Understanding Vegetation of the Tundra
Tundra vegetation is tough. It has adapted to the extremely harsh conditions of the tundra. Plants have to be strong to survive the acute cold, drought, bitter winds and extremely short growing season of the tundra.
There are two types of tundra: Alpine and Arctic. The Arctic tundra circles the North Pole and is known for its cold, desert-like conditions. Tundra vegetation in the arctic has to survive the permafrost, ground that stays frozen year round. Roots are shallow and grow out sideways to accommodate the frozen layers of soil. The sun does not rise for a large portion of the year forcing plants into a dormant state. The growing season lasts from 50 to 60 days.
The Alpine tundra is found on mountain ranges throughout the world at high altitudes, above the tree line. The growing season is approximately 180 days. Both types of tundra feature similar vegetation which consist mainly of grasses, shrubs, mosses, and lichens.
Tundra comes from a Finnish word meaning treeless plain. Although some dwarf varieties of trees can be found in the Alpine region, most tundra plants grow to a height of around one foot. The majority of plants are perennial and evergreen while annuals are rare. The short growing season cannot support annual plants, those that complete their entire life-cycle from seed to adult to reproduction in one growing season.
Small shrubs and perennial herbs often grow in a cushion or mound form over the ground. This holds the buds away from the cold soil while keeping a low, sturdy profile so the icy winds can blow over the top without damaging the plant.
Evergreen leaves are common among tundra plants. Evergreen leaves are an adaptation to the short growing season, by having leaves already in place the plant can begin photosynthesis as soon as the sun comes out in the spring and the temperature is warm enough. Other adaptations to the harsh climate include sun-tracking flowers, an anti-freeze like compound, thick-waxy leaves and hair like coverings.
One of the most successful types of tundra vegetation is moss. Mosses are quite tough despite their small size. Over 100 species of moss grow in the tundra. Many varieties are able to dry out and survive for years before beginning to grow again. They can continue photosynthesis and growth at much lower temperatures than flowering plants. Biologists refer to mosses as simple and primitive but their adaptations to survival in the tundra are advanced.
Lichens of the Tundra
Lichens are abundant in the tundra regions. Lichens are actually two organisms bound together in an interdependent union. Lichens consist of a fungus and either a green alga or a blue-green bacterium. The alga or bacterium supplies the food by photosynthesis to the union while the fungus provides the protection of the organism. Lichen takes many different forms. One of the most common forms is the orange paint like substance found on rocks. Lichens are rarely taller than two inches. Since lichens can grow in dense colonies and form compact mats over the surface sometimes they are the main vegetation cover over the cold, dry soils of the tundra.
The tundra is a valuable region despite its lack of biodiversity. The amazingly well-adapted vegetation of the tundra can be found nowhere else on earth.
Moore, Peter D., Tundra: Biomes of the Earth, Chelsea House, 2006.
Alaska Department of Fish and Game. What Is Tundra?