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Half a century of discontinuous permafrost persistence and degradation in western Canada
Permafrost and Periglacial Processes ( IF 3.0 ) Pub Date : 2019-08-14 , DOI: 10.1002/ppp.2017
Jean E. Holloway 1 , Antoni G. Lewkowicz 1
Affiliation  

Long‐term field studies of permafrost change are needed to validate predictive models but few are possible because of a paucity of direct observations prior to the late 1970s. To help fill this knowledge gap, we resurveyed a transect of 68 sites, originally investigated in 1962, to evaluate change in the isolated patches and sporadic discontinuous permafrost zones between Keg River, Alberta (57.8°N) and Hay River, Northwest Territories (60.8°N). The goal was to establish the degree of permafrost degradation due to approximately 2°C of regional climate warming over the intervening 55 years, compounded at some sites by forest fire. By 2017–2018, permafrost had degraded at 36% of the 44 sites which exhibited it in 1962, but had persisted at a minimum of 50% with a further 14% potentially retaining permafrost. This is much less degradation than reported for a 1988–1989 survey of the same transect. Permafrost was maintained under thicker organic layers (86% > 40 cm) and at the majority of sites with fine‐grained substrates, while degradation occurred preferentially at sites with coarse soils and thinner organic layers. Forest fire did not enhance the degree of permafrost loss, but greater frost table depths were observed at some burned locations. This study demonstrates that while the trajectory of change is towards permafrost loss, thin permafrost in the discontinuous zone can be persistent, even when disturbed. It also underlines the importance of considering the range of landscape types when projecting the rate of future permafrost thaw.

中文翻译:

加拿大西部半个世纪不连续的永久冻土持续和退化

需要对永久冻土变化进行长期实地研究来验证预测模型,但由于 1970 年代后期之前缺乏直接观察,因此几乎没有可能。为了帮助填补这一知识空白,我们重新测量了最初于 1962 年调查的 68 个地点的样带,以评估艾伯塔省凯格河(北纬 57.8 度)和西北地区海河(60.8 °N)。目标是确定由于在此期间 55 年内区域气候变暖约 2°C 以及森林火灾在某些地点加剧了永久冻土退化的程度。到 2017-2018 年,在 1962 年出现的 44 个地点中,有 36% 的永久冻土已经退化,但至少持续了 50%,还有 14% 的永久冻土可能保留。这比 1988-1989 年对同一横断面的调查报告的退化要少得多。永久冻土保持在较厚的有机层(86% > 40 cm)下和大多数具有细粒基质的地点,而退化优先发生在土壤粗糙和有机层较薄的地点。森林火灾并没有增加永久冻土流失的程度,但在一些被烧毁的地方观察到了更大的霜台深度。这项研究表明,虽然变化的轨迹是朝着永久冻土流失的方向发展,但不连续带中的薄永久冻土可以持续存在,即使受到干扰。它还强调了在预测未来永久冻土融化速度时考虑景观类型范围的重要性。40 cm) 和在大多数具有细粒基质的地点,而降解优先发生在土壤粗糙和有机层较薄的地点。森林火灾并没有增加永久冻土流失的程度,但在一些被烧毁的地方观察到了更大的霜台深度。这项研究表明,虽然变化的轨迹是朝着永久冻土流失的方向发展,但不连续带中的薄永久冻土可以持续存在,即使受到干扰。它还强调了在预测未来永久冻土融化速度时考虑景观类型范围的重要性。40 cm) 和在大多数具有细粒基质的地点,而降解优先发生在土壤粗糙和有机层较薄的地点。森林火灾并没有增加永久冻土流失的程度,但在一些被烧毁的地方观察到了更大的霜台深度。这项研究表明,虽然变化的轨迹是朝着永久冻土流失的方向发展,但不连续带中的薄永久冻土可以持续存在,即使受到干扰。它还强调了在预测未来永久冻土融化速度时考虑景观类型范围的重要性。但是在一些被烧毁的地方观察到了更大的霜台深度。这项研究表明,虽然变化的轨迹是朝着永久冻土流失的方向发展,但不连续带中的薄永久冻土可以持续存在,即使受到干扰。它还强调了在预测未来永久冻土融化速度时考虑景观类型范围的重要性。但是在一些被烧毁的地方观察到了更大的霜台深度。这项研究表明,虽然变化的轨迹是朝着永久冻土流失的方向发展,但不连续带中的薄永久冻土可以持续存在,即使受到干扰。它还强调了在预测未来永久冻土融化速度时考虑景观类型范围的重要性。
更新日期:2019-08-14
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