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TitleRe-evaluating the relevance of vegetation trimlines in the Canadian Arctic as an indicator of Little Ice Age paleoenvironments
AuthorWolken, G J; England, J H; Dyke, A S
SourceArctic vol. 58, no. 4, 2005 p. 341-353, Open Access logo Open Access
LinksAbstract - Résumé
Alt SeriesEarth Sciences Sector, Contribution Series 2004247
PublisherThe Arctic Institute of North America
Mediapaper; on-line; digital
File formatpdf
NTS27; 28; 29; 37; 38; 39; 47; 48; 49; 57; 58; 59; 67; 68; 69; 77; 78; 79; 87; 88; 89; 97; 98; 99; 120; 340; 560
AreaCanadian Arctic; Canadian Arctic Archipelago; Queen Elizabeth Islands
Lat/Long WENS-128.0000 -60.0000 84.0000 68.0000
Subjectssurficial geology/geomorphology; Nature and Environment; Recent; paleoenvironment; paleoclimatology; glaciation; neoglaciation; glaciers; vegetation; trimlines; snow; carbonate rocks; climate; Little Ice Age; Lichen; Climate change; Cenozoic; Quaternary
Illustrationssketch maps; photographs; aerial photographs; cross-sections; models
ProgramReducing Canada's Vulnerability to Climate Change
ProgramNSERC Natural Sciences and Engineering Research Council of Canada
ProgramUniversity of Alberta, Canadian Circumpolar Institute, Northern Research Grants
Released2010 01 29
AbstractThe origin of trimlines associated with the so-called "lichen-free" areas in the Canadian Arctic has been attributed both to perennial snowfield expansion during the Little Ice Age (LIA) and to seasonally persistent snow cover in more recent times. Because of the disparate hypotheses (ecological versus paleoclimatic) regarding the formation of these trimlines, their use as a paleoclimatic indicator has been abandoned for more than two decades. We re-examine this debate and the validity of the opposing hypotheses in the light of new regional mapping of trimlines across the Queen Elizabeth Islands (QEI). The ecological hypothesis-insufficient duration of the growing season resulting from seasonally persistent snow cover-fails to account for the poikilohydric nature of lichens and their ability to endure short growing seasons. It cannot adequately explain the existence of sharp trimlines or account for the occurrence of those trimlines on sparsely vegetated carbonate terrain. Furthermore, trimlines outlining the former extent of thin plateau ice caps are accordant with trimlines associated with former perennial snowfields, indicating that these trimlines record snow and ice expansion during the LIA rather than the seasonal persistence of more recent snow cover. We suggest that these features represent an important LIA climate indicator and should therefore be used for paleoclimatic reconstruction.

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