Drought-induced carbon loss in peatlands
Drought-induced carbon loss in peatlands
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DOI：
10.1038/ngeo1323
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发表时间：
2011-12-01
影响因子：
18.3
通讯作者：
Freeman, Chris
中科院分区：
文献类型：
--
作者：
Fenner, Nathalie;Freeman, Chris
泥炭地储存着大量的有机碳，总量约为455加仑。由于酚类化合物的存在，碳在这些水饱和的环境中积聚--酚类化合物抑制微生物活动，从而防止有机物的分解。缺氧条件限制了酚氧化酶的活性，酚氧化酶是负责分解酚类化合物的酶。干旱将氧气引入这些系统，而且这些事件的频率正在上升。在这里，我们结合体外操作、中微体实验和野外观察来研究干旱对泥炭地碳损失的影响。我们发现，干旱刺激了细菌的生长和酚氧化酶的活性，导致泥炭中酚类化合物的浓度降低。这进一步刺激了微生物的生长，导致有机物的分解和生物地球化学级联反应中二氧化碳的释放。我们进一步表明，重新润湿泥炭会加速碳流失到大气和接收水中，这是由于干旱导致的养分和不稳定碳水平的增加，从而提高了pH并刺激了厌氧分解。我们认为，严重干旱和随后的重新湿润可能会破坏泥炭地碳储量的稳定；了解这一过程将有助于理解泥炭地与其他环境趋势之间的相互作用，并导致制定增加碳储量的战略。
Peatlands store vast amounts of organic carbon, amounting to approximately 455 Pg. Carbon builds up in these water-saturated environments owing to the presence of phenolic compounds-which inhibit microbial activity and therefore prevent the breakdown of organic matter. Anoxic conditions limit the activity of phenol oxidase, the enzyme responsible for the breakdown of phenolic compounds. Droughts introduce oxygen into these systems, and the frequency of these events is rising. Here, we combine in vitro manipulations, mesocosm experiments and field observations to examine the impact of drought on peatland carbon loss. We show that drought stimulates bacterial growth and phenol oxidase activity, resulting in a reduction in the concentration of phenolic compounds in peat. This further stimulates microbial growth, causing the breakdown of organic matter and the release of carbon dioxide in a biogeochemical cascade. We further show that re-wetting the peat accelerates carbon losses to the atmosphere and receiving waters, owing to drought-induced increases in nutrient and labile carbon levels, which raise pH and stimulate anaerobic decomposition. We suggest that severe drought, and subsequent re-wetting, could destabilize peatland carbon stocks; understanding this process could aid understanding of interactions between peatlands and other environmental trends, and lead to the development of strategies for increasing carbon stocks.