Five-Year Growth of Rock Lichens in a Low-Arctic Mountain Environment, Northern Labrador
In 1978, three lichen growth stations were established for Rhizocarpon section Rhizocarpon species and one for Alectoria miniscula in the Cirque Mountain area of the Torngat mountains. Five years later, in 1983, the lichens were remeasured. The five-year growth represented by the change in the theor...
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1986
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fterudit:oai:erudit.org:032625ar 2023-05-15T14:58:08+02:00 Five-Year Growth of Rock Lichens in a Low-Arctic Mountain Environment, Northern Labrador Rogerson, R. J. Evans, D. J. A. McCoy, W. D. 1986 http://id.erudit.org/iderudit/032625ar https://doi.org/10.7202/032625ar en eng Les Presses de l'Université de Montréal Érudit Géographie physique et Quaternaire vol. 40 no. 1 (1986) http://id.erudit.org/iderudit/032625ar doi:10.7202/032625ar Tous droits réservés © Les Presses de l'Université de Montréal, 1986 text 1986 fterudit https://doi.org/10.7202/032625ar 2022-09-24T23:13:38Z In 1978, three lichen growth stations were established for Rhizocarpon section Rhizocarpon species and one for Alectoria miniscula in the Cirque Mountain area of the Torngat mountains. Five years later, in 1983, the lichens were remeasured. The five-year growth represented by the change in the theoretical diameter is very variable, between 0.10 and 0.54 mm per year. These rates are larger than expected and exceed rates previously determined for an eastern Arctic area, the Northern Cumberland Peninsula of Baffin Island, by more than 3 to more than 20 times. Similar rates are known for 'great period' growth outside Arctic regions. If the growth rates represent long-term growth, the ages of recessional moraines in the Torngat Mountains should be recalculated. Moraines formerly described as Late Wisconsin to mid-Holocene may be of Neoglacial age. Variability of growth rates from one individual to another precludes using these data for constructing growth curves which may be used, even locally, in lichenometric dating. En 1978, on a établi quatre sites de croissance du lichen dans la région du mont du Cirque dans les monts Torngat: trois sites des espèces Rhizocarpon de la section Rhizocarpon et un site de Alectoria miniscula. Cinq ans plus tard, en 1983, on a mesuré de nouveau les lichens pour constater que le diamètre moyen, qui témoigne de la croissance, a crû de manière très variable, soit de 0,10 à 0,54 mm par année. Ces taux de croissance sont plus élevés que prévu puisqu'ils dépassent de 3 à 20 fois les taux déjà mesurés dans le nord de la péninsule de Cumberland, île de Baffin. De tels taux de croissance du lichen s'apparentent davantage à ceux que l'on a observé dans les régions non arctiques au cours de sa période dite de grande croissance. Si ces taux s'appliquent à de longues périodes, il faudrait réévaluer la date de dépôt des moraines de récession dans les monts Torngat. Les moraines, que l'on croit dater de la période s'étendant du Wisconsinien supérieur à l'Holocène moyen, pourraient en fait dater ... Text Arctic Arctique* Baffin Island Baffin Cumberland Peninsula Île de Baffin Érudit.org (Université Montréal) Alectoria ENVELOPE(-58.640,-58.640,-63.977,-63.977) Arctic Baffin Island Cumberland Peninsula ENVELOPE(-64.497,-64.497,66.501,66.501) Dater ENVELOPE(-64.825,-64.825,-67.145,-67.145) Île de Baffin ENVELOPE(-74.998,-74.998,68.001,68.001) Mont du Cirque ENVELOPE(69.962,69.962,-49.274,-49.274) Monts Torngat ENVELOPE(-64.415,-64.415,59.500,59.500) Torngat Mountains ENVELOPE(-63.665,-63.665,59.000,59.000) Géographie physique et Quaternaire 40 1 85 91 |
institution |
Open Polar |
collection |
Érudit.org (Université Montréal) |
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fterudit |
language |
English |
description |
In 1978, three lichen growth stations were established for Rhizocarpon section Rhizocarpon species and one for Alectoria miniscula in the Cirque Mountain area of the Torngat mountains. Five years later, in 1983, the lichens were remeasured. The five-year growth represented by the change in the theoretical diameter is very variable, between 0.10 and 0.54 mm per year. These rates are larger than expected and exceed rates previously determined for an eastern Arctic area, the Northern Cumberland Peninsula of Baffin Island, by more than 3 to more than 20 times. Similar rates are known for 'great period' growth outside Arctic regions. If the growth rates represent long-term growth, the ages of recessional moraines in the Torngat Mountains should be recalculated. Moraines formerly described as Late Wisconsin to mid-Holocene may be of Neoglacial age. Variability of growth rates from one individual to another precludes using these data for constructing growth curves which may be used, even locally, in lichenometric dating. En 1978, on a établi quatre sites de croissance du lichen dans la région du mont du Cirque dans les monts Torngat: trois sites des espèces Rhizocarpon de la section Rhizocarpon et un site de Alectoria miniscula. Cinq ans plus tard, en 1983, on a mesuré de nouveau les lichens pour constater que le diamètre moyen, qui témoigne de la croissance, a crû de manière très variable, soit de 0,10 à 0,54 mm par année. Ces taux de croissance sont plus élevés que prévu puisqu'ils dépassent de 3 à 20 fois les taux déjà mesurés dans le nord de la péninsule de Cumberland, île de Baffin. De tels taux de croissance du lichen s'apparentent davantage à ceux que l'on a observé dans les régions non arctiques au cours de sa période dite de grande croissance. Si ces taux s'appliquent à de longues périodes, il faudrait réévaluer la date de dépôt des moraines de récession dans les monts Torngat. Les moraines, que l'on croit dater de la période s'étendant du Wisconsinien supérieur à l'Holocène moyen, pourraient en fait dater ... |
format |
Text |
author |
Rogerson, R. J. Evans, D. J. A. McCoy, W. D. |
spellingShingle |
Rogerson, R. J. Evans, D. J. A. McCoy, W. D. Five-Year Growth of Rock Lichens in a Low-Arctic Mountain Environment, Northern Labrador |
author_facet |
Rogerson, R. J. Evans, D. J. A. McCoy, W. D. |
author_sort |
Rogerson, R. J. |
title |
Five-Year Growth of Rock Lichens in a Low-Arctic Mountain Environment, Northern Labrador |
title_short |
Five-Year Growth of Rock Lichens in a Low-Arctic Mountain Environment, Northern Labrador |
title_full |
Five-Year Growth of Rock Lichens in a Low-Arctic Mountain Environment, Northern Labrador |
title_fullStr |
Five-Year Growth of Rock Lichens in a Low-Arctic Mountain Environment, Northern Labrador |
title_full_unstemmed |
Five-Year Growth of Rock Lichens in a Low-Arctic Mountain Environment, Northern Labrador |
title_sort |
five-year growth of rock lichens in a low-arctic mountain environment, northern labrador |
publisher |
Les Presses de l'Université de Montréal |
publishDate |
1986 |
url |
http://id.erudit.org/iderudit/032625ar https://doi.org/10.7202/032625ar |
long_lat |
ENVELOPE(-58.640,-58.640,-63.977,-63.977) ENVELOPE(-64.497,-64.497,66.501,66.501) ENVELOPE(-64.825,-64.825,-67.145,-67.145) ENVELOPE(-74.998,-74.998,68.001,68.001) ENVELOPE(69.962,69.962,-49.274,-49.274) ENVELOPE(-64.415,-64.415,59.500,59.500) ENVELOPE(-63.665,-63.665,59.000,59.000) |
geographic |
Alectoria Arctic Baffin Island Cumberland Peninsula Dater Île de Baffin Mont du Cirque Monts Torngat Torngat Mountains |
geographic_facet |
Alectoria Arctic Baffin Island Cumberland Peninsula Dater Île de Baffin Mont du Cirque Monts Torngat Torngat Mountains |
genre |
Arctic Arctique* Baffin Island Baffin Cumberland Peninsula Île de Baffin |
genre_facet |
Arctic Arctique* Baffin Island Baffin Cumberland Peninsula Île de Baffin |
op_relation |
Géographie physique et Quaternaire vol. 40 no. 1 (1986) http://id.erudit.org/iderudit/032625ar doi:10.7202/032625ar |
op_rights |
Tous droits réservés © Les Presses de l'Université de Montréal, 1986 |
op_doi |
https://doi.org/10.7202/032625ar |
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Géographie physique et Quaternaire |
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40 |
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1 |
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85 |
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