九段沙不同演替阶段湿地土壤微生物呼吸的差异性及其影响因素

通过分析九段沙不同演替阶段湿地土壤微生物呼吸及其土壤微环境因子,研究了不同类型湿地土壤微生物呼吸的差异性及其影响因素。结果表明,处于不同植被演替阶段的湿地土壤微生物呼吸具有显著差异(P0.05),海三棱藨草区高于芦苇区,互花米草区最高(0.367 mg.g-1.(24h)-1),互花米草的引种及蔓延增强了入侵区域土壤微生物呼吸。综合考虑不同植被类型湿地土壤微生物呼吸及植被生物量,芦苇区呼吸微弱、植被生物量最高,在理论上具有更高的有机碳碳汇聚能力。通径分析结果显示,影响土壤微生物呼吸强度的主要生物因素有:原核微生物多样性(Shannon指数)和土壤微生物生物量;土壤有机质、硝态氮及土壤含水量对上述微生物活性指标有显著影响,因此也属于土壤微生物呼吸的主要影响因素。

Variability in and factors influencing soil microbial respiration in the Jiuduansha Wetland under different successional stages

To clarify variability in soil microbial respiration (SMR) and its influencing factors, characteristics of SMR and soil physical and biochemical factors under different successional stages were studied at the Jiuduansha Wetland, located at the Yangtze Estuary. Results indicate that SMR varies significantly among different successional stages of vegetation (P<0.05). SMR in the Phragmites australis district is lower than that in the Scirpus mariqueter district, and SMR of Spartina alterniflora district (~0.367 mg CO2 g-1 24 h-1) is the highest among the five vegetation types. This implies that S. alterniflora can greatly enhance SMR. Considering both SMR and input of organic matter from decayed plant biomass of different vegetation types, wetlands composed of a P. australis community, in theory, have higher capability to accumulate carbon. Results from Path analysis show that the main biological factors influencing SMR include prokaryon microbial diversity (Shannon index) and soil microbial biomass (SMB). In addition, soil organic matter (SOM), nitrate nitrogen and soil water content significantly affect the above-mentioned biological factors, thereby also influence SMR.