Filters: Tags: P2-Changes in Plant and Animal Species Due to Climate Change (X)265 results (135ms)
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...
A selective review of lichenometry as used to date Holocenemoraines in five diverse regions of Alaska and in southeastern Kamchatka suggests that growth curves for this North Pacific areamay be improved by attention to several factors. These includedlichen identification, control point number and distribution,radiocarbon calibration, alternative curve models, andcompatibility of lichen growth rate with climate. Support forcontrol points presented for Kamchatka and published for Alaska areas will benefit from supplementary control at and beyond thebreak from the great growth curve segments of the last centuries.With regard to alternative-linear, logarithmic, and compositecurve-models drawn for the published lichenometric...
Experiments have been conducted with a regional climate model to indicate the conditions required to generate preferred regions of frontal activity in the Alaskan region. Several objective methods of frontal identification were first investigated. It was found that· the vertical component of relative vorticity,· a thermal front parameter -&nablaB;|&nablaB;Tsub 850] | · n, where Tsub 850] is the 850-hPa temperature and n is a unit vector in the direction of the 850-hPa temperature gradient, and· a parameter derived from the Q vector as a measure of vertical motionwere useful in combination to determine the occurrence of fronts. The preferred locations for frontal activity were located to the southern side of the...
Climate sensitivity of reproduction in a mast-seeding boreal conifer across its distributional range from lowland to treeline forests
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,...
Categories: Publication; Types: Citation; Tags: P2-Changes in Plant and Animal Species Due to Climate Change, M1-Changes in Plant and Animal Distributon
Examining barriers and opportunities for sustainable adaptation to climate change in Interior Alaska
Human Impacts on the Fire Regime of Interior Alaska: Interactions among Fuels, Ignition Sources, and Fire Suppression
Response of the carbon cycle in sub-arctic black spruce forests to climate change: Reduction of a carbon sink related to the sensitivity of heterotrophic respiration [electronic resource]
Spruce beetle outbreaks on the Kenai Peninsula, Alaska, and Kluane National Park and Reserve, Yukon Territory: Relationship to summer temperatures and regional differences in disturbance regimes
The early Holocene Milankovitch thermal maximum and humans :adverse conditions for the Denali complex of eastern Beringia
Pattern and extent of treeline change using sequential vertical aerial photography in the northern section of the Kluane Ranges of southwest Yukon are examined. One of the most common predictions is that continued global temperature increases will cause the tree-line to advance in elevation and latitude. Comparison of aerial photographs of southwest Yukon indicates significant changes in the spruce forest-shrub tundra transition. Many areas exhibit increased growth of individual spruce without an increase in stand density or an advance in spruce distribution. Increase in the elevational distribution of spruce is observed in comparatively fewer areas, typically in combination with other two types of change.