The Arctic environment is relatively young: Animals have had only about 10,000 years to colonize and to adapt to totally new conditions. The limited selection of habitats has limited the number of species found in the region.
At first glance, the Arctic landscape appears desolate and lifeless. With vegetation generally limited to a few inches in height, and often sparsely distributed, the term "barren grounds" would seem highly appropriate. Yet there is a surprising richness in this vegetation. Trees are there, even though they cling close to the soil rather than reaching upwards. Lichens mosses, grasses and even flowering plants, though quite tiny, cover the ground when they can find conditions even slightly favorable for them.
The Arctic is characterized by a harsh, cool climate. The amount of summer warmth available strongly affects the occurrence and growth of plants. The growing season is short, with fewer than 50 days between late and early frosts. This is somewhat mitigated by the nearly continuous daylight that occurs for one to four months of the year.
Arctic soils are generally acidic because of poor drainage and poor aeration. This results in slow organic decay by soil bacteria and thus low levels of nitrogen for plant growth. Plant species include algae, mosses, grasses, low woody shrubs, small trees and bright colored herbs. With adequate soil and water miniature forests of alder, willow and birch form small, low thickets on protected slopes. In river valleys, alders can grow quite tall and thick - so thick that they can hide the moose feeding on them. The tundra vegetation is largely composed of sedges, rushes, reeds and grasses with lichens and mosses growing freely among them, interspersed with perennial flowering herbs.
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Musk oxen are survivors from prehistoric times.
Birds, with the benefit of their extreme mobility, avail themselves of Arctic resources during periods of optimum abundance. They migrate north during short spring and summer seasons to reproduce. They return to more southern latitudes when these resources diminish. Only a few species, notably Ptarmigan, Raven, Ivory and Ross' Gull, and Snowy Owl, spend the winter in the north, and these occur in quite small populations.
The two most common members of the auk tribe, the Thick-billed or Brunnich's Murre and the Dovekie, move south into ice-free waters in the fall. The latter, a tiny, stubby-bodied bird, nests in colonies in loose rock screes. The Murre or Guillemot lays its single egg on narrow, crowded ledges on sea cliffs, and also assembles in colonies numbering in the millions.
Arctic Land Mammals
Several species of lemming occur in the tundra. These small vole-like rodents, feeding entirely on vegetation. They are the vital link in the food chain for many Arctic mammals and birds. Even a hungry polar bear will sometimes dig them out of their burrows.
Only about 48 mammal species are found in the Arctic. Like the polar bear and walrus, musk oxen are unique to the Arctic. They have disappeared from much of their former range, but now are recovering under strict protection. The animal is so superbly insulated by its hair, and its dense underwool, that in summer it may become overheated.
Arctic Marine Mammals
Arctic seas, partially frozen so much of the time, would also seem to be too inhospitable for large concentrations of life. It is a physical law that the lower the temperature of the ocean water, the greater its capacity for dissolved gases like oxygen and carbon dioxide. Nutrients such as silicates, nitrates and phosphates borne by riverine runoff from the surrounding landmasses combine in the photosynthesis process with oxygen to form diatoms and other single-celled plant life, which is the flora at the base of the marine food chain. These organisms propagate at an incredibly rapid rate in the late summer. These in turn feed zooplankton. In the Arctic Ocean where cold and warm water masses intermingle, we find good fishing grounds.
Whales: Many species of cetaceans (dolphins and whales) occur in Arctic seas but most of them have been so drastically reduced in numbers by over-exploitation they are now usually encountered singly or in very small groups. There are only three cetacean species that can be truly considered Arctic: the bowhead, the beluga and the narwhal. Several other whale species migrate in Arctic waters.
Seals: Fur seals, sea lions and walruses make up a group called pinnipeds. Male walruses, the largest game animal in North America, may weigh up to two tons and grow to 3.5 meters (12 ft) in length. Like other marine mammals, walruses are sensitive to climatic changes and their pattern of distribution has changed drastically as a result of post-glacial temperature conditions.