4.3 Threats to Ecological Integrity
Local, regional and international factors all influence the ecological integrity of Mount Revelstoke National Park and Glacier National Park.
Local impacts include the transportation corridor, the invasion of non-native plants, loss of valley bottom habitat, and visitor facilities and use. The Trans-Canada Highway and the Canadian Pacific Railway affect ecological integrity in many ways, including wildlife mortality through collisions, changing water flow patterns in riparian and wetland habitats, and habitat fragmentation. Highway traffic, maintenance activities and visitor facilities have all introduced non-native weeds to the parks. Many facilities, including bridges and culverts, cross riparian zones and road maintenance and construction in these areas exposes potential sites for weeds to establish. Although many non-native plants occur in the parks, only a few, such as spotted knapweed, are considered invasive (Parks Canada, 1997).
Valley bottoms are the areas most affected by development. Cedar-hemlock forests are critical habitat for old-growth dependent species. Although the parks contain valley bottom old-growth and wetland habitats, these may be insufficient to attain ecological integrity at a regional scale.
In the 1997 State of the Parks Report, significant external and internal ecological stressors were recorded for Mount Revelstoke and Glacier. External stressors included such things as forestry and loss of the Columbia River valley bottom from dams. Significant internal stressors included transportation/utility corridors and human disturbance. The introduction of exotic vegetation is an effect of the significant internal stressors and has been outlined here as a local threat.
Analysis of the impact of visitor facilities and use on ecological integrity is hampered by the general lack of medium to long term human use data for trails, picnic areas, viewpoints, and off-trail activities (e.g., ski-touring) and specific research into the effect of these activities on wildlife and vegetation. This information is necessary to establish sustainable levels of use. For example large numbers of visitors to the Illecillewaet and Meadows-in-the-Sky Parkway area may already be reducing habitat use by sensitive species (caribou, grizzly bear and wolverine). The transportation corridor and its facilities have the potential to create movement barriers for sensitive wildlife and to reduce habitat effectiveness.
Regional impacts include forestry, hydro-electric dams, and recreational activities and facilities. Forestry operations, including access roads and fire suppression, can stress ecological integrity by changing the age structure of the forest and impairing natural processes. Dams on the Columbia River eliminated much of the productive valley bottom habitat within the greater ecosystem. The lack of this habitat within the parks is aggravated by the loss of low-elevation riparian and wetland areas in the surrounding region. Another regional threat to ecological integrity is related to the potential for human disturbance of wildlife (displacement, mortality, removal) due to increased numbers of people recreating in areas adjacent to the parks. As well, communities and rural hinterlands within the greater ecosystem attract grizzly and black bears with garbage, fruit trees and livestock. These bears can become habituated to human foods, leave their natural habitat and sometimes must be destroyed to protect people.
International Threats to Ecological Integrity
International impacts include hydro-electric dams, climate change and transport of long-range pollutants. The Columbia is an international river and dams in the United States and Canada block the migration of fish between the Pacific Ocean and the parks. The altered water flow is also having a serious impact on the ability of white sturgeon (federally listed as a species of special concern by COSEWIC) to reproduce. Climate change involving a warming trend may lead to the acceleration of glacier melt in the parks. Long-range atmospheric transport of pollutants also affects the greater ecosystem.
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