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通过分析上海崇明东滩南部冲刷带芦苇型砂壤土(A区)和东北部淤涨带芦苇/米草型粘土(B区)的有机碳含量和植被输入量,研究了异质性湿地土壤的有机碳汇聚能力,并从异质型土壤的微生物活性和理化性质的差异角度分析了造成土壤有机碳汇聚能力差异的主要原因.结果表明:A区土壤平均总有机碳含量仅为B区的46.10%(P<0.05),而A区地上部分的年均植物量仅比B区低9.16%,说明A区湿地土壤有机碳的输出量大于B区.A区细菌总数比B区高3.82倍(P<0.05),过氧化氢酶和转化酶活性分别比B区高46.81%和34.33%(P<0.05),且土壤微生物呼吸强度也高于B区.说明A区土壤的微生物碳代谢能力较强是导致其土壤有机碳保留能力较弱的重要原因.A区砂壤土粒间孔隙较大、土壤通气透水性较好、含水率与含盐量较低,有利于微生物生长,促进了土壤有机碳的分解;而B区的芦苇/米草型粘土的含水量和含盐量高、微生物活性弱,有机碳氧化分解能力较低,具有较高的有机碳汇聚能力.
By analyzing the organic carbon content and vegetation input of reed-type sandy loam (A zone) in the scouring belt in the south of Chongming East Beach in Shanghai and reed / paxillite clay in the upwelling zone in the northeast of China, Carbon aggregation ability and the main reason that caused the difference of soil organic carbon aggregation ability were analyzed from the difference of microbial activity and physicochemical properties of heterogeneous soil.The results showed that the average soil total organic carbon content in area A was only 46.10% (P <0.05), while the average annual plant biomass in area A was only 9.16% lower than that in area B, indicating that the output of soil organic carbon in wetland in area A was greater than that in area B. The total number of bacteria in area A was 3.82 times higher than that in area B <0.05), and the activities of catalase and invertase were 46.81% and 34.33% higher than those in B area, respectively (P <0.05), and the respiration intensity of soil microorganisms was also higher than that of B area, indicating that the soil microbial biomass C Is the main reason for its weak retention of soil organic carbon.A sandstone loam area A larger intergranular porosity, soil aeration permeability is better, the water content and salt content is lower, is conducive to microbial growth, and promote soil organic carbon Of the decomposition; and B area reed / grass-grass clay moisture content and containing Volume, microbial activity is weak, the lower organic carbon oxidation and decomposition, and higher organic carbon accumulation.