Alaska can be generalized into a few zones characterized by the climate and other physical factors, which determine the biological communities found there. [Learn more about the ecoregions of Alaska.]
Arctic and Subarctic
The Arctic and subarctic tundra is characterized by aridity, brief summer with long hours of daylight, and treeless landscape. Permafrost underlies most of the northern tundra. Most plants grow low to the ground; lichens are particularly important, as well as mosses, sedges, and grasses. Animals that live there, from insects to muskoxen, are adapted to the particular harsh weather conditions.
The boreal region, also known as taiga, of interior Alaska is diverse in its expression. It is characterized by a harsh climate--the coldest ecosystem on Earth. Permafrost is primarily non-continuous in this region. Black spruce and white spruce are the most common conifers; poplar, birch, aspen, willow, and alder are the most common deciduous trees and shrubs; the understory is a thick mat of mosses, lichens, sedges, grasses, and berries. Fire shapes this landscape, contributing to the mosaic of tree and shrub growth, along with meadows, marshes, lakes, and braided rivers.
The coastal mountain region of Alaska is heavily influenced by the ocean. The maritime climate is milder in the winter and cooler in the summer. This region experiences more precipitation (rain and snow) and the vegetation responds with bigger trees and lush understory. Conifers are prevalent, including Sitka spruce, western hemlock, western red cedar, and yellow cedar. This landscape is also shaped by glaciers and have numerous fjords and rivers with sea-run fisheries. Wind is a primary disturbance of these ecosystems along the coast, as well as landslides, avalanches, and floods associated with glaciers.