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Ecosystems

Author(s): Deanne Erdmann MS

Biomes

Biomes are terrestrial sets of ecosystems characterized by rainfall, temperature, and the dominant form of vegetation. A single biome occupies a large geographic area and usually is found on more than one continent. 

  • Tropical Rainforests - contain at least one-half of the world's species of plants and animals and are dominated by tall, broad-leaved trees. Tropical rainforests are wet and hot year-round and have nutrient poor soil (most of the nutrients are held in the vegetation).
  • Savannas - dry grasslands with widely spaced broadleaf, deciduous, and evergreen trees. Savannas are characterized by low rainfall or prolonged periods of drought. Herds of migratory grazing animals and fire are important in maintaining savannas.
  • Deserts - lack of water is the most influential feature. Vegetation is limited and life is based on water conservation. Many animals are active at night to avoid high daytime temperatures.
  • Temperate Grasslands - sometimes called prairies. Summers are hot and wet, winters are cold. Fire, seasonal drought, and grazing are instrumental in maintaining grasslands, recycling nutrients and preventing the succession of shrubs and trees. Temperate grasslands have extremely fertile soil and have been converted to some of the richest agricultural areas on earth. Grasslands usually lie in a zone between temperate deciduous forests and deserts, and intergrade with both biome types.
  • Temperate Deciduous Forests - warm summers, cold to moderate winters, plentiful rainfall, and rich soils. Hardwood and deciduous (shed leaves in winter) trees are characteristic of this biome type.
  • Coniferous (Evergreen) Forests - cold winters, seasonal dry periods, and nutrient poor soils. Cone-bearing trees such as the Douglas Fir, redwoods, spruce, hemlock, and pines make up the dominant vegetation. The northern coniferous forest, or taiga, is the largest terrestrial biome.
  • Arctic Tundra - cold temperatures, strong winds, and permanently frozen soil (permafrost). Dominant vegetation types are grasses, mosses, and lichens.