A Model Intercomparison Analysis for Controls on C Accumulation in North American Peatlands
A Model Intercomparison Analysis for Controls on C Accumulation in North American Peatlands
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DOI：
10.1029/2021jg006762
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发表时间：
2022-04
期刊：
影响因子：
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通讯作者：
Bailu Zhao;Q. Zhuang;C. Treat;S. Frolking
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作者：
Bailu Zhao;Q. Zhuang;C. Treat;S. Frolking
泥炭地生态地球化学过程在现有的地球系统模型中没有得到充分的体现，这可能会使北极碳-气候反馈的量化产生偏差。我们修改了泥炭地陆地生态系统模型（PTEM）纳入额外的泥炭地生态化学过程。通过与全新世泥炭地模型（HPM）在模拟北美三个泥炭地（一个永久冻土沼泽地、一个永久冻土沼泽地和一个永久冻土沼泽地）的泥炭物理和地球化学动态方面的比较，对修正后的PTEM进行了评价。泥炭地碳动态模拟从泥炭形成到1990年，然后到2300年。分析了模式对温度和降水变化的响应，以确定影响泥炭地碳积累速率的关键过程。我们发现，净碳平衡是敏感的地下水位深度和养分供应。在RCP 2.6、RCP 4.5和RCP 8.5下，用这两个模型进行了到2300年的未来模拟。PTEM预测这些泥炭地是C源或较弱的C汇时，降水不足，抑制土壤水分，从而净N矿化和净初级生产，而HPM预测相同的干燥气候导致增加地下水位深度。我们的研究结果强调了水平衡和碳氮反馈对泥炭地碳动态的重要性。随着气候变暖，这些泥炭地可能成为一个较弱的C汇或源在干燥的条件下，否则一个较大的C汇，如果潮湿。进一步了解泥炭地的过程，可以帮助未来量化泥炭地碳动力学在北方和北极地区。
Peatland biogeochemical processes have not been adequately represented in existing earth system models, which might have biased the quantification of Arctic carbon‐climate feedbacks. We revise the Peatland Terrestrial Ecosystem Model (PTEM) by incorporating additional peatland biogeochemical processes. The revised PTEM is evaluated by comparing with Holocene Peatland Model (HPM) in simulating peat physical and biogeochemical dynamics in three North American peatlands: a permafrost‐free fen site, a permafrost‐free bog site and a permafrost bog site. Peatland carbon dynamics are simulated from peat initiation to 1990 and then to year 2300. Model responses to the changes in temperature and precipitation are analyzed to identify key processes affecting peatland carbon accumulation rates. We find that the net C balance is sensitive to water table depth and nutrient availability. Future simulations to year 2300 are conducted with both models under RCP 2.6, RCP 4.5, and RCP 8.5. PTEM predicts these peatlands to be C sources or weaker C sinks when insufficient precipitation suppresses soil moisture and thereby net N mineralization and net primary production, while HPM predicts the same when drier climate leads to increasing water table depth. Our results highlight the importance of water balance and C‐N feedback on peatland C dynamics. With a warmer climate, these peatlands could become a weaker C sink or a source under drier conditions, otherwise a larger C sink if wetter. Improved understanding to peatland processes can help future quantification of peatland C dynamics in the boreal and Arctic regions.