Late-Quaternary Vegetation and Climate Near the Arctic Tree Line of Northwestern North America

Earlier studies in Alaska and northwest Canada have shown inconsistent evidence for the expected northward extension of the Arctic tree line during the Hypsithermal Interval. Only megafossil evidence has supported this suggestion; the palynological findings have been inconclusive. The Tuktoyaktuk Pe...

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Bibliographic Details
Published in:Quaternary Research
Main Authors: Ritchie, J.C., Hare, F.K.
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press (CUP) 1971
Subjects:
Arctic
Canada
Northwest Territories
Pacific
Tuktoyaktuk
Tuktoyaktuk Peninsula
Beaufort Sea
Dwarf birch
Tundra
Alaska
Online Access:http://dx.doi.org/10.1016/0033-5894(71)90069-x
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Description
Summary:Earlier studies in Alaska and northwest Canada have shown inconsistent evidence for the expected northward extension of the Arctic tree line during the Hypsithermal Interval. Only megafossil evidence has supported this suggestion; the palynological findings have been inconclusive. The Tuktoyaktuk Peninsula, in the Northwest Territories of Canada, offers critical sites for studies of late-Pleistocene ecology, because of its geological, biotic, and climatological features. Palynological and megafossil evidence is presented from sites on the Tuktoyaktuk Peninsula, indicating northward advance of the Arctic tree line during the period 8500-5500 B.P. Relative pollen frequencies of a core of lake sediment suggest a late-Pleistocene sequence as follows: 12,900-11,600 dwarf birch tundra; 11600-8500 forest tundra; 8500-5500 closed-crown spruce-birch forest; 5500-4000 tall shrub tundra; 4000-present dwarf birch heath tundra. These results suggest that during the Hypsithermal Interval the Arctic Front (July position) was further north, over the Beaufort Sea, a displacement from its present position of about 350 km. The Tuktoyaktuk Peninsula, presently occupied by tundra, and dominated by the Arctic airstream in July, was apparently under forest, with warm, moist Pacific air during the Hypsithermal Interval.

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