Response Of Soil Microbial Community To Drought And Drought-Flood Abrupt Alternation In Poyang Lake Wetland

As an important part of the wetland ecosystem,Soil microorganisms are extremely sensitive to soil environment change.In recent years,drought and drought-flood abrupt alternation phenomenon in Poyang Lake Wetland are more and more frequently due to climate change and anthropogenic activities.In this study,laboratory experiments were conducted to analyze the response of soil microbial communities to the drought-flood abrupt alternation,which helps to identify soil microbial communities changes in Poyang Lake wetland under the phenomenon of drought-flood abrupt alternation,and significantly to the protects of Poyang Lake wetland.Typical wetland,Poyang Lake Wetland,are selected in this study,and surface soil samples are sampling in three typical vegetation belts based on different elevations along lake beach to the sloping fields.Three moisture gradients,heavy drought(30% soil moisture content),moderate drought(50% soil moisture content),and suitable moisture conditions(80% soil moisture content),are incubate a month in laboratory and then add water moisture content to 200 % simulates the phenomenon of drought-flood abrupt alternation.High-throughput sequencing techniques were used to determine bacterial,fungal diversity,abundance,and community structure.Changes in bacterial and fungal communities under the different vegetation communities,drought levels,and drought-flood abrupt alternation were studied by one way ANOVA,and the effects of environmental factors on bacteria and fungi community was analyzed by Redundancy analysis.Based on the R vegan package Bio Env program,non-metric multidimensional scale analysis are used to the bacterial community changes in different vegetation communities,drought degree and drought-flood abrupt alternations.The main conclusions can be drawn as follows:(1)Among the three typical vegetation belts in the Poyang Lake wetland,the higher and lower diversity,abundance index of soil bacteria,fungi are reed belt and alfalfa grass belt,respectively.After incubate of different drought grades,the diversity of soil bacteria and fungi are decrease as the aggravation of the degree of drought,but the effects of drought on the abundance of fungi was not obvious.The diversity of soil bacteria(after incubate by soil suitable moisture conditions and heavy drought)are decrease first and then increase as incubate time goes by after drought-flood abrupt alternation incubate.The diversity of soil bacteria(after incubate by moderate drought)are increase after drought-flood abrupt alternation incubate.The abundance of soil bacteria are decrease first and then increase after drought-flood abrupt alternation incubate;the diversity and abundance of fungi are increase first and then decrease as incubate time goes by after drought-flood abrupt alternation incubate.(2)The highest abundance of bacterial community in Poyang Lake Wetland was Proteobacteria then Actinobacteria and Firmicutes.After incubate in different drought levels,the highest abundance of bacterial community are Actinomycetes then Proteobacteria and Firmicutes.The highest abundance of bacterial community was Actinobacteria then Proteobacteria and Firmicutes after drought-flood abrupt alternation incubate.(3)Significant different are founded in Actinobacteria,Proteobacteria and Acidobacteria after incubate in different levels of drought.The highest abundance of Actinobacteria was founded in heavy drought incubate and abundance of Proteobacteria and Acidobacteria are highest in suitable moisture conditions.The abundance of Acidobacteria are increase as incubate time goes by after drought-flood abrupt alternation incubate,opposite results are founded in Actinobacteria and Acidobacteria,no significant difference are founded in other bacteria.(4)The highest abundance of fungal community was Ascomycota(57.47%),then Basidiomycota and Ciliophora.There was no obvious change in fungal predominant bacteria after different drought grades,Ascomycota increase.The highest abundance of fungal community was Ascomycota then Ciliophora and Chytridiomycota after drought-flood abrupt alternation incubate.(5)The fungal community abundance of Ascomycota are increase as drought level increase after different drought grades,opposite results are founded in Ciliophora and Chytridiomycota,no significant different in other fungal community abundance.In fungal community,Chytridiomycota(incubate in suitable moisture conditions)was significant higher in first day than in third and fifth day after drought-flood abrupt alternation incubate,and the abundance are decrease as incubate goes by,no significant different in other fungal community.