| 摘要: |
| 植物枯落物分解是维持湿地生态系统能量流动、物质循环和养分平衡的关键生态过程。于2017年11月-2018年4月在鄱阳湖湿地开展野外原位分解实验。利用分解袋法对3种优势植物芦苇(Phragmites australis)、南荻(Triarrhena lutarioriparia)和薹草(Carex cinerascens)枯落物纤维素和木质素分解过程和δ13C、δ15N分异特征开展了模拟实验研究。结果表明: 芦苇、南荻和薹草枯落物的纤维素和木质素的分解速率、干物质残留率以及δ13C、δ15N差异性极显著,造成这种差异的主要原因是不同种类植物枯落初始化学特性的不同,尤其是C/N和木质素/N的不同。枯落物中纤维素和木质素的分解速率都表现芦苇最大,薹草次之,南荻最小。Olson负指数衰减模型能非常好地模拟和预测3种植物枯落物的分解过程。伴随分解过程,3种植物枯落物δ13C上下波动,总体上呈显著降低的趋势,而δ15N则都呈现波动性的略有升高趋势,这说明在枯落物分解过程的不同阶段内,受枯落物基质质量和微生物代谢活动的双重影响,13C与15N既有释放也有富集。δ13C与枯落物纤维素和木质素分解速率都有极显著的正相关关系。δ15N与分解速率相关性不显著,这说明除了氮元素的迁移转化外,还有其他因素影响δ15N的变化。本研究有助于加深枯落物分解过程中基质质量调控机制的认识,深化对鄱阳湖湿地生物地球化学循环过程的科学理解。 |
| 关键词: 鄱阳湖 湿地植物枯落物 纤维素 木质素 分解过程 δ13C δ15N 稳定同位素 |
| DOI：10.18307/2023.0529 |
| 分类号: |
| 基金项目:国家自然科学基金项目(41971133,41471088)和地方合作项目(JXPJB20160101)联合资助。 |
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| Variation characteristics of the decomposition process δ13C and δ15N of three dominant plant litter in Lake Poyang wetland |
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Zhang Quanjun1, Yu Xiubo2,3, Zhang Guangshuai4
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1.CMA Meteorological Observation Centre, Beijing 100081, P.R. China;2.Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, P.R. China;3.University of Chinese Academy of Sciences, Beijing 100049, P.R. China;4.National Marine Environmental Monitoring Center, Dalian 116023, P.R. China
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| Abstract: |
| Litter decomposition is an important ecological process for maintaining energy flow, material cycling and nutrient balance in wetland ecosystems. From November 2017 to April 2018, a field decomposition experiment was conducted in the Lake Poyang wetland. The decomposition process and δ13C, δ15N differentiation characteristics of cellulose and lignin in the litter of three dominant plants, Phragmites australis, Triarrhena lutarioriparia and Carex cinerascens, were investigated using the decomposition bag method. The results showed that there were significant differences in cellulose and lignin residues, decomposition rate and δ13C, δ15N among the three plant litter types during the 150 d experiment. The main cause of these differences was attributed to the initial chemical properties of the different plant litter types, especially differences in C/N and lignin/N. The decomposition rate of litter cellulose and lignin was fastest in P. australis, followed by C. cinerascens and T. lutarioriparia. The decomposition process of the three plant litters was simulated and predicted using the Olson negative exponential decay model. During the decomposition of the three plant litters, δ15C fluctuated continuously but showed an overall significant decreasing trend, while δ15N for all litter types showed a slightly increasing trend in volatility, indicating that it was influenced by both substrate quality and microbial metabolic activities at different stages of decomposition. There was a significant positive correlation between δ13C and the decomposition rate of cellulose and lignin in the litter. However, the correlation between δ15N and the decomposition rate was not significant, indicating that there are other factors besides the migration and transformation of nitrogen elements that affect the change in δ15N. This study can contribute to a better scientific understanding of the substrate quality control mechanism in the process of litter decomposition, and provide a scientific basis for the protection and restoration of Lake Poyang wetland. |
| Key words: Lake Poyang wetland plants litter cellulose lignin decomposition δ13C δ15N stable isotope |
