北京松山林地nirK型反硝化微生物群落立地及林型效应OA北大核心CSTPCD

[Objective]This work aims to explore the traits and influence factors of soil nirK-type denitrifying microbial community in different forests in Songshan,Beijing,providing novel insights into the nitrogen cycling process and environmental change of forest soil ecosystem in the warm temperate forest soil ecosystem of North China.[Method]Three typical forest types of Pinus tabuliformis,Populus davidiana and Quercus mongolica were selected in the Songshan Nature Reserve of Beijing.Three standard sample plots(20 m×20 m)were set up in each forest type for investigation.The 0-20 cm surface mixed soil samples were collected to analyze soil properties,and extract total soil microbial DNA,PCR was used to amplify nirK gene coding the key enzyme,nitrate reductase,in the denitrification process.The second generation high-throughput sequencing was used to analyze the composition and diversity of soil denitrifying microbial communities in the different forest types,and to explore the effects of soil properties on the characteristics of denitrifying microbial communities.Pearson's correlation analysis and redundancy analysis(RDA)were used to examine the soil properties factors influencing the trait of denitrifying microbial community.[Result]1)A total of 993 401 effective sequences with 770 328 high-quality sequences of nirK gene were obtained by high-throughput sequencing from 9 soil samples in P.tabuliformis forest,P.davidiana forest and Q.mongolica forest.There were 7 phyla and 78 genera of nirK gene detected in the soil of three different forest types.Among the identified microorganisms,the dominant bacteria of soil nirK denitrification microorganisms in the three forests were Proteobacteria,with the relative abundance of 50%in the three forest types,and the highest of 58.2%in the P.tabuliformis forest.The dominant genera were Bradyrhizobium,Mesorhizobium and Rhodopseudomonas,with a total relative abundance of more than 50%,among which the core genus was Bradyrhizobium.2)The analysis of alpha diversity of nirK denitrifying microorganisms showed that the Shannon,Simpson and Chao1 diversity index of nirK-type denitrifying microorganisms in P.tabuliformis forest(7.59±0.56,0.98±0.01,2 164.24±214.08)were significantly higher than those in P.davidiana forest(5.23±0.26,0.89±0.02,1 650.56±136.69)and Q.mongolica forest(5.76±0.38,0.93±0.02,1 621.36±156.70)(P<0.05).Based on Bray-Curtis distance algorithm and PCoA analysis,the difference among soil denitrifying microbial communities in different forest types was greater than that within the community.3)Redundancy analysis showed that soil alkali hydrolyzable nitrogen,nitrate nitrogen and soil organic matter were the key factors that significantly affected the composition of the nirK-type denitrifying microbial community(P<0.05).[Conclusion]There are obvious differences in the composition and diversity of soil nirK-type denitrifying microbial communities among P.tabuliformis forest,P.davidiana forest and Q.mongolica forest in the warm temperate zone of North China.Forest types and soil properties such as alkali hydrolyzable nitrogen,nitrate nitrogen and soil organic matter are important factors affecting the traits of soil nirK-type denitrifying microbial communities.