The Influence Mechanism Of Dominant Species On The Characteristics Of Denitrifying Microbial Communities In Qinghai Lake Wetlands

Soil denitrification is an important process in the emission of N₂O,an atmospheric greenhouse gas.Environmental factors of different dominant species are largely heterogeneous,which may directly or indirectly affect N₂O fluxes.The Qinghai-Tibet Plateau is extremely sensitive to climate change due to its regional uniqueness,and has always been a hot area concerned by researchers.Wetland ecosystem,as one of the main ecosystems on the Qinghai-Tibet Plateau,contributes greatly to the emission of N₂O gas and plays an extremely important role in global climate change.However,vegetation is an important factor affecting N₂O gas emissions,and there are few studies on the effect of alpine wetland vegetation on N₂O gas emissions.This paper takes the soil of Qinghai Lake wetland in the northeast of the Qinghai-Tibet Plateau as the research object.Using high-throughput sequencing of nir S,nir K,nos Z,we explored the influence mechanism of four dominant species dominated by Carex regescens,Blysmus sinocompressus,Elymus nutans and Leymus secalinus on denitrifying microbial community characteristics in Qinghai Lake wetland.The results show that:(1)The Alpha diversity of denitrifying microbial community in Qinghai Lake wetland was significantly responsive to plant association,and the response modes of denitrifying microorganisms with different genotypes were different.Among the species richness of the nir S-type denitrifying microbial communities,CR were the highest,LS had the lowest species richness index.The species richness index of nir K and nos Z denitrifying microbial communities was opposite to that of nir S.The diversity index of denitrifying microbial community of different genotypes was higher in LS.(2)Denitrifying microbial communities of Qinghai Lake wetland were dominated by Proteobacteria,Bradyrhizobia is an important genus in the denitrification process of Qinghai Lake wetland.In Qinghai Lake wetland,different genotypes of denitrifying microorganisms under the four dominant species had different flora,but most of them belonged to proteobacteria.Magnetospirillum in nir S-type denitrifying microorganisms and Sinorhizobium?Nisaea?Chelativorans?Pseudomonas?Paracoccus in nir K-type denitrifying microorganisms were the main groups of N cycle responding to plant association.Compared with nos Z type denitrifying microorganisms,nir S and nir K were more sensitive to the change of plant association.(3)The soil in the wetlands of Qinghai Lake was weakly alkaline,the plant biomass and soil physical and chemical properties of different dominant species were significantly different.The plant biomass of CR were significantly higher than those of other types,but its soil p H,TN,TC,NO₃^--N content,and NH₄⁺-N content were similar to those of BS.The TN,TC,and NH₄⁺-N content of LS were significantly lower than those of other soils,though its AB,BB,and soil p H were not significantly different from those of EN.The BB and TC content of EN and LS were significantly lower than those in the other two types.(4)Different genotypes of denitrifying microorganisms in Qinghai Lake wetland were regulated by many environmental factors,and soil moisture was the most important environmental factor.The response of different genotypes of denitrifying bacteria to environmental factors is not consistent.Soil humidity was the most important factor affecting the nir S-type denitrifying microbial communities in Qinghai Lake wetlands.nir K-type denitrifying microorganisms are mainly affected by soil moisture and nitrate content.The most important influencing factors of nos Z denitrifying microorganisms were soil moisture and temperature.