Beringia lowland tundra
The region experiences a climate that is transitional between maritime and continental influences. Average annual precipitation varies widely, ranging from 250 millimeters (mm) in Kotzbue Sound to 860 mm near Bristol Bay. Mean daily minimum temperatures in winter range from -25°C in the northern parts to -10°C along the Alaska Peninsula. Summer high temperatures can reach 18°C. In the Koetzebue Sound and the Yukon-Kuskokwim Delta areas, soils are shallow to permafrost and consist mostly of Histic Pergelic Cryoquepts and Pergelic Cryofibrists. In the more southerly and better drained Bristol Bay area, the permafrost table is deep to discontinuous and somewhat more developed soil profiles can occur. All but the Yukon-Kuskokwim delta was covered in Pleistocene glaciation.
The abundance of surface water makes this ecoregion excellent habitat for waterfowl, and the tidal flats of the coast provide an abundance of habitat for shorebirds. Many species of birds depend on the habitats of this ecoregion for the majority, if not all, of their nesting habitat. These include the Arctic loon (Gavia artica), Canada geese (Branta canadensis), bristle-thighed curlew (Numenius tahitiensis), dovekies (Alle alle), McKay's buntings (Plectrophenax hyperboreus), and white wagtails (Motacilla alba). The highest densities of nesting tundra swans, the majority of the world's emperor swans, and 50 percent of the world's black brant (Branta bernicla) are supported by the Yukon-Kuskokwim delta alone. This delta is the most expansive area of highly productive waterfowl nesting habitat in Alaska, and among the most significant on earth. Izembek Lagoon, on the Alaska Peninsula, is the most important migratory staging area for black brant in Alaska. St. Lawrence and St. Matthew Islands also support large seabird colonies. St. Lawrence Island colonies support approximately 2,000,000 seabirds, including the largest murre (Uria spp.) colonies in the eastern Bering Sea.
Mammals include river otters (Lontra canadensis), short-tailed and least weasels (Mustela erminea and M. nivalis), brown bear (Ursus arctos horribilis), moose (Alces alces), and caribou (Rangifer spp.). Populations of all top-level predators are intact, and brown bears reach extraordinary natural densities in the Katmai and Lake Iliamna areas. All five species of North American Pacific salmon are native here, and Bristol Bay supports the largest run of sockeye salmon (Oncorhynchus nerka) in the world.
Habitat Loss and Degradation
The Beringia Lowland Tundra is almost entirely intact. Human disturbance consists of small permanent and seasonal settlements, mostly along rivers and coasts. These communities depend on subsistence fishing and on hunting of marine mammals (seals, whales), caribou, moose, and birds. For the most part, the terrestrial impacts of these settlements are local and slight.
Remaining Blocks of Intact Habitat
The largest blocks of intact habitat include the Ahklun Mountains and the Bendeleben Mountains, which contain diverse habitat types.
Degree of Fragmentation
This ecoregion is naturally fragmented into three large mainland areas and numerous islands. The southernmost block of habitat around the Ahklun Mountains is relatively unfragmented. The norrthernmost block is still mostly intact but is becoming trisected by roads and is increasingly impacted by mining. This area has the potential to be much more fragmented in the future.
Degree of Protection
This ecoregion is represented by several protected areas. Those in the Seward Penninsula/Kotzebue area include:
- Bering Land Bridge National Park - western Alaska
- Selawik National Wildlife Refuge - western Alaska
- The Yukon-Kuskokwim Delta is contained completely within the Yukon Delta National Wildlife Refuge.
Protected areas of the ecoregion surrounding Bristol Bay and on the Alaska Peninsula include:
- Togiak National Wildlife Refuge - western Alaska
- Egegik, Pilot Point, Cinder River, Pt. Moller State Critical Habitat Areas - western Alaska
- Izembek National Wildlife Refuge - western Alaska
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