Quantifying landscape-level methane fluxes in subarctic Finland using a multiscale approach.
Quantifying landscape-level methane fluxes in subarctic Finland using a multiscale approach.
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DOI：
10.1111/gcb.12975
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发表时间：
2015-10
影响因子：
11.6
通讯作者：
Baxter R
中科院分区：
文献类型：
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作者：
Hartley IP;Hill TC;Wade TJ;Clement RJ;Moncrieff JB;Prieto-Blanco A;Disney MI;Huntley B;Williams M;Howden NJ;Wookey PA;Baxter R
量化来自北方和北极地区的地貌尺度甲烷(CH4)通量，并确定它们的控制方式，对于预测CH4排放对气候变化的反馈程度至关重要。此外，在控制景观水平的通量方面，小面积产甲烷活动强的区域与净吸收CH4的大区域之间的相对重要性仍然存在不确定性。我们测量了芬兰亚北极AAPA沼泽中多个微地形亚单位(莎草为主的草坪、丘陵和丘陵)以及更广泛的景观、地衣石南和山桦林中更干燥的生态系统的CH4通量。对使用静态小室测量的通量进行了相互比较，并使用航空摄影得到的高分辨率地形图和涡旋协方差进行了放大。这两种方法之间有很强的一致性，草坪的排放率最高。草坪CH4通量与季节温度波动密切相关，但其漂浮性意味着地下水位不是控制CH4释放的关键因素。相反，室内测量确定了白桦林土壤对甲烷的净吸收。航空摄影和卫星遥感之间的相互比较表明，从卫星上量化关键的CH4排放和消耗植物群落的分布是可能的，从而使通量能够扩大到100千平方公里的面积。在整个生长季(5月至10月)，100亿平方公里的区域内释放了~1.1g-1.4g的CH4和−2。这是基于放大的草坪排放1.2%-1.5%的CH4m−2，而更广泛的景观则放大了0.07%-0.15%的CH4m−2的吸收。鉴于主要草坪通量对温度的强烈敏感性，以及草坪不太可能干涸的事实，气候变暖可能会大幅增加芬兰北部和整个AAPA沼泽地区的CH4排放。
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.