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Prairie

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Prairie in Effigy Mounds National Monument, Iowa, United States

Prairies are considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type. Temperate grassland regions include the Pampas of Argentina, and the steppes of Russia and Central Asia.

Lands typically referred to as "prairie" tend to be in North America. The term encompasses much of the area referred to as the Great Plains of the United States and Canada. In the U.S., the area is constituted by most or all of the states of North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, Texas, Colorado, Wyoming and Montana, and sizable parts of the states of Indiana, Illinois, Iowa, Wisconsin, Missouri, and Minnesota. The Central Valley of California is also prairie. The Canadian Prairies occupy vast areas of Manitoba, Saskatchewan, and Alberta.

Contents

[edit] Formation

Prairie grasses

The formation of the North American Prairies started with the upwelling of the Rocky Mountains. The mountains created a rainshadow that killed most of the trees.

Most prairie soil was deposited during the last glacial advance that began about 110,000 years ago. The glaciers expanding southward scraped the soil, picking up material and leveling the terrain. As the glaciers retreated about 10000 years ago, it deposited this material in the form of till.

These treeless grasslands have an extreme climate: cold in winters and hot in summers.

[edit] Fire

Fire is an important part of the prairie ecosystem. Fire does at least two important jobs, removing trees and clearing dead grasses. Forests can overwhelm a prairie grassland, as too many trees create shade, killing the grasses. Fire destroys the trees, but not the grass, as most of the grass is underground and will regrow from its deep roots. As fire clears the dead leaves, the ashes fertilize the soil

[edit] Fertility

In spite of long recurrent droughts and occasional torrential rains, the grasslands of the Great Plains are not subject to great soil erosion. The deep, interconnected root systems of prairie grasses firmly hold the soil in place and prevent run-off of soil. When a plant dies, the fungi, bacteria and the other decomposers slowly eat the roots and leaves, returning nutrients to the soil.

These deep roots also help prairie plants to reach water in even the driest conditions. The grass suffers much less damage from dry conditions than the farm crops that have replaced many former prairies.

[edit] Types

The types of prairie grass, on North America, is usually split into three groups, depending on how much water that area gets. The types are wet, mesic, and dry.

[edit] Wet

In this type of prairie, the soil is usually very moist most of the growing season, and has poor water drainage. This can possibly contain a bog or fen, since it often has plentiful stagnant water.

[edit] Dry

Dry Prairie is a prairie which has medium-wet to dry soil during the growing season because of good drainage. Often, this prairie can be found on uplands or slopes.

[edit] Mesic

Mesic prairies have good drainage, but have good soil moisture during the growing season. This type of prairie is the one most often converted for agricultural usage, consequently it is one of the more endangered types of prairie.

[edit] Farming

The very dense soil plagued the first settlers using wooden plows, perfectly good for the forest where the soil is loose. On a prairie, the plows just bounced around, and the soil stuck to the plow.

This was solved in 1837, when an Illinois blacksmith named John Deere developed a steel moldboard plough that was stronger and cut the roots, making the fertile soils ready for farming.

The prairie today is one of the most plentiful crop producing areas. Illinois became a figurative breadbasket for the United States. Illinois ranks 49 of 50 states in total land remaining uncultivated.

[edit] Biofuels

Main article: Biofuel

Research, by David Tilman, ecologist at the University of Minnesota, suggests that "biofuels made from high-diversity mixtures of prairie plants can reduce global warming by removing carbon dioxide from the atmosphere. Even when grown on infertile soils, they can provide a substantial portion of global energy needs, and leave fertile land for food production." [1] Unlike corn and soybeans which are major food crops, prairie grasses are not used for human consumption. Prairie grasses can be grown in infertile soil, eliminating the cost of adding nutrients to the soil. Tilman and his colleagues estimate that prairie grass biofuels fuel would yield 51 percent more energy per acre than ethanol from corn grown on fertile land.[1] Some grasses commonly used are lupine, turkey foot, blazing star, switchgrass, and prairie clover.

[edit] Preservation

Only 1% of tallgrass prairie remains in the U.S. today.[2]

Significant preserved areas of prairie include:

[edit] Virgin prairies

Virgin prairie refers to prairie land that has never been plowed. Small virgin prairies exist in the American Midwestern states and in Canada. Restored prairie refers to a prairie that has been reseeded after plowing or other disturbance.

[edit] Prairie garden

A prairie garden is a garden primarily consisting of plants from a prairie.

[edit] See also

[edit] References

  1. ^ a b David Tilman. "Mixed Prairie Grasses Better Source of Biofuel Than Corn Ethanol and Soybean Biodiesel"". National Science Foundation (NSF). http://www.nsf.gov/news/news_summ.jsp?cntn_id=108206. Retrieved on December 7, 2006. 
  2. ^ Roy Robison, Donald B. White, and Mary H. Meyer: Plants in Prairie Communities. University of Minnesota, 1995.

[edit] External links

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