Influence of Permafrost Type and Site History on Losses of Permafrost Carbon After Thaw
Influence of Permafrost Type and Site History on Losses of Permafrost Carbon After Thaw
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DOI：
10.1029/2021jg006396
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发表时间：
2019-12
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影响因子：
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通讯作者：
K. Manies;Miriam C. Jones;M. Waldrop;M. Leewis;Christopher Fuller;R. Cornman;K. Hoefke
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文献类型：
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作者：
K. Manies;Miriam C. Jones;M. Waldrop;M. Leewis;Christopher Fuller;R. Cornman;K. Hoefke
我们量化了阿拉斯加内陆地区多年冻土泥炭高原和解冻后的碳（C）储量，以评估解冻后的C损失量。大型化石重建揭示了泥炭的三个地层：（a）沼泽/沼泽泥炭的基层，（B）来自森林泥炭高原（有永久冻土）的泥炭，和（c）塌陷-疤痕沼泽泥炭（在永久冻土融化发生的地点）。放射性碳年代测定显示，泥炭是在过去2,500年内形成的，永久冻土是在小冰河时代（约2,500年）形成的。250-575年前），并在过去几十年内退化。在每个功能的永久冻土融化的时间是不相关的解冻沼泽的大小。它们的扩张速度可能更多地受到当地因素的影响，如地面冰含量和地下水的输入。我们发现，在过去的世纪中，由于解冻而造成的碳损失高达可用碳的46%，但碳损失的绝对量（kg m−2）比以前在阿拉斯加泥炭地年代序列中描述的损失低50%以上。我们假设，这种差异源于永冻土加积的过程中，与形成永冻土表观遗传（显着晚于大多数泥炭积累）经历的绝对碳损失与解冻比同生（同时与泥炭积累）形成的网站。后生泥炭从我们的网站有较低的C：N比相比，阿拉斯加的网站，同生泥炭。这种差异可以帮助预测跨范围或永久冻土类型和历史融化的C损失的幅度。
We quantified permafrost peat plateau and post‐thaw carbon (C) stocks across a chronosequence in Interior Alaska to evaluate the amount of C lost with thaw. Macrofossil reconstructions revealed three stratigraphic layers of peat: (a) a base layer of fen/marsh peat, (b) peat from a forested peat plateau (with permafrost), and (c) collapse‐scar bog peat (at sites where permafrost thaw has occurred). Radiocarbon dating revealed that peat initiated within the last 2,500 years and that permafrost aggraded during the Little Ice Age (ca. 250–575 years ago) and degraded within the last several decades. The timing of permafrost thaw within each feature was not related to thaw bog size. Their rate of expansion may be more influenced by local factors, such as ground ice content and subsurface water inputs. We found C losses due to thaw over the past century were up to 46% of the C available, but the absolute amount of C lost (kg m−2) was over 50% lower than losses previously described in other Alaskan peatland chronosequences. We hypothesize that this difference stems from the process by which permafrost aggraded, with sites that formed permafrost epigenetically (significantly later than most peat accumulation) experiencing less absolute C loss with thaw than sites that formed syngenetically (simultaneously with peat accumulation). Epigenetic peat from our site had lower C:N ratios as compared to Alaskan sites that have syngenetic peat. This difference could help predict the magnitude of C loss with thaw across a range or permafrost types and histories.