Methane dynamics regulated by microbial community response to permafrost thaw
Methane dynamics regulated by microbial community response to permafrost thaw
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DOI：
10.1038/nature13798
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发表时间：
2014-10-23
期刊：
影响因子：
64.8
通讯作者：
Saleska, Scott R.
中科院分区：
文献类型：
--
作者：
McCalley, Carmody K.;Woodcroft, Ben J.;Saleska, Scott R.
永久冻土含有全球约50%的土壤碳(1)。人们认为，永久冻土的融化可能会导致土壤碳以甲烷和二氧化碳排放的形式损失(2，3)。由此产生的这种温室气体排放的气候正反馈的幅度仍然未知(3)，可能在很大程度上取决于人们对微生物群落组成在调节推动这种生态系统规模温室气体通量的代谢过程中所起的作用知之甚少。在这里，我们表明，随着永久冻土融化，植被的变化和甲烷排放的增加与从水力遗传营养转变为部分乙酰化甲烷作用有关，从而导致排放的甲烷的增量C-13特征发生巨大变化(千分之1015)。我们使用瑞典北部永久冻土融化的自然景观坡度(4，5)作为模型，研究微生物群落在调节甲烷循环中的作用，并测试群落动力学知识是否可以改善对永久冻土丧失情况下碳排放的预测。产甲烷假丝酵母的甲烷丰度(6)是甲烷同位素变化的一个关键预测因子，而甲烷同位素又预测作为甲烷和二氧化碳排放的碳的比例，这是在全球模型中模拟与永久冻土融化有关的气候反馈的一个重要因素(3，7)。通过证明关键微生物谱系的丰度可以用来预测与大气相关的甲烷同位素模式以及在多年冻土融化期间代谢成甲烷的碳的比例，我们为将变化中的微生物群落扩展到生态系统同位素动态奠定了基础。我们的发现表明，微生物生态在生态系统规模对全球变化的反应中可能很重要。
Permafrost contains about 50% of the global soil carbon(1). It is thought that the thawing of permafrost can lead to a loss of soil carbon in the form of methane and carbon dioxide emissions(2,3). The magnitude of the resulting positive climate feedback of such greenhouse gas emissions is still unknown(3) and may to a large extent depend on the poorly understood role of microbial community composition in regulating the metabolic processes that drive such ecosystem-scale greenhouse gas fluxes. Here we show that changes in vegetation and increasing methane emissions with permafrost thaw are associated with a switch from hydrogenotrophic to partly acetoclastic methanogenesis, resulting in a large shift in the delta C-13 signature (1015 parts per thousand) of emitted methane. We used a natural landscape gradient of permafrost thaw in northern Sweden(4,5) as a model to investigate the role of microbial communities in regulating methane cycling, and to test whether a knowledge of community dynamics could improve predictions of carbon emissions under loss of permafrost. Abundance of the methanogen Candidatus Methanoflorens stordalenmirensis(6) is a key predictor of the shifts in methane isotopes, which in turn predicts the proportions of carbon emitted as methane and as carbon dioxide, an important factor for simulating the climate feedback associated with permafrost thaw in global models(3,7). By showing that the abundance of key microbial lineages can be used to predict atmospherically relevant patterns in methane isotopes and the proportion of carbon metabolized to methane during permafrost thaw, we establish a basis for scaling changing microbial communities to ecosystem isotope dynamics. Our findings indicate that microbial ecology may be important in ecosystem-scale responses to global change.