scholarly journals Aspects of the Postglacial Climate of Alberta: Calibration of the Pollen Record

2007 ◽  
Vol 40 (2) ◽  
pp. 153-160 ◽  
Author(s):  
Robert E. Vance
Keyword(s):  
Growing Season ◽  
Late Glacial ◽  
Climatic Data ◽  
Pollen Record ◽  
Current Position ◽  
Middle Holocene ◽  
Modern Pollen ◽  
Vegetational Change ◽  
Calibration Equations ◽  
Herbaceous Pollen

ABSTRACT This reconstruction of the postglacial climate of Alberta is based on a review of pollen studies within the province and the application of calibration equations to a pollen record from central Alberta. Regional palynological studies indicate that the late glacial vegetation, dominated by non-arboreal taxa and, on occasion, Populus, was replaced by a Picea dominated assemblage between 12,000 and 10,000 BP. In central Alberta, increased herbaceous pollen representation suggests that grassland was established north of its current position in early to middle Holocene time. By 3500 BP, the grassland boundary had retreated southward. Little vegetational change is evident during the last 3500 years. Calibration equations, derived from modern pollen and climatic data in the western interior of Canada and applied to an 11,400 year pollen record, suggest growing season temperature was 1.5°C greater than at present while growing season precipitation was 50 mm below current values during the middle Holocene.

scholarly journals Holocene Environmental Change in the Frobisher Bay Area, Baffin Island, N.W.T.: Deglaciation, Emergence, and the Sequence of Vegetation and Climate

2007 ◽  
Vol 39 (2) ◽  
pp. 151-162 ◽  
Author(s):  
J. D. Jacobs ◽  
W. N. Mode ◽  
C. A. Squires ◽  
G. H. Miller
Keyword(s):  
Late Holocene ◽  
Late Glacial ◽  
Pollen Record ◽  
Baffin Island ◽  
Bay Area ◽  
Modern Pollen ◽  
Moist Environment ◽  
Organic Fractions ◽  
Late Glacial And Holocene ◽  
Inland Ice

ABSTRACT The late-glacial and Holocene paleoenvironmental sequence for the Frobisher Bay area is outlined using glacial, sea level, and palynological evidence. A rapid retreat of ice from the late Foxe glacial maximum in the lower part of the bay after 11,000 BP was followed by a series of stillstands or minor readvances between ca. 8500 and 7000 BP and possibly later, before the final disappearance of the inland ice centred near Amadjuak Lake. Lithostratigraphy of three buried organic sections which together represent deposition occurring over the period from 5500 to 400 BP indicates a change from a relatively warm, moist environment before 5500 BP to neoglacial conditions, with the coldest phases centred around 5000, 2700, 1200 BP and probably sometime after 400 radiocarbon years BP. As evidenced by peat growth and pollen data, milder, wetter conditions prevailed from 4500 to 3000 BP and again from ca. 2600 to 1800 BP. Peat growth and soil organic fractions point to lesser mild intervals ca. 900 BP and 400 BP, but these are not apparent in the pollen assemblage. The pollen record does not extend to the last four centuries; however, lichenometric studies of neoglacial moraines by DOWDESWELL (1984) show that the maximum late Holocene advance of glaciers in the area occurred within the last century. Modern pollen samples indicate that the present vegetation of the inner Frobisher Bay area is comparable to that of the milder intervals of the late Holocene.

scholarly journals Bodengeographische Beobachtungen zur pleistozänen und holozänen Vergletscherung des Westlichen Tienshan (Usbekistan)

1996 ◽  
Vol 46 (1) ◽  
pp. 144-151
Author(s):  
Wolfgang Zech ◽  
Rupert Bäumler ◽  
Oksana Savoskul ◽  
Anatoli Ni ◽  
Maxim Petrov
Keyword(s):  
Little Ice Age ◽  
Late Glacial ◽  
Ice Age ◽  
Lower Side ◽  
Glacial Ice ◽  
Middle Holocene ◽  
Glacial Origin ◽  
Weathered Soils ◽  
Recent Origin ◽  
The Alps

Abstract. Soil geographic studies were carried out in the Oigaing valley between Ugamsky and Pskemsky range NE of Tashkent (W-Tienshan, Republic of Uzbekistan) with special regard to the Pleistocene and Holocene glaciation. Clear end moraines of the last main glaciation are preserved at the junction of Maidan and Oigaing river at 1500-1600 m a.s.l. They show intensively weathered soils with a depth of more than 80 cm. Similar deposits ol presumably Pleistocene or late glacial origin are also located upvalley at the embouchure of numerous side valleys (Beschtor, Tekesch, Aütor) into the main valley of Oigaing. All side valleys are characterized by late glacial ground and end moraines in 2500-2700 m a.s.l. showing intensively weathered brown colored soils of 30-40 cm depth. Further moraines of Holocene or recent origin are located approach of the recent glaciers which descend to 3000-3200 m. They show shallow, initial soils, and presumably correspond with glacial advances during the so-called "Little Ice Age" with a maximum advance at about 1850 in the Alps, and in the middle Holocene at about 2000 or 4000 a BP. Highly weathered, and rubefied interglacial soils developed from old Quaternary gravel are preserved above high glacial ice marginal grounds of the last main glaciation (>2850 m a.s.l.) in the lower side valley of the Barkrak river. In the upper valley huge drift could be shown above the ice marginal grounds, but without typical forms of morainic deposits. They give evidence for older glaciations with a greater extent compared with the last main glaciation. However, no corresponding moraines are present in the working area.

scholarly journals UV-B-absorbing compounds in modern Cedrus atlantica pollen: The potential for a summer UV-B proxy for Northwest Africa

The Holocene ◽  
2018 ◽  
Vol 28 (9) ◽  
pp. 1382-1394 ◽  
Author(s):  
Benjamin A Bell ◽  
William J Fletcher ◽  
Peter Ryan ◽  
Alistair WR Seddon ◽  
Roy A Wogelius ◽  
...  
Keyword(s):  
Relative Abundance ◽  
Late Glacial ◽  
Ftir Spectra ◽  
Ultraviolet B ◽  
Infrared Spectrometry ◽  
Unexpected Finding ◽  
Cedrus Atlantica ◽  
Modern Pollen ◽  
Northwest Africa ◽  
Place Of Origin

Sporopollenin is a complex biopolymer which is the main component of the pollen grain exine and is partly composed of the aromatic compounds para-coumaric acid ( pCA) and ferulic acid (FA). These compounds absorb ultraviolet-B radiation (UV-B, 280–315 nm), and their abundance in pollen and spores has been shown to increase in response to increased UV-B flux. Here, we show that the relative abundance of UV-B-absorbing compounds (UACs) measured using Fourier Transform Infrared Spectrometry (FTIR) in modern pollen of autumn-pollinating Cedrus atlantica trees increases in response to summer UV-B flux. This relationship was observed in native Moroccan samples ( r2 = 0.84, p < 0.0001), but not across a larger environmental gradient including non-Moroccan samples ( r2 = 0.00, p = 0.99). For non-Moroccan samples of known provenance, the abundance of UACs is similar to the abundance of UACs found in samples from their place of origin. The FTIR spectra of these samples also closely resemble the FTIR spectra of samples from their place of origin. This unexpected finding suggests there could be a heritable component to UAC production possibly associated with epigenetic memory, an important adaptive mechanism in conifers. Our results indicate that the relative abundance of UACs in Cedrus atlantica pollen could be used as a proxy to reconstruct historic summer UV-B flux in Northwest Africa during at least the Holocene and Late Glacial period while also highlighting how UV-B proxies should be established using pollen samples from specimens growing in their native range or environment.

Late Quaternary Vegetation and Climate of Southern Tierra del Fuego

1989 ◽  
Vol 31 (3) ◽  
pp. 396-406 ◽  
Author(s):  
Calvin J. Heusser
Keyword(s):  
Late Quaternary ◽  
Pollen Dispersal ◽  
Late Glacial ◽  
Tierra Del Fuego ◽  
Fossil Pollen ◽  
Radiocarbon Dates ◽  
Modern Pollen ◽  
Open Woodland ◽  
Glacial Time ◽  
Vegetation And Climate

AbstractVegetation and climate over approximately the past 13,000 yr are reconstructed from fossil pollen in a 9.4-m mire section at Caleta Róbalo on Beagle Channel, Isla Navarino (54°56′S, 67°38′W), southern Tierra del Fuego. Fifty surface samples reflecting modern pollen dispersal serve to interpret the record. Chronologically controlled by nine radiocarbon dates, fossil pollen assemblages are: Empetrum-Gramineae-Gunnera-Tubuliflorae (zone 3b, 13,000–11,850 yr B.P.), Gramineae-Empetrum-assorted minor taxa (zone 3a, 11,850-10,000 yr B.P.), Nothofagus-Gramineae-Tubuliflorae-Polypodiaceae (zone 2, 10,000–5000 yr B.P.), Nothofagus-Empetrum (zone 1b, 5000-3000 yr B.P.), and Empetrum-Nothofagus (zone 1a, 3000-0 yr B.P.). Assemblages show tundra under a cold, dry climate (zone 3), followed by open woodland (zone 2), as conditions became warmer and less dry, and later, with greater humidity and lower temperatures, by closed forest and the spread of mires (zone 1). Comparisons drawn with records from Antarctica, New Zealand, Tasmania, and the subantarctic islands demonstrate broadly uniform conditions in the circumpolar Southern Hemisphere. The influences of continental and maritime antarctic air masses were apparently considerable in Tierra del Fuego during cold late-glacial time, whereas Holocene climate was largely regulated by interplay between maritime polar and maritime tropical air.

Holocene Climatic Change in the Northern Midwest: Pollen-Derived Estimates

1984 ◽  
Vol 22 (3) ◽  
pp. 361-374 ◽  
Author(s):  
P. J. Bartlein ◽  
T. Webb ◽  
E. Fleri
Keyword(s):  
Maximum Temperature ◽  
Pollen Record ◽  
Regression Equations ◽  
Climate Data ◽  
The South ◽  
The North ◽  
Modern Pollen ◽  
Quantitative Estimates ◽  
Multiple Regression Models ◽  
July Temperature

Mapping of Holocene pollen data in the midwestern United States has revealed several broadscale vegetational changes that can be interpreted in climatic terms. These changes include (1) the early Holocene northward movement of the spruce-dominated forest and its later southward movement after 3000 yr B.P. and (2) the eastward movement of the prairie/forest border into southwestern Wisconsin by 8000 yr B.P. and its subsequent westward retreat after 6000 yr B.P. When certain basic assumptions are met, multiple regression models can be derived from modern pollen and climate data and used to transform the pollen record of these vegetational changes into quantitative estimates of temperature or precipitation. To maximize the reliability of the regression equations, we followed a sequence of procedures that minimize violations of the assumptions that underlie regression analysis. Reconstructions of precipitation during the Holocene indicated that from 9000 to 6000 yr B.P. precipitation decreased by 10 to 25% over much of the Midwest, while mean July temperature increased by 0.5° to 2.0°C. At 6000 yr B.P. precipitation was less than 80% of its modern values over parts of Wisconsin and Minnesota. After 6000 yr B.P. precipitation generally increased, while mean July temperature decreased in the north, and increased in the south. The time of the maximum temperature varies within the Midwest and is earlier in the north and later in the south.

scholarly journals A late Pleistocene long pollen record from Lake Urmia, Nw Iran

2008 ◽  
Vol 69 (03) ◽  
pp. 413-420 ◽  
Author(s):  
Morteza Djamali ◽  
Jacques-Louis de Beaulieu ◽  
Madjid Shah-hosseini ◽  
Valérie Andrieu-Ponel ◽  
Philippe Ponel ◽  
...  
Keyword(s):  
Late Glacial ◽  
Interglacial Period ◽  
Pollen Record ◽  
Glacial Period ◽  
Last Interglacial ◽  
Lake Urmia ◽  
Nw Iran ◽  
Shrub Steppe ◽  
Isotope Record ◽  
Palynological Study

A palynological study based on two 100-m long cores from Lake Urmia in northwestern Iran provides a vegetation record spanning 200 ka, the longest pollen record for the continental interior of the Near East. During both penultimate and last glaciations, a steppe ofArtemisiaand Poaceae dominated the upland vegetation with a high proportion of Chenopodiaceae in both upland and lowland saline ecosystems. WhileJuniperusand deciduousQuercustrees were extremely rare and restricted to some refugia,Hippophaë rhamnoidesconstituted an important phanerophyte, particularly during the late last glacial period. A pronounced expansion inEphedrashrub-steppe occurred at the end of the penultimate late-glacial period but was followed by extreme aridity that favoured anArtemisiasteppe. Very high lake levels, registered by both pollen and sedimentary markers, occurred during the middle of the last glaciation and late part of the penultimate glaciation. The late-glacial to early Holocene transition is represented by a succession ofHippophaë, Ephedra, Betula, Pistaciaand finallyJuniperusandQuercus. The last interglacial period (Eemian), slightly warmer and moister than the Holocene, was followed by two interstadial phases similar in pattern to those recorded in the marine isotope record and southern European pollen sequences.

Late Weichselian Environmental History in Southeastern Sweden during the Deglaciation of the Scandinavian Ice Sheet

1987 ◽  
Vol 28 (1) ◽  
pp. 1-37 ◽  
Author(s):  
Svante Björck ◽  
Per Möller
Keyword(s):  
Environmental History ◽  
Vegetation Change ◽  
Time Lag ◽  
Ice Sheet ◽  
Late Glacial ◽  
Climatic Data ◽  
Basal Ice ◽  
Tundra Vegetation ◽  
History Of ◽  
Late Weichselian

AbstractLate Weichselian litho-, bio-, and chronostratigraphy (14C and varves) in southeastern Sweden provide a detailed picture of the deglaciation pattern and dynamics, shore displacement, late-glacial sedimentation, and history of the landscape, vegetation, and climate. Two plausible glacial models were tested against lithologic, chronologic, and climatic data. Permafrost at and outside the ice margin and topographic conditions beneath the ice apparently caused inward spread of frozen glacier-bed conditions. This led to a buildup of a large zone of debris-rich basal ice. A climatic amelioration about 12,700 yr B.P. changed the temperature profile in the ice sheet. Deposition of basal melt-out till began at the previously frozen glacier bed, and a rapid recession of the clean ice set in; thin exposed debris-rich basal ice which was separated from the active ice margin about 150 yr later. In this zone of stagnant ice there followed a 200– 300-yr period marked by subglacial and supraglacial melt-out and resedimentation, forming a large hummocky/transverse moraine. The mild climate favored rapid plant immigration, and a park-tundra was established. The gradual closing of the landscape was interrupted by a 100- to 150-yr period of tundra vegetation and a cool, dry climate, with local vegetational differences caused by differences in soil moisture. About 12,000 yr B.P. a second climatic amelioration set in, and during the next 1000 yr a birch (and pine) woodland gradually developed. Soils stabilized and Empetrum heaths became abundant as the climate gradually deteriorated at the end of this period. By 11,000 yr B.P. the area had become a tundra again with scattered birch stands, dominated by herbs such as Artemisia, Chenopodiaceae, grasses, and sedges. Some 500 yr later a birch/pine woodland again succeeded, and within about 500 yr the vegetation changed to a rather closed woodland as the climate ameliorated further. However, the time lag between climatic and vegetation change was considerable.

Modern pollen spectra from lakes in arctic western Canada

1987 ◽  
Vol 65 (8) ◽  
pp. 1605-1613 ◽  
Author(s):  
J. C. Ritchie ◽  
K. A. Hadden ◽  
K. Gajewski
Keyword(s):  
Late Glacial ◽  
High Arctic ◽  
Pollen Deposition ◽  
Tree Pollen ◽  
Indicator Taxa ◽  
Modern Pollen ◽  
Banks Island ◽  
Arboreal Pollen ◽  
Low Arctic ◽  
Trees And Shrubs

Fifty-four samples of modern sediment from Banks Island and the Melville–Horton region of the Northwest Territories illustrate the major features of pollen deposition from the high to low arctic. Modern pollen deposition in the high arctic of Banks Island is characterized by up to 14% windblown tree pollen. Indicator taxa of the high and mid arctic include Oxyria (<5–23%), Saxifragaceae, Saxifraga oppositifolia, and Cruciferae (all up to 8%) and Dryas (up to 3%). Arboreal pollen increases to 60% in low-arctic and subarctic samples. Pollen concentration decreases from between 3 500 and 20 000 in the low arctic to less than 5 000 grains/cm3 in the high and mid arctic. Pollen spectra from the Late Glacial of northwestern Canada differ from those of the modern high and mid arctic not only by the absence of trees and shrubs but also in the relative proportions of Artemisia and of such indicator taxa as Oxyria and Saxifragaceae.

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