Analysis Of Soil Archaeal Community Structure And Methane Emission Characteristics Under Different Vegetation In The Yellow River Delta

Archaea,as a major component of microorganisms,play a key role in mediating global carbon and nutrient cycling processes.Among the archaea,methanogenic archaea and methane anaerobic oxidizing archaea（ANME）are moreover the main driving microorganisms in the carbon biogeochemical cycling process in wetlands.Therefore,studying the structure,diversity and function of soil archaeal communities is beneficial for early response to changes in the soil environment.However,archaeal community structure is influenced by various factors such as vegetation type and soil physicochemical properties,and the complex interactions among these factors make the archaeal community structure respond differently to different environmental factors.In addition,the effects of methanogenic archaea and ANME archaea-mediated methane（CH₄）production and oxidation processes on CH₄ fluxes are still unclear.In this paper,we chose the Yellow River Delta,a distinctive salt vegetation succession series,as the study area and used16S r RNA high-throughput sequencing technology to investigate the structure and diversity of soil archaeal communities and their influencing factors under different vegetation types.The fluorescence quantitative polymerase chain reaction（q PCR）technique was used in combination with the determination of soil CH₄ emission fluxes to reveal the characteristics of soil methanogenic archaea and ANME archaea communities under different vegetation types and their effects on methane fluxes.The main conclusions are as follows:（1）Thaumarchaeota is the most dominant archaebacterial phylum in the Yellow Rive r Delta soil,Nitrososphaeria is the most dominant archaebacterial phylum,and Candidatu s＿Nitrososphaera is the most dominant archaebacterial genus.The archaeal OTUs are mai nly in paracrine or mutualistic symbiosis,and soil salinization has increased the interconn ectedness and closeness of the archaeal communities.（2）The soil archaeal communities in the modern Yellow River Delta are more similar in composition than those in the abandoned Yellow River Delta in northern Jiangsu,and the diversity and richness of soil archaea in the modern Yellow River Delta are higher than those in the abandoned Yellow River Delta in northern Jiangsu.Moreover,the information exchange and environmental response among archaea in the modern Yellow River Delta were faster than those in the Northern Jiangsu Waste Yellow River Delta.Nitrosopumilales and Nitrosopumilaceae were the taxa that contributed most to the differences in soil archaea between regions.（3）Soil pH and temperature（T）significantly affected archaeal community diversity and abundance.Electrical conductivity（EC）was the main physicochemical factor（R²=0.45,P=0.002）driving the differences in archaeal community structure and was the most influential physicochemical factor on the composition of archaeal community phylum,order and genus.In addition,nitrogen,EC,pH and T were the key physicochemical factors driving changes in the community structure of methanogenic Archaea and ANME Archaea.（4）Vegetation cover significantly reduced the abundance of methanogenic archaea,but ANME archaea increased significantly.The results of PLS-PM indicated that soil physicochemical factors in the Yellow River Delta indirectly influenced CH₄ fluxes by affecting archaeal communities,and from the perspective of functional microorganisms,methanogenic processes dominated by methanogenic archaea and anaerobic oxidation of methane involving ANME archaea were the key factors affecting CH₄ emissions in the Yellow River Delta.From the perspective of functional microorganisms,the methanogenic process dominated by methanogenic archaea and the anaerobic oxidation process involving ANME archaea were the key pathways affecting CH₄ emission in the Yellow River Delta wetlands.