The Driving Mechanism Of Assemblage Of Soil Microbial Community In Typical Temperate Forests In Pangquangou Natural Reserve,Shanxi Province

Environmental selection and dispersal limitation are two basic processes underlying assembly of community in ecosystem.However,the relative importance of two processes differs with different research scales,traits of groups and so on.The processes responsible for structuring microbial communities in soil of subalpine forest in temperate zone are poorly understood so far.Here,we investigated the relationship between the structure of microbial communities and environmental factors,and quantified the relative role of edaphic factors,vegetation,and spatial variables in shaping the structure of six soil microbial communities(LpMC1,LpMC2,PwMC,PmMC,PtMC,and BMC)in five forest types including Larix principis-rupprechtii,Picea wilsonii,Picea meyeri,Pinus tabulaeformis,and Betula platyphylla in Pangquangou Nature Reserve by using PCR-DGGE technology.Hereby,we could discuss the construction mechanism of soil microbial community in this area,and provide some data support for the theory of microbial community construction.We come to the following conclusion:(1)PCR-DGGE technology based on 16 s rDNA showed that:1)The structure and biodiversity of bacterial communities were significantly different among six communities.The biodiversity of bacterial community in LpMC2 and PtMC were higher,and that in PmMC was lowest and in LpMC1 was highest.2)Edaphic factors,such as pH,soil water content,total carbon,total nitrogen,soil organic matter,available phosphorous,and soil enzymes,were correlated significantly with biodiversity and structure of soil bacterial community;The ?-diversity of bacterial communities in research area was significantly correlated with geographic distance,indicating the influence of dispersal limitation on structure of bacterial community;Variation partitioning analysis showed the order of driving force on the structure of bacterial community was edaphic factors(0.27),spatial factor(0.19)and vegetation(0.15)in six samples;Null modelanalysis showed that the soil bacterial community structure in the study area was mainly influenced by deterministic processes.3)Using regional soil microbes from ten samples around reserve as source community,microcosm experiments showed that the edaphic factors were the predominant driving factors(0.35)on structure of artificial dispersal bacterial community,while the high diversity of source microbial community had effect on the structure of microcosm soil.In summary,at local scale,environmental selection predominantly determined the structural dynamics and biodiversity of soil bacterial communities in temperate subalpine forest,while dispersal limitation played significant role.Deterministic processes and stochastic processes played important roles in shaping the structure of soil bacterial community at local scale,and the former played the leading role.(2)PCR-DGGE technology based on 18 s rDNA show that:1)The structure and biodiversity of fungal communities were significantly different among six communities.The structure of fungal community in PmMC was most complex and that in LpMC1 was simplest.The biodiversity of fungal community in PmMC was highest and that in LpMC1 was lowest;2)Edaphic factors,such as temperature,soil water content,pH,soil organic matter,total carbon,total nitrogen,available phosphorous,ammonium nitrogen and soil invertase activity were correlated significantly with biodiversity and structure of soil fungal community;Variation partitioning analysis showed the order of driving force on the structure of fungal community was edaphic factors(0.45),spatial factor(0.18)and vegetation(0.11)in 6 samples;Null model analysis showed that the soil fungal community structure in the study area was mainly influenced by deterministic processes.3)Using regional soil microbes from 10 samples around reserve as source community,microcosm experiments showed that the edaphic factors were the predominant driving factors(0.4936)on structure ofartificial dispersal fungal community,while the high diversity of source microbial community had effect on the structure of microcosm soil.In summary,at local scale,environmental selection predominantly determined the structural dynamics and biodiversity of soil fungal communities in temperate subalpine forest,while dispersal limitation played significant role.Deterministic processes and stochastic processes play important role in shaping the structure of soil fungal community at local scale,while former play the leading role.For soil microbial(bacteria and fungi)community,it is influenced by the deterministic process and the stochastic process,and the deterministic process dominates the community.The composition of dispersal soil fungal community is source-dependent but also modulated by local environmental selection.