Temperate Grasslands

 

 

Grassland Ecosystems of the Temperate Zone Vary with Climate and Geography

 

  • Natural grasslands occupy regions where rainfall is between 25 (10 inches) and 80 cm/year (30 inches)
    • Many grasslands exist through the intervention of fire and human activity
    • Natural grasslands have shrunk to less than 12 percent of their original size
  • Grasslands occur in the mid-latitudes in mid-continental regions where annual precipitation is reduced
     

 

 


 

 

 

 

 

Temperate Grasslands of Other Continents

  • Eurasia
    • Steppes are treeless and are divided into four belts of latitude (map)
  • South America
    • Pampas (map) extend westward in a large semicircle from Buenos Aires to cover about 15 percent of Argentina
  • Southern Africa
    • Velds (map) occupy the eastern part of a high plateau
       
  • Australia
    • Arid tussock mean rainfall 20 cm (8 inches) to 50 cm/year (20 inches) (most falls in the summer)
    • Hummock grasslands rainfall <20 cm/year (8 inches)
    • Coastal grasslands tropical summer rainfall region
    • Subhumid grasslands along coastal areas mean rainfall 50 cm (20 inches) to 100 cm/year (40 inches)
       

 

 

  • Grasslands are dominated by herbivorous species
    • Large grazing ungulates (hoofed animals)
    • Burrowing mammals
  • North American grasslands
    • Bison, pronghorn antelope, prairie dog

 

 

  • Eurasian steppes and Argentine pampas lack herds of large ungulates
    • Pampas deer and guanaco
  • African veld
    • Historically, wildebeests and zebras with their associated predators (e.g., lion)
    • Replaced with sheep, cattle, and horses
  • Australia
    • Kangaroo species

 

 

 

  • Grasslands evolved under the selective pressure of grazing
    • Grazing stimulates primary production
  • The major consumers in grassland ecosystems are invertebrates
    • Heaviest consumption takes place belowground (by nematodes)
       

 

 

  • There are three strata in the grassland
    • Tall, green, ephemeral herbaceous growth
    • Ground layer
    • Belowground root layer
       

 

 

  • Grasslands accumulate a layer of mulch that retains moisture and adds organic matter to the mineral soil
  • Soils of the grasslands
    • Mollisols relatively thick, dark-brown/black surface horizon rich in organic matter
  • Temperate grassland productivity is related to annual precipitation