Identifying the tundra – forest border in the stomate record: an analysis of lake surface samples from the Yellowknife area, Northwest Territories, Canada

1996 ◽  
Vol 74 (5) ◽  
pp. 796-800 ◽  
Author(s):  
Barbara C. S. Hansen ◽  
Glen M. MacDonald ◽  
Katrina A. Moser
Keyword(s):  
Northwest Territories ◽  
Picea Glauca ◽  
The Arctic ◽  
Tree Line ◽  
Forest Tundra ◽  
Surface Samples ◽  
Pollen Surface ◽  
Closed Forest ◽  
Common Tree ◽  
Potential Use

Conifer stomata were identified in surface samples from lakes in the treeline zone near Yellowknife, Northwest Territories, to assess the potential use of fossil stomata for reconstructing past changes in the arctic tree line. Stomata of Larix, Pinus, Picea mariana, and Picea glauca were distinguished. Conifer stomata were absent in samples from tundra lakes, whereas they were generally present in forest–tundra and forest lakes. Stomate analysis recorded the presence of Larix trees in the area; in contrast, the pollen of this relatively common tree was infrequent in pollen surface samples from the same sites. Conifer stomate analysis, however, is not able to resolve differences between forest–tundra and closed forest. The potential of stomata for providing improved resolution of past locations of the tree line, coupled with the presence of stomata in lakes that would lack good macrofossil records, suggest that stomate analysis will become an important technique supplementing pollen analysis for reconstructing past tree-line changes. Keywords: Northwest Territories, conifer stomata and pollen, tree line, tundra, forest–tundra, closed forest.

Modern pollen assemblages near the arctic tree line, Mackenzie Delta region, Northwest Territories

1974 ◽  
Vol 52 (2) ◽  
pp. 381-396 ◽  
Author(s):  
J. C. Ritchie
Keyword(s):  
Northwest Territories ◽  
Lake Sediment ◽  
Local Community ◽  
The Arctic ◽  
Forest Site ◽  
Mackenzie Delta ◽  
Forest Tundra ◽  
Transitional Area ◽  
Modern Pollen ◽  
Pollen Rain

Samples of surficial lake sediment and of moss polsters from 39 sites in the forest-tundra transitional area immediately east of the Mackenzie Delta, Northwest Territories, were investigated palynologically. Lake sediment samples within the forest and tundra regional vegetation zones are constant in pollen frequencies, but forest–tundra sites are very variable. Forest site spectra are composed of just over 50% arboreal types (spruce, 25–30%; birch, 30%), with 30–40% alder pollen. Tundra spectra have 60–70% non-arboreal types, and 10–15% each of alder and spruce. Forest–tundra values are variable, generally lying between the forest and tundra proportions. Polster samples show as much variability within as between regions, because of local effects. Polster samples indicate local community composition with the regional pollen rain variably masked by the local elements.

scholarly journals Microplastics distribution in the Eurasian Arctic is affected by Atlantic waters and Siberian rivers

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Evgeniy Yakushev ◽  
Anna Gebruk ◽  
Alexander Osadchiev ◽  
Svetlana Pakhomova ◽  
Amy Lusher ◽  
...  
Keyword(s):  
Surface Water ◽  
Surface Waters ◽  
Water Masses ◽  
The Arctic ◽  
Plastic Pollution ◽  
Siberian River ◽  
Highest Weight ◽  
Surface Samples ◽  
Atlantic Origin ◽  
Type Size

AbstractPlastic pollution is globally recognised as a threat to marine ecosystems, habitats, and wildlife, and it has now reached remote locations such as the Arctic Ocean. Nevertheless, the distribution of microplastics in the Eurasian Arctic is particularly underreported. Here we present analyses of 60 subsurface pump water samples and 48 surface neuston net samples from the Eurasian Arctic with the goal to quantify and classify microplastics in relation to oceanographic conditions. In our study area, we found on average 0.004 items of microplastics per m3 in the surface samples, and 0.8 items per m3 in the subsurface samples. Microplastic characteristics differ significantly between Atlantic surface water, Polar surface water and discharge plumes of the Great Siberian Rivers, allowing identification of two sources of microplastic pollution (p < 0.05 for surface area, morphology, and polymer types). The highest weight concentration of microplastics was observed within surface waters of Atlantic origin. Siberian river discharge was identified as the second largest source. We conclude that these water masses govern the distribution of microplastics in the Eurasian Arctic. The microplastics properties (i.e. abundance, polymer type, size, weight concentrations) can be used for identification of the water masses.

Pseudoditrichum mirabile gen. et sp. nov. (Musci: Pseudoditrichaceae fam. nov.), a unique moss from Great Bear Lake, Northwest Territories

1974 ◽  
Vol 52 (4) ◽  
pp. 701-705 ◽  
Author(s):  
William Campbell Steere ◽  
Zennoske Iwatsuki
Keyword(s):  
Northwest Territories ◽  
New Genus ◽  
The Arctic ◽  
Phylogenetic Position ◽  
New Genus And Species ◽  
Arctic Circle ◽  
New Family ◽  
Bear Lake ◽  
Evolutionary Level

The name Pseudoditrichum mirabile Steere et Iwatsuki is proposed for a minute moss with leafy stem 1-3 mm high and seta 6 mm long; it was collected on calcareous silt near the Sloan River, Great Bear Lake, Northwest Territories, only a few miles south of the Arctic Circle. The gametophytic characters agree well with those of the Ditrichaceae, a relatively primitive family, but the peristome is clearly double, with the inner and outer teeth opposite, which thereby indicates a much more advanced phylogenetic position, perhaps at the evolutionary level of the Funariaceae. As the combination of gametophytic and sporophytic characteristics exhibited by this moss does not occur in any existing family of mosses, it is therefore deemed necessary to create the new family Pseudoditrichaceae for the new genus and species described here.

Inuit vulnerability and adaptive capacity to climate change in Ulukhaktok, Northwest Territories, Canada

Polar Record ◽  
2009 ◽  
Vol 46 (2) ◽  
pp. 157-177 ◽  
Author(s):  
Tristan Pearce ◽  
Barry Smit ◽  
Frank Duerden ◽  
James D. Ford ◽  
Annie Goose ◽  
...  
Keyword(s):  
Climate Change ◽  
Northwest Territories ◽  
Adaptive Capacity ◽  
Adaptive Strategies ◽  
The Arctic ◽  
Future Climate Change ◽  
Sources Of Information ◽  
Structured Interviews ◽  
Climate Change Research ◽  
Climate Conditions

ABSTRACTClimate change is already being experienced in the Arctic with implications for ecosystems and the communities that depend on them. This paper argues that an assessment of community vulnerability to climate change requires knowledge of past experience with climate conditions, responses to climatic variations, future climate change projections, and non-climate factors that influence people's susceptibility and adaptive capacity. The paper documents and describes exposure sensitivities to climate change experienced in the community of Ulukhaktok, Northwest Territories and the adaptive strategies employed. It is based on collaborative research involving semi-structured interviews, secondary sources of information, and participant observations. In the context of subsistence hunting, changes in temperature, seasonal patterns (for example timing and nature of the spring melt), sea ice and wind dynamics, and weather variability have affected the health and availability of some species of wildlife important for subsistence and have exacerbated risks associated with hunting and travel. Inuit in Ulukhaktok are coping with these changes by taking extra precautions when travelling, shifting modes of transportation, travel routes and hunting areas to deal with changing trail conditions, switching species harvested, and supplementing their diet with store bought foods. Limited access to capital resources, changing levels of traditional knowledge and land skills, and substance abuse were identified as key constraints to adaptation. The research demonstrates the need to consider the perspectives and experiences of local people for climate change research to have practical relevance to Arctic communities such as for the development and promotion of adaptive strategies.

Acoustic detections of Arctic marine mammals near Ulukhaktok, Northwest Territories, Canada

2019 ◽  
Vol 97 (1) ◽  
pp. 72-80 ◽  
Author(s):  
W.D. Halliday ◽  
M.K. Pine ◽  
S.J. Insley ◽  
R.N. Soares ◽  
P. Kortsalo ◽  
...  
Keyword(s):  
Northwest Territories ◽  
Marine Mammals ◽  
Bowhead Whale ◽  
The Arctic ◽  
Delphinapterus Leucas ◽  
Anthropogenic Activity ◽  
Marine Animals ◽  
Vocal Activity ◽  
Beluga Whale Delphinapterus Leucas ◽  
Passive Acoustic

The Arctic marine environment is changing rapidly through a combination of sea ice loss and increased anthropogenic activity. Given these changes can affect marine animals in a variety of ways, understanding the spatial and temporal distributions of Arctic marine animals is imperative. We use passive acoustic monitoring to examine the presence of marine mammals near Ulukhaktok, Northwest Territories, Canada, from October 2016 to April 2017. We documented bowhead whale (Balaena mysticetus Linnaeus, 1758) and beluga whale (Delphinapterus leucas (Pallas, 1776)) vocalizations later into the autumn than expected, and we recorded bowhead whales in early April. We recorded ringed seal (Pusa hispida (Schreber, 1775)) vocalizations throughout our deployment, with higher vocal activity than in other studies and with peak vocal activity in January. We recorded bearded seals (Erignathus barbatus (Erxleben, 1777)) throughout the deployment, with peak vocal activity in February. We recorded lower bearded seal vocal activity than other studies, and almost no vocal activity near the beginning of the spring breeding season. Both seal species vocalized more when ice concentration was high. These patterns in vocal activity document the presence of each species at this site over autumn and winter and are a useful comparison for future monitoring.

scholarly journals Potential of Passive Microwave around 183 GHz for Snowfall Detection in the Arctic

2019 ◽  
Vol 11 (19) ◽  
pp. 2200 ◽  
Author(s):  
Léo Edel ◽  
Jean-François Rysman ◽  
Chantal Claud ◽  
Cyril Palerme ◽  
Christophe Genthon
Keyword(s):  
Detection Algorithm ◽  
The Arctic ◽  
Mountainous Areas ◽  
Phase Precipitation ◽  
Water Path ◽  
Brightness Temperatures ◽  
Microwave Humidity Sounder ◽  
Snow Water ◽  
Potential Use ◽  
Selection Of

This study evaluates the potential use of the Microwave Humidity Sounder (MHS) for snowfall detection in the Arctic. Using two years of colocated MHS and CloudSat observations, we develop an algorithm that is able to detect up to 90% of the most intense snowfall events (snow water path ≥400 g m−2 and 50% of the weak snowfall rate events (snow water path ≤50 g m−2. The brightness temperatures at 190.3 GHz and 183.3 ± 3 GHz, the integrated water vapor, and the temperature at 2 m are identified as the most important variables for snowfall detection. The algorithm tends to underestimate the snowfall occurrence over Greenland and mountainous areas (by as much as −30%), likely due to the dryness of these areas, and to overestimate the snowfall occurrence over the northern part of the Atlantic (by up to 30%), likely due to the occurrence of mixed phase precipitation. An interpretation of the selection of the variables and their importance provides a better understanding of the snowfall detection algorithm. This work lays the foundation for the development of a snowfall rate quantification algorithm.

Gas exchange and growth of three arctic tree-line tree species under different soil temperature and drought preconditioning regimes

1996 ◽  
Vol 74 (5) ◽  
pp. 686-693 ◽  
Author(s):  
Simon M. Landhäusser ◽  
Ross W. Wein ◽  
Petra Lange
Keyword(s):  
Soil Temperature ◽  
Picea Mariana ◽  
Tree Species ◽  
Withholding Treatment ◽  
The Arctic ◽  
Betula Papyrifera ◽  
Tree Line ◽  
Populus Balsamifera ◽  
Soil Temperatures ◽  
Net Assimilation

Low soil temperatures and water availability are thought to be major factors determining the distribution of tree species at the arctic tree line. A comparative study examined the response of Betula papyrifera, Populus balsamifera, and Picea mariana seedlings to different soil temperatures and drought regimes in a growth chamber experiment. Morphological and ecophysiological responses (net assimilation rate, stomatal conductance to water vapour, and residual conductance) of these tree line tree species were measured and compared. Mean biomass accumulation of the deciduous species was greater than that of Picea mariana with increasing soil temperatures. Root biomass showed an increase of 30% in the three species between the soil temperatures of 3 and 15 °C. Response of ecophysiological variables to increased soil temperature was greater in B. papyrifera and Populus balsamifera than in Picea mariana. In a second experiment, drought-preconditioned B. papyrifera and Populus balsamifera seedlings were subjected to a 6-day water-withholding treatment. Drought decreased shoot mass and increased the root to shoot ratio equally in B. papyrifera and Populus balsamifera. Drought-preconditioned B. papyrifera and Populus balsamifera seedlings responded differently to the 6-day water-withholding treatment. Betula papyrifera used a water-conserving strategy and maintained low net assimilation rates and low water use after drought preconditioning, whereas in Populus balsamifera greater net assimilation rates were associated with drought preconditioning. These results are consistent with the distribution of these three tree species at the arctic tree line. Keywords: Picea mariana, Populus balsamifera, Betula papyrifera, drought preconditioning, soil temperature, arctic tree line.

Late-Quaternary summer temperature changes in the northern-European tree-line region

2008 ◽  
Vol 69 (03) ◽  
pp. 404-412 ◽  
Author(s):  
Heikki Seppä ◽  
Glen M. MacDonald ◽  
H. John B. Birks ◽  
Bruce R. Gervais ◽  
Jeffrey A. Snyder
Keyword(s):  
Kola Peninsula ◽  
Younger Dryas ◽  
Summer Temperature ◽  
The Arctic ◽  
Fossil Pollen ◽  
Tree Line ◽  
Temperature Changes ◽  
The Holocene ◽  
Northern European ◽  
Line Region

We present two new quantitative July mean temperature (Tjul) reconstructions from the Arctic tree-line region in the Kola Peninsula in north-western Russia. The reconstructions are based on fossil pollen records and cover the Younger Dryas stadial and the Holocene. The inferred temperatures are less reliable during the Younger Dryas because of the poorer fit between the fossil pollen samples and the modern samples in the calibration set than during the Holocene. The results suggest that the Younger Dryas Tjulin the region was 8.0–10.0°C, being 2.0–3.0°C lower than at present. The Holocene summer temperature maximum dates to 7500–6500 cal yr BP, with Tjulabout 1.5°C higher than at present. These new records contribute to our understanding of summer temperature changes along the northern-European tree-line region. The Holocene trends are consistent in most of the independent records from the Fennoscandian–Kola tree-line region, with the beginning of the Holocene thermal maximum no sooner than at about 8000 cal yr BP. In the few existing temperature-related records farther east in the Russian Arctic tree line, the period of highest summer temperature begins already at about 10,000 cal yr BP. This difference may reflect the strong influence of the Atlantic coastal current on the atmospheric circulation pattern and the thermal behaviour of the tree-line region on the Atlantic seaboard, and the more direct influence of the summer solar insolation on summer temperature in the region east of the Kola Peninsula.

Identification and morphology of the aecial state of Pucciniastrum sparsum in northwestern Canada

1970 ◽  
Vol 48 (3) ◽  
pp. 433-435
Author(s):  
Y. Hiratsuka
Keyword(s):  
North America ◽  
Northwest Territories ◽  
Picea Glauca ◽  
Yukon Territory ◽  
New Hosts ◽  
First Time

From inoculation experiments and morphological examinations, the aecial state of Pucciniastrum sparsum (Wint.) E. Fisch. (= Thekopsora sparsa (Wint.) Magn.) has been identified for the first time in North America from specimens collected in the Northwest Territories and the Yukon Territory. Picea glauca (Moench) Voss, P. mariana (Mill.) BSP., and P. pungens Engelm. (from inoculation only) are reported as new hosts of this fungus. An expanded description of the spermogonia and aecia of the fungus is given.

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