### The Tundra

The word tundra derives from the Finnish word for barren or treeless land. The tundra is the simplest biome in terms of species composition and food chains.

Vegetation: lichens, mosses, sedges, perennial forbs, and dwarfed shrubs,birches and willows. Climate: The high latitude conditions that impact life in this biome include

- extremely short growing season
- long, cold, dark winters
- low precipitation coupled with strong, drying winds. Snowfall is actually advantageous to plant and animal life as it provides an insulating layer on the ground surface.

Edaphic controls: Permafrost, not cold temperatures per se, is generally believed to be what prevents tree growth. Furthermore, freeze-thaw activity, a thin active layer, and solifluction during the warmer months contribute to strong controls on vegetation patterns and create a mosaic of microhabitats and plant communities.

Soil: No true soil is developed in this biome due to the edaphic factors mentioned above.

Fauna: Strategies evolved to withstand the harsh conditions of the tundra can be divided among those species that are resident and those that are migratory.

- Among the small number of bird (e.g., ptarmigan) and mammal (e.g., muskox, arctic hare, arctic fox, musk ox) species that reside year-round on the tundra one commonly finds:
- Migratory species such as waterfowl, shorebirds and caribou adapt to the tundra by avoiding the most severe conditions of winter. Each year at the end of the short growing season they move southward into the boreal forest or beyond, but return to the tundra to breed. A periodic emigration from the tundra is exhibited by the snowy owl during those years that the lemming populations have crashed. Those winters see snowy owl irruptions as far south as Virginia. Most owls are found with empty stomachs and do not survive to return to the Arctic.