Grassland Biomes

Chapter 8

8.1 GrasslandsObjectives

Describe the characteristics of grasslands Identify where grasslands are located

A grassland is an ecosystem where there is too much water to form a desert, but not

enough water to support a forest.

The land between the desert and the forest.

                

Grassland Climate A little wetter than the climate of a desert The desert-grassland boundary is the area

between deserts and grasslands where increased rainfall enable some grasses to grow.

This boundary shifts with long-term changes in climate patterns

Rainfall is the most significant limiting factor in grasslands

Grassland Video

Grassland Organisms Grass is the most common Most of the mass of grass is below ground Grasses not as limited by factors such as

rain and fires

Grass and Fires Natural grass fires play an important role Fires help prevent forests from

overgrowing grasslands Fires help by burning away dead grass

allowing more water and air to reach soil Fires help release valuable nutrients Germination of seeds is aided by fire

Animals Help Grasses Grazing animals help keep other vegetation

from growing without harming grass Burrowing animals help to aerate the soil

and by helping nutrients and water to reach the roots

Rainfall and Grasslands Types of grasses vary based on the amount

of rainfall Irrigation important to cultivated grass

crops When it rains is also important Some grasslands have rainy and drought

seasons Some plants have become drought-resistant

Types of Grasslands

Steppe (Chaparral)

PrairieSavanna

8.2 Steppes and PrairiesObjectives

Compare and contrast a steppe and a prairie Describe the importance of steppes and prairies in

agriculture

Steppes are grasslands that get less than 50 cm of rain a year

Prairies are grasslands characterized by rolling hills, plains, and sod-forming grasses.

Steppes and Prairies continued

Steppes have very low rainfall and sparse plant life – almost a desert

U.S. prairies are Called the Great Plains Large fertile areas where most food is grown Grains – breads and cereal Breadbasket

Steppe and Prairie Climates Steppe

25cm to 50 cm rainfall per year Rain evaporates quickly only reaching top 25 cm of

soil Temperature range from –5 oC to 30 oC

Prairie 50 cm to 75 cm of rain per year Sometimes much more rain and floods Rain usually as thunderstorms

Steppe and Prairie Organisms Prairie

soil holds water well roots of grass (sod-forming grasses) form a

mat called sod Humus is a layer of organic matter

Holds water and provides nutrients and food

Steppes Short grass prairies Mostly bunchgrasses – fine bladed grasses

that grow in clumps Clumping helps save water by holding water

in a small root area, under the shade of the grass.

Steppe and Prairie Organisms

Animal adaptations Migration Hibernation Burrowing

Plant adaptations Seeds and pollen carried by wind Spreads over a wide area

Steppe and Prairie Organisms

Buffalo

Migrating grazers do little damage But poor farming and ranching practices

cause extensive damage Overgrazing, poor farming practices

combined with droughts caused the Dust Bowl n the 30’s.

Today new techniques help reduce the impact

Steppe and Prairie Organisms

8.3 SavannasObjectives

Define savannas, and state where they are located.

Explain how savannas can support a wide range of organisms.

Savannas are tropical grasslands ranging from dry scrubland to wet open woodland.

Savanna Video

Savanna Climate Rainy seasons and long periods of drought As much as 150 cm rainfall per year Most falls heavily during thunderstorms Rest of year can be very dry Extreme climate demands a wide range of

adaptations of organisms.

Savanna Plants Grasses, shrubs and trees must be resistant to

drought, fires and grazing animals Many grow runners

long horizontal stems above or below ground Grasses grow in tufts

large clumps of tall, coarse grasses Thorns or sharp leaves

Protects from grazing animals They grow rapidly to recover quickly

               

Savanna Animals Reproduce during rainy season when food

is abundant Migrate to follow the rain Vertical feeding pattern

Animals eat vegetation at different heights Can feed in the same area without competing Allows more animals to live on limited

resources

TheEnd

1. Rhino2. Vertical feeding pattern3. Fire is important to health of the ecosystem4. Large areas with deep, fertile soils5. Mostly clumps of grasses with bare soil between6. Bison7. 50 cm to 75 cm of rain per year8. Climate wetter than a desert, but not as wet as a forest9. No real winter, but long dry season followed by intense

wet season10. Grazing and burrowing animals help

Quick Quiz 8QQ1. Grasslands 2. Prairie 3. Steppe 4. Savanna

1. 4

2. 4

3. 1

4. 2

5. 3

6. 2

7. 2

8. 1

9. 4

10. 1

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