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Symbiotic fungi's role in providing nitrogen to host plants is well-studied in tundra at Toolik Lake, Alaska, but little-studied in the adjoining boreal forest ecosystem. Along a 570 km north-south transect from the Yukon River to the North Slope of Alaska, the 15N content was strongly reduced in ectomycorrhizal and ericoid mycorrhizal plants including Betula, Salix, Picea mariana (P. Mill.) B.S.P., Picea glauca Moench (Voss), and ericaceous plants. Compared with the 15N content of soil, the foliage of nonmycorrhizal plants (Carex and Eriophorum) was unchanged, whereas content of the ectomycorrhizal fungi was very much higher (e.g., Boletaceae, Leccinum and Cortinarius). It is hypothesized that similar processes...
High-latitude northern ecosystems are experiencing rapid climate changes, and represent a large potential climate feedback because of their high soil carbon densities and shifting disturbance regimes. A significant carbon flow from these ecosystems is soil respiration (RS, the flow of carbon dioxide, generated by plant roots and soil fauna, from the soil surface to atmosphere), and any change in the high-latitude carbon cycle might thus be reflected in RS observed in the field. This study used two variants of a machine-learning algorithm and least squares regression to examine how remotely-sensed canopy greenness (NDVI), climate, and other variables are coupled to annual RS based on 105 observations from 64 circumpolar...
Here we quantitatively summarize the conservation ecology of one group of dead-wood-dependent organisms, the polyporous fungi, in boreal Europe. At the substrate scale, the decay stage is the strongest determinant of species richness, with large (>20 cm diameter) downed logs hosting more species than other dead-wood types. At the stand scale, the amount of dead wood is the strongest determinant of polypore species richness; the minimum average amount of dead wood for the occurrence of rare polypores appears to be 20–40 m3/ha. Species-area analysis shows that in mature boreal forests species accumulation levels off at around 20–30 ha. This leads us to suggest a heuristic 20/20/20 rule of thumb: a 20 ha stand, with...
This study describes Native community perceptions of the Hook Lake Wood Bison Recovery Project and options for its future management. In 1999, I conducted thirty in-depth, semi-structured interviews with residents in the community of Fort Resolution, NT including participant and non-participant observations. Resident perceptions about the recovery project and priorities for the future care of the bison appeared to be strongly influenced by their knowledge of the project, their views on proper relationships between humans and nature, and beliefs about the aetiology of disease in bison. Dissemination of knowledge from managers to residents is complicated by challenges of communication between project staff and residents...
Habitat quality is largely heterogeneous over space and time, although common simplifying assumptions in ecological research include homogeneity of areas occupied by a population and equal resource availability among individuals. These assumptions are made due to difficulties in quantifying the food available to individuals and following the effects of food on individual performance under natural conditions. My objectives were to document temporal and spatial variability in food availability, and its effects on seed predator individual performance and population dynamics in a white spruce-red squirrel system near Kluane Lake, Yukon. This system was ideal for my study because white spruce is the only conifer present,...
Mast-seeding conifers such as Picea glauca exhibit synchronous production of large seed crops over wide areas, suggesting climate factors as possible triggers for episodic high seed production. Rapidly changing climatic conditions may thus alter the tempo and spatial pattern of masting of dominant species with potentially far-reaching ecological consequences. Understanding the future reproductive dynamics of ecosystems including boreal forests, which may be dominated by mast-seeding species, requires identifying the specific cues that drive variation in reproductive output across landscape gradients and among years. Here we used annual data collected at three sites spanning an elevation gradient in interior Alaska,...
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Recent studies have shown that ice duration in lakes and rivers over the Northern Hemisphere has decreased over the 19th and 20th centuries in response to global warming. However, lake ice trends have not been well documented in Canada. Because of its size, considerable variability may exist in both freeze-up and break-up dates across the country. In this paper, results of the analysis of recent trends (1951-2000) in freeze-up and break-up dates across Canada are presented. Trends toward earlier break-up dates are observed for most lakes during the time periods of analysis which encompass the 1990s. Freeze-up dates, on the other hand, show few significant trends and a low degree of temporal coherence when compared...
map background search result map search result map Molecular Genetic Approaches in Wildlife Management Modeling Breeding Waterfowl Distribution in the Southern Lakes Region of the Yukon Recent trends in Canadian lake ice cover Recent trends in Canadian lake ice cover Molecular Genetic Approaches in Wildlife Management Modeling Breeding Waterfowl Distribution in the Southern Lakes Region of the Yukon