Jentzsch Katharina, Männistö Elisa, Marushchak Maija E, Rettelbach Tabea, Golde Lion, Korrensalo Aino, Hashemi Joshua, van Delden Lona, Tuittila Eeva-Stiina, Knoblauch Christian, Treat Claire C
Alfred Wegener Institute (AWI) Helmholtz Center for Polar and Marine Research, Potsdam, Germany.
Institute of Environmental Science and Geography, University of Potsdam, Potsdam, Germany.
Glob Chang Biol. 2025 Jul;31(7):e70372. doi: 10.1111/gcb.70372.
Wetlands are the largest natural source of atmospheric methane (CH), but substantial uncertainties remain in the global CH budget, partly due to a mismatch in spatial scale between detailed in situ flux measurements and coarse-resolution land surface models. In this study, we evaluated the importance of capturing small-scale spatial heterogeneity within a patterned bog to better explain seasonal variation in ecosystem-scale CH emissions. We conducted chamber-based flux measurements and pore water sampling on vegetation removal plots across different microtopographic features (microforms) of Siikaneva bog, southern Finland, during seasonal field campaigns in 2022. Seasonal and spatial patterns in CH fluxes were analyzed in relation to key environmental and ecological drivers. High-resolution (6 cm ground sampling distance) drone-based land cover mapping enabled the extrapolation of microscale (< 0.1 m) fluxes to the ecosystem scale (0.75 km). Methane emissions from wetter microforms (mud bottoms and hollows) closely followed seasonal changes in peat temperature and green leaf area of aerenchymatous plants, while emissions from drier microforms (high lawns and hummocks) remained seasonally stable. This constancy was attributed to persistently low water tables, which moderated environmental fluctuations and reduced seasonality of CH production, CH oxidation and plant-mediated transport. The strong spatial pattern in CH emissions and their seasonal dynamics made both the magnitude and seasonal cycle of ecosystem-scale emissions highly sensitive to the areal distribution of microforms. Our findings underscore the need to integrate microscale spatial variability into CH modelling frameworks, as future shifts in peatland hydrology due to climate change may alter the balance between wet and dry microforms-and with it, the seasonal and annual CH budget.
湿地是大气甲烷（CH）的最大天然来源，但全球CH收支仍存在很大的不确定性，部分原因是详细的原位通量测量与粗分辨率陆地表面模型在空间尺度上不匹配。在本研究中，我们评估了捕捉 patterned bog 内小尺度空间异质性对于更好地解释生态系统尺度CH排放季节变化的重要性。2022年季节性野外考察期间，我们在芬兰南部Siikaneva沼泽不同微地形特征（微地貌）的植被去除样地进行了基于气室的通量测量和孔隙水采样。分析了CH通量的季节和空间模式与关键环境和生态驱动因素的关系。基于无人机的高分辨率（地面采样距离6厘米）土地覆盖制图能够将微观尺度（<0.1米）的通量外推到生态系统尺度（0.75千米）。较湿润微地貌（泥底和洼地）的甲烷排放密切跟随泥炭温度和气腔植物绿叶面积的季节变化，而较干燥微地貌（高草甸和小丘）的排放则保持季节性稳定。这种稳定性归因于地下水位持续较低，这缓和了环境波动并减少了CH产生、CH氧化和植物介导运输的季节性。CH排放的强烈空间模式及其季节动态使得生态系统尺度排放的幅度和季节周期对微地貌的面积分布高度敏感。我们的研究结果强调了将微观尺度空间变异性纳入CH建模框架的必要性，因为未来气候变化导致的泥炭地水文变化可能会改变湿润和干燥微地貌之间的平衡，进而改变季节性和年度CH收支。
