Organic matter chemistry controls greenhouse gas emissions from permafrost peatlands
Organic matter chemistry controls greenhouse gas emissions from permafrost peatlands
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DOI：
10.1016/j.soilbio.2016.03.016
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发表时间：
2016-07
影响因子：
9.7
通讯作者：
S. Sjögersten;S. Caul;T. Daniell;Andrew P S Jurd;Odhran S. O’Sullivan;C. S. Stapleton;J. Titman
中科院分区：
文献类型：
--
作者：
S. Sjögersten;S. Caul;T. Daniell;Andrew P S Jurd;Odhran S. O’Sullivan;C. S. Stapleton;J. Titman
大片北极和亚北极泥炭地被永久冻土覆盖。这些泥炭地储存了大量的碳(C)，目前正受到气候变化的严重威胁。本研究的目的是确定多年冻土泥炭地中易降解碳库的大小和有机化学，并将功能有机化学与温室气体排放的温度和湿度控制联系起来。首先，我们使用现场测量和实验室实验相结合的方法，评估了气温上升和洪水对瑞典和加拿大亚北极地区16个永久冻土泥炭地二氧化碳和甲烷排放的影响。其次，我们分别使用定量的13C固体核磁共振和分子生物标志物，确定了泥炭活动层的有机质化学和相关微生物群落组成随深度的变化。我们证明，泥炭有机化学强烈控制着泥炭中二氧化碳的释放，在瑞典和加拿大的泥炭地，分别约有35%和26%的泥炭有机质很容易被异养微生物降解。与二氧化碳相反，甲烷的排放与泥炭功能有机化学是脱钩的。我们发现微生物群落结构与泥炭有机化学之间有很强的相关性，这表明底物类型和丰度是亚北极泥炭地微生物组成的重要驱动因素。尽管泥炭化学和微生物群落组成随深度有很大差异，但整个活动层的温度敏感性是可比的。我们的研究表明，功能有机化学既控制土壤呼吸速率，又控制微生物群落的组成。此外，如果这些泥炭地在融化过程中坍塌并泛滥，它们不太可能成为CH4的大排放者，而不是额外输入不稳定的底物。
Large tracts of arctic and subarctic peatlands are underlain by permafrost. These peatlands store large quantities of carbon (C), and are currently under severe threat from climate change. The aim of this study was to determine the size and organic chemistry of the easily degradable C pool in permafrost peatlands and link the functional organic chemistry to temperature and moisture controls of greenhouse gas emissions. First, we used a combination of field measurements and laboratory experiments to assess the influence of increased temperature and flooding on CO2and CH4emissions from sixteen permafrost peatlands in subarctic Sweden and Canada. Second, we determined the variation in organic matter chemistry and the associated microbial community composition of the peat active layer, with depth using quantitative13C solid-state NMR and molecular biomarkers respectively. We demonstrate that the peat organic chemistry strongly controls CO2release from peat and that ca. 35 and 26% of the peat organic matter, at the Swedish and Canadian peatlands sites, respectively, is easily degradable by heterotrophic microorganisms. In contrast to CO2, CH4emissions were decoupled from peat functional organic chemistry. We show a strong relationship between the microbial community structure and the peat organic chemistry suggesting that substrate type and abundance is an important driver of microbial composition in sub-arctic peatlands. Despite considerable variation in peat chemistry and microbial community composition with depth the temperature sensitivity was comparable throughout the active layer. Our study shows that functional organic chemistry controls both soil respiration rates and the composition of the microbial community. Furthermore, if these peatlands collapse and flood on thawing, they are unlikely to become large emitters of CH4without additional input of labile substrates.