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The Seward Peninsula REA is comprised of three ecoregions: the Seward Peninsula, the Nulato Hills, and the Kotzebue Sound Lowlands (SNK). These three ecoregions’ climate is classified as moist polar. At this latitude, ice spans the sea early every winter, allowing direct passage of cold Siberian air. Persistent cold, windy conditions occur in the winter and fog blankets the coastlines in the summer. Vegetation is generally tundra on the peninsula (alpine Dryas-lichen tundra and barrens at high elevations) and moist sedge-tussock tundra in the lowlands with patches of low-growing ericaceous and willow-birch shrubs on better-drained areas. In the hills, vegetation patterns generally follow the terrain, with Dryas-lichen and sedge-ericaceous shrub tundra on hilltops, grading into willow-birch-alder shrublands and eventually spruce and birch woodlands at lower elevations. Moose, brown bears, caribou, arctic foxes, and Alaska hares are common in all of these ecoregions. Ribbon seals and walruses comb the coastline, and huge summer runs of pink salmon ascend the Unalakleet drainage.

The Nulato Hills are the remains of an ancient mountain range after extended periods of down cutting, weathering, and erosion. East of Norton Sound, these hills ripple inland in a southwest-northeast orientation with streams flowing in intervening valleys. Due to their modest elevation, most of these hills have been spared from recent glaciations and were part of the ice-free Beringia corridor linking North America and Asia.

The Seward Peninsula is a cold, wind-swept landmass jutting out into the Bering Sea and represents the southernmost haunt of polar bears on mainland Alaska. It is a landscape mosaic of coastal lowlands, expansive convex hills with scattered broad valleys, and small, isolated groups of rugged mountains. Permafrost is continuous and soils are therefore often wet, shallow, and organic. Ice-related features such as pingos and patterned ground are present. Dense concentrations of lakes and ponds support abundant waterfowl and nesting birds on the coastal plains. At its height, Pleistocene glaciation covered only the highest mountains and the peninsula was also part of the ice-free migration corridor between North America and Asia.

These ecoregions have strong ecological affinities to Asia that remain to this day with the presence of Eurasian birds (gray-headed chickadee, yellow and white wagtails, bluethroat), fishes (Alaska blackfish), and flora.

Ecoregion descriptions were excerpted and modified from “Ecoregions of Alaska,” Nowacki et al. 2000.