GrasslandsGrasslands

By Mira Mooreville and Dana GitlinBy Mira Mooreville and Dana Gitlin

What is a grassland?What is a grassland? Regions with enough average annual Regions with enough average annual

precipitation to allow grass to prosper but precipitation to allow grass to prosper but with precipitation so erratic that drought with precipitation so erratic that drought and fire prevent large stands of trees and fire prevent large stands of trees from growing.from growing.

Where are Grasslands?Where are Grasslands?

Grasslands can be found on all continents except Antarctica.

ClimatogramClimatogram

Three Main Types of Three Main Types of GrasslandsGrasslands

TropicalTropical TemperateTemperate Polar (tundra)Polar (tundra)

Tropical GrasslandsTropical Grasslands Found in areas with high average Found in areas with high average

temperatures, low to moderate temperatures, low to moderate precipitation, and a prolonged dry precipitation, and a prolonged dry season.season.

They are widely spread on either side of They are widely spread on either side of the equator beyond the borders of tropical the equator beyond the borders of tropical rain forests.rain forests.

A type of tropical grassland is a savanna.A type of tropical grassland is a savanna.

SavannasSavannas Have warm temperatures Have warm temperatures

year round, two prolonged year round, two prolonged dry seasons, and abundant dry seasons, and abundant rain the rest of the year.rain the rest of the year.

Largest Savannas are Largest Savannas are found in central and found in central and southern Africa, but can southern Africa, but can also be found in Central also be found in Central South America, Australia, South America, Australia, and Southeast Asia.and Southeast Asia.

Savanna SpeciesSavanna Species Common Savanna animal species include wildebeests, Common Savanna animal species include wildebeests,

gazelles, zebras, giraffes, antelopes, cheetahs, lions, gazelles, zebras, giraffes, antelopes, cheetahs, lions, hyenas, eagles, and hawks.hyenas, eagles, and hawks.

Many large Savanna animal species are killed for their Many large Savanna animal species are killed for their economically valuable coats and parts (tigers), tusks economically valuable coats and parts (tigers), tusks (rhinoceroses), and ivory tusks (elephants).(rhinoceroses), and ivory tusks (elephants).

Some Savanna plant species include Bermuda grass, Some Savanna plant species include Bermuda grass, candelabra tree, elephant grass, gum tree eucalyptus, candelabra tree, elephant grass, gum tree eucalyptus, whistling thorn, and river bush willow.whistling thorn, and river bush willow.

Temperate GrasslandsTemperate Grasslands Cover vast expanses of plains Cover vast expanses of plains

and gently rolling hills in the and gently rolling hills in the interiors of North and South interiors of North and South America, Europe, and Asia.America, Europe, and Asia.

Winters are bitterly cold, Winters are bitterly cold, summers are hot and dry, and summers are hot and dry, and annual precipitation is fairly annual precipitation is fairly sparse and falls unevenly sparse and falls unevenly through the year.through the year.

Types of temperate grasslands Types of temperate grasslands are the tall-grass prairies and are the tall-grass prairies and short-grass prairies of the short-grass prairies of the midwestern and western US midwestern and western US and Canada, South American and Canada, South American pampas, African veldt, and pampas, African veldt, and steppes of central Europe and steppes of central Europe and Asia.Asia.

Prairie

Prairie SpeciesPrairie Species Common prairie animal species include Common prairie animal species include

the American Bald Eagle, bobcat, bumble the American Bald Eagle, bobcat, bumble bee, coyote, prairie dog, and swift fox. bee, coyote, prairie dog, and swift fox.

Some prairie plant species include big Some prairie plant species include big bluestem grass, blue grama grass, bluestem grass, blue grama grass, buffalo grass, milkweed, and stinging buffalo grass, milkweed, and stinging nettle. nettle.

Food WebFood Web (Prairie) (Prairie)

Symbiotic RelationshipSymbiotic Relationship Certain types of ants and aphids have a relationship Certain types of ants and aphids have a relationship

known as mutualism, a type of symbiosis, in which known as mutualism, a type of symbiosis, in which species help each other to survive. Aphids, tiny slow-species help each other to survive. Aphids, tiny slow-moving insects, live on plants. They feed on nectar, moving insects, live on plants. They feed on nectar, which they suck out of plant stems with their long, which they suck out of plant stems with their long, pointed mouths. As the aphids digest the nectar, it is pointed mouths. As the aphids digest the nectar, it is formed into a sugary substance called honeydew. The formed into a sugary substance called honeydew. The aphids then release honeydew through specialized aphids then release honeydew through specialized organs called cornicles. Honeydew is one of the ants organs called cornicles. Honeydew is one of the ants favorite food. The ants eat as much honeydew as the favorite food. The ants eat as much honeydew as the aphids can produce. The ants treat the aphids like their aphids can produce. The ants treat the aphids like their own private heard. By keeping the aphids close to own private heard. By keeping the aphids close to them at all times, ants have a natural food supply. them at all times, ants have a natural food supply.

Abiotic Factors of Abiotic Factors of GrasslandsGrasslands

SoilSoil SunlightSunlight WaterWater RocksRocks AirAir

SoilSoil Aboveground parts of most of the grasses die and Aboveground parts of most of the grasses die and

decompose each year, allowing organic matter to decompose each year, allowing organic matter to accumulate and produce a deep, fertile soil. The soil is accumulate and produce a deep, fertile soil. The soil is held in place by a thick network of intertwined roots of held in place by a thick network of intertwined roots of drought-tolerant grasses. drought-tolerant grasses.

Because of their thick and fertile soils, temperate Because of their thick and fertile soils, temperate grasslands are plowed up and widely used to grow grasslands are plowed up and widely used to grow crops.crops.

The plowing however breaks up the soil leaving it The plowing however breaks up the soil leaving it vulnerable to erosion by wind and water. vulnerable to erosion by wind and water.

Major Human Impacts on Major Human Impacts on GrasslandsGrasslands

Conversion of savanna and temperate Conversion of savanna and temperate grassland to cropland.grassland to cropland.

Release of carbon dioxide to atmosphere Release of carbon dioxide to atmosphere from burning and conversion of grassland from burning and conversion of grassland to cropland.to cropland.

Overgrazing of tropical and temperate Overgrazing of tropical and temperate grasslands by livestock.grasslands by livestock.

Example of a Human Example of a Human ImpactImpact Indian tribes and wildlife used to settle on the vast Indian tribes and wildlife used to settle on the vast

grasslands of the Great Plains in the United grasslands of the Great Plains in the United States. The settlers brought cattle and sheep which States. The settlers brought cattle and sheep which grazed the plains. Settlers farmed the land and plowed grazed the plains. Settlers farmed the land and plowed the topsoil. But in the 1930’s, there was an eight-year the topsoil. But in the 1930’s, there was an eight-year drought which brought major wind and dust storms. As drought which brought major wind and dust storms. As a result, the soil became dry and loose and crops could a result, the soil became dry and loose and crops could not grow. Because humans allowed the natural not grow. Because humans allowed the natural grassland ecosystems to be overgrazed and grassland ecosystems to be overgrazed and improperly utilized, the land was unable to endure such improperly utilized, the land was unable to endure such a long drought. The government set up regulations to a long drought. The government set up regulations to help the farmers restore the land.help the farmers restore the land.

The Dust Bowl.

Environmental Damage Environmental Damage and Solutionsand Solutions Grasslands are adapted to high levels of animal impact by herds of Grasslands are adapted to high levels of animal impact by herds of

animals. Animal impact includes dunging, urinating, trampling, animals. Animal impact includes dunging, urinating, trampling, rubbing, wallowing, salivating, etc. Their trampling and dunging is rubbing, wallowing, salivating, etc. Their trampling and dunging is extremely beneficial to the land and has maintained the grasslands extremely beneficial to the land and has maintained the grasslands for millions of years. The beneficial effects of animal impact exist only for millions of years. The beneficial effects of animal impact exist only on high impact for a short duration. Low impact for a long duration on high impact for a short duration. Low impact for a long duration leads to environmental damage because plants and soils do not get a leads to environmental damage because plants and soils do not get a chance to recover and restore itself, therefore becoming overgrazed. chance to recover and restore itself, therefore becoming overgrazed.

Animal impact maintains grasslands by:Animal impact maintains grasslands by: Planting seeds and guaranteeing good seed-to-soil contact Planting seeds and guaranteeing good seed-to-soil contact Breaking soil crusts that obstruct the process of seed germination and Breaking soil crusts that obstruct the process of seed germination and

rainfall absorption rainfall absorption Pruning plants to keep them fertile and activePruning plants to keep them fertile and active Eliminating weeds Eliminating weeds Mulching the soil surface with trampled vegetation, which protects it from Mulching the soil surface with trampled vegetation, which protects it from

erosion and reduces soil surface evaporation erosion and reduces soil surface evaporation Composting plant material Composting plant material Fertilizing the soil Fertilizing the soil

Environmental Damage Environmental Damage and Solutions (cont’d)and Solutions (cont’d)

If grasslands do not have any animal impact, they will deteriorate, If grasslands do not have any animal impact, they will deteriorate, especially in very dry areas. When grazing animals leave an especially in very dry areas. When grazing animals leave an ecosystem, damage to the land will occur. Example: Nevada used to ecosystem, damage to the land will occur. Example: Nevada used to be a grassland 100 years ago, but today it is mostly an arid desert. be a grassland 100 years ago, but today it is mostly an arid desert.

Animal impact is the most effective way known to renew the damaged Animal impact is the most effective way known to renew the damaged land and deserts. land and deserts.

Today, animal impact is used worldwide to:Today, animal impact is used worldwide to: Help vegetation in mine dumps in Nevada and Arizona, U.S.A. Help vegetation in mine dumps in Nevada and Arizona, U.S.A. Restore desertified grasslands in South Africa, Zimbabwe, and the western Restore desertified grasslands in South Africa, Zimbabwe, and the western

U.S. U.S. Control invasive weeds in South Africa, Oregon and Montana. Control invasive weeds in South Africa, Oregon and Montana. Repair erosion damage in Mexico and California.Repair erosion damage in Mexico and California. Prevent soil-surface erosion in Australia Prevent soil-surface erosion in Australia Build new topsoil at rates of up to 1" per yearBuild new topsoil at rates of up to 1" per year Increase the ability of soil to absorb water in Australia, Africa, and New Increase the ability of soil to absorb water in Australia, Africa, and New

Mexico.Mexico. Encourage biodiversity in Australia, Africa and the western US.Encourage biodiversity in Australia, Africa and the western US.

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