Grasslands

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Grasslands are open areas which are dominated by grasses or grass-like plants with few trees. Grasses dominate here because they are better able to thrive in hot, dry climates where spring and summer rain is sparse. Mostly located between forests and deserts, about 25 percent of the Earth's land is covered with grasslands. Grasslands are generally open and fairly flat, exist on every continent and mostly lie in the drier portions of a continent's interior.

Contents

Why should I be aware of this?

  • Grassland is a habitat which is agriculturally most useful humans as soils tend to be deep and fertile, making them perfect for cropland or pastures. Much of the North American prairielands have been converted into one of the richest agricultural regions on Earth.
  • Distinct plant and animal species live in the grasslands. Many like the California Bighorn Sheep, and many, like the marmot, burrow underground. Some animals, such as the Sharp-tailed Grouse, use both the grasslands and nearby forests during the year, while others such as the Western Harvest Mouse (vole) spend their whole lives in the grasslands.

All about grasslands

Grasslands have several names. In the U.S. Midwest, they're known as prairies. In South America, they're called pampas. Central Eurasian grasslands are referred to as steppes, while in Africa they're named savannas. The prairies in North America were once inhabited by huge herds of bison and pronghorns who fed on the prairie grasses. These herds are almost gone now, and most of the prairies have been converted into the richest agricultural region on earth. Crops grow well in the rich soil.

Grasslands receive about 10 to 30 inches of rain per year. This is the right amount of rainfall to maintain the grass. Any more than this and the area would turn to forest. Any less, it would become a desert.

Fires, both natural and human-caused, are important in maintaining grasslands. Ancient hunting peoples set regular fires to maintain and extend grasslands, and prevent fire-intolerant trees and shrubs from taking over. Grasses are able to survive fires because they grow from the bottom instead of the top.

Tropical and temperate grasslands

There are two different kinds of grasslands: tropical and temperate.

Tropical grasslands are warm year round, but usually have a dry and a rainy season. One such tropical grassland, the African savanna, is home to some of the world’s most recognizable species, including elephants, giraffes, rhinos, zebras, lions, hyenas, and warthogs.

Temperate grasslands, which average between 10 and 30 inches (25 and 75 centimeters) of rain per year, have shorter grasses, sometimes just a few millimeters. These areas have two seasons: a growing season and a dormant season. During the dormant season, no grass can grow because it is too cold.

The animals that live in temperate grasslands have adapted to the dry, windy conditions. There are grazing animals like gazelle and deer; burrowing animals such as mice and jack rabbits; and predators such as snakes and coyotes. The North American grasslands were once home to millions of bison, before most of them were slaughtered by humans.

Better water and pasture quality

Water and soil quality improves as grassland vegetation becomes denser. Grasslands are the best "crop" for reducing runoff, erosion, and phosphorus pollution. Grassland soils are an excellent biological filter to recover nutrients passing through the soil. Grass roots are active almost year-round and can recover nutrients from the soil that can leach out from other land uses.

Controlled grazing, improved habitat

As grasslands contain better permanent and diverse plant cover, it is good as habitat for wildlife as well as forage for livestock. Research has consistently shown that ground-nesting birds and small mammals thrive in properly managed pastures. Grazing lands can provide nesting habitat, cover, and food when adequate plant residues remain following grazing or mowing.

Grazing and greenhouse effect

Grassland soils are a tremendous reservoir for storage of this organic carbon. In grassland ecosystems, more than 90% of the organic matter produced is found in the roots, while more than half of the organic matter in a forest ecosystem is above-ground. Grasses and legumes use atmospheric carbon as building blocks for plant tissue. The unutilized and decomposed plant tissue is returned to the soil and becomes part of the carbon pool. This process helps reduce carbon dioxide levels in the atmosphere and reduces the "greenhouse effect." A permanent grassland ecosystem stores significantly more soil carbon than cropland areas do.

CopperBytes

  • While the South African Grassland Biome is now unique in Africa grasslands once used to cover nearly 50% of Africa’s surface. A change in climate, around 3 million years ago allowed trees to encroach into these grasslands and create the savannas we know today. [1]
  • The United States is starting to perserve the wild grasslands, too. It is even replanting grass where it has been cleared for farming.
  • True prairies and grasslands are becoming harder and harder to find. People are taming the wild lands, and the grasslands are becoming as extinct as the animals that are missing from them today.
  • Grasslands cover nearly fifty percent of the land surface of the continent of Africa. [2]

90 degrees

Scientists have discovered 14 new animal species in Brazil's Cerrado, a vast woodland-savanna ecoregion that stretches across more than 2 million square kilometers of the country's central plateau. The new species include eight fish, three reptiles, one mammal, one bird, and one amphibian. [3]

References:

  • What Are Grasslands?
  • Grasslands

Source

  1. South African Water Crisis
  2. AbsoluteAstronomy
  3. About.com