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Soil Microbial Community Structure And Mineralization Enzyme Response To Nitrogen Deposition In Korean Pine Plantation

Posted on:2021-01-18Degree:MasterType:Thesis
Country:ChinaCandidate:W Y HeFull Text:PDF
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Nitrogen deposition is an important component of global climate change,which will increase the nitrogen content in soil and thus affect soil microbial activity.This study explored the physicochemical properties,mineralization enzymes and microbial community structure of Pinus koraiensis plantation soils in Northeast China under simulated nitrogen deposition levels(0,20,40,80 kg N ha-1 yr-1).The relationships between soil physical and chemical factors and mineralizing enzymes and soil microbial community structure were explored to reveal the ecological effects of different nitrogen deposition levels and soil microorganisms.The results show that:?1?High nitrogen deposition(80 kg N ha-1 yr-1)for five consecutive years significantly increased the soil organic matter?SOM?content of broad-leaved Korean pine forests and significantly reduced the total soil potassium?TK?content.The content of ammonium nitrogen?NH4+-N?in the soil with high nitrogen treatment was significantly higher than that of the other three treatments,and the content of nitrate nitrogen?NO3--N?in the medium nitrogen treatment was significantly lower than that in the blank treatment.?2?The effects of different nitrogen depositions on the activities of four mineralizing enzymes in the soil of broad-leaved Korean pine forest plots for five consecutive years are not consistent.Among them,the urease content of the medium nitrogen treatment was significantly lower than that of the blank treatment,the protease activity of the three nitrogen addition treatments was significantly lower than that of the blank treatment,and there was no significant difference in the activities of L-asparaginase and L-glutaminease.?3?After applying different concentrations of ammonium nitrate for five consecutive years,the LN treatment resulted in a significant reduction in Simpson and Shannon indices of soil bacteria in broad-leaved Korean pine forest,but the?-diversity index of soil fungi did not produce significant differences.Different nitrogen deposition treatments make the bacterial community composition different,but the bacterial community composition under high nitrogen deposition treatment is similar to the other three treatments.Proteobacteria and Acidobacteria are the dominant bacteria in all treatments,and the average relative abundance are also greater than 20%.Although the average relative abundance of Verrucomicrobia and Gemmatimonadetes are less than 10%,but also has changed significantly compared with the blank.The top 20 bacterial genera that cause different community composition among the four treatments are Tardiphaga,Massilia,Bradyrhizobium.Different nitrogen deposition treatments also caused the fungal community composition to be different.The community composition of the medium nitrogen treatment and the high nitrogen treatment had certain similar.Basidiomycota and Ascomycota are the dominant bacterial groups in the fungal community composition,the average relative abundance of both is greater than 30%and the relative abundance of Basidiomycota is significant difference between low nitrogen treatment and high nitrogen treatment.The top 20 fungal genera with different community composition among the four treatments are mainly Taeniolella,Archaeorhizomyces,Cutaneotrichosporon,Cladophialophora,Malassezia,Sporobolomyces,Exophiala.?4?Compared with blank,low nitrogen deposition(20 kg N ha-1 yr-1)will reduce the relative abundance of ammonia oxidation-associated bacteria?Nitrosomonadaceae and Betaproteobacteriales?,thereby inhibiting the mineralization of organic nitrogen in the soil,and will reduce the abundance of symbiotic nutrition?Symbiotroph?fungi.?5?Redundant analysis revealed that soil organic matter?SOM?,ammonium nitrogen?NH4+-N?,nitrate nitrogen?NO3--N?,and available phosphorus?AP?are the main factors driving soil bacterial and fungal community changes,and the ammonium state Nitrogen?NH4+-N?is the most significant soil factor affecting the fungal community structure.Berkelbacteria and Polyporales can be used as indicator species for response of soil bacteria and fungi to nitrogen deposition,respectivelyThis study provides more data support for changes in soil microbial community structure and response of mineralizing enzyme activities to nitrogen deposition in broad-leaved Korean pine forests in the context of global environmental changes.
Keywords/Search Tags:Nitrogen deposition, Korean pine plantation, Microbial community structure, Nitrogen mineralization, Enzyme activity
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