崇明东滩不同演替阶段湿地土壤有机碳汇聚能力的差异性及其微生物机制

旨在阐明崇明东滩不同演替阶段湿地土壤有机碳汇聚能力的差异性及其机制,以期为优化湿地的管理与保育措施,进而保持和提升湿地的碳汇功能提供理论指导和决策依据。研究结果表明,4个不同演替阶段湿地土壤有机碳含量和微生物呼吸强度有显著差异(P<0.05),中高潮滩处的土壤有机碳汇聚能力最高,这是由于其具有较高的有机碳输入(植物枯落物)和相对较低的碳输出(土壤呼吸)。PCR-DGGE分析和系统进化树结果表明,4个不同演替阶段土壤的微生物群落结构存在差异,一些特异性优势菌的存在可能是影响土壤微生物呼吸强度,并最终影响土壤有机碳汇聚能力的重要原因。出现在高潮滩的噬纤维菌和假单胞属菌具有较高降解纤维素等有机质的能力,它们的存在可能强化了高潮滩的土壤呼吸作用,从而降低了高潮滩土壤的有机碳汇聚能力。

Variability in Organic Carbon Storage Capability of Soils at Different Successional Stages in Chongming Dongtan Wetland and Its Microbial Mechanism

Chongming Dongtan is a young tidal wetland at Yangtze Estuary,which has important ecological and environmental functions,such as sequestration of organic carbon and alleviation of CO2 emission.Currently,the wetland is undergoing a rapidly successional process.The soil organic carbon storage capability may vary at different successional stages due to their different soil properties and vegetation type.The aim of this study was to clarify the variability in soil organic carbon storage capability in Chongming Dongtan tidal wetland at different successional stages and its mechanisms.The work will provide a theoretic guide for optimizing the pattern of the wetland to maintain and improve its organic carbon storage capability.The results showed that the soil organic carbon(SOC) and soil microbial respiration(SMR) varied significantly(P<0.05) among different successional stages.The middle/high tidal flat had the highest SOC due to its relatively high organic carbon input from plant litter and lower carbon output from SMR,indicating middle/high tidal flats have a relatively high organic carbon storage capability.PCR-DGGE and phylogenetic analysis revealed that the bacterial community structure along the successional stages varied due to their different soil phycochemical properties.Some dominant and unique bacteria inhabited in the tidal zone may influence the SMR.Uncultured Cytophagales bacterium and Pseudomonas sp.,which were primarily found in higher tidal flat,were efficient in the degradation of complex organic molecules such as cellulose,thus strengthened the SMR and ultimately reduced the soil organic carbon storage capability there.