scholarly journals The Post-glacial history of vegetation and climate at Ennadai Lake, Keewatin, and Lynn Lake, Manitoba (Canada)

1967 ◽  
Vol 18 (1) ◽  
pp. 176-197 ◽  
Author(s):  
Harvey Nichols
Keyword(s):  
The Arctic ◽  
Radiocarbon Dates ◽  
Tundra Vegetation ◽  
History Of Vegetation ◽  
Northwest Europe ◽  
History Of ◽  
Summer Temperatures ◽  
Cold Episode ◽  
Climatic History ◽  
Lynn Lake

Abstract. Peat from Keewatin and Manitoba contained macrofossil and palynological evidence of former latitudinal movements of the forest — tundra boundary probably in response to the changing location of the mean summer position of the Arctic front. There was very rapid melting of the large late-Wisconsin icesheet between 8000 and 6000 years B. P., and swift immigration of Picea, with no evidence of tundra vegetation after deglaciation. From 6000 to 3500 years B. P. the Boreal forest extended far north of its present limit, with a short-lived cooler phase about 5000 years ago. This generally warm period was followed by cooler and variable climatic episodes after 3500 B. P. and by a climatic deterioration about 2600 years ago. There was an amelioration between 1500 and 600 B. P., followed by a prolonged cold episode which terminated peat growth in the tundra. The approximate mean summer temperatures at Ennadai Lake have been estimated from the changing location of the northern limit of forest. The radiocarbon dates for these climatic events coincide with a number of changes recorded in the climatic history of northwest Europe.

Holocene Vegetation Change at Treeline North of Yellowknife, Northwest Territories, Canada

1990 ◽  
Vol 34 (2) ◽  
pp. 227-239 ◽  
Author(s):  
K. A. Moser ◽  
G. M. MacDonald
Keyword(s):  
Picea Mariana ◽  
Vegetation Change ◽  
Geographic Location ◽  
The Arctic ◽  
Small Lakes ◽  
Radiocarbon Dates ◽  
Glacial Ice ◽  
Forest Tundra ◽  
Long Wave ◽  
History Of

AbstractTwo radiocarbon-dated cores from small lakes located approximately 25 km north of the mapped boundary between forest-tundra and tundra provide records of postglacial vegetation change at the treeline near Yellowknife, NWT, Canada. Basal radiocarbon dates of 6180 and 7470 yr B.P. were obtained from the cores. The fossil pollen evidence suggests that the initial vegetation wasBetulatundra with a peatland component.Alnusbecame an important constituent of the pollen assemblages between 6900 and 5500 yr B.P. Both lakes record sharp increases inPiceacf.marianapollen at approximately 5000 yr B.P., suggesting the establishment of forest-tundra. By 3500 yr B.P.Picea marianaforest-tundra had withdrawn. The proportion of organic to inorganic sediment in the cores was at a maximum between 5000 and 3500 yr B.P. Tundra has dominated the region since 3500 yr B.P. In northwestern Canada, the maximum northward advance of treeline occurred between 9000 and 5000 yr B.P. The asynchrony in treeline advance in central and northwestern Canada may reflect that glacial ice persisted in the interior NWT longer than previously believed. Alternatively, the asynchronous history of the treeline may be a result of the geometric properties of the long-wave westerly disturbance that is manifest in the median summer position of the arctic front and ultimately controls the geographic location of the treeline.

CENOZOIC CLIMATIC HISTORY OF THE ARCTIC COAST OF NORTHEAST ASIA

1992 ◽  
Vol 34 (2) ◽  
pp. 197-206
Author(s):  
S. A. Laukhin ◽  
O. V. Grinenko ◽  
A. F. Fradkina
Keyword(s):  
Northeast Asia ◽  
The Arctic ◽  
History Of ◽  
Climatic History ◽  
Arctic Coast

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.

Climatic variations in Arctic region in Cretaceous and Cenozoic

2019 ◽  
pp. 30-37
Author(s):  
R. R. Gabdullin ◽  
N. V. Badulina ◽  
Yu. I. Rostovtseva ◽  
A. V. Ivanov
Keyword(s):  
Low Temperatures ◽  
Marine Invertebrates ◽  
Membrane Lipids ◽  
Arctic Region ◽  
The Arctic ◽  
Climatic Variations ◽  
History Of ◽  
Climatic History ◽  
Dinosaur Teeth ◽  
The Arctic Region

As a result of the analysis of published sources, a database on paleotempertures for the Arctic and Subarctic regions was collected on the skeletons of marine invertebrates, marine palynomorphs, dinosaur teeth, analysis of the ability of reptiles to lay eggs at low temperatures, continental flora (CLAMP-analysis), on the presence of coal layers in continental sediments within Arctic region, on membrane lipids of glycerol and dialkylglycerol tetraether in marine sediments and glendonite. Based on it, a paleotemperature curve was constructed for the Arctic region for the Cretaceous-Cenozoic span of geological history, which has common trends with the global paleotemperature curve [Scotise, 2015] (with the exception of cooling in the Tortonian age due to local factors). In the climatic history of the Arctic 16 climatic cycles have been established, comprising 16 climatic minima (including the glaciation in the Northern Hemisphere) and 15 climatic maxima.

Ecosystem development in the Girdwood area, south-central Alaska, following late Wisconsin glaciation

2010 ◽  
Vol 47 (7) ◽  
pp. 971-985 ◽  
Author(s):  
T. A. Ager ◽  
P. E. Carrara ◽  
J. P. McGeehin
Keyword(s):  
Picea Sitchensis ◽  
Coastal Forest ◽  
Postglacial History ◽  
South Central ◽  
Tundra Vegetation ◽  
History Of Vegetation ◽  
Clayey Silt ◽  
Birch Trees ◽  
History Of ◽  
Tsuga Mertensiana

Pollen analysis of two cores with discontinuous records from a peat bog near Girdwood, in south-central Alaska, provides the basis for reconstructing the first radiocarbon-dated outline of postglacial history of vegetation in the upper Turnagain Arm area of Cook Inlet. Pollen data from clayey silt underlying peat at one site indicate that the earliest known vegetation in the Girdwood area was shrub–herb tundra. Tundra vegetation developed by ∼13 800 cal years BP, soon after local retreat of glacial ice from the maximum position of the Elmendorf glacial advance (∼15 000 – 11 000 cal years BP). By ∼10 900 cal years BP, the tundra vegetation became shrubbier as Betula nana , Salix , and Ericales increased, and scattered Alnus shrubs began to colonize Turnagain Arm. By ∼9600 cal years BP, Alnus thickets with Polypodiaceae ferns became the dominant vegetation. By ∼6600 cal years BP, birch trees ( Betula neoalaskana , B. kenaica ) from the Anchorage and Kenai lowlands began to spread eastward into eastern Turnagain Arm. Mountain hemlock ( Tsuga mertensiana ) began to colonize the Girdwood area by ∼3400 cal years BP, followed soon after by Sitka spruce ( Picea sitchensis ), both Pacific coastal forest species that spread westward from Prince William Sound after a long migration from southeastern Alaska. For at least the past 2700 cal years, Pacific coastal forest composed mostly of Tsuga mertensiana , Picea sitchensis , and Alnus has been the dominant vegetation of eastern Turnagain Arm.

A Late-glacial Insect Fauna from Red Moss, Lancashire, England

1972 ◽  
Vol 3 (3) ◽  
pp. 211-224 ◽  
Author(s):  
Allan C. Ashworth
Keyword(s):  
Positive Response ◽  
Thermal Conditions ◽  
Late Glacial ◽  
Insect Fauna ◽  
Faunal Change ◽  
History Of ◽  
Summer Temperatures ◽  
Climatic History ◽  
Organic Sediments ◽  
Glacial Time

AbstractThe Red Moss deposits rest in a hollow which began to collect organic sediments I2,ooo years ago. The sediments, moss peat, sandy organic mud and Phragmites peat, yielded abundant wellpreserved insect remains. The species are all living today but many no longer in the British Isles. The fauna of the Late-glacial environment is one of an open and exposed bog but by Post-glacial time this had been superseded by a fauna of shrub and tree-covered wetland. Other changes in faunal composition have been observed which are thought to have been caused by oscillating thermal conditions. A series of colder and warmer episodes has been postulated which may be broadly correlated to the palynologically inferred climatic history of the Late-glacial. A marked faunal change was observed between the Late- and Post-glacial episodes and it is estimated that summer temperatures rose from IO° C to I6° C in a period of 3o to 45o years based on radiocarbon dating. Faunal changes are independent of lithological boundaries, which, because of the largely organic nature of the sediments, are vegetation controlled and this is thought to demonstrate the more positive response of insects to climatic change.

The Quaternary history of vegetation in the South Atlantic islands

1960 ◽  
Vol 152 (949) ◽  
pp. 516-529 ◽  
Keyword(s):  
South Africa ◽  
New Zealand ◽  
South America ◽  
History Of Vegetation ◽  
Gough Island ◽  
History Of ◽  
Antarctic Continent ◽  
Climatic History ◽  
Quaternary History ◽  
The Antarctic

My contribution to the exploration of the southern temperate zone is the pollenanalytical investigation of a number of peat cores, collected by Dr Christophersen, the leader of the Norwegian scientific expedition to Tristan da Cunha 1937/38, and by Mr N. M. Wace, the botanist on the British Gough Island survey 1955/56. I am most grateful to these explorers, especially to Mr Wace, for placing this valuable material at my disposal. Since von Post, on receiving the Vega medal in 1944, gave his famous lecture ‘The prospect for pollen analysis in the study of the earth’s climatic history’ (published in English in 1946), a number of pollen-analytical investigations have been carried out in the Southern Hemisphere. In extreme South America, especially by Auer; in New Zealand, by Cranwell-Smith, Deevey, Harris, Moar, Moore and others; in Australia, by Cookson, Duigan and others; in South Africa, by van Zinderen Bakker, Coetzee, Martin and others; and also in some of the isolated islands around the Antarctic continent.

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