Added: 02/19/2006 |
Vegetation regions - Tundra vegetationVegetation regions are geographical areas characterized by distinct plant communities. Community composition, determined primarily by climate (eg, temperature, precipitation, sunlight), may be affected by factors such as geology, soil composition and erosion, water drainage patterns and human interference. Each vegetation region supports a characteristic animal community which may affect its composition.
The main Vegetation Regions are the following.
Tropical Rainforest
Description: The trees are very tall and of a great variety of species. One rarely finds two trees of the same species growing close to one another. The vegetation is so dense that little light reaches the forest floor. Most of the plants are evergreen, not deciduous. The branches of the trees are festooned with vines.
Examples: The Amazon Basin in Brazil and the islands of Indonesia.
Mid-Latitude (deciduous) Forest
Description: Hardwood trees (e.g., beech, maple, oak, hickory) which are deciduous; that is, shed their leaves in the autumn. The number of different species is far more limited than in the jungle. Large stands dominated by a single species are common. Deer, raccoons, and salamanders are characteristic inhabitants.
Examples: New England and Northern Europe.
Mixed Forest
Description: An overlap area between coniferous (needle trees) and deciduous (broadleaf trees).
Examples: The Rocky Mountains and the area around Moscow, Russia.
Coniferous Forest
Description: Colder parts of the mid-latitudes. Trees have needles and seed cones. Trees are evergreen.
Examples: Canada and Siberia, Russia.
Chaparral
Description: Trees in the chaparral are mostly oaks, both deciduous and evergreen - scrub oaks and shrubs like manzanita and the California lilac. All plants are adapted to drought by such mechanisms as waxy, waterproof coatings on their leaves.
Examples: Texas and Southern California.
Savanna (Tropical grassland)
Description: Tropical areas close to the equator. Mostly grasses with scattered trees and shrubs. Has a wet season and dry season. Wildfires are common.
Examples: Most of southern Africa and parts of Brazil.
Prairie (Temperate grassland)
Description: Two types, depending on rainfall: "tall grass" or "short grass". Cooler climates. Wildfires are common. Also are called "steppes".
Examples: Central Asia has steppes; the American Midwest is prairie.
Desert Scrub
Description: Cactus plants, specialized to store water. Cactus grow widely scattered due to little rain.
Examples: Arizona and parts of Pakistan.
Desert
Description: Pure desert - little or no plant life.
Examples: The Sahara in Africa and most of Saudi Arabia.
Tundra
Description: Climate is always cold. No trees. Short growing season. Small plants, wildflowers, lichen (tiny, brightly colored plants). Permafrost under the soil.
Examples: Alaska, Iceland, Chukotka.
The coast of the Arctic Ocean and all peninsula Chukotka north of 59°N are covered by tundra vegetation. The Tundra Zone is subdivided into 2 subzones: typical Arctic tundra occurs along the coast of Ice Ocean and lichen tundra is the main zonal vegetation on Chukotka peninsula and the lower part of Anadyr River basin. Far Eastern sectors of Arctic Polar Desert Area and Arctic Tundra Area are differed from the rest of circum-Arctic zone by presence of so-called Beringian plant species, which are also common to Alaskan and Eastern Canadian sectors of Arctic zone.
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, (often heaths, but also birches and willows).
The specific traits of tundra vegetation regions are: one-layer closed vegetation cover; predominance of perennial plants; high importance of dwarf shrubs; high importance of mosses and lichens; the lack of shrubs and trees. Most of typical tundra plants have the buds at a height lower than 20-30 cm above ground and presumably vegetative reproduction. All tundra plants are adapted to the short vegetative season and to the long daytime.
Tundra communities vary in composition depending on edaphic and climatic features of a site. The vegetation regions lying along the coast of the Northern Ocean are characterized by predominance of sedge and hearth tundra communities with Carex spp., Eriophorum vaginatum, Vaccinium uliginosum, Betula exilis and leafy mosses. On Chukotka peninsula sedge tundra communities are also important, but the role of lichen tundra communities with Cladina spp. and some ericatious dwarf shrubs increases.
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