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Beringia upland tundra

The Beringia Upland Tundra consists of three disjunct areas on the Bering Sea coast of Alaska, one comprised of the upland and mountainous areas of Seward Peninsula, one corresponding to the hills and moutains of the Ahklun and Kilbuck mountain ranges in southwest Alaska, and one of much smaller extent on the western half of St. Lawrence Island in the northern Bering Sea. These areas are similar in their varied terrain and elevation, and corresponding variety of vegetation, habitats, and communities. The ecoregion consists of steep, jagged mountain ranges set among large areas of rolling hills, broad valleys, and lowlands. Elevation ranges from sea level to 500 m in the hilly uplands to over 1,500 m in the tallest ranges. Plant communities respond to these differences in topography and accompanying drainage. Low-lying, poorly drained areas support wet graminoid herbaceous vegetation similar to that of ecoregion 101. Better drained areas contain either mesic graminoid herbaceous communities dominated by sedges (Eriophorum vaginatum, Carex bigelowii) or low scrub communities. The scrub communities are dominated by either ericaceous shrubs (e.g. Arctostaphylos alpina, Vaccinium vitis-idaea, Empetrum nigrum) or a mix of mountain-avens (Dryas octopetala) and dwarf arctic birch (Betula nana). Protected, well-drained valley bottoms may contain coniferous forests dominated by white spruce (Picea glauca), broadleaf forests of balsam poplar (Populus balsamifera), or mixed forests characterized by white spruce and paper birch (Betula papyrifera). The steep peaks and ridges of the tallest mountains are almost barren, and some retain cirque glaciers.

Climatic characteristics of the Beringia Upland Tundra ecoregion are also varied, ranging from maritime along the coast to continental in inland areas. An average of 250-1,000 mm of precipitation falls annually, ranging up to 2,000 mm in the higher areas of the Ahklun and Kilbuck Mountains. Average daily winter temperatures range from -24°C to -16°C, and average daily summer temperatures range from 13°C to 19°C. These temperature averages are cooler when taken for the Seward Penninsula portion alone, a trend that reflects the generally colder, harsher climate in the more northern parts of the ecoregion. Permafrost is continuous on the Seward Penninsula, while it is discontinous to patchy in the Ahklun and Kilbuck Mountains (Gallant et al. 1995). The highlands of the Seward Penninsula were glaciated in the Pleistocene, as were most of the Aklun and Kilbuck Mountains (Pielou 1994, Gallant et al. 1995).

Wildfire occurrence is common on the Seward Penninsula, where lichens and mosses dry out in summer. Burns are less frequent and smaller in the Ahklun and Kilbuck Mountains (Bailey et al 1994).

  • Scientific Code
    (NA1107)
  • Ecoregion Category
    Nearctic
  • Size
    37,600 square miles
  • Status
    Relatively Stable/Intact
  • Habitats

Description
Biological Distinctiveness
A variety of birds use the assorted habitats of this ecoregion to breed, from spectacled eiders (Somateria fishceri) and turnstones (Arenaria spp.) in the lower portions to bristle-thighed curlews (Numenius tahitiensis) along the coast to blackpoll warblers (Dendroica striata) in the conifer stands along protected river valleys. The breeding range of the bristle-thighed curlew is restricted completely to this ecoregion. In the Seward Penninsula portion, arctic foxes (Alopex lagopus) and tundra hares (Lepus othos) are common, and polar bears (Ursus maritimus) are frequently seen. Caribou (Rangifer spp.) and muskoxen (Ovibos moschatus) were both introduced there, in the 1890's and 1970, respectively. In the southern portion, beaver (Castor canadensis) are numerous, and wood frogs (Rana sylvatica) are reported. Across the ecoregion the diversity of lichens and tundra plants is high, including many representatives of the Siberian flora in St. Lawrence Island and the Seward Peninsula. These parts of the ecoregion also support an Asian avifaunal component.

Coastal areas, especially on the Seward Peninsula and St. Lawrence Island, have seabird colonies with abundant populations of cliff-nesting alcids and other species including common and thick-billed murres (Uria aalge and U. lomvia), and tufted puffins (Fratercula cirrhata). The Walrus Islands in Togiak Bay also support Alaska's largest walrus (Odobenus rosmarus) haul-out site.

Like most ecoregions in Alaska, these areas are large blocks of essentially intact natural habitat with populations of all indigenous plants and animals, including top-level predators, occurring in populations within their range of natural variation.

Conservation Status

Habitat Loss and Degradation
Very scattered pockets of habitat loss are associated with human communities. Human population in this ecoregion is low, consisting mostly of small settlements spread throughout the region. Levels are low, however, and impacts on populations are generally small. Mining activity on the Seward Penninsula is responsible for the majority of human impact; the region of the Bendeleben Mountains, north of Nome, has experienced the most extensive development of any area in the ecoregion.

Remaining Blocks of Intact Habitat
The ecoregion has several widely disjunct blocks, all of them greater than 5,000 km2.

Degree of Fragmentation
The mines in this area and the roads between them are increasingly fragmenting and altering the tundra habitat. This development has the potential to interrupt mammal movements and migrations, and to result in severe local degradation of the delicate tundra habitats. Recovery from roads, construction sites, and even human trails requires as many as 25-50 years, longer if areas greater than 1 km2 are disturbed (Bliss, 1988).

Degree of Protection
Several protected areas exist in the southern (Aklun and Kilbuck Mountains) section of the ecoregion:

•Wood-Tikchik State Park - southwestern Alaska
•Walrus Islands State Game Sanctuary - western Alaska
•Yukon Delta National Wildlife Refuge - western Alaska
•Togiak National Wildlife Refuge - southwestern Alaska
In the northern section, on the Seward Peninsula, the only protected area is Bering Land Bridge National Park, which includes mostly lowland tundra.

Most of the larger seabird colonies in the ecoregion are also conserved within units of the Alaska Maritime National Wildlife Refuge.

Types and Severity of Threats
The main threat to the ecoregion is the expanding development of mines and mining roads on the Seward Peninsula. Areas in the Ahklun and Kilbuck Mountains show potential for mineral extraction as well, so threats of similar habitat fragmentation and degradation are present there, too.

There have been conservation concerns recently regarding the Kilbuck caribou herd that is at low levels. Additionally, a limited hunt has recently been allowed on walrus in the Walrus Islands.

Suite of Priority Activities to Enhance Biodiversity Conservation

•Priority in this ecoregion should be place on the Seward Peninsula, which is becoming increasingly roaded and developed. Creation of an upland tundra protected area in this region and greater oversight and management of mining activities are recommended.
•Monitoring of harvested species, especially caribou and walrus, is also recommended.
Conservation Partners

•National Audubon Society (for Beringia) - Alaska-Hawaii Regional Office
•The Sierra Club
•The Wilderness Society
Relationship to other classification schemes
This ecoregion combines Gallant et al. (1995) ecoregions 110 and 111. It delineates the upland and mountainous areas between the continuously forested inland areas and the coast. The ecoregion is delineated from the other coastal tundra ecoregions by its higher topography, better drainage, and resulting dominance of more mesic tundra and dwarf shrub communities. Combination decisions were based on Gallant et al. (1995) and Küchler (1985).

Prepared by: R. Hagenstein, T. Ricketts