed+supplemental meadow,but lower than those in undisturbed meadow,indicating that grazing could increase soil nitrogen cycling capacity.The Shannon index and Chao1 index of nir S,nir K and nos Z were higher than those of grazing meadows,indicating that grazing meadows improved microbial community richness and diversity.Prohibition of grazing increased the abundance of nitrogen-fixing bacteria and plant pathogenic fungi,and decreased the relative abundance of nitrifying bacteria and fecal rot bacteria,indicating that prohibition of grazing can improve the potential of biological nitrogen fixation.（4）Ground biomass was significantly and positively associated with soil water and water-soluble organic carbon.Plant richness index and fast-acting phosphorus showed a significant positive correlation.Plants contribute more to changes in microbial community composition than soil properties,with biomass changes in Careaceae and Poaceae being the main reason for changes in bacterial and fungal composition.Soil water-soluble organic carbon,water-soluble organic nitrogen,and soil water are the main environmental drivers of N₂O emissions,Brucelbiaceae of nir K gene community,Proteobacteria of nos Z gene community,and Bradyrhizobiaceae of nir K gene community are the major microbial drivers of N₂O emissions.The diversity of nitrogen cycle functional genes is driven by meadow biomass and soil nutrients.Whole nitrogen,p H and plant Shannon are the main influencing factors of nitrification reaction,while water-soluble organic carbon,water-soluble organic nitrogen,whole nitrogen,whole phosphorus,nitrogenous nitrogen,plant Shannon diversity index and p H are the main influencing factors of denitrification reaction.