中文摘要：

为了解河口潮汐沼泽湿地土壤有机碳（SOC）及其活性组分沿水文梯度分布特征,以闽江口鳝鱼滩短叶茳芏（Cyperus malaccensis Lam.var.brevifolius Bocklr）湿地土壤为研究对象,测定并分析高、中和低3个不同水淹频率土壤SOC及其活性组分,包括微生物生物量碳（MBC）、可溶性有机碳（DOC）和易氧化态碳（EOC）含量的变化情况。结果表明：不同水淹频率0-20cm土层SOC含量差异明显（P〈0.05）,表现为低水淹频率〉中水淹频率〉高水淹频率;土壤有机碳活性组分沿水文梯度分布特征与SOC分布特征相似,并且与SOC均呈极显著正相关（r〉0.48,n=45）,其中EOC和SOC相关关系最好（r=0.88,n=45）,说明SOC一定程度上决定了有机碳活性组分的含量,有机碳活性组分也可以反映SOC含量的变化情况;研究区内MBC/SOC、DOC/SOC和EOC/SOC范围分别为0.14%～0.88%,0.1%～0.47%和25.54%～45.02%,MBC/SOC和DOC/SOC随着水淹频率增大而增大,而EOC/SOC则相反,预示着随水淹频率的增加,MBC和DOC周转速率加快,而EOC稳定性增强;此外,SOC及其活性组分还一定程度受到土壤理化性质的影响,均与含水量呈显著或极显著正相关（r〉0.35,n=45）,与容重呈极显著负相关（r〈-0.39,n=45）;土壤pH与SOC和EOC呈极显著负相关（r〈-0.51,n=45）,而电导率（EC）与MBC和DOC呈极显著正相关（r〉0.46,n=45）。

英文摘要：

The field study was carried out in Cyperus malaccensis Lam.var.brevifolius Bocklr wetlands with3 different flooding frequencies in the Shanyutan of Minjiang River to investigate spatial distributions of soil organic carbon（SOC）and active composition which included microbial biomass carbon（MBC）,dissolved organic carbon（DOC）and ease of oxidation of carbon（EOC）along a hydrologic gradient.The results indicated that：The SOC contents of 0-20 cm soil profile had significant difference in different flooding frequencies（P〈0.05）,which presented low flooding frequency〉medium flooding frequency〉high flooding frequency.The spatial distributions of soil organic carbon active compositions were similar to SOC,there was significant correlation between the SOC and soil organic carbon active compositions（r〉0.48,n=45）,and the correlation between the SOC and EOC was the best（r=0.88,n=45）,which illustrated that SOC contents determines the content of soil organic carbon active compositions,and the soil organic carbon active compositions also reflected the change of SOC contents.The range of MBC/SOC,DOC/SOC and EOC/SOC were 0.14% ～0.88%,0.1%～0.47%and 25.54%～45.02%in study area.MBC/SOC and DOC/SOC were increasing withthe increasing of flooding frequencies,EOC was decreased with the increasing of flooding frequencies,which suggested that with the increasing of flooding frequencies,the turnover rate of MBC and DOC were decreased and the stability of EOC was increased.The soil organic carbon and active composition were influenced by soil property,and its significant or extremely significant related to moisture content of soil（r〈-0.39,n=45）,while bulk density of soil was very significant negative correlation with SOC and active composition（r〈-0.39,n=45）.Negative correlation was showed between pH and SOC or EOC（r〉-0.51,n=45）,while positive correlation was showed between the electrical conductivity（EC）and MBC or DOC（r0.46,n=45）.