Assessing Drivers of Cross-Scale Variability in Peat Smoldering Combustion Vulnerability in Forested Boreal Peatlands
Assessing Drivers of Cross-Scale Variability in Peat Smoldering Combustion Vulnerability in Forested Boreal Peatlands
复制标题
评估森林北方泥炭地泥炭阴燃燃烧脆弱性跨尺度变异的驱动因素
DOI：
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
J. Waddington
中科院分区：
文献类型：
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作者：
S. Wilkinson;P. Moore;J. Waddington
野火是北方森林泥炭地最大的面积干扰，这些泥炭火灾严重程度的空间变异性既是北部野火碳排放不确定性的主要来源，也是区域野火管理的主要挑战。泥炭的阴燃会向大气中排放大量的碳和烟雾，因此可能会造成有害的空气质量。荒地-工业界面和荒地-城市界面都横跨亚湿润的北部平原(BP)生态带，那里三分之一的面积被泥炭地覆盖。因此，越来越多的研究需要确定阴燃燃烧中可变性的驱动因素。这项研究使用水物理泥炭特性来评估BP地区森林泥炭地中泥炭阴燃燃烧脆弱性的跨尺度变异性的驱动因素。利用120年火灾重现间隔和三个主要水文地质背景的时空序列，并结合隆起、凹陷和边缘位置，研究了跨尺度的变异性。我们发现，基于泥炭的特性，如比产量(Sy)和重量含水率，森林泥炭地边缘代表着泥炭冒烟的高脆弱性区域，并且这种情况随着起火时间(林分年龄)的增加而加剧。虽然泥炭地中部的Sy随起火时间增加可以缓冲地下水位的下降，但考虑到冠层燃料负荷的增加，蒸腾作用和羽毛苔藓优势也使泥炭地中部变得更容易受到起火时间的阴燃燃烧的影响。此外，泥炭地边缘与粗颗粒和非均匀颗粒水文地质环境的相互作用导致了比细颗粒环境中更低的Sy和更高的密度边缘泥炭，进一步增加了阴燃脆弱性。我们估计，在BP的中-高水分亏缺下，森林泥炭地边缘在整个剖面上都很容易燃烧，即烧毁。此外，我们确定泥炭地边缘：总面积比率是阴燃脆弱性的驱动因素，定期与区域地下水系统断开的小泥炭地最容易受到泥炭碳总损失的影响。我们建议，这些跨尺度变化的驱动因素应纳入泥炭地和野火管理战略，特别是在靠近荒地-工业和荒地-城市交界处的地区。
Wildfire represents the largest areal disturbance of forested boreal peatlands and the spatial variability in the severity of these peat fires is both a leading source of uncertainty in boreal wildfire carbon emissions and a major challenge for regional wildfire management. Peat smouldering can emit large quantities of carbon and smoke to the atmosphere, and therefore can contribute to hazardous air quality. The wildland-industry interface and wildland-urban interface are both extensive across the sub-humid boreal plains (BP) ecozone where one-third of the area is covered by peatlands. As such, there is a growing research need to identify drivers of variability in smouldering combustion. This study uses hydrophysical peat properties to assess the drivers of cross-scale variability in peat smouldering combustion vulnerability in forested peatlands across the BP. Using a space-for-time chronosequence across the 120-year fire return interval and three main hydrogeological settings, and by incorporating hummock, hollow and margin locations, cross-scale variability is studied. We find that, based on peat properties such as specific yield (Sy) and gravimetric water content, forested peatland margins represent areas of high peat smouldering vulnerability, and that this is exacerbated with an increasing time-since-fire (stand-age). Although increasing Sy with time-since-fire in peatland middles may buffer water table drawdown, when accounting for increases in canopy fuel load, transpiration, and feather moss dominance forested peatland middles also become more vulnerable to smouldering combustion with time-since-fire. Moreover, the interaction of peatland margins with coarse- and heterogeneous-grained hydrogeological settings leads to lower Sy and higher density margin peat than in fine-grained settings, further increasing smouldering vulnerability. We estimate that forested peatland margins are vulnerable to combustion throughout their entire profile i.e. burn-out, under moderate-high water deficits in the BP. Furthermore, we identify peatland margin: total area ratio as a driver of smouldering vulnerability where small peatlands that are periodically disconnected from regional groundwater systems are the most vulnerable to high total peat carbon loss. We suggest that these drivers of cross-scale variability should be incorporated into peatland and wildfire management strategies, especially in areas near the wildland-industry and wildland-urban interface.
影响因子：
64.8
作者：
Walker, Xanthe J.;Baltzer, Jennifer L.;Mack, Michelle C.
通讯作者：
Mack, Michelle C.