| The purpose of this study was to investigate the soil environmental factors,soil biological properties and the relationship between soil environmental factors and soil biological properties under the Chinese soil taxonomy.The humus layer(Ah)of 8 typical soil series of Isohumisols: DFm,DCl,DBg,DMs,MDx,MXf,MWx and MPd were studied,through laboratory analysis and high-throughput sequencing,simple correlation,stepwise regression,RDA,CCA and other statistical analysis methods were used to study the change characteristics of environmental factors(chemical properties,iron oxide and mineral composition)and biological properties(soil enzymes,bacteria and fungi)of 8 soil systems.The relationship between environmental factors and biological properties was discussed,and the effects of environmental variables on soil biological properties were analyzed,it is expected to provide data support for the study of biological diagnostic characteristics of Isohumisols in CST.The correlation analysis between environmental factors and enzyme activity showed that there was a significant correlation between TN and enzyme activity except urease;stepwise regression analysis showed that SOC and EX-Mg were the main factors affecting soil enzyme activity except catalase;among them,TN is the primary factor affecting catalase and TP is the primary factor affecting urease.EX-Mg is the primary factor affecting sucrase.CEC is the primary factor affecting alkaline phosphatase.Iron oxide: only sucrase and phosphatase were significantly correlated with iron oxide.Stepwise regression analysis showed that the main factors affecting sucrase were activation and free iron.The main factors affecting alkaline phosphatase are active iron,complex degree and complex iron.among them,the degree of activation is the primary factor affecting sucrase,and active iron is the primary factor affecting alkaline phosphatase.Mineral composition: except for K2 O and Na2 O,there is a significant or very significant correlation between mineral composition and enzyme activity.Stepwise regression analysis showed that the main factors affecting catalase were Mn O and Si O2.the main factors affecting urease are Mg O and Mn O.The main factors affecting sucrase are P2O5,Na2 O,Mn O and Mg O.The main factors affecting alkaline phosphatase are Mg O,Si O2 and Ca O.among them,Mn O is the dominant factor affecting catalase,Mg O is the dominant factor affecting urease,P2O5 is the dominant factor affecting sucrase,and Mg O is the dominant factor affecting alkaline phosphatase.Through the analysis of the composition of bacterial community,it was found that at the gate level,Proteobacteria,Actinobacteria and Acidobacteria were the dominant flora of seven soil series,namely,DFm,DCl,DBg,MDx,MXf,MWx,MPd.Chloroflexi,Proteus and actinomycetes were the main dominant flora in the DMs.At the class level,the main dominant flora are: Alphaproteobateria,Gammaproteobacteria,Gemmatimonadete,Actinobacteria,Thermoleophilia,Bacteroidia,Acidobacteriia.at the order level,the main dominant flora are Sphingomonadales,Betaproteobateria,Gemmatimonadales,Gaiellales,Pyrinomonadales,Rhizobiales,Micrococcales.At the family level,the main dominant flora are Sphingomonadaceae,Gemmatimonadaceae,Burkholderiaceae,Pyrinomonadaceae,Micrococcaceae,Chthoniobacteraceae.at the genus level,the bacterial communities of different soil series were quite different.The heat map analysis of the samples showed that the bacterial communities of 8 soil series in Isohumisols were mainly divided into two types,Dry and Moist Isohumisols were divided into one type,and Moist Isohumisols was divided into one type.Mental test found that complexing iron,active iron,free iron,complexing degree and free degree in p H,EX-Ca,EX-Mg,TP,CEC and SOC,iron oxides and Si O2,Mg O,Fe2O3,P2O5,Al2O3,Ca O,Ti O2 and Mn O in mineral composition were the main factors affecting the change of bacterial community structure in Isohumisols.RDA analysis showed that p H value,complexed iron in iron oxide and Si O2 in mineral composition were the main factors affecting the bacterial community structure of Isohumisols.Through the analysis of the composition of fungal community,it was found that Ascomycota,Mortierellomycota and Basidiomycota were the main dominant flora of 8 soil series at the phylum level.At the class level,the main dominant flora are: Sordariomycetes,Mortierelliomycetes,Leotiomycetes,Dothideomycetes,Tremellomycetes,Eurotiomycetes.at the order level,the main dominant flora are: Sordariales,Mortierellales,Hypocreales,Helotiales,Pleosporales;at the family level,the main dominant flora are: Mortierellaceae,Nectriaceae,Chaetomiaceae,Helotiaceae,Aspergillaceae;at the genus level,there were significant differences among different soil systems of uniform rot soil fungal communities.The heat map analysis of the samples showed that,except DBg and MXf,8 soil series fungal communities were grouped into Dry and Moist Isohumisols respectively.Mental test found that the chemical properties of EX-Mg,TK,CEC,EX-Ca,TP,p H,EX-K,SOC and free iron,active iron,complex iron and activation degree in iron oxide were the main factors affecting the community structure of fungi in Isohumisols.The mineral composition was significantly correlated with the community structure of fungi in Isohumisols(P<0.05).CCA analysis showed that p H value,complex iron in iron oxide and Ca O in mineral composition were the main factors affecting the structure of fungal community.To sum up,under the CST system,there were significant differences in environmental factors and biological properties among the 8 typical soil series.All of them were significantly correlated with soil enzyme activity,bacteria and fungi.The microbial diversity of 8 soil series of different subclasses showed that the microbial diversity of Dry Isohumisols was higher than that of Mosit Isohumisols.At the same time,the dominant bacteria groups of bacteria and fungi in Isohumisols are different,the microbial community structure of Dry Isohumisols and Mosit Isohumisols are grouped into one group respectively,in addition,the change of soil environmental factors is the main driving factor leading to the differentiation of soil microbial community structure. |
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