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.

scholarly journals Holocene stratigraphy and vegetation history in the Scoresby Sund area, East Greenland

1978 ◽  
Vol 129 ◽  
pp. 1-66
Author(s):  
S Funder
Keyword(s):  
Vegetation History ◽  
High Arctic ◽  
Dwarf Shrub ◽  
Betula Nana ◽  
Isostatic Uplift ◽  
Cassiope Tetragona ◽  
Pollen Diagrams ◽  
Salix Arctica ◽  
Low Arctic ◽  
Holocene Stratigraphy

The Holocene stratigraphy in Scoresby Sund is based on climatic change as reflected by fluctuations in fjord and valley glaciers, immigration and extinction of marine molluscs, and the vegetation history recorded in pollen diagrams from five lakes. The histories are dated by C-14, and indirectly by emergence curves showing the patterns of isostatic uplift. From c. 10100-10400 to 9400 yr BP the major fjord glaciers showed oscillatory retreat with abundant moraine formation, the period of the Milne Land Moraines. The vegetation in the ice-free areas was a sparse type of fell field vegetation but with thermophilous elements indicating temperatures similar to the present. From 9400 yr BP the fjord glaciers retreated rapidly in the narrow fjords, the few moraines formed are referred to the Rødefjord stages and indicate topographically conditioned stillstands. At 8000 yr BP the low arctic Betula nana immigrated into the area, and in the period until 5000 yr BP dense dwarf shrub heath grew in areas where it is now absent. In the fjords the subarctic Mytilus edulis and Pecten islandica lived, suggesting a climate warmer than the present. From c. 5000 yr BP the dense dwarf shrub heath began to disappear in the coastal areas, and a 'poor' heath dominated by the high arctic Salix Arctica and Cassiope tetragona expanded. These two species, which are now extremely common, apparently did not grow in the area until c. 6000 yr BP. In lakes in the coastal area minerogenic sedimentation at c. 2800 yr BP, reflecting the general climatic deterioration.

scholarly journals The Relative Pollen Productivity and Pollen Representation of North European Trees, and Correction Factors for Tree Pollen Spectra. Determined by Surface Pollen Analyses from Forests

1970 ◽  
Vol 96 ◽  
pp. 1-99
Author(s):  
Svend Th. Andersen
Keyword(s):  
Tree Species ◽  
Small Sample ◽  
Forest Composition ◽  
Pollen Deposition ◽  
Correction Factors ◽  
Tree Crown ◽  
Tree Pollen ◽  
Surface Samples ◽  
Pollen Productivity ◽  
Pollen Analyses

The present work deals primarily with a determination of the relative pollen productivity of various trees from North Europe by means of their representation in pollen analyses of surface samples from forests, with the aim to calculate correction factors for pollen diagrams.Surface samples from 2 forests in Denmark were examined. The forest composition was determined by tree crown areas and tree basal areas in small sample plots. The relation of the tree crown areas to the tree basal areas was determined for the various tree species, and the data for crown area composition, basal area composition and tree frequency were compared.The pollen preservation in the various surface samples was examined.Data on wind conditions are mentioned in the chapter about pollen dispersal in the forest, and the various modes of pollen transfer are discussed. The amount of exotic pollen in the samples is used as a calculation basis for the tree pollen frequencies, and the occurrence and composition of the exotic pollen is discussed.The relationship of the forest composition to the tree pollen deposition is discussed. Pollen deposition and pollen productivity is expressed by a regression equation. The relative pollen productivity of the tree species is expressed in relation to a reference species, in the present case Fagus silvatica. Pollen representation and relative pollen representation are determined by a comparison of pollen percentages with percentages for areal frequency.Pollen productivity factors, pollen representation and correction factors were determined for Danish species of Quercus, Betula, Alnus, Carpinus, Ulmus, Fagus, Tilia and Fraxinus by means of the pollen frequencies in the surface samples. Corrected pollen percentages were compared with the tree areal percentages in the sample plots. Data for the pollen frequencies of forest plants other than the trees are presented. The data on trees from Denmark are compared with other data from Northern Europe, and correction factors were calculated for species of Pinus, Picea and Abies.Tree pollen spectra from outside the forest are discussed and the relative pollen representation is calculated. The present calculations of the relative pollen productivity of the trees are compared with previous estimates, and the application of the correction factors to pollen diagrams is discussed.

scholarly journals Relación lluvia de polen-vetación en selvas de Quintana Roo

2017 ◽  
pp. 31 ◽  
Author(s):  
Gerald A. Islebe ◽  
Rogel Villanueva-Gutiérrez ◽  
Odilón Sánchez-Sánchez
Keyword(s):  
Zea Mays ◽  
Quintana Roo ◽  
Vegetation Types ◽  
Pollen Data ◽  
Indicator Taxa ◽  
Modern Pollen ◽  
Pollen Content ◽  
Ordination Techniques ◽  
Ordination Analysis ◽  
Pollen Rain

Modern pollen rain was studied along a 450 km long transect between Cancun-La Unión (Belizean border). Ten moss samples were collected in different vegetation types and analyzed for pollen content. The data were analyzed with classification (TWINSPAN), ordination analysis (DCA) and different association indices. Classification and ordination techniques allowed us to recognize three different pollen signals from semievergreen forest (with Maclura, Apocynaceae, Moraceae, Sapotaceae, Araceae, Cecropia, Celtis, Eugenia and Bursera), acahual (with con Coccoloba, Metopium, Anacardiaceae, Urticales, Melothria, Croton, Palmae) and disturbed vegetation (with Zea mays, Mimosa and Asteraceae ) . The degree of over-representation and underrepresentation of the pollen data with respect to the modem vegetation was established, being under-represented mostly entomophilous species. We can conclude that the actual pollen signal can be used for calibrating paleosignals, if clear groups of indicator taxa can be established.

Why do we monitor? Using seabird eggs to track trends in Arctic environmental contamination

2021 ◽  
Author(s):  
Kristin Bianchini ◽  
Mark L. Mallory ◽  
Birgit Braune ◽  
Derek C.G. Muir ◽  
Jennifer F. Provencher
Keyword(s):  
Emerging Contaminants ◽  
Monitoring Program ◽  
High Arctic ◽  
Future Research ◽  
Arctic Canada ◽  
Seabird Species ◽  
Contaminant Monitoring ◽  
History Of ◽  
Low Arctic ◽  
High Level

Contaminant levels and trends have been monitored in eggs of seabirds from the Canadian Arctic since 1975. Nearly 50 years of monitoring have provided key information regarding the temporal and spatial variation of various contaminant classes in different seabird species. However, previous work has primarily assessed individual or related contaminant classes in isolation. There is therefore a need to collectively consider all of the contaminants monitored in seabird eggs to determine where monitoring has been successful, to find areas for improvement, and to identify opportunities for future research. In this review, we evaluated monitoring data for the major legacy and emerging contaminants of concern in five seabird species from three High Arctic and three Low Arctic colonies in Canada. We review the history of Canada’s Arctic seabird egg monitoring program and discuss how monitoring efforts have changed over time; we summarize temporal, spatial, and interspecies variations in Arctic seabird egg contamination and identify important knowledge gaps; and we discuss future directions for ecotoxicology research using seabird eggs in Arctic Canada. Ultimately, this paper provides a high-level overview of the egg contaminant monitoring program and underscores the importance of long-term and continued seabird contaminant monitoring in Arctic Canada.

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.

A Holocene Ice-Core Pollen Record from Ellesmere Island, Nunavut, Canada

2000 ◽  
Vol 54 (2) ◽  
pp. 275-283 ◽  
Author(s):  
Jocelyne C. Bourgeois ◽  
Roy M. Koerner ◽  
Konrad Gajewski ◽  
David A. Fisher
Keyword(s):  
Atmospheric Transport ◽  
Ice Core ◽  
Early Holocene ◽  
Pollen Deposition ◽  
Pollen Record ◽  
Tree Pollen ◽  
Eastern Canada ◽  
Ice Cap ◽  
Pollen Concentrations ◽  
Holocene Record

A Holocene record of pollen deposition was obtained from an ice core drilled through the Agassiz Ice Cap. The pollen records long-range atmospheric transport to the ice cap. Pollen concentrations were highest in the early Holocene (∼15 grains/L), decreased in the mid-Holocene (∼6 grains/L), and increased in the late Holocene (∼9 grains/L). In the early Holocene, the higher concentration of tree pollen at a time when large parts of Canada were still ice-covered, and when forest was generally farther away, implies that atmospheric circulation was stronger than at present. Following deglaciation, as vegetation migrated north in central and eastern Canada, sources of pollen were closer to the Agassiz Ice Cap. However, the concentration of tree pollen decreased on the ice cap. This was followed by several relatively rapid changes after 3500 yr ago. Until ca. 3500 yr ago, the pollen concentration curves resembled the ice core δ18O and summer melt layer curves, both regarded as temperature proxies.

High Arctic sea ice conditions influence marine birds wintering in Low Arctic regions

2010 ◽  
Vol 89 (1) ◽  
pp. 97-106 ◽  
Author(s):  
Laura McFarlane Tranquilla ◽  
April Hedd ◽  
Chantelle Burke ◽  
William A. Montevecchi ◽  
Paul M. Regular ◽  
...  
Keyword(s):  
Sea Ice ◽  
High Arctic ◽  
Arctic Sea Ice ◽  
Marine Birds ◽  
Arctic Regions ◽  
Arctic Sea ◽  
Ice Conditions ◽  
Low Arctic
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