The contemporary moss assemblages of a high arctic upland, northern Ellesmere Island, N.W.T., Canada

1989 ◽  
Vol 67 (2) ◽  
pp. 491-504 ◽  
Author(s):  
Catherine LaFarge-England
Keyword(s):  
Environmental Gradients ◽  
Specific Conductivity ◽  
Detrended Correspondence Analysis ◽  
Distribution Patterns ◽  
High Arctic ◽  
Organic Content ◽  
Ellesmere Island ◽  
Physical Parameters ◽  
Major Species ◽  
Species Groups

A quantitative analysis of contemporary moss assemblages is presented for a fault block at the southern end of Piper Pass, northern Ellesmere Island, N.W.T. (82°12′N, 68°31′W). Twenty-eight stands are analyzed using the two-way indicator species analysis, resulting in seven major species groups and five major stand groups. Physical parameters correlated with the stand data show soil moisture and slope to be the most important factors influencing the distribution of moss assemblages. Sodium, organic content, and specific conductivity are also correlated with the vegetation data. Detrended correspondence analysis confirms these stand relationships. The interdependence of physical, chemical, and vegetation data is also discussed. Distribution patterns of the species groups within the stand groups are analyzed by means of a percent frequency diagram. A direct gradient analysis of the vegetation below a late-lying snowbank also demonstrates the selective distribution of species in terms of environmental gradients.

Evaluating the influence of environmental and spatial variables on diatom species distributions from Melville Island (Canadian High Arctic)

Botany ◽  
2008 ◽  
Vol 86 (1) ◽  
pp. 76-90 ◽  
Author(s):  
Bronwyn E. Keatley ◽  
Marianne S.V. Douglas ◽  
John P. Smol
Keyword(s):  
Environmental Gradients ◽  
Wide Spectrum ◽  
Specific Conductivity ◽  
High Arctic ◽  
Weighted Averaging ◽  
Diatom Species ◽  
Canadian High Arctic ◽  
Total Dissolved Nitrogen ◽  
Bioclimatic Zone ◽  
Ecological Relationship

Diatom species assemblages were identified and enumerated from the surface sediments of 45 lakes and ponds across a wide spectrum of spatial and environmental gradients on Melville Island, Nunavut/N.W.T, Arctic Canada. Whereas the most common taxa were similar to those recorded elsewhere in the Canadian High Arctic, significant differences in assemblages existed between sites located in the different bioclimatic zones of Melville Island. For example, taxa recorded in the most lushly vegetated bioclimatic zone were similar to those found in lushly vegetated regions elsewhere in the Canadian Arctic Archipelago, and generally different from diatoms in the poorly vegetated regions on Melville Island. Of the measured environmental variables, pH, specific conductivity, surface area, elevation, and chlorophyll a explained significant portions of the variance in diatom assemblage composition at the scale of the entire island. However, only total dissolved nitrogen was an important explanatory variable within the most lushly vegetated bioclimatic zone. The strongest ecological relationship was between diatoms and pH, and regression and calibration by weighted averaging produced predictive models with r2boot of 0.432 to 0.746 and RMSEP of 0.341 to 0.242. Spatial factors were of little importance, confirming that diatoms are not likely to be dispersal limited, at least at the landscape scale explored in this study.

Vascular plant communities of a polar oasis at Alexandra Fiord (79° N), Ellesmere Island, Canada

1989 ◽  
Vol 67 (4) ◽  
pp. 1126-1136 ◽  
Author(s):  
M. Muc ◽  
B. Freedman ◽  
J. Svoboda
Keyword(s):  
Cluster Analysis ◽  
Plant Species ◽  
Plant Community ◽  
Plant Communities ◽  
Vascular Plants ◽  
Vascular Plant ◽  
Detrended Correspondence Analysis ◽  
High Arctic ◽  
Ellesmere Island ◽  
Community Types

A cluster analysis was used to apportion 136 stands in a High Arctic lowland among six vascular plant community types. These communities are described on the basis of the average prominence values of vascular species and the total cover of macroalgae, bryophytes, lichens, and vascular plants within the designated clusters of stands. The relationships among the community types was explored by a detrended correspondence analysis. The ordination of stands showed considerable floristic overlap among the most widespread plant communities on the lowland. This largely reflects the microtopographic heterogeneity of the sites, the relatively depauperate flora of the High Arctic, and the considerable ecological amplitude of the most prominent vascular plant species.

scholarly journals A comparison of the vegetation of forested and non-forested solution dolines in Hungary: a preliminary study

Biologia ◽  
2014 ◽  
Vol 69 (10) ◽  
Author(s):  
Zoltán Bátori ◽  
Tünde Farkas ◽  
László Erdős ◽  
Csaba Tölgyesi ◽  
László Körmöczi ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Forest Cover ◽  
Environmental Gradients ◽  
Species Turnover ◽  
Detrended Correspondence Analysis ◽  
Future Research ◽  
Linear Regression Models ◽  
Species Groups ◽  
Vegetation Characteristics ◽  
Floristic Variation

AbstractThe present study compares the vegetation characteristics of two large forested and one large non-forested solution dolines in Hungary. We investigated the species composition and vegetation pattern along north to south transects (across the doline bottoms) and compared the richness of different species groups (dry and wet groups) on the doline slopes. We applied linear regression models for each slope to explore the effects of topography on species richness, and Detrended Correspondence Analysis (DCA) to detect the major gradients of floristic variation within each site. We found that the vegetation changed significantly along all transects; and, regardless of the vegetation cover, the doline bottoms contained several cool-adapted species. Variations within the two species groups were more pronounced on the south-facing slopes. The changes were similar in the forested dolines, indicating the role of forest cover in maintaining many cool-adapted species on the north-facing slopes as well. However, the number of cool-adapted species increased significantly along both slopes of the non-forested doline from the upper edge to the bottom. Contrary to our expectations, the species turnover along the slopes of the non-forested doline was lower than that along the slopes of the forested ones. We conclude that both the forested and non-forested dolines serve as refuges for many plant species adapted to different environmental conditions. Apart from providing an understanding of population patterns along environmental gradients, our results may also contribute to our understanding of an even more fundamental question for a future research agenda: the probable effects of climate change on vegetation characteristics in climatic islands with environmental conditions substantially different from the surrounding areas.

Odontopleura (Trilobita, Silurian), and a method of constrained congruency analysis

1990 ◽  
Vol 64 (4) ◽  
pp. 600-614 ◽  
Author(s):  
Jonathan M. Adrain ◽  
Brian D. E. Chatterton
Keyword(s):  
Cladistic Analysis ◽  
Canadian Arctic ◽  
Wide Distribution ◽  
Parsimony Analysis ◽  
Directed Tree ◽  
Shelf Slope ◽  
Major Species ◽  
Species Groups ◽  
The Universe ◽  
A New Species

Odontopleura (Odontopleura) arctica, a new species of odontopleurine trilobite, is described from the Canadian Arctic. A method of cladistic analysis is detailed. Parsimony analysis should be performed treating all characters as unordered. The universe of directed trees implied by the resulting rootless network(s) can then be examined and a preferred tree selected by a criterion of congruency. Namely, the most parsimonious directed tree that accommodates the most congruent arrangement of character-states should be taken as the preferred cladogram. Since this is essentially a general congruency method operating within the constraints of parsimony, it is termed “constrained congruency.” The method is applied to the genus Odontopleura, resulting in the recognition of two major species groups, the nominate subgenus and Sinespinaspis n. subgen. Odontopleura (Ivanopleura) dufrenoyi Barrande is tentatively included in the genus, but considered too poorly known for cladistic analysis. Species assigned to Odontopleura (Odontopleura) include Odontopleura ovata Emmrich, Odontopleura brevigena Chatterton and Perry, Odontopleura (Odontopleura) arctica n. sp., and Diacanthaspis serotina Apollonov. Species assigned to Sinespinaspis n. subgen. include Taemasaspis llandoveryana Šnajdr, Odontopleura greenwoodi Chatterton and Perry, Odontopleura maccallai Chatterton and Perry, and Odontopleura nehedensis Chatterton and Perry. Odontopleura bombini Chatterton and Perry is tentatively placed in synonymy with Odontopleura nehedensis. The genus had a wide distribution throughout the Early and Middle Silurian, due to preferences for deep-water, distal shelf or shelf-slope transition zone habitats.

Limnology of high arctic ponds (Cape Herschel, Ellesmere Island, N. W. T.)

1994 ◽  
Vol 131 (4) ◽  
pp. 401-434
Author(s):  
Marianne S. V. Douglas ◽  
John P. Smol
Keyword(s):  
High Arctic ◽  
Ellesmere Island ◽  
Arctic Ponds

An analysis of the stability of thawing slopes, Ellesmere Island, Nunavut, Canada

2000 ◽  
Vol 37 (2) ◽  
pp. 449-462 ◽  
Author(s):  
Charles Harris ◽  
Antoni G Lewkowicz
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Active Layer ◽  
Factor Of Safety ◽  
High Arctic ◽  
Ellesmere Island ◽  
Sensitivity Analyses ◽  
Pore Water Pressures ◽  
Hot Weather ◽  
The Stability

Active-layer detachment slides are locally common on Fosheim Peninsula, Ellesmere Island, where permafrost is continuous, the active layer is 0.5-0.75 m thick, and summer temperatures are unusually high in comparison with much of the Canadian High Arctic. In this paper we report pore-water pressures at the base of the active layer, recorded in situ on two slopes in late July and early August 1995. These data form the basis for slope stability analyses based on effective stress conditions. During fieldwork, the factor of safety within an old detachment slide on a slope at Hot Weather Creek was slightly greater than unity. At "Big Slide Creek," on a slope showing no evidence of earlier detachment failures, the factor of safety was less than unity on a steep basal slope section but greater than unity elsewhere. In the upper slope, pore-water pressures were only just subcritical. Sensitivity analyses demonstrate that the stability of the shallow active layer is strongly influenced by changes in soil shear strength. Possible mechanisms for reduction in shear strength through time include weathering of soils and gradual increases in basal active layer ice content. However, we suggest here that soil shearing during annual gelifluction movements is most likely to progressively reduce shear strengths at the base of the active layer from peak values to close to residual, facilitating the triggering of active-layer detachment failures.Key words: detachment slides, Ellesmere Island, pore-water pressures, gelifluction.

Chrysophycean stomatocysts from the postglacial sediments of a High Arctic lake

1988 ◽  
Vol 66 (6) ◽  
pp. 1117-1128 ◽  
Author(s):  
Katharine E. Duff ◽  
John P. Smol
Keyword(s):  
Species Composition ◽  
Light Microscopy ◽  
High Arctic ◽  
Ellesmere Island ◽  
Arctic Lakes ◽  
Ecological Research ◽  
Stratigraphic Analysis ◽  
Morphological Detail ◽  
Electron And Light Microscopy ◽  
Scanning Electron

Twenty-six chrysophycean stomatocyst morphotypes were described from the postglacial sediments of a small, rock basin lake near Baird Inlet, Ellesmere Island. Scanning electron and light microscopy were used to classify the stomatocysts, following the guidelines of the International Statospore Working Group. None of the stomatocysts could be related with certainty to the chrysophyte species that produced them, but sufficient morphological detail is present in most of the stomatocysts to allow for taxonomic differentiation. A stratigraphic analysis of the dominant stomatocyst morphotypes revealed that chrysophyte species composition changed most markedly during the lake's early development but then remained relatively constant. This study demonstrated that chrysophycean stomatocysts provide useful paleoecological information in High Arctic lakes, but further taxonomic and ecological research is required to fully exploit these microfossils.

Rotifers from five high arctic ponds (Cape Herschel, Ellesmere Island, N.W.T.)

Hydrobiologia ◽  
1989 ◽  
Vol 173 (3) ◽  
pp. 231-242 ◽  
Author(s):  
Thomas Nogrady ◽  
John P. Smol
Keyword(s):  
High Arctic ◽  
Ellesmere Island ◽  
Arctic Ponds
Sign in / Sign up

Export Citation Format

Share Document