Holocene Vegetation Histories from Three Sites in the Tundra of Northwestern Quebec, Canada

Gajewski, Konrad; Garralla, Silvina Susana

doi:10.2307/1551288

Cited by 25 publications

(11 citation statements)

References 10 publications

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“…Southeast Labrador may have experienced the HTM ca 8-6 ka (Sawada et al, 1999) whereas northern sites, in regions that were deglaciated late, may have peaked as late as 3.7 ka, when Picea replaced Alnus pollen at most sites in the lichen woodland and forest tundra (Gajewski and Garralla, 1992;Gajewski et al, 1993Gajewski et al, , 1996. Pollen evidence from some treeline sites suggests a slight expansion of Picea treeline or increased density of taxa between 5 and 2 ka (Short and Nichols, 1977;Richard, 1981).…”

Section: Quebec and Labradormentioning

confidence: 99%

Holocene thermal maximum in the western Arctic (0–180°W)

Kaufman

Ager

Anderson

et al. 2004

Quaternary Science Reviews

782

572

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The spatio-temporal pattern of peak Holocene warmth (Holocene thermal maximum, HTM) is traced over 140 sites across the Western Hemisphere of the Arctic (0-180 W; north of B60 N). Paleoclimate inferences based on a wide variety of proxy indicators provide clear evidence for warmer-than-present conditions at 120 of these sites. At the 16 terrestrial sites where quantitative estimates have been obtained, local HTM temperatures (primarily summer estimates) were on average 1.670.8 C higher than present (approximate average of the 20th century), but the warming was time-transgressive across the western Arctic. As the precession-driven summer insolation anomaly peaked 12-10 ka (thousands of calendar years ago), warming was concentrated in northwest North America, while cool conditions lingered in the northeast. Alaska and northwest Canada experienced the HTM between ca 11 and 9 ka, about 4000 yr prior to the HTM in northeast Canada. The delayed warming in Quebec and Labrador was linked to the residual Laurentide Ice Sheet, which chilled the region through its impact on surface energy balance and ocean circulation. The lingering ice also attests to the inherent asymmetry of atmospheric and oceanic circulation that predisposes the region to glaciation and modulates the pattern of climatic change. The spatial asymmetry of warming during the HTM resembles the pattern of warming observed in the Arctic over the last several decades. Although the two warmings are described at different temporal scales, and the HTM was additionally affected by the residual Laurentide ice, the similarities suggest there might be a preferred mode of variability in the atmospheric circulation that generates a recurrent pattern of warming under positive radiative forcing. Unlike the HTM, however, future warming will not be counterbalanced by the cooling effect of a residual North American ice sheet. r ARTICLE IN PRESS

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Section: Quebec and Labradormentioning

confidence: 99%

Holocene thermal maximum in the western Arctic (0–180°W)

Kaufman

Ager

Anderson

et al. 2004

Quaternary Science Reviews

782

572

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“…The broad-scale similarities of the three diagrams from the lichen woodland and forest-tundra were noted. A fourth pollen diagram from the tundra showed no changes during the past 6000 years, and further studies confirmed that Picea had never been north of its present day limit in the past 6000 years (Gajewski and Garralla, 1992). One of the questions to be addressed here is: how representative is one pollen diagram of the vegetation history of its vegetation zone?…”

Section: Introductionmentioning

confidence: 86%

“…In addition, we reanalyzed the Picea pollen from several previously published pollen diagrams from northwestern Québec: GB2, EC1, LB1 and LR1 (Gajewski et al, 1993) and BI7 (Gajewski and Garralla, 1992). Again, the majority of the spruce grains were assigned to P. mariana by both methods (Table A3).…”

Section: Appendixmentioning

confidence: 99%

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Postglacial Vegetation at the Northern Limit of Lichen Woodland in Northwestern Québec

Gajewski¹,

Garralla²,

Milot-Roy³

2007

gpq

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RÉSUMÉTrois diagrammes polliniques provenant de la limite septentrionale de la pessiere à lichens du nord-ouest du Québec montrent des séquences en grande partie similaires durant l'Holocène. Après la déglaciation, survenue vers 6000 BP, la végétation de la région a été dominée par les plantes herbacées et arbustives de la toundra. Larix laricina, Populus et Juniperus ont aussi constitué des éléments importants du paysage. Un maximum d'AInus crispa et de Betula a été suivi par une période dominée par Picea. Dans le site le plus nordique, les forêts se sont ouvertes durant les 1000 dernières années en réponse au refroidissement néoglaciaire. Actuellement, seule l'épinette noire (Picea mariana) croît au nord-ouest du Québec, et les résultats laissent croire que l'épinette blanche (P. glauca) ne s'est jamais établie dans la région.

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“…Several treeline studies (Lichti Federovich and Ritchie, 1968;Ritchie, 1974;Anderson and Brubaker, 1986;Gajewski, 1991) clearly indicated that the different zones that comprise the forest-tundra boundary can be distinguished using pollen assemblages from lake sediments. Treeline movements of several scales can be identified, when a sufficient number of detailed diagrams are prepared (Gajewski and Garralla, 1992;Gajewski et al, 1993Gajewski et al, , 1996. The use of pollen accumulation rates has proven successful in delimiting species limits, reviewed by Seppä and Hicks (2006).…”

Section: Spatial Resolutionmentioning

confidence: 99%

Essai: Is Arctic Palynology a “Blunt Instrument”?

Gajewski

2007

gpq

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AbstractFor nearly forty years, palynologists and other scientists studying the Quaternary have claimed that palynology, when applied in the Arctic, is a “blunt instrument” for analysing environmental change in this region. In this essay, the author explains why this expression should be laid to rest. Limits to palynological resolution are spatial, temporal and taxonomic. These are discussed and examples are shown where both the temporal and spatial resolution of pollen analyses is far higher than previously thought possible. The supposed “bluntness” of Arctic palynology is due to the way this tool has been applied in Arctic environments rather than inherent limits of palynology in Arctic ecosystems.

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Holocene Vegetation Histories from Three Sites in the Tundra of Northwestern Quebec, Canada

Cited by 25 publications

References 10 publications

Holocene thermal maximum in the western Arctic (0–180°W)

Holocene thermal maximum in the western Arctic (0–180°W)

Postglacial Vegetation at the Northern Limit of Lichen Woodland in Northwestern Québec

Essai: Is Arctic Palynology a “Blunt Instrument”?

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