Origin of the southernmost Arctic tundra of continental North America

The Arctic tundra extends beyond the treeline north of 58°N in eastern North America and north of 66°N in western North America and Eurasia. A marked exception to this distribution is the azonal tundra situated as far south as 54°30′–45′N, in the Pointe-Louis-XIV area (JABA), along the fast-rising c...

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Bibliographic Details
Published in:Arctic Science
Main Authors: Payette, Serge, Pilon, Vanessa, Frégeau, Mathieu
Format: Article in Journal/Newspaper
Language:English
Published: Canadian Science Publishing 2018
Subjects:
Online Access:http://dx.doi.org/10.1139/as-2018-0007
https://cdnsciencepub.com/doi/full-xml/10.1139/as-2018-0007
https://cdnsciencepub.com/doi/pdf/10.1139/as-2018-0007
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Summary:The Arctic tundra extends beyond the treeline north of 58°N in eastern North America and north of 66°N in western North America and Eurasia. A marked exception to this distribution is the azonal tundra situated as far south as 54°30′–45′N, in the Pointe-Louis-XIV area (JABA), along the fast-rising coasts of James Bay–Hudson Bay. The unusual position of JABA calls into question the influence of climate as the main causal factor for its existence. Macrocharcoal remains extracted from tundra and forest soils were used along a 105 km transect to date the onset of the boreal environment based on past occurrence of conifer fires. Assuming crustal uplift 1.3 m 100 year −1 and 2.4 m 100 year −1 over and before the last 1000 years, and after correcting site elevation at the time the oldest conifer fires occurred, trees established along the coast before 4000 cal. BP. Given charcoal distribution suggesting boreal vegetation in sites ≤13 m a.s.l., JABA was created after 4000 cal. BP when the flat, elongated peninsula emerged above marine waters. It is concluded that JABA origin was most likely caused by the synergistic impact of geophysical factors, isostatic uplift and topography, on a coastal environment already influenced by cold, wind-exposed conditions.