Impacts of wildfire on the permafrost in the boreal forests of Interior Alaska
Impacts of wildfire on the permafrost in the boreal forests of Interior Alaska
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DOI：
10.1029/2001jd000438
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发表时间：
2002-01
影响因子：
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通讯作者：
K. Yoshikawa;W. Bolton;V. Romanovsky;M. Fukuda;L. Hinzman
中科院分区：
文献类型：
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作者：
K. Yoshikawa;W. Bolton;V. Romanovsky;M. Fukuda;L. Hinzman
[1] 使用 11 个北方森林火灾现场（其中包括两次受控燃烧）研究了野火期间和之后对永久冻土的影响。火灾期间，通过传导至永久冻土层的热传递并不显着。火灾发生后，地面热导率可能会增加 10 倍，地表反照率可能会降低 50%，具体取决于地表有机土壤的燃烧程度。剩余有机层的厚度强烈影响永久冻土的退化和积聚。如果有机层厚度在燃烧过程中没有减少，那么尽管表面反照率降低，但活性层（每年冻结和融化的永久冻土层之上的土壤层）在燃烧后不会发生变化。对表面有机层的任何显着干扰都会增加通过活性层进入永久冻土层的热流量。严重扰动后大约 3-5 年，根据现场条件，活动层将增加到不会在下一个冬天完全重新冻结的厚度。这导致塔利克（talik）的形成（季节性冻土下方和永久冻土上方的未冻层）。在 1983 年燃烧地点观察到融化层（4.15 m 厚）。模型研究表明，如果野火后留下超过 7-12 厘米的有机层，那么对阿拉斯加内陆北方森林中的永久冻土的热影响将很小。
[1] The impact to the permafrost during and after wildfire was studied using 11 boreal forest fire sites including two controlled burns. Heat transfer by conduction to the permafrost was not significant during fire. Immediately following fire, ground thermal conductivity may increase 10-fold and the surface albedo can decrease by 50% depending on the extent of burning of the surficial organic soil. The thickness of the remaining organic layer strongly affects permafrost degradation and aggradation. If the organic layer thickness was not reduced during the burn, then the active layer (the layer of soil above permafrost that annually freezes and thaws) did not change after the burn in spite of the surface albedo decrease. Any significant disturbance to the surface organic layer will increase heat flow through the active layer into the permafrost. Approximately 3–5 years after severe disturbance and depending on site conditions, the active layer will increase to a thickness that does not completely refreeze the following winter. This results in formation of a talik (an unfrozen layer below the seasonally frozen soil and above the permafrost). A thawed layer (4.15 m thick) was observed at the 1983 burned site. Model studies suggest that if an organic layer of more than 7–12 cm remains following a wildfire then the thermal impact to the permafrost will be minimal in the boreal forests of Interior Alaska.