Ogilvie-MacKenzie alpine tundra

The Ahklun and Kilbuck Upland Tundra ecoregion spans the rugged Ahklun and Kilbuck mountain ranges of southwestern Alaska, bounded by the Bering Sea and its bays. Steep, sharp mountains-glaciated during the Pleistocene, with only a few small glaciers remaining-are separated by broad, flat valleys. Vegetation is largely moist and alpine tundra and dwarf scrub thickets dominated by heath-family plants, dwarf Arctic birch, and mountain avens; trees such as white and black spruce, paper birch, and balsam poplar are confined to valley floors and lower slopes. The climate mixes maritime and continental influences, with annual precipitation ranging from about 1,020 mm in lowlands to 2,030 mm in the high mountains. It is among the most pristine ecoregions on the continent, with 99% of habitat intact, much of it within the Togiak National Wildlife Refuge.

The Alaska-St. Elias Range tundra spans a broad arc of northern mountains across Alaska, southwestern Yukon, and northwestern British Columbia, encompassing the Alaska Range and Wrangell-St. Elias Range and reaching the summit of Denali, North America's highest peak. Much of the ecoregion is rocky slopes, ice fields, and glaciers; where permanent snow and ice are absent, alpine tundra dominated by dwarf shrub communities, mountain avens, and heath-family shrubs prevails, with willows, alders, and dwarf birch on more protected slopes. The climate is alpine and glacierized North Pacific cordilleran, largely continental except for a maritime influence near Cook Inlet. The hoary marmot is the flagship species, and roughly 45% of the ecoregion is protected.

The Aleutian Islands tundra spans the 1,500-km arc of volcanic islands stretching from the Alaska Peninsula toward Russia's Kamchatka, plus the Pribilof Islands, dividing the North Pacific from the Bering Sea. Treeless maritime tundra covers the islands: dwarf scrub of crowberry and willows on exposed high ground, bluejoint-grass meadows on moist sites, and heath, sedge, and sphagnum bogs in the lowlands. The climate is cool and maritime, with mild winters, cool summers, and annual precipitation ranging from roughly 530 to 2,080 mm. About 98% of the ecoregion is protected within the Alaska Maritime National Wildlife Refuge, which supports breeding habitat for an estimated 40 million seabirds.

The Arctic Coastal Tundra spans most of Alaska's northern coastline, a low coastal plain (0-150 m) along the Beaufort Sea in the Nearctic realm. Poorly drained terrain is dotted with thaw lakes covering up to half the ecoregion, and vegetation is dominated by wet tundra, fens, bogs, and marshes of grasses, sedges, and mosses, with dwarf shrubs on better-drained ground. The Arctic climate brings low precipitation (100-300 mm) and continuous, ice-rich permafrost with ice wedges and pingos. Its flagship species is the beluga whale; only about 4% lies in protected areas though most remains intact.

The Arctic foothills tundra is a transitional belt of rounded hills and plateaus spanning northwestern Alaska, northern Yukon, and the northwestern Northwest Territories, lying between the Arctic Coastal Tundra to the north and the Brooks-British Range Tundra to the south. Its better-drained terrain-with fewer thaw lakes than the saturated coast-supports moist tussock sedges, dwarf shrubs, and scrub, with open white spruce stands mixed with balsam poplar and willow along the Noatak River Valley. The climate is Arctic, with continuous, thick permafrost and an active layer averaging about 1 m, while much of the landscape escaped glaciation during the Pleistocene. The region remains roughly 99% intact, though the Trans-Alaska Pipeline, Dalton Highway, and coal and mineral mining pose growing threats; the gyrfalcon is its flagship species.

The Beringia lowland tundra is a flat, wetland-rich tundra ecoregion along the Bering Sea coast of western Alaska, from Bristol Bay and the Yukon-Kuskokwim Delta north to Kotzebue Sound and the Seward Peninsula, including offshore islands such as St. Lawrence. Lakes and ponds cover nearly a quarter of the area, and sedge- and grass-dominated wet meadows give way to dwarf-shrub heath and crowberry on better-drained, sloping ground. The subarctic climate brings harsh winters and cool summers, with rainfall ranging from roughly 250 mm near Kotzebue Sound to far wetter conditions toward Bristol Bay. Globally important for waterbirds, it hosts the world's largest tundra swan communities, most of the emperor goose population, and is largely intact, much of it protected within refuges like the Yukon Delta National Wildlife Refuge.