胡启凯,罗敏,黄佳芳,吴杰,朱爱菊,谭季,李敬.闽江河口潮汐沼泽湿地天然低盐度梯度土壤胞外酶活性特征[J].环境科学学报,2019,39(9):3107-3116
闽江河口潮汐沼泽湿地天然低盐度梯度土壤胞外酶活性特征
- Soil extracellular enzyme activities in low salinity gradient tidal marshes of the Min River estuary, southeast China
- 基金项目：国家自然科学基金资助项目（No.41877335，41501252）；福建省大学生创新创业项目（No.41601102）；湿润亚热带生态-地理过程教育部重点实验室开放基金（No.2017KFJJ02）；中国科学院海岸带环境过程与生态修复重点实验室开放基金（No.2018KFJJ10）
- 胡启凯
- 福州大学环境与资源学院, 福州 350116
- 罗敏
- 1. 福州大学环境与资源学院, 福州 350116;2. 福建师范大学地理科学学院, 福州 350116;3. 湿润亚热带生态-地理过程教育部重点实验室, 福州 350007
- 黄佳芳
- 1. 福建师范大学地理科学学院, 福州 350116;2. 湿润亚热带生态-地理过程教育部重点实验室, 福州 350007
- 朱爱菊
- 1. 福建师范大学地理科学学院, 福州 350116;2. 湿润亚热带生态-地理过程教育部重点实验室, 福州 350007
- 谭季
- 1. 福建师范大学地理科学学院, 福州 350116;2. 湿润亚热带生态-地理过程教育部重点实验室, 福州 350007
- 李敬
- 1. 福建师范大学地理科学学院, 福州 350116;2. 湿润亚热带生态-地理过程教育部重点实验室, 福州 350007
- 摘要：为了揭示河口潮汐沼泽湿地天然低盐度梯度下土壤胞外酶活性的时空变化差异，对闽江河口淡水潮汐沼泽湿地和半咸水潮汐沼泽湿地短叶茳芏（Cyperus malaccensis）植被下不同季节的土壤胞外酶活性、土壤容重和含水率、植物生物量、以及有机碳特征值（SOC、POXC、DOC和C∶N比）进行测定与分析.研究结果表明在闽江河口天然盐度梯度上，当土壤盐度从0‰增加至4.2‰，土壤β-葡萄糖苷酶（BG）、纤维素水解酶（CBH）、酚氧化酶（PHO）和过氧化物酶（PEO）活性均显著增加，增幅分别为201%、305%、493%和252%.沿着闽江河口天然盐度梯度，土壤容重和含水率以及孔隙水DOC浓度没有显著变化，但土壤易氧化有机碳（POXC）含量、有机碳（SOC）含量和土壤C∶N比逐渐减少.半咸水潮汐沼泽湿地站点短叶茳芏的地上生物量低于淡水潮汐沼泽湿地站点，但地下生物量则显著高于淡水潮汐沼泽湿地站点.4种土壤胞外酶活性均与土壤C∶N比呈现显著的负相关，酚氧化酶（PHO）和过氧化物酶（PEO）与土壤SOC含量呈负相关.土壤β-葡萄糖苷酶（BG）活性最高值出现在春季，而纤维素水解酶（CBH）活性最高值出现在夏季.以上研究结果表明，土壤盐度是影响闽江河口潮汐沼泽湿地生态系统土壤胞外酶活性和碳库演变的重要环境因子.从河口淡水潮汐沼泽湿地至低盐的半咸水潮汐沼泽湿地，沼泽植物地下生物量增加，与碳分解相关的土壤胞外酶活性增加，并抑制土壤的有机碳积累.
- Abstract：To reveal the changes in the activities of soil extracellular enzymes in estuarine tidal marshes, we investigated seasonal soil extracellular enzyme activities, plant biomass, soil bulk densities, and water content, as well as soil organic carbon inventories (including SOC, POXC, DOC, and C∶N ratios) in the Cyperus malaccensis tidal marshes of the Min River estuary in southeast China. The results showed that higher activities of β-glucosidase (BG), cellobiohydrolase (CBH), phenol oxidase (PHO), and peroxidase (PEO) were observed in the tidal brackish marshes than in the freshwater marshes. For the salinity gradient (0‰ to 4.2‰), the increased rates of activities of soil extracellular enzymes BG, CBH, PHO, and PEO were 201%, 305%, 493%, and 252%, respectively. The soil bulk densities and water content, and porewater DOC concentrations did not change with changes in the salinity gradient. Soil SOC content and C∶N ratios decreased with increased soil salinity. The belowground biomass of C. malaccensis was significantly higher in the brackish water sites than in the freshwater sites; however, the trend was opposite for the aboveground biomass. All activities of soil extracellular enzymes were negatively correlated with C∶N ratios, and activities of PHO and PEO negatively correlated with POXC and SOC contents. The highest activities of BG and CBH appeared in the spring and summer, respectively. In conclusion, salinity is an important environmental factor for controlling soil extracellular enzyme activities and carbon cycling in the estuarine tidal marshes. From the tidal freshwater marshes to brackish water marshes, the increasing soil salinity promotes the belowground biomass and activities of soil extracellular enzymes, but depletes the soil organic carbon pool in the estuarine tidal marshes.
