The rewetting of long-term drained peatlands leads to the development of eutrophic shallow lakes, gradually inhabited by reed communities. These shallow lakes are characterized by significant nutrient and methane emissions. To comprehend the fate of organic compounds from decaying Phragmites australis litter in water and anaerobic soil layers, we conducted a 1.6-year decomposition experiment. The experiment employed bulk and lignin-derived phenol analysis, as well as Fourier-transform infrared spectroscopy. As anticipated, the highest level of decomposition was observed in the surface water body of the shallow lake, while the non-rooted degraded peat exhibited the lowest decay. The bulk mass loss of plant litter decreased with depth from 55 to 27% across the four decomposition environments. Analysis using infrared spectroscopy indicated that the decrease in mass loss was primarily driven by the breakdown of carbohydrates, which constitute a significant portion of plant litter. Interestingly, litter in the rooted degraded peat layer exhibited the highest degree of lignin decay. Furthermore, the study revealed a preferential loss of vanillin phenols and an accumulation of p-hydroxyl phenols. These findings suggest that the increased methane emissions in rewetted fens may be partially attributed to the demethoxylation of vanillin phenols and the subsequent formation of p-hydroxyl phenols. In conclusion, this study provides valuable insights into anaerobic lignin decomposition of plant litter and sheds light on potential mechanisms underlying elevated methane emissions in rewetted peatlands. Furthermore, the study’s findings hold significant implications for both carbon cycling and sequestration within these ecosystems, thereby stimulating further research into the microbial community and its extended effects.

长期排水的泥炭地的再湿润导致富营养化浅湖的发展，逐渐被芦苇群落栖息。这些浅湖的特点是大量的营养物和甲烷排放。为了了解水和厌氧土壤层中腐烂的芦苇凋落物中有机化合物的命运，我们进行了为期 1.6 年的分解实验。该实验采用了本体苯酚和木质素衍生的苯酚分析，以及傅里叶变换红外光谱。正如预期的那样，在浅湖地表水体中观察到最高程度的分解，而无根退化泥炭的腐烂程度最低。在四种分解环境中，植物凋落物的总体质量损失随着深度从 55% 下降到 27%。使用红外光谱分析表明，质量损失的减少主要是由碳水化合物的分解驱动的，碳水化合物构成了植物凋落物的很大一部分。有趣的是，生根的退化泥炭层中的枯落物表现出最高程度的木质素腐烂。此外，研究还揭示了香草醛酚的优先损失和对羟基酚的积累。这些发现表明，再润湿沼泽中甲烷排放量的增加可能部分归因于香草醛酚的脱甲氧基化以及随后形成的对羟基酚。总之，这项研究为植物凋落物的厌氧木质素分解提供了有价值的见解，并揭示了再湿泥炭地甲烷排放增加的潜在机制。此外，该研究的结果对这些生态系统内的碳循环和封存具有重要意义，从而刺激了对微生物群落及其延伸影响的进一步研究。