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The Alaska/St. Elias Range Tundra is a long belt of high, rugged mountains arcing north from the base of the Alaska Peninsula, east to encompass the Alaska Range, and south to include the Wrangell/St. Elias Range on the Canadian/Alaskan border near Yakutat Bay. The Canadian portion of this ecoregion encompasses the southwestern corner of the Yukon Territory and extreme northwestern British Columbia. Elevations range from sea level at the western end, to 600 meters in the broad, lower valleys, often to over 4,000 meters. Mt. McKinley, the highest point in North America, lies within the ecoregion, with an elevation of over 6,100 meters. The St. Elias Mountains are among the highest in Canada, ranging upward to 6000 m asl. Peaks stand as isolated blocks separated by broad ice fields. Because the limit of permanent snow is 2150 m asl, the mountains present great masses of ice and snow, causing great valley glaciers. Permafrost is continuous at high elevation and sporadic and discontinuous at low elevation (ESWG 1995). The ecoregion, which covers 169,091 km2, consists mostly of rocky slopes, icefields, and glaciers. Where permanent ice and snow fields do not dominate, alpine tundra vegetation is usually dominated by dwarf shrub communities, including mountain-avens (Dryas octopetala, D. integrifolia) and ericaceous species (e.g. Vaccinium vitis-idaea, Cassiope tetragona). More protected slopes support low or tall scrub communities, consisting of dwarf birch (Betula glandulosa and B. nana), willows (Salix spp.), alder (Alnus sinuata and A. crispa) and ericaceous shrubs. Well-drained sites in the lower valleys can support open forests of white and black spruce (Picea glauca, P. mariana), or paper birch (Betula papyrifera) and quaking aspen (Populus tremuloides). Wet sites in this area support cottongrass and sedge. For much of its distance, this ecoregion is inland of another mountain belt, the Pacific Coastal Mountain Icefields and Tundra [NA1117], resulting in a dominance of continental climate influences. Annual precipitation averages about 400 mm in the lower elevations and estimated to average over 2,000 mm in the higher elevations. Average daily minimum temperatures in the winter range from -25°C to -34°C, while average daily maximum temperatures in the summer range from 18°C to 22°C. Temperatures are lower throughout the year at higher elevations. Further south in the Canadian portion of the ecoregion, annual temperature decreases with elevation, but at valley bottoms it is -1.5°C, with a summer mean of 9.5°C, and a winter mean of -14°C. Mean annual precipitation increases with elevation, ranging from approximately 300 mm at low elevations, to more than 1000 mm in the ice fields. Generally, this ecoregion has an alpine and glacierized North Pacific Cordilleran ecoclimate (ESWG 1995). This region is characterized by permanent ice and snow fields, and minor areas of rock outcrop, rubbly colluvium, and alpine tundra vegetation. Glaciation was extensive during the Pleistocene, and much of the ecoregion's area remains under permanent ice. Soils are quite poor, shallow over bedrock, and generally do not retain enough moisture to form permafrost (Summarized from Gallant et al. 1995).
The Alaska/St. Elias Range Tundra ecoregion is an almost entirely intact ecological system, with its full complement of top level predators within their natural range of variation. There are significant brown bear concentrations in Denali Park, Prairie Creek, and in coastal portions in the southwest part of the ecoregion, near Lake Iliamna and Kamishak Bay. Other wildlife includes mountain goat (Oreamnos americanus), caribou (Rangifer tarandus), moose (Alces alces), Dalls sheep (Ovis dalli), beaver (Castor canadensis), Snowshoe hare ( Lepus americanus), salmon, and other fish. This ecoregion has suffered very little habitat loss, degradation, or fragmentation. Minor losses are associated with development at the entrance to Denali National Park, at the north side of Denali Park at Kantishna, surrounding the abandoned Kennicott copper mine in the Wrangell Mountains, and at Nabesna in the Wrangells. Also, coal mining at Healy (northeast of Denali Park) has caused some habitat loss. Several roads cross the ecoregion, but their fragmentation effect is relatively low, and habitat blocks between them are all larger than 10,000km2. Human habitation is low, and human use is generally limited to recreation, subsistence, and sport hunting and fishing. Wildfire occurrence is low, with most of the fires occurring in the central part of the ecoregion, and ranging in size from 0.01 km2 to 32.9 km2 (Gallant et al. 1995). Degree of Protection Important protected areas include:
Types and Severity of Threats No severe threats currently face this ecoregion on a large-scale. Some smaller-scale threats include:
This ecoregion combines Gallant (1995) ecoregions 116 and 118 and Ecological Stratification Working Group (1995) ecoregion 173. Major delineation features are high elevation, moderate to very steep terrain, sparse vegetation, and general inland position with accompanying continental climate. Combination decisions were based on Gallant et al. (1995), McNab and Avers (1994), Ecoregions Working Group (1989), Viereck, et al (1992), and Küchler (1985). On the Canadian side of the border, the St. Elias Mountains (TEC 173) cover this ecoregion (Ecological Stratification Working Group 1995). In addition to Tundra vegetation, this area of south-eastern Yukon also occurrences of Northern Pacific Coast forests and Boreal forest (Kluane) (Rowe 1972). Prepared by: R. Hagenstein, T. Ricketts, J. Peepre, K. Kavanagh, M. Sims, G. Mann.This text was originally published in the book Terrestrial ecoregions of North America: a conservation assessment from Island Press. This assessment offers an in-depth analysis of the biodiversity and conservation status of North America's ecoregions. All text by World Wildlife Fund © 2001 For more general information on this ecoregion, go to the WildWorld version of this description.
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