Changes of the CO2 and CH4 production potential of rewetted fens in the perspective of temporal vegetation shifts
Changes of the CO2 and CH4 production potential of rewetted fens in the perspective of temporal vegetation shifts
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DOI：
10.5194/bg-12-2455-2015
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发表时间：
2014-10
期刊：
影响因子：
4.9
通讯作者：
D. Zak;Hendrik Reuter;J. Augustin;T. Shatwell;M. Barth;J. Gelbrecht;R. McInnes
中科院分区：
文献类型：
--
作者：
D. Zak;Hendrik Reuter;J. Augustin;T. Shatwell;M. Barth;J. Gelbrecht;R. McInnes
抽象的。长期排干的沼泽地的再湿润常常导致平均水深小于1 m的富营养化浅水湖泊的形成。这是伴随着一个快速的植被转变，从种植草通过沉水水生植物到沼生植物。由于植物快速死亡和分解，这些系统是高度动态的湿地，其特征是养分的高动员和CO2和CH4的排放量增加。然而，具体植物物种对这些现象的影响尚不清楚。因此，我们调查了CO2和CH4的生产，由于水下分解的拍摄生物量的五个选定的植物物种，代表不同的再湿润阶段（Phalaris arundinacea，金鱼藻，香蒲，芦苇和苔草riparia）在154天的围隔生态系统的研究。除了连续的气体通量测量，我们进行了大量的植物组织化学分析，包括碳，氮，磷和植物聚合物动力学。154天后，植物特定的质量损失范围从25%（P. australis）到64%（C. demersum）。结果表明，不同碳源的甲烷产量存在显著差异，碳源分解的甲烷产量最高。demersum（0.4 g CH4 kg−1干质量日）的CH4产量比C.河岸。因此，我们发现了一个很强的分歧之间的质量损失的凋落物和分解过程中产生的甲烷。如果C.在统计分析中仅包括作为水生植物的demersum，营养物含量（氮和磷）解释了不同植物物种的不同温室气体产生，而木质素和多酚显示根本没有显著影响。考虑到作为产甲烷菌重要碳源的年度生物量生产数据，只要淹没和营养丰富的条件占上风，预计高CH4排放量将持续几十年。不同的恢复措施，如水位控制，生物量提取和表层土壤去除的背景下，从回湿沼泽CH4排放的缓解进行了讨论。
Abstract. Rewetting of long-term drained fens often results in the formation of eutrophic shallow lakes with an average water depth of less than 1 m. This is accompanied by a fast vegetation shift from cultivated grasses via submerged hydrophytes to helophytes. As a result of rapid plant dying and decomposition, these systems are highly dynamic wetlands characterised by a high mobilisation of nutrients and elevated emissions of CO2 and CH4. However, the impact of specific plant species on these phenomena is not clear. Therefore we investigated the CO2 and CH4 production due to the subaqueous decomposition of shoot biomass of five selected plant species which represent different rewetting stages (Phalaris arundinacea, Ceratophyllum demersum, Typha latifolia, Phragmites australis and Carex riparia) during a 154 day mesocosm study. Beside continuous gas flux measurements, we performed bulk chemical analysis of plant tissue, including carbon, nitrogen, phosphorus and plant polymer dynamics. Plant-specific mass losses after 154 days ranged from 25% (P. australis) to 64% (C. demersum). Substantial differences were found for the CH4 production with highest values from decomposing C. demersum (0.4 g CH4 kg−1 dry mass day) that were about 70 times higher than CH4 production from C. riparia. Thus, we found a strong divergence between mass loss of the litter and methane production during decomposition. If C. demersum as a hydrophyte is included in the statistical analysis solely nutrient contents (nitrogen and phosphorus) explain varying greenhouse gas production of the different plant species while lignin and polyphenols demonstrate no significant impact at all. Taking data of annual biomass production as important carbon source for methanogens into account, high CH4 emissions can be expected to last several decades as long as inundated and nutrient-rich conditions prevail. Different restoration measures like water level control, biomass extraction and top soil removal are discussed in the context of mitigation of CH4 emissions from rewetted fens.