水淹频率增加对闽江口湿地土壤有机碳及其活性组分的影响

研究河口湿地土壤有机碳及其活性组分对水淹频率的响应,对认识海平面上升背景下湿地土壤碳循环具有重要意义.本文以闽江河口湿地为研究区,测定了区内6、7和8月高潮滩(偶尔水淹,H样地)和中潮滩(频繁水淹,M样地)表层土壤有机碳(SOC)及其活性组分-微生物生物量碳(MBC)、易氧化有机碳(EOC)及可溶性有机碳(DOC)的含量,并进一步通过原位培养方法(H样地植物-土壤移动到M样地进行培养)分析了水淹频率增加对SOC及其活性组分的影响.结果表明:H样地SOC、EOC、MBC和DOC含量平均值分别为45.11 g·kg-1、30.21 g·kg-1、385.29 mg·kg-1和749.98 mg·kg-1,总体显著高于而M样地SOC、EOC、MBC和DOC含量(p0.05),高出的比例分别为161.81%、136.2%、200.6%和710.86%;野外培养90 d后,SOC和EOC均无显著变化,而MBC和DOC随培养时间延长,影响逐渐增大,90 d培养后,两者均显著下降,下降比例分别为28.21%和93.84%;此外,SOC及其活性组分在一定程度上受到土壤理化性质的影响,除EOC外,SOC、MBC和DOC均与p H、TN和TP呈显著相关(p0.01).这些结果表明,在较长时间尺度,水淹频率可以直接影响SOC及其活性组分,也可能通过影响p H、TN和TP等因子,间接影响SOC及其活性组分.

Effects of increasing flooded frequency on soil organic carbon and its active composition in the Min River estuarine wetland

It is important to study the soil organic carbon and its active composition in estuarine wetland for understanding the soil carbon cycle of wetland under sea level rise. Min River estuarine wetland was chosen as the study area, the soil organic carbon (SOC) and its active composition (microbial biomass carbon (MBC), dissolved organic carbon (DOC) and easily oxidized carbon (EOC)) were determined in high tidal flat (occasionally flooded, H plot), middle tidal flat (frequently flooded, M plot). Moreover, the effects of increasing flooded frequency on soil organic carbon and its active composition were also analyzed by using incubation method in situ (plant-soil in H plot move to M plot). The result indicated that the SOC, EOC, MBC and DOC concentrations in H plot were 45.11 g·kg^-1, 30.21 g·kg^-1, 385.29 mg·kg^-1 and 749.98 mg·kg^-1, respectively, which were higher than those of M plot, and the increment were 161.81%,136.2%,200.6% and 710.86%, respectively. After 90-day incubation in situ, SOC and EOC concentrations were not obviously changed, while significantly decreased 28.21% and 93.84% for MBC and DOC concentrations, respectively (p<0.05). The SOC and its active composition were partially influenced by soil properties. SOC, MBC and DOC were significant related to pH, TN and TP(p<0.01) except EOC. These results indicated that SOC and the active compositions can be influenced directly by the flooded frequency and the indirectly through changing the pH, TN and TP under longer time scale.