| Soil microbes play a key role in the regulation of biogeochemical cycle and the maintenance of ecosystem functions,which are related to the function of soil and vegetation characteristics.Inner Mongolia Daqing Mountain Forest Area is the largest and best preserved secondary forest area in the middle of Yinshan Mountain,and it is the key region of biodiversity conservation,as well as an ideal place to study the microbial diversity of forest soil.In this paper,Pinus tabulaefornis,Betula platyphylla,Larix principis-rupprechtii and Picea crassifolia were studied in the forest ecosystem of Daqing Mountain,with the help of high-throughput sequencing,we can compare the diversity and the community steucture difference of rhizosphere soil bacteria and fungi from different altitudes and different depth,then combine with the distribution of soil physical and chemical properties,enzyme activities and cultivable microbes,we could reveal the distribution of soil microbes in forest ecosystem in Daqing Mount.The main results and conclusions are as follows:(1)The number of cultivable bacteria in the rhizosphere soils of the four tree species was 0.99×106-16.4×106 CFU/g,and the number of fungi varied from 0.07×104-5.69×104 CFU/g,the number of actinomycetes varied from 0.79×106 to 11.3×106 CFU/g.The effects of organic matter,pH,water content,altitude,N-acetylglucosaminidase activity and peroxidase activity on the number of three kinds of culturable microorganisms were relatively large,while the effects of available phosphorus,available nitrogen,the activity of protease and alkaline phosphatase on the number of culturable microbes were relatively small.(2)The species abundance index(Chao1 of the lower rhizosphere soils of P.tabulaeformis and L.principis-rupprechtii increased with the altitude.The bacterial diversity enlarged index(Shannon and Simpson)of the lower rhizosphere soils of P.tabulaeformis and Picea crassifolia as well as those of the upper rhizosphere soil of B.platyphylla increased with the altitude.The bacterial diversity index(Shannon and Simpson)of four rhizosphere soils decreased with soil depth.The species abundance index(Chao1 of the lower rhizosphere soils of P.tabulaeformis,B.platyphylla and L.principis-rupprechtii increased with the altitude.The fungi diversity index(Shannon)of upper rhizosphere soils of L.principis-rupprechtii and Picea crassifolia increased with the increasing altitude.The fungi diversity index(Simpson)of the upper rhizosphere soils of P.tabulaeformis and B.platyphylla reduced than that of lower layers.(3)According to the analysis of the bacteria phylum,Proteobacteria,Acidobacteria,Actinobacteria were the dominant community in the rhizosphere soils of four tree species.The contents of Actinobacteria in the lower rhizosphere soils layers of B.platyphylla、Picea crassifolia and P.tabulaeformis as well as in the upper rhizosphere soil of P,tabulaeformis increased with the altitude.The contents of Proteobacteria in the upper rhizosphere soil of P.tabulaeformis and the lower rhizosphere soil of L.principis-rupprechtii increased with the increasing altitude.The amounts of Acidobacteria in the upper rhizosphere soils of P.tabulaeformis and Picea crassifolia decreased with incrasing altitude.All the other rhizosphere soils had higher Proteobacteria content in the upper layers than in the lower layers.In bacteria genus,the contents of Gp6,Gp4 and Gp16 in the rhizosphere soils of the four tree species were relatively high.The effects of organic matter,available nitrogen,pH and protease activity on the bacterial community structure were relatively large,while the effects of available phosphorus,altitude,N-acetylglucosaminidase activity,alkaline phosphatase activity and peroxidase activity on the bacterial community structure were relatively Smaller.According to the analysis of the fungal phylum,Basidiomycota,Ascomycota and Zygomycota were were the dominant community in the rhizosphere soils of four tree species.The contents of Basidiomycota in the upper rhizosphere soils of P.tabulaeformis and L.principis-rupprechtii decreased with increasing altitude.The contents of Ascomycota in the upper rhizosphere soils of L.principis-rupprechtii and Picea crassifolia increased with altitude.The distribution of fungal dominant community in each sample of four tree tree species varied greatly.Soil organic matter,available nitrogen,N-acetylglucosaminidase activity and peroxidase activity had a significant effect on the composition of fungi,and the effects of available phosphorus,water content,pH,altitude,protease activity and alkaline phosphatase activity on fungal community composition were relatively Smaller. |
