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 By 3500 yr B.P.Picea marianaforest-tundra had withdrawn.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.

Peatland development at the arctic tree line (Québec, Canada) influenced by flooding and permafrost

2007 ◽  
Vol 67 (3) ◽  
pp. 426-437 ◽  
Author(s):  
Najat Bhiry ◽  
Serge Payette ◽  
Élisabeth C. Robert
Keyword(s):  
Little Ice Age ◽  
Ice Age ◽  
The Arctic ◽  
Tree Line ◽  
Small Lakes ◽  
The West ◽  
Peatland Development ◽  
History Of ◽  
Flooding Events ◽  
Differential Timing

AbstractIn this study, we documented the Holocene history of a peat plateau at the arctic tree line in northern Québec using stratigraphic and macrofossil analyses to highlight the effects of geomorphic setting in peatland development. Paludification of the site began about 6800 cal yr BP. From 6390 to 4120 cal yr BP, the peatland experienced a series of flooding events. The location of the peatland in a depression bounded by two small lakes likely explains its sensitivity to runoff. The proximity of a large hill bordering the peatland to the south possibly favored the inflow of mineral-laden water. The onset of permafrost aggradation in several parts of the peatland occurred after 3670 cal yr BP. Uplifting of the peatland surface caused by permafrost stopped the flooding. According to radiocarbon dating of the uppermost peat layers, permafrost distribution progressed from the east to the west of the peatland, indicating differential timing for the initiation of permafrost throughout the peatland. Most of the peatland was affected by permafrost growth during the Little Ice Age.Picea marianamacroremains at 6450 cal yr BP indicate that the species was present during the early stages of peatland development, which occurred soon after the sea regression.

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.

A Well-Ordered Thing

2018 ◽  
Author(s):  
Michael D. Gordin
Keyword(s):  
Nineteenth Century ◽  
History Of Science ◽  
Periodic Table ◽  
The Arctic ◽  
Classic Work ◽  
Hot Air ◽  
History Of ◽  
First Time

Dmitrii Mendeleev (1834–1907) is a name we recognize, but perhaps only as the creator of the periodic table of elements. Generally, little else has been known about him. This book is an authoritative biography of Mendeleev that draws a multifaceted portrait of his life for the first time. As the book reveals, Mendeleev was not only a luminary in the history of science, he was also an astonishingly wide-ranging political and cultural figure. From his attack on Spiritualism to his failed voyage to the Arctic and his near-mythical hot-air balloon trip, this is the story of an extraordinary maverick. The ideals that shaped his work outside science also led Mendeleev to order the elements and, eventually, to engineer one of the most fascinating scientific developments of the nineteenth century. This book is a classic work that tells the story of one of the world's most important minds.

scholarly journals Direct dating reveals the early history of opium poppy in western Europe

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Aurélie Salavert ◽  
Antoine Zazzo ◽  
Lucie Martin ◽  
Ferran Antolín ◽  
Caroline Gauthier ◽  
...  
Keyword(s):  
Western Europe ◽  
Western Alps ◽  
Western Mediterranean ◽  
Opium Poppy ◽  
Radiocarbon Dates ◽  
Macrobotanical Remains ◽  
History Of ◽  
Temperate Europe ◽  
Radiocarbon Chronology ◽  
Botanical Remains

AbstractThis paper aims to define the first chrono-cultural framework on the domestication and early diffusion of the opium poppy using small-sized botanical remains from archaeological sites, opening the way to directly date minute short-lived botanical samples. We produced the initial set of radiocarbon dates directly from the opium poppy remains of eleven Neolithic sites (5900–3500 cal BCE) in the central and western Mediterranean, northwestern temperate Europe, and the western Alps. When possible, we also dated the macrobotanical remains originating from the same sediment sample. In total, 22 samples were taken into account, including 12 dates directly obtained from opium poppy remains. The radiocarbon chronology ranges from 5622 to 4050 cal BCE. The results show that opium poppy is present from at least the middle of the sixth millennium in the Mediterranean, where it possibly grew naturally and was cultivated by pioneer Neolithic communities. Its dispersal outside of its native area was early, being found west of the Rhine in 5300–5200 cal BCE. It was introduced to the western Alps around 5000–4800 cal BCE, becoming widespread from the second half of the fifth millennium. This research evidences different rhythms in the introduction of opium poppy in western Europe.

scholarly journals Holocene polynya dynamics and their interaction with oceanic heat transport in northernmost Baffin Bay

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rebecca Jackson ◽  
Anna Bang Kvorning ◽  
Audrey Limoges ◽  
Eleanor Georgiadis ◽  
Steffen M. Olsen ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Active Role ◽  
Atlantic Water ◽  
The Arctic ◽  
Negative Consequences ◽  
Baffin Bay ◽  
The North ◽  
North Water ◽  
History Of ◽  
Ocean Conditions

AbstractBaffin Bay hosts the largest and most productive of the Arctic polynyas: the North Water (NOW). Despite its significance and active role in water mass formation, the history of the NOW beyond the observational era remains poorly known. We reconcile the previously unassessed relationship between long-term NOW dynamics and ocean conditions by applying a multiproxy approach to two marine sediment cores from the region that, together, span the Holocene. Declining influence of Atlantic Water in the NOW is coeval with regional records that indicate the inception of a strong and recurrent polynya from ~ 4400 yrs BP, in line with Neoglacial cooling. During warmer Holocene intervals such as the Roman Warm Period, a weaker NOW is evident, and its reduced capacity to influence bottom ocean conditions facilitated northward penetration of Atlantic Water. Future warming in the Arctic may have negative consequences for this vital biological oasis, with the potential knock-on effect of warm water penetration further north and intensified melt of the marine-terminating glaciers that flank the coast of northwest Greenland.

scholarly journals RADIOCARBON DATES FROM THE MONASTERY ON KOM H IN OLD DONGOLA (SUDAN) AND THE CHRONOLOGY OF MEDIEVAL NUBIAN POTTERY

Radiocarbon ◽  
2021 ◽  
pp. 1-21
Author(s):  
Dorota Dzierzbicka ◽  
Katarzyna Danys
Keyword(s):  
Historical Research ◽  
Crucial Importance ◽  
Radiocarbon Dates ◽  
14Th Century ◽  
15Th Century ◽  
History Of

ABSTRACT The paper presents and discusses a series of radiocarbon (14C) dates from a medieval Nubian monastery found on Kom H of Old Dongola, the capital of the kingdom of Makuria located in modern-day Sudan. The monastery was founded in the 6th–7th century AD and although it probably ceased to function in the 14th century, the site remained occupied until the beginning of the 15th century. The investigated courtyard of the monastery was in use from the 11th to the 14th century, as indicated by the ceramics and 14C analysis results presented here. The dates under consideration are the first published series of 14C dates from this site, which is of crucial importance for historical research on medieval Nubian Christianity and monasticism. They permit to begin building an absolute chronological framework for research on the archaeological finds from the site and region. A group of finds in particular need of such a framework are ceramics, and the implications of the 14C dates for pottery assemblages found in the dated contexts are discussed. The conclusions summarize the significance of the datings for the history of the site.

scholarly journals XIX.—The Bone-Cave in the Valley of Allt nan Uamh (Burn of the Caves), near Inchnadamff, Assynt, Sutherlandshire

1918 ◽  
Vol 37 ◽  
pp. 327-349 ◽  
Author(s):  
B. N. Peach ◽  
J. Horne ◽  
E. T. Newton
Keyword(s):  
Characteristic Feature ◽  
Late Glacial ◽  
Early History ◽  
The Arctic ◽  
Geological History ◽  
Collateral Evidence ◽  
History Of ◽  
Glacial Time

A characteristic feature of the plateau of Cambrian Limestone in the neighbourhood of Inchnadamff is the occurrence in it of swallow-holes, caves, and subterranean channels which are intimately associated with the geological history of the region. The valley of Allt nan Uamh (Burn of the Caves), locally known as the Coldstream Burn, furnishes striking examples of these phenomena. One of the caves in this valley yielded an interesting succession of deposits, from which were collected abundant remains of mammals and birds. The discovery of bones of the Northern Lynx, the Arctic Lemming, and the Northern Vole among these relics, and the collateral evidence of the materials forming some of these layers, seem to link the early history of this bone-cave with late glacial time, or at least with a period before the final disappearance of local glaciers in that region.

Life history of tundra-dwelling wolf spiders (Araneae: Lycosidae) from the Yukon Territory, Canada

2012 ◽  
Vol 90 (6) ◽  
pp. 714-721 ◽  
Author(s):  
J.J. Bowden ◽  
C.M. Buddle
Keyword(s):  
Reproductive Effort ◽  
Abiotic Factors ◽  
Wolf Spider ◽  
Local Variation ◽  
Yukon Territory ◽  
The Arctic ◽  
Wolf Spiders ◽  
Female Body Size ◽  
Trade Offs ◽  
History Of

We studied populations of three tundra-dwelling wolf spider (Lycosidae) species to determine reproductive trait relationships and developmental timing in the Arctic. We collected 451 Pardosa lapponica (Thorell, 1872), 176 Pardosa sodalis Holm, 1970, and 117 Pardosa moesta Banks, 1892 during summer 2008. We used log-likelihood ratio tests and multiple linear regressions to determine the best predictors of fecundity and relative reproductive effort. Female body size best explained the variation in fecundity and body condition was the best predictor for relative reproductive effort. We tested for a trade-off between the allocation of resources to individual eggs and the number of eggs produced (fecundity) within each species using linear regression. There was variation in detectable egg size and number trade-offs among sites and these may be related to local variation in resource allocation linked to density-related biotic or abiotic factors. These findings contribute to knowledge about the fitness of arctic wolf spiders in the region of study and are particularly relevant in light of the effects that climate changes are predicted to have on the arctic fauna.

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