Life Zones

Also known as bunchgrass prairie, this grass association stretches in a narrow band from southern Alberta into Montana. In Glacier, the fescue grasslands are found on the southern slopes and valley bottoms of major drainages on the east side of the mountains. Due to the close relationship of the mountains with the grasslands, in some places prairie species have been found above tree limit in association with alpine species. Grasslands west of the divide exist as prairies nestled in the North Fork Valley. Historically, a short natural fire interval has swept through that valley, preserving native prairie species. More than a hundred species of grasses thrive in the drier, windblown areas of the park. Waterton Lakes National Park contains a 13-square-mile (34-sq.-km) area of prairie that is one of only two preserved within the Canadian national park system. [Note: Parks Canada information on life zones, or ecoregions, lists four and does not include grasslands as a separate zone. Their lowest classified zone is the Foothills Parkland Ecoregion "with its associated grasslands and aspen forests." In this discussion that zone is listed next as the Aspen Parkland.]

Aspen Parkland
This zone consists of a broad band of forest and groves, which stretches across parts of three Canadian provinces and south into Montana. This region serves as a transition belt between the grasslands and the coniferous forest zone. The dominant tree cover is quaking aspen along with black cottonwood. Aspen forests are common in the eastern half of Waterton Lakes but are primarily restricted to valley bottoms in Glacier National Park. Shrub wetlands and marsh habitats are common constituents of this region. The aspen parkland is the most important winter range for elk and deer.

Ten percent of Waterton's area is composed of foothills fescue-oatgrass-aspen parkland. Unlike cultivated grasses, native fescues retain much of their nutrient value through the winter. This is crucial for the large herds of elk wintering in the park. Frequent chinook winds also benefit ungulates, as the winds sweep snow from grassy areas. Winds also cause snow drifts on the lee side of hills and in sheltered gullies, creating a distributions pattern of trees and shrubs, shelterbelts for animals during windy winter days.

Montane Forest
This zone occurs at low to mid-elevations in both parks but on the eastern slopes is largely restricted to the dry foothills and major river valleys. It is a mix of dry grasslands and relatively open mixed poplar and coniferous forests. Douglas fir, white spruce, and limber pine are distinctive trees of this zone. Lodgepole pine is found but is not a good indicator species as it extends up into the Subalpine. In areas of greater moisture west of the divide in Glacier, cedar-hemlock forest is at the eastern edge of its range. On drier sites with higher fire frequencies, ponderosa pines predominate. Shrubs associated with the Montane are bearberry and juniper. Twinflower, thimbleberry, and meadow rue grow on the forest floor.

Subalpine Zone
With increased elevation, the dense forest zone gives way to widely-spaced islands of dwarfed trees and lush meadows. The subalpine forest is the single most extensive vegetation community in both Waterton and Glacier. It is a region characterized by heavy snowfall and a short growing season. A boreal element is present with dwarf birch and fireweed.

In Waterton, at around 5000 – 6000 feet (1500-1800 m), the lower subalpine is a dense forest of spruce and fir characterized by heavy snowpack. In the upper subalpine, firs provide shelter for each other against battering winds and frigid temperatures. Wind and ice can shear off the growing buds of a tree so that the branches only grow on the leeward side; this is called flagging, as the trees resemble flags unfurled. Trees often form krummholz vegetation, growing stunted and twisted on exposed slopes.

Whitebark pine can grow in the harshest of sites, creating a microhabitat suitable for subalpine fir, thus extending the elevation of treeline. The park's whitebark pine populations have nearly been decimated by white pine blister rust which was introduced from Europe in 1910. Other species include Englemann spruce and lodgepole pine.

Subalpine meadows are key habitat for bighorn sheep and seasonally for bears. The elusive wolverine inhabits this zone. Marmots, chipmunks and ground squirrels are commonly seen during summer months. Logan Pass is a good example of a well-traveled subalpine area.

Alpine Tundra
The word "tundra" comes from the Finnish tunturi meaning "a treeless plain." Treeline occurs at about 6 900 feet (2100 m) on the west slope and 6000 feet (1800 m) on the east side. The alpine zone above that covers nearly one-quarter of Glacier and Waterton. This is the land above the trees. Expanses of bare rock make up much of this zone. The high country is a land of harsh conditions. Winds are often strong. The sun is intense, 5 percent brighter than at sea level with increased ultraviolet radiation. Plant leaves are often covered by tiny hairs, as an adaptation to diffuse light and prevent burning. Though there is ample rainfall, the winds neutralize much of it. Summers are short, temperatures low, soils shallow.

There is a profusion of miniature plants, a universal adaptation. Short stature protects life from the most whipping winds. It means less exposed surface, cutting evaporation. It spares energy that might be used for growing tall stalks and broad leaves and puts the energy into essentials: production by seed or vegetatively (through rhizomes, bulbs, tubers). Most plants are perennial and grow in cushions, mats, and low clumps. Many alpine plants cope with the short growing season by developing in stages: stems and leaves one year, buds the next, blossoms, and seeds the third year. In Waterton-Glacier, cushion plant communities, alpine meadows, and alpine bog areas are common. A number of mammals including the pika, marmot, and mountain goat have also adapted to this harshest of environments.

Natural Processes and Baseline Studies
The components of local plant communities constantly change over time. Short-term natural disturbances (fires, avalanches, floods, windstorms) and long-term shifts in environmental conditions (climate, glaciation) continue to cause change. All parks have already been modified to some extent by human activities. A major challenge for ecosystem researchers and managers will be to distinguish between natural changes and human-caused changes. Waterton-Glacier is unique in that, although there is human influence here, the area is relatively pristine and therefore offers a benchmark for baseline studies of such things as air quality, water quality, and wildlife in a relatively uncontrolled environment.

Last updated: February 24, 2015

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