The Prairies

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Characteristics: Climate

Temperature

  • Hot summers up to 35°C
  • Cold winters down to -30°C
  • Due to moderating influence of the sea as well as continentality

Precipitation

  • Low rainfall of 400-500mm per year as far from sea
  • Higher levels in spring but high temps means evapotranspiration so reduces water available to soil
  • Thunderstorms- much rain flows to river and doesn't enter soil

Noticeable in west/east as precipitation increases as move further west due to rain shadow effect and Rocky Mountains to west

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Characteristics: Vegetation

  • CCV is lots of species of grass- diverse, graases stratified in two layers- shorter grasses eg prairie dropseed and smooth brome from shallower roots mix with taller grasses eg big blue stem
  • Due to high evapotranspiration there is little soil moisture to support trees as well as dense grasses
  • During autumn and before cold, harsh winter grasses die back to form a turf mat and then in late spring the temps rise snow melts and grasses grow can also retain mositure in summer
  • In wetter east grasses are larger eg big blue stem and in drier west they are shorter such as buffalo grass
  • Larger herbivores include pronghrn antelope and bison
  • Smaller herbivores include jack rabbits, meadowlarks, praire chicken which are the pray of eagles
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Characteristics: Soil

  • Soil of Prairies is a mollisol (chernozem)
  • 1.5m deep
  • horizon is a crumbly, black topsoil that is rich in humus with summer soil organisms including earthworms that decompose litter and add it to topsoil forming humus
  • Limited leaching but it does occur after thunderstorms and snowmelt
  • In summer due to lack of moisture capillary action draws water up through the soil leading to nodules of calcium carbonate in C/A horizon
  • C horizon is lime or calcium rock that is loess in origin
  • Small biomass as grass is the main species- does provide deep roots stabilising the soil
  • Crumb structure give a neutral to slightly acidic pH
  • Mollisols are very fertile
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