page_title: Grassland
section_title: Tallgrass in North America
hierarchical_section_title: Grassland / Vegetation / Tallgrass in North America
context_page_description: grassland is an area of land that mostly contains grasses. There are wild grasses, and there may be some trees. Several parts of the world have grasslands. Grasslands are found in Africa, North America, Central Asia, South America, and near the coasts of Australia. The largest grasslands are in East Africa. Grasslands with a few scattered trees are called savannas. Others are called prairies or steppes.
  Little rain falls in a Grassland. Between 25 and 75 cm of rain falls each year, which makes the weather in these savannas hot and sunny in the summer and cool in the winter months.
context_section_description: The tallgrass prairie is the native ecosystem of North America before it was replaced by modern crops. Retreating glaciersdropped moraine material about 10,000 years ago. Wind-dropped loess and organic matter accumulated. This made the soil. The prairie had the deepest level of topsoil recorded anywhere. Animals such as buffalo, elk, deer, and rabbits
  A added nitrogen to the soil with their urine and feces. Prairie dogs dug tunnels that "aerated the soil and channeled water several feet below the surface".
  For 5,000 to 8,000 years, more than 240 million acres (970,000 km²) of prairie grasslands were a major feature of the landscape. 
  Between 1800 and 1930, most of it was destroyed. Settlers transformed what they called "the Great American Desert" or "The Inland Sea" into farmland. They replaced the old grasses with new ones, mostly wheat and maize. They replaced the bison with cattle, another kind of bovine. About 40% of the world's maize for example grows in the United States, mostly on land that formerly grew grass. The grazing pattern of European cattle, the near-extermination of prairie dogs, and the plowing and cultivation of the land, did the damage. Plowing cut tallgrass root systems and interrupted reproduction. Drainage changed the soil's water content, and soil erosion lost soil.
  Estimates differ of how much original tallgrass prairie survives. Perhaps less than 1% mostly in "scattered remnants found in pioneer cemeteries, restoration projects, along highways and railroad rights-of-way, and on steep bluffs high above rivers", to 4%.
caption: Cereal crop on former grassland
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