Quantifying landscape‐scale methane (CH 4) fluxes from boreal and arctic regions, and determining how they are controlled, is critical for predicting the magnitude of any CH 4 emission feedback to climate change. Furthermore, there remains uncertainty regarding the relative importance of small areas of strong methanogenic activity, vs. larger areas with net CH 4 uptake, in controlling landscape‐level fluxes. We measured CH 4 fluxes from multiple microtopographical subunits (sedge‐dominated lawns, interhummocks and hummocks) within an aapa mire in subarctic Finland, as well as in drier ecosystems present in the wider landscape, lichen heath and mountain birch forest. An intercomparison was carried out between fluxes measured using static chambers, up‐scaled using a high‐resolution landcover map derived from aerial photography and eddy covariance. Strong agreement was observed between the two methodologies, with emission rates greatest in lawns. CH 4 fluxes from lawns were strongly related to seasonal fluctuations in temperature, but their floating nature meant that water‐table depth was not a key factor in controlling CH 4 release. In contrast, chamber measurements identified net CH 4 uptake in birch forest soils. An intercomparison between the aerial photography and satellite remote sensing demonstrated that quantifying the distribution of the key CH 4 emitting and consuming plant communities was possible from satellite, allowing fluxes to be scaled up to a 100 km2 area. For the full growing season (May to October), ~ 1.1–1.4 g CH 4 m−2 was released across the 100 km2 area. This was based on up‐scaled lawn emissions of 1.2–1.5 g CH 4 m−2, vs. an up‐scaled uptake of 0.07–0.15 g CH 4 m−2 by the wider landscape. Given the strong temperature sensitivity of the dominant lawn fluxes, and the fact that lawns are unlikely to dry out, climate warming may substantially increase CH 4 emissions in northern Finland, and in aapa mire regions in general.
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机译：量化来自北方和北极地区的景观尺度甲烷（CH 4）通量，并确定如何控制通量，对于预测任何CH 4排放对气候变化的反馈的幅度至关重要。此外，在控制景观水平通量方面，关于产甲烷活性强的小区域与净吸收CH 4的较大区域之间的相对重要性仍然存在不确定性。我们测量了南亚北极地区aapa泥潭中以及周围较宽阔的景观，地衣荒地和白桦林中较干燥的生态系统中多个微观地形亚单位（以莎草为主的草坪，草间草丛和山岗）的多个CH 4通量。使用静态室测量的通量之间进行了比较，并使用了从航空摄影和涡度协方差得到的高分辨率土地覆盖图进行了放大。两种方法之间观察到强烈的一致性，在草坪上的排放速率最大。来自草坪的CH 4流量与温度的季节性波动密切相关，但它们的漂浮性意味着地下水位的深度不是控制CH 4释放的关键因素。相反，室内测量结果表明桦木林土壤中的CH 4净吸收量。航空摄影与卫星遥感的对比表明，可以通过卫星量化CH 4关键排放植物群落和消费植物群落的分布，从而使通量放大到100 km 2 。在整个生长季节（5月至10月），在100 km 2 区域释放了〜1.1–1.4 g CH 4 m −2 。这是基于1.2-1.5 g CH 4 m -2 的草坪排放量的增加，而0.07-0.15 g CH 4 m -2 范围更广。考虑到主要的草坪通量对温度的强烈敏感性，以及草坪不太可能变干的事实，气候变暖可能会大大增加芬兰北部以及整个Aapa沼泽地区的CH 4排放。
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