One of the most extensive of the biomes:
North America: prairies 350 million ha running from eastern deciduous forest border to western cordilleras
Eurasia: steppes 250 million ha running from Hungary to Manchuria
Southern Africa: grassveld
Australia/New Zealand (South Island)
Temperate grasslands are adapted to recurring drought (50 - 120 cm rain)
emperate grasslands appear homogenous but important structural and floristic differences have developed in response to regional and local conditions (e.g. in prairie province [similar elsewhere in trends]
increasing latitude: warm to cold and moist to dry
east to west: moist to dry and warm to cold
Rich 'chernozens' or 'udolls' characterize grasslands. Possess a thick organic layer of very dark humus; active earthworm and soil fauna activity making this soil one of the most productive of terrestrial systems.
Light rainfall and high evporation makes mild leaching; therefore soil is neutral or only slightly acidic.
D. Other factors
Fire supression; once frequent and kept out woody species
Large areas destroyed by agriculture (wheat, maize, legumes): Cradle of Civilization (bread, barley, beer)
Loss of characteristic cursorial fauna: ungulates (bison, antelope, gazelle, wild horse) or equivalent flightless birds in S. America (rhea) and New Zealand (extinct moa), and rodents
E. Prairies (in more detail; but we come back to them again)
3 dominant families: Poaceae (grasses), Leguminosae (legumes), Compositae (composites)
Tall grass prairie: Andropogon gerardi (big bluestem), Panicum virgatum (switch grass), Sorghastrum nutans (Indian grass)
Tall/short grass prairie (intermediate)
Short grass prairie: Bouteloua (grama grass), Sporobolus (prairie dropseed), Agropyron (wheatgrass)
F. Evolution of grasslands
Flora of Great Plains, N. America has few endemic species suggesting that prairies developed comparatively recently and attainded present distribution only in post-glaciation (Axelrod, 1985)
Fire to some degree has been important, especially in drier times
Grazing by ungulates critical (coevolution!). Grasses and sedges have high silica content in leaves; ungulates acquired early on high-crowned teeth in which growth continually replaces the worn surfaces as adaptation; grasses and sedges have ability to resprout after grazing (good example is the prairie ungulate replacer: the lawn mower).