Response Of Soil Microbial Community Structure Of Tamarix Chinensis To The Deposition Of "Tamarix Nebkhas" In The Lower Tarim River

Tamarix chinensis is a dominant species with strong drought and salt tolerance in the Tarim River Basin,which is of great significance to the restoration of the ecological environment in the region.In this study,the nebkhas Tamarix chinensis shrubs and non-nebkhas Tamarix chinensis shrubs in the lower reaches of the Tarim River were used as the research objects to conduct a preliminary study on the composition and function of soil microorganisms by high-throughput sequencing technology.Besides,the physicochemical properties of soil and the spatial distribution characteristics of soil microorganisms and their correlation were analyzed,and to explore the effects of shrubs nebkhas on soil microorganisms community and soil factor.The results show that:（1）Tamarix chinensis nebkhas and canopy have certain enrichment effects on soil nutrients and salinity,but soil water content（SWC）,total salt（TDS）,electrical conductivity（EC）,organic matter（OM）,total nitrogen（TN）,total phosphorus（TP）and nitrate nitrogen（NO₃^-）content in the whole Tamarix chinensis shrubs have no significant effect.Therefore,the overall enrichment effect is not obvious.（2）The number of OTUs of soil bacteria and fungi in the Tamarix chinensis shrubs was 7958 and2004.Through comparison,we found that the number,community diversity and species richness of soil bacteria were higher than that of soil fungi.（3）Soil bacteria in Tamarix chinensis shrubs were divided into2 kingdoms,71 phyla,161 classes,345 orders,473 families,702 genera,and fungi were divided into 1kingdom,14 phyla,48 classes,110 orders,227 families,410 genera.Among them,Halobacterota,Unidentified-Bacteria,Proteobacteria and Actinobacteriota are the dominant phyla in Tamarix chinensis shrubs,and Halobota-Halobacteria,Gammaproteobacteria,Unidentified-Archaea-Halobacteria,Bacilli,Actinobacteria were the dominant bacteria classes,as well as Salinimicrobium,Halorussus,Halomicrobium,Haladaptatus are the dominant genera.Different from bacteria,Ascomycota is the only dominant phylum in Tamarix chinensis shrubs,and Sordariomycetes,Eurotiomycetes,Dothideomycetes are the dominant fungi classes,Alternaria,Aspergillus,Stolonocarpus are the dominant genera.（4）Through principal coordinate（PCo A）analysis,it was found that there were some differences in soil microorganisms community structure between nebkhas Tamarix chinensis shrubs and non-nebkhas Tamarix chinensis shrubs,and nebkhas had certain influence on soil microorganisms community structure,but it was not obvious.（5）The PICRUSt software was employed to predict the functional genes of bacteria,a total of6195 KEGG ortholog genes were obtained.The function of soil bacteria was annotated,and 6 metabolic pathways in level 1,41 metabolic pathways in level 2,and 307 metabolic pathways in level 3 were enriched,among which the functional gene related to metabolism,genetic information processing,and environmental information processing was found to have the dominant advantage in Tamarix chinensis shrubs.Based on the fungal function prediction of FUNGuild database,8 types of trophic functions of soil fungi were detected,among which Saprotroph and Pathotroph-Saprotroph-Symbiotroph are the main dominant fungal functions in Tamarix chinensis shrubs.In addition,the study found that the distribution differences of bacteria at each taxonomic level in different groups were smaller than that of fungi,and the distribution of bacterial functions in Tamarix chinensis shrubs was relatively uniform,while the distribution of fungal functions in the shrubs had greater differences.Bacterial communities and functions are more stable than fungi.（6）The relationship between soil factors and soil microbial communities was analyzed at the OTU level,and it was found that available potassium（AK）,ammonium nitrogen（NH₄⁺）,electrical conductivity,p H,organic matter,total nitrogen,total phosphorus is the main soil factor affecting bacterial community structure,and ammonium nitrogen,available potassium,available phosphorus（AP）,and total phosphorus are the main soil factors affecting the fungal community structure.It can be seen from the above that available potassium,ammonium nitrogen,and total phosphorus all have important effects on soil microbial（bacterial and fungal）community structure.Overall,soil factors had neutral effects on microbial communities.At the class and genus levels,soil factors had negative and positive effects on soil bacterial communities,respectively,but positive effects on soil fungal communities were higher than negative effects.The results of this study revealed the community composition and distribution characteristics of soil microorganisms in nebkhas Tamarix chinensis shrubs and non-nebkhas Tamarix chinensis shrubs in the lower reaches of Tarim River,which provided basic data for the study of soil microorganisms in arid areas and the ecological restoration of vegetation in the Tarim River Basin.