Relationship Between Soil C,N,P Ecological Stoichiometric Characteristics And Rhizosphere Microorganisms Of Dominant Plants In Different Elevations Of Helan Mountains

Mountain ecosystem is an important part of terrestrial ecosystem,and meadow ecosystem in mountain ecosystem is a complex ecosystem composed of biological factors and animal factors,which has good ecological performance and resource performance.Inter-root,as a special type of microecosystem,is not only the node of material and energy exchange between plants and soil environment,but also the active area of various nutrient material cycles.The inter-root soil microorganisms in the interroot environment provide nutrients for plant growth and development by decomposing apoplastic matter and activating nutrients and minerals in the soil.Therefore,exploring the interrelationship between nutrients and inter-root microbial communities in inter-root soils can help to understand the mechanism of nutrient cycling regulated by inter-root soil microorganisms.In this paper,we collected inter-root soil samples from dominant plant species in meadows at different altitudes(2600-3450 m)in Helan Mountains,and conducted detailed studies on the inter-root soil physicochemical factors,inter-root soil C,N,P ecological stoichiometry characteristics and inter-root soil microbial C,N,P ecological stoichiometry characteristics and inter-root soil microbial community characteristics to reveal the inter-soil-microbial relationships.The main results were as follows The main results of the study are as follows:(1)The biomass of herbaceous vegetation in the study area showed an overall trend of increasing and then decreasing along the elevation from low to high.The vegetation cover of the herbaceous samples in the study area was greater than 90%,and the vegetation cover was high.The Simpson dominance index of the plant community showed a decreasing trend with increasing elevation;the Shannon-Wiener index,Pielou index,Margalef index and vegetation cover all showed alternating trends of "decreasingincreasing" along the elevation.(2)There are significant differences in the ecological stoichiometry of C,N and P in the inter-root soil of dominant plants at different altitudes,and the contents of inter-root soil organic carbon,total nitrogen and total phosphorus all show significant correlation with altitude:soil organic carbon does not show obvious regular changes along the altitude;soil total nitrogen shows a fluctuating upward trend along the altitude,and the total nitrogen content of inter-root soil of shrub dominant plants in this study is significantly higher than that of herb dominant plants.The total phosphorus content showed a singlepeak pattern of "increase-decrease" along the altitude.The results of redundancy analysis showed that alkaline nitrogen,soil water content,total carbon,electrical conductivity,and fast-acting potassium were the soil physicochemical factors affecting the ecological stoichiometry of C,N,and P in inter-rhizosphere soils;microbial carbon content showed a pattern of increasing with elevation,and the microbial carbon content of inter-rhizosphere soils of shrub dominant plants was significantly higher than that of interrhizosphere soils of herbaceous plants.The microbial nitrogen content showed no obvious pattern of change with altitude,and the microbial phosphorus content showed a single-peak pattern of increasing and then decreasing with altitude.The microbial phosphorus content and microbial carbon to nitrogen ratio were significantly and positively correlated with altitude.Soil water content,conductivity,pH,fastacting potassium,and total phosphorus,soil carbon to nitrogen ratio,soil carbon to phosphorus ratio,and soil nitrogen to phosphorus ratio were the factors that mainly influenced the ecological stoichiometry characteristics of inter-rooted soil microbial load carbon,nitrogen,and phosphorus,indicating that the ecological stoichiometry characteristics of inter-rooted soil microbial load were the main factors driving the changes in the ecological stoichiometry characteristics of inter-rooted soil microbial load carbon,nitrogen,and phosphorus.(3)At the phylum level,Proteobacteria,Acidobacteria,Actinobacteria and Bacteroidetes were the main bacteroidetes.At the order level,Sphingomonadales,Rhizobiales and Myxococcales are predominant.At the genus level,Gp6,Gp4 and Gemmatimonas are predominant.At the phylum level,fungi are predominant.Basidiomycota,Ascomycota,Mortierellomycota,etc.At the order level,Agaricales,Pleosporales and Thelephorales were the main ones.At the genus level,Inocybe and Hygrocybe are the main genera.The conductivity,carbon nitrogen ratio and carbon phosphorus ratio of microbial biomass were the factors that significantly affected the rhizosphere soil microbial community.Soil organic carbon,whole carbon and microbiomass carbon were the main soil environmental factors that significantly influenced the abundance of microbial taxa,indicating that the abundance of interrhizosphere soil microbial communities of dominant plants in meadows at different elevations of Helan Mountains were more susceptible to the influence of soil carbon elements.In summary,the dominant plants in meadows at different elevations have certain effects on the physicochemical properties,carbon,nitrogen and phosphorus ecological stoichiometry characteristics of inter-rhizosphere soil microorganisms,and microbial community interactions,indicating that vegetation can influence the bacterial and fungal communities of soil through inter-rhizosphere effects,and also affect inter-rhizosphere soil nutrient transformation and energy flow.