Postglacial migration history of lodgepole pine near Yakutat, Alaska

1991 ◽  
Vol 69 (4) ◽  
pp. 786-796 ◽  
Author(s):  
Dorothy M. Peteet
Keyword(s):  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Late Glacial ◽  
Peat Core ◽  
Pollen Stratigraphy ◽  
The North ◽  
Migration History ◽  
History Of ◽  
Ice Retreat ◽  
The North Pacific

Pollen stratigraphy from three peat sections near Yakutat, Alaska, suggests that lodgepole pine only recently arrived in southeastern Alaska. In contrast with this palynological interpretation, however, are lodgepole pine (Pinus contorta) macrofossils that are present throughout one entire peat core. 14C dating by accelerator mass spectrometry confirms the establishment of lodgepole pine in this region of Alaska about 10 000 BP. The surprising disparity between the pollen and macrofossil results has important implications for paleomigration research. These results imply that the use of assigned pollen percentages to indicate the presence of a species within a region may not be valid, particularly where a species is at the edge of its geographic range. Comparison of the timing of the first appearance of lodgepole pine pollen from a dozen sections along the north Pacific coast suggests either a late Wisconsin refugium for this pine in southeastern Alaska or extremely rapid late-glacial coastal migration northwestward following ice retreat. Key words: Alaska, pollen, macrofossils, lodgepole pine, phytogeography.

Holocene and latest Pleistocene fluctuations of Stutfield Glacier, Canadian Rockies

2001 ◽  
Vol 38 (8) ◽  
pp. 1141-1155 ◽  
Author(s):  
G D Osborn ◽  
B J Robinson ◽  
B H Luckman
Keyword(s):  
19Th Century ◽  
18Th Century ◽  
Late Glacial ◽  
Ice Age ◽  
Late 19Th Century ◽  
Canadian Rockies ◽  
The Holocene ◽  
The North ◽  
History Of ◽  
Glacier Advance

The Holocene and late glacial history of fluctuations of Stutfield Glacier are reconstructed using moraine stratigraphy, tephrochronology, and dendroglaciology. Stratigraphic sections in the lateral moraines contain tills from at least three glacier advances separated by volcanic tephras and paleosols. The oldest, pre-Mazama till is correlated with the Crowfoot Advance (dated elsewhere to be Younger Dryas equivalent). A Neoglacial till is found between the Mazama tephra and a paleosol developed on the Bridge River tephra. A log dating 2400 BP from the upper part of this till indicates that this glacier advance, correlated with the Peyto Advance, culminated shortly before deposition of the Bridge River tephra. Radiocarbon and tree-ring dates from overridden trees exposed in moraine sections indicate that the initial Cavell (Little Ice Age (LIA)) Advance overrode this paleosol and trees after A.D. 1271. Three subsequent phases of the Cavell Advance were dated by dendrochronology. The maximum glacier extent occurred in the mid-18th century, predating 1743 on the southern lateral, although ice still occupied and tilted a tree on the north lateral in 1758. Subsequent glacier advances occurred ca. 1800–1816 and in the late 19th century. The relative extent of the LIA advances at Stutfield differs from that of other major eastward flowing outlets of the Columbia Icefield, which have maxima in the mid–late 19th century. This is the first study from the Canadian Rockies to demonstrate that the large, morphologically simple, lateral moraines defining the LIA glacier limits are actually composite features, built up progressively (but discontinuously) over the Holocene and contain evidence of multiple Holocene- and Crowfoot-age glacier advances.

scholarly journals Life history of a secondary bark beetle, Pseudips mexicanus (Coleoptera: Curculionidae: Scolytinae), in lodgepole pine in British Columbia

2009 ◽  
Vol 141 (1) ◽  
pp. 56-69 ◽  
Author(s):  
G.D. Smith ◽  
A.L. Carroll ◽  
B.S. Lindgren
Keyword(s):  
Life History ◽  
Bark Beetle ◽  
Pinus Contorta ◽  
Life History Traits ◽  
Lodgepole Pine ◽  
Degree Days ◽  
Northern Portion ◽  
History Of ◽  
Bark Beetle Associates

AbstractPseudips mexicanus (Hopkins) is a secondary bark beetle native to western North and Central America that attacks most species of pine (Pinus L. (Pinaceae)) within its range. A pair of life-history studies examined P. mexicanus in other host species, but until now, no work has been conducted on lodgepole pine (Pinus contorta Douglas ex Louden var. latifolia Engelm. ex S. Watson). Pseudips mexicanus in lodgepole pine was found to be polygynous. Galleries were shorter, offspring smaller, and the eggs laid per niche and the potential progeny fewer than in populations from California and Guatemala. Development from the time of female attack to emergence of adult offspring took less than 50 days at 26.5 °C, and the accumulated heat required to complete the life cycle was determined to be 889.2 degree days above 8.5 °C, indicating that in the northern portion of its range P. mexicanus is univoltine. Determination of these life-history traits will facilitate study of interactions between P. mexicanus and other bark beetle associates in lodgepole pine.

A late-glacial – Holocene palaeoecological record from Pye Lake on the eastern shore of Nova Scotia, CanadaGeological Survey of Canada Contribution 20080395.

2009 ◽  
Vol 46 (9) ◽  
pp. 637-650 ◽  
Author(s):  
Robert J. Mott ◽  
Ian R. Walker ◽  
Samantha L. Palmer ◽  
Martin Lavoie
Keyword(s):  
Nova Scotia ◽  
Younger Dryas ◽  
Late Glacial ◽  
Forest Composition ◽  
Eastern Shore ◽  
The North ◽  
Tundra Vegetation ◽  
History Of ◽  
Climatic History ◽  
Recent Sediments

Pollen and chironomid analyses and radiocarbon dating at Pye Lake on the eastern shore of Nova Scotia are used to outline the vegetation and climatic history of the area. The coast was deglaciated prior to ∼12 200 14C BP (14 300 cal BP), and herbaceous tundra vegetation invaded the area. Midge-inferred maximum summer surface-water temperatures in the lake ranged between 9 and 11 °C. Subsequent gradual warming to ∼18 °C by 10 800 14C BP (12 725 cal BP) favoured the migration of a variety of herbaceous and shrub taxa into the region. Rapid cooling to ∼10 °C saw vegetation revert to herbaceous tundra communities. This interval, related to the Younger Dryas cold interval of the North Atlantic and Europe, lasted until ∼10 000 14C BP (11 630 cal BP). The climate then warmed again to conditions similar to those that prevailed immediately before onset of Younger Dryas cooling. Further warming saw successive tree species migrate into the area until, by the mid-Holocene, the forests contained most of the taxa prevalent today. Since ∼3500 years ago, cooling of the climate has favoured conifer species over broad-leaved taxa. Agriculture and logging practices in the last 150 years have altered the forest composition, but pollen analysis of the most recent sediments cannot resolve these changes adequately.

Late Pleistocene Glaciations in the Northwestern Sierra Nevada, California

2002 ◽  
Vol 57 (3) ◽  
pp. 409-419 ◽  
Author(s):  
L. Allan James ◽  
Jon Harbor ◽  
Derek Fabel ◽  
Dennis Dahms ◽  
David Elmore
Keyword(s):  
Sierra Nevada ◽  
Late Glacial ◽  
Lateral Moraine ◽  
Riparian Ecosystems ◽  
Glacial Ice ◽  
Central California ◽  
Minimum Age ◽  
History Of ◽  
Ice Retreat ◽  
Moraine Ridge

AbstractPleistocene fluvial landforms and riparian ecosystems in central California responded to climate changes in the Sierra Nevada, yet the glacial history of the western Sierra remains largely unknown. Three glacial stages in the northwestern Sierra Nevada are documented by field mapping and cosmogenic radionuclide surface-exposure (CRSE) ages. Two CRSE ages of erratic boulders on an isolated till above Bear Valley provide a limiting minimum age of 76,400±3800 10Be yr. Another boulder age provides a limiting minimum age of 48,800±3200 10Be yr for a broad-crested moraine ridge within Bear Valley. Three CRSE ages producing an average age of 18,600±1180 yr were drawn from two boulders near a sharp-crested bouldery lateral moraine that represents an extensive Tioga glaciation in Bear Valley. Nine CRSE ages from striated bedrock along a steep valley transect average 14,100±1500 yr and suggest rapid late-glacial ice retreat from lower Fordyce Canyon with no subsequent extensive glaciations. These ages are generally consistent with glacial and pluvial records in east-central California and Nevada.

scholarly journals Whales and Men: genetic inferences uncover a detailed history of hunting in bowhead whale

2020 ◽  
Author(s):  
TB Hoareau
Keyword(s):  
Population Change ◽  
Natural Populations ◽  
Late Glacial ◽  
Population History ◽  
Bowhead Whale ◽  
The Arctic ◽  
Arctic Seas ◽  
The North ◽  
Time Calibration ◽  
History Of

AbstractAfter millennia of hunting and a population collapse, it is still challenging to understand the genetic consequences of whaling on the circumarctic bowhead whale. Here I use published modern mtDNA sequences from the Bering-Chukchi-Beaufort population and a new time calibration to show that late–glacial climate changes and whaling have been the major drivers of population change. Cultures that hunted in the Arctic Seas from as early as 5000 years ago appear to be responsible for successive declines of the population growth, bringing the effective size down to 38% of its pristine population size. The Thules and the Basques (year 1000–1730) who only hunted in the North Atlantic had a major impact on this North Pacific population, indicating that bowhead whale stocks respond to harvesting as a single population unit. Recent positive growth is inferred only after the end of commercial whaling in 1915, and for levels of harvesting that are close to the current annual quota of 67 whales. By unfolding the population history of the bowhead whale, I provide compelling evidence that mtDNA yields critical yet undervalued information for management and conservation of natural populations.

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