Peatland Heterogeneity Impacts on Regional Carbon Flux and Its Radiative Effect Within a Boreal Landscape
Peatland Heterogeneity Impacts on Regional Carbon Flux and Its Radiative Effect Within a Boreal Landscape
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DOI：
10.1029/2021jg006774
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发表时间：
2022-09
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通讯作者：
D. Kou;T. Virtanen;C. Treat;J. Tuovinen;Aleksi Räsänen;S. Juutinen;J. Mikola;M. Aurela;L. Heiskanen
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作者：
D. Kou;T. Virtanen;C. Treat;J. Tuovinen;Aleksi Räsänen;S. Juutinen;J. Mikola;M. Aurela;L. Heiskanen
泥炭地在生态类型和微形态上具有很高的空间变异性，构成了北方景观的重要组成部分，在全球碳(C)循环中发挥着重要作用。然而，这种泥炭地在北方景观中的异质性的影响很少被量化。在这里，我们使用基于现场的测量，高分辨率的土地覆盖分类，以及生物地球化学和大气模型来估计芬兰北部北部寒带景观(Kaamanen)的大气-生态系统C通量和相应的辐射效应(RE)。我们的结果表明，Kaamanen集水区目前的功能是二氧化碳(CO2)的汇和甲烷(CH4)的源。泥炭地(占总面积的26%)贡献了22%的二氧化碳吸收和89%的甲烷排放；森林(61%)吸收了78%的二氧化碳，抵消了6%的甲烷排放；水体(13%)抵消了7%的二氧化碳吸收和11%的甲烷排放。泥炭地在25年的CO2通量、CH4通量以及CO2和CH4交换的综合RE中的面积加权变异性(与流域内不同土地覆盖类型(LCT)之间的面积加权平均值的偏差)的异质性分别占11%、88%和75%。泥炭地LCT的聚集或将其错误分类为非泥炭地LCT会显著(p<；0.05)偏离区域CH4交换和RE估计，而区分更干燥的未淹没泥炭地和更潮湿的淹没泥炭地可以有效地减少这种偏差。目前的土地覆盖产品在泥炭地异质性方面缺乏这样的细节，这将是更好地限制北方碳预算和全球碳气候反馈所必需的。
Peatlands, with high spatial variability in ecotypes and microforms, constitute a significant part of the boreal landscape and play an important role in the global carbon (C) cycle. However, the effects of this peatland heterogeneity within the boreal landscape are rarely quantified. Here, we use field‐based measurements, high‐resolution land cover classification, and biogeochemical and atmospheric models to estimate the atmosphere‐ecosystem C fluxes and the corresponding radiative effect (RE) for a boreal landscape (Kaamanen) in northern Finland. Our result shows that the Kaamanen catchment currently functioned as a sink of carbon dioxide (CO2) and a source of methane (CH4). Peatlands (26% of the area) contributed 22% of the total CO2 uptake and 89% of CH4 emissions; forests (61%) accounted for 78% of CO2 uptake and offset 6% of CH4 emissions; water bodies (13%) offset 7% of CO2 uptake and contributed 11% of CH4 emissions. The heterogeneity of peatlands accounted for 11%, 88%, and 75% of the area‐weighted variability (deviation from the area‐weighted mean among different land cover types (LCTs) within the catchment) in CO2 flux, CH4 flux, and the combined RE of CO2 and CH4 exchanges over the 25‐year time horizon, respectively. Aggregating peatland LCTs or misclassifying them as nonpeatland LCTs can significantly (p < 0.05) bias the regional CH4 exchange and RE estimates, while differentiating between drier noninundated and wetter inundated peatlands can effectively reduce the bias. Current land cover products lack such details in peatland heterogeneity, which would be needed to better constrain boreal C budgets and global C‐climate feedbacks.