The Prairies

Characteristics: Climate

Temperature

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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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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Soil of Prairies is a mollisol (chernozem)
1.5m deep
A 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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