Drivers of Holocene peatland carbon accumulation across a climate gradient in northeastern North America
Drivers of Holocene peatland carbon accumulation across a climate gradient in northeastern North America
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DOI：
10.1016/j.quascirev.2015.05.012
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发表时间：
2015-08-01
影响因子：
4
通讯作者：
Mauquoy, Dmitri
中科院分区：
文献类型：
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作者：
Charman, Dan J.;Amesbury, Matthew J.;Mauquoy, Dmitri
泥炭地是全新世全球碳（C）循环的重要组成部分，碳封存和储存的速率由净初级生产力和腐烂之间的平衡驱动。目前许多研究表明，气候是泥炭地碳在大空间尺度和长时间尺度上积累的关键驱动因素，气候变暖与碳积累速率较高相关。然而，其他因素也可能在确定当地碳积累率方面发挥重要作用，并且这些因素可能会改变过去、现在和未来的泥炭地碳固存。在这里，我们通过北美东北部三个地点在凸起沼泽分布的南北气候梯度上的碳积累记录，与水文变化、火灾、氮含量和植被类型进行比较，测试了气候作为碳积累驱动因素的重要性。每个站点的放射性碳年龄模型、堆积密度值和 %C 测量值用于构建从 11,200 到 8000 cal 之间开始的 C 积累历史。年英国石油公司。通过线性和多元回归分析评估碳积累和环境变量（过去的地下水位深度、火灾、泥炭形成植被和氮含量）之间的关系。不同地点之间长期碳积累速率的差异支持了这样的论点：气候变暖和生长季节较长会导致长期碳积累速率加快。但全新世中晚期的堆积速率呈现出北减南升的不同趋势。我们假设，在全新世晚期，接近湿度阈值的沼泽分布增加了其生长速率，以应对全新世晚期蒸散量较低的凉爽气候，但同期北部地区的净初级生产力下降，导致碳积累减少。碳积累与水文变化、植被、氮含量或火灾之间没有明确的关系，但泥炭地生长的早期演替阶段的碳积累速度较快，尽管当时的温度可能较低。我们的结论是，气候是千年时间尺度上泥炭地积累率的最重要驱动因素，但植被演替变化是一个重要的额外影响。虽然在未来气候变暖的情况下，大多数北部泥炭地的碳积累率可能会增加，但南部分布范围的泥炭地的碳积累率可能会降低。然而，在泥炭地分布北部边界的未来变暖条件下形成的早期演替泥炭地可能具有较高的碳积累率，并将补偿其他地方的一些损失。 (C) 2015 年作者。由 Elsevier Ltd 出版。这是一篇基于 CC BY 许可的开放获取文章。
Peatlands are an important component of the Holocene global carbon (C) cycle and the rate of C sequestration and storage is driven by the balance between net primary productivity and decay. A number of studies now suggest that climate is a key driver of peatland C accumulation at large spatial scales and over long timescales, with warmer conditions associated with higher rates of C accumulation. However, other factors are also likely to play a significant role in determining local carbon accumulation rates and these may modify past, present and future peatland carbon sequestration. Here, we test the importance of climate as a driver of C accumulation, compared with hydrological change, fire, nitrogen content and vegetation type, from records of C accumulation at three sites in northeastern North America, across the N-S climate gradient of raised bog distribution. Radiocarbon age models, bulk density values and %C measurements from each site are used to construct C accumulation histories commencing between 11,200 and 8000 cal. years BP. The relationship between C accumulation and environmental variables (past water table depth, fire, peat forming vegetation and nitrogen content) is assessed with linear and multivariate regression analyses. Differences in long-term rates of carbon accumulation between sites support the contention that a warmer climate with longer growing seasons results in faster rates of long-term carbon accumulation. However, mid-late Holocene accumulation rates show divergent trends, decreasing in the north but rising in the south. We hypothesise that sites close to the moisture threshold for raised bog distribution increased their growth rate in response to a cooler climate with lower evapotranspiration in the late Holocene, but net primary productivity declined over the same period in northern areas causing a decrease in C accumulation. There was no clear relationship between C accumulation and hydrological change, vegetation, nitrogen content or fire, but early successional stages of peatland growth had faster rates of C accumulation even though temperatures were probably lower at the time. We conclude that climate is the most important driver of peatland accumulation rates over millennial timescales, but that successional vegetation change is a significant additional influence. Whilst the majority of northern peatlands are likely to increase C accumulation rates under future warmer climates, those at the southern limit of distribution may show reduced rates. However, early succession peatlands that develop under future warming at the northern limits of peatland distribution are likely to have high rates of C accumulation and will compensate for some of the losses elsewhere. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license.