| Soil microorganis ms drive the biogeochemical process of carbon,nitrogen,phosphorus and sulfur,and play a key role in maintaining soil carbon s ink and forest ecosystem function.We study the effects of environmental and spatial factors on bacterial community structure and the influence of function microorganis m to carbon storage and decompos ition in forest soil to explore microbial community building mechanis m of temperate forests and carbon cycle mechanis m of temperate coniferous forests driven by microorganis m and can provide theoretical bas is for making management measures in local forest ecosystem.Pangquangou Natural Reserve is located in hinterland of Guandi Mountain of Luliang Mountains in Shanxi Province.It protects Crossoptilon mantchuricum and their habitats where are abundant of natural s econdary forests such as Larix gmelinii var.Principis rupprechtii,Picea meyeri,Picea wilsonii and so on.Its forest community type is divers ity,structure difference is obvious and can be a small scale where can ignore climate factors to study the influence of vegetation type and soil factors on microbial community structure and function,and can also study the change of climate along with altitude,so it is ideal to study microbial community structure and function.Based on 16 s r DNA and ribosomes ITS ?,the study us ed high-throughput s equencing technology to analyze soil bacterial community structure in evergreen coniferous forests(Picea wilsonii and Pinus tabulaeformis)and deciduous coniferous forests(Larix p rincipis-rupprechtii)and soil fungal community structure in deciduous broad-leaved forest(Betula platyphylla and Betu la albosinensis Burkill mixing forest),evergreen coniferous forests(Picea wilsonii and Pinus tabulaeformis)and deciduous coniferous forests(Larix principis-rupprechtii).Meanwhile,the study used real-time fluorescent quantitative PCR technology to study the abundance and spatiotempo ral dynamics of carbon sequestration function gene(cbb M),amylase coding amylase enzyme and cellulose coding cellulose enzyme in evergreen coniferous forests(Picea wilsonii,Picea meyeri and Pinus tabulaeformis)and deciduous coniferous forests(Larix p rincipis-rupprechtii)to reveal microbial community structure and function mechanis m regulated by climate,environmental factors and plant community.Hereby,we can make different forest tending measures to change the soil environment for optimizing the structure of soil microbial community.It can also improve the soil carbon sink,and maintain the stability of soil carbon library.Major conclusions were as follows:(1)High-throughput sequencing based on 16 s rDNA results showed that:1)Soil mois ture content,carbon and nitrogen ratio,p H and soil enzyme activity were the main influence factors that affected soil bacterial community structure;Proteobacteria and Bacteroidetes were more suitable for living in the acid,humidity and good nutritional status s oil and active carbon was the main carbon source,while Actinobacteria,Planctomycetes and Chloroflexi were more dominant in alkaline,drought and poor nutrient soil and res istant carbon was the main carbon source.2)Geographic distance and beta divers ity of bacterial community had a significant correlation(R2 = 0.853),which showed that dispersal limitation had a significant effect on bacterial community structure.In a word,environmental s election and dispersal limitation led to significant difference of soil bacterial community structure and biodivers ity of different coniferous forests in this study area.(2)High-throughput sequencing based on ITS?results showed that:1)There were seven eumycotas and thirty-three advantage fungal generas in the five sample sites.2)Redundancy analys is res ults showed that soil p H,temperature,moisture,total nitrogen,the content of NH4+-N,total carbon,invertase activity,urease activity,undergrowth dominance and evenness were associated with soil fungal community structure significantly.3)Cluster analysis and principal component analysis showed that forest vegetation type,soil environmental factors and und ergrowth had significant effects on soil fungal community structure.4)The results of PCNM analys is showed that at a local scale,dispersal limitation had no s ignificant influence on fungal community structure in this study area.In a word,forest soil fungal community structure in this study area was significantly impacted by environmental selection(soil p H,temperature,moisture,total nitrogen,the content of NH4+-N,total carbon,invertase activity,urease activity,undergrowth dominance and evenness,forest type).(3)Carbon metabolic characteristics of forest soil microorganis ms1)Seasonal dynamics of soil microbial carbon metabolism genesThe abundance of soil carbon decomposition function genes increas ed with the increas ing of soil temperature in April;carbon decompos ition genes had the lowest abundance in July;the abundance of soil labile carbon(LC)gene was dominant In April and October while soil labile carbon(LC)gene and recalcitrant carbon(RC)gene had the s imilar abundance in May.The abundance of decompos ition function genes was greater than carbon fixation gene of soil microbial community in this study area.2)Soil phys icochemical properties(p H and temperature),soil nutrient status(TN,urease activity,sucrase activity),organic carbon and forest type determined carbon metabolis m microbial abundance which affected the abundance of carbon metabolis m genes by influencing soil microbial community structure and finally impacted soil carbon metabolic process.(1)Soil p H and temperature had impact on soil carbon cycle by affecting soil functional microorganis ms activity.(2)Soil Nitrogen content and soil enzyme activity regulated soil fertility to influence soil microorganis m activity,which influence soil carbon cycle.The content of soil nitro gen had a greater influence on decomposition ability of resistant carbon.(3)The content of soil organic matter and organic carbon had the greatest influence on soil carbon cycle,which could not only directly affect soil functional microbial community,but also had indirect effect on soil microbial community structure by adjusting soil p H and soil enzyme activity(urease and sucrase)and both eventually affected soil carbon cycle process.The content of soil organic matter was s ignificantly positively related to the abundance of soil carbon metabolis m genes and had significant negative correlation with labile carbon(LC)abundance / recalcitrant carbon(RC)abundance(amylase/cellulase).The results showed that with increase of soil organic matter,the abundance of decomposing recalcitrant carbon(RC)gene increased faster than decomposing labile carbon(LC)gene.(4)The soil of the same forest types had similar functional microbial community structure,which led to similar soil carbon cycle process. |
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