The response (1958-1997) of permafrost and near-surface ground temperatures to forest fire, Takhini River valley, southern Yukon Territory
Forest fires in permafrost areas often modify ground surface conditions, causing deepening of the active layer and thawing of near-surface permafrost. Takhini River valley lies in the discontinuous permafrost zone of southern Yukon Territory. The valley floor is covered by glaciolacustrine deposits,...
Published in: | Canadian Journal of Earth Sciences |
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Canadian Science Publishing
1998
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Online Access: | http://dx.doi.org/10.1139/e97-105 http://www.nrcresearchpress.com/doi/pdf/10.1139/e97-105 |
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crcansciencepubl:10.1139/e97-105 2024-09-30T14:36:22+00:00 The response (1958-1997) of permafrost and near-surface ground temperatures to forest fire, Takhini River valley, southern Yukon Territory Burn, C R 1998 http://dx.doi.org/10.1139/e97-105 http://www.nrcresearchpress.com/doi/pdf/10.1139/e97-105 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 35, issue 2, page 184-199 ISSN 0008-4077 1480-3313 journal-article 1998 crcansciencepubl https://doi.org/10.1139/e97-105 2024-09-05T04:11:16Z Forest fires in permafrost areas often modify ground surface conditions, causing deepening of the active layer and thawing of near-surface permafrost. Takhini River valley lies in the discontinuous permafrost zone of southern Yukon Territory. The valley floor is covered by glaciolacustrine deposits, which are locally ice rich. In 1958 extensive forest fires burned most of the vegetation and the soil organic horizon in the valley, but, 50 km west of Whitehorse, 1 km 2 of spruce forest adjacent to the Alaska Highway escaped burning. Permafrost beneath this stand of trees is in equilibrium with surface conditions: the active layer is 1.4 m thick, the base of permafrost is at 18.5 m, the annual mean temperature at the top of permafrost (1.5 m) is -0.8°C, and the temperature gradient in permafrost is constant with depth. At burned sites nearby there has been little regeneration of forest vegetation since the fire, and long-term permafrost degradation has occurred. At one burned site, the permafrost table is more than 3.75 m below the ground surface, the mean annual ground temperature is -0.2°C or warmer throughout the profile, the annual mean temperature at 1.5 m is 0.1°C, and permafrost is thawing from top and bottom. A simplified analytical model for thawing of permafrost indicates that over a millennium will be required to degrade permafrost completely at this site, if thawing proceeds from the top down. The result demonstrates the persistence of ice-rich permafrost a few metres below the ground surface, even at sites near the southern margin of permafrost in Canada. Article in Journal/Newspaper Ice permafrost Whitehorse Alaska Yukon Canadian Science Publishing Yukon Canada Takhini ENVELOPE(-135.094,-135.094,60.738,60.738) Takhini River ENVELOPE(-135.854,-135.854,59.999,59.999) Canadian Journal of Earth Sciences 35 2 184 199 |
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Open Polar |
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Canadian Science Publishing |
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crcansciencepubl |
language |
English |
description |
Forest fires in permafrost areas often modify ground surface conditions, causing deepening of the active layer and thawing of near-surface permafrost. Takhini River valley lies in the discontinuous permafrost zone of southern Yukon Territory. The valley floor is covered by glaciolacustrine deposits, which are locally ice rich. In 1958 extensive forest fires burned most of the vegetation and the soil organic horizon in the valley, but, 50 km west of Whitehorse, 1 km 2 of spruce forest adjacent to the Alaska Highway escaped burning. Permafrost beneath this stand of trees is in equilibrium with surface conditions: the active layer is 1.4 m thick, the base of permafrost is at 18.5 m, the annual mean temperature at the top of permafrost (1.5 m) is -0.8°C, and the temperature gradient in permafrost is constant with depth. At burned sites nearby there has been little regeneration of forest vegetation since the fire, and long-term permafrost degradation has occurred. At one burned site, the permafrost table is more than 3.75 m below the ground surface, the mean annual ground temperature is -0.2°C or warmer throughout the profile, the annual mean temperature at 1.5 m is 0.1°C, and permafrost is thawing from top and bottom. A simplified analytical model for thawing of permafrost indicates that over a millennium will be required to degrade permafrost completely at this site, if thawing proceeds from the top down. The result demonstrates the persistence of ice-rich permafrost a few metres below the ground surface, even at sites near the southern margin of permafrost in Canada. |
format |
Article in Journal/Newspaper |
author |
Burn, C R |
spellingShingle |
Burn, C R The response (1958-1997) of permafrost and near-surface ground temperatures to forest fire, Takhini River valley, southern Yukon Territory |
author_facet |
Burn, C R |
author_sort |
Burn, C R |
title |
The response (1958-1997) of permafrost and near-surface ground temperatures to forest fire, Takhini River valley, southern Yukon Territory |
title_short |
The response (1958-1997) of permafrost and near-surface ground temperatures to forest fire, Takhini River valley, southern Yukon Territory |
title_full |
The response (1958-1997) of permafrost and near-surface ground temperatures to forest fire, Takhini River valley, southern Yukon Territory |
title_fullStr |
The response (1958-1997) of permafrost and near-surface ground temperatures to forest fire, Takhini River valley, southern Yukon Territory |
title_full_unstemmed |
The response (1958-1997) of permafrost and near-surface ground temperatures to forest fire, Takhini River valley, southern Yukon Territory |
title_sort |
response (1958-1997) of permafrost and near-surface ground temperatures to forest fire, takhini river valley, southern yukon territory |
publisher |
Canadian Science Publishing |
publishDate |
1998 |
url |
http://dx.doi.org/10.1139/e97-105 http://www.nrcresearchpress.com/doi/pdf/10.1139/e97-105 |
long_lat |
ENVELOPE(-135.094,-135.094,60.738,60.738) ENVELOPE(-135.854,-135.854,59.999,59.999) |
geographic |
Yukon Canada Takhini Takhini River |
geographic_facet |
Yukon Canada Takhini Takhini River |
genre |
Ice permafrost Whitehorse Alaska Yukon |
genre_facet |
Ice permafrost Whitehorse Alaska Yukon |
op_source |
Canadian Journal of Earth Sciences volume 35, issue 2, page 184-199 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e97-105 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
35 |
container_issue |
2 |
container_start_page |
184 |
op_container_end_page |
199 |
_version_ |
1811639438130806784 |