Download Grasslands

Ch. 8
http://people.eku.edu/ritchisong/birdbiogeography1.htm
 Ecosystem
in which there is more water
than in a desert
 Not enough precipitation to create a
forest
 Tend to be located between the desert
and forest biomes
 In Africa, central Asia, North and South
America, Australia
 We live in the grasslands
 More
rain than desert, but less than
forests
 Desert-grassland
boundary: area
between the deserts and grasslands
where increased rainfall enables some
grasses to grow.
• Rainfall increases: boundary becomes grassland
• Rainfall decrease: climate too dry to support the
organisms  becomes desert
 Hot, dry
summers
 Limiting
factor: rainfall
 Not
enough rain  grasslands can’t
develop
 Natural
and man-made fires play a role in
the development of the grasslands
 Abiotic
and biotic factors determine the
organisms in a biome
 Grasses are the most common organism
• Most of the shrubs and trees are destroyed by
fires
 Grasses roots are deep so they are sometimes
unaffected by fires
 Rye
Plant: grows to 2 m in height, but
roots are up to 600 km deep
 Bison:
• Graze to keep grass short and help its growth
• Poop fertilizes the ground for further growth
 Burrowing
animals:
• Prairie dogs, earthworms, insects
• Aerate the soil by making tunnels/digging
• Helps nutrients, oxygen, and water reach roots
more quickly
 Bison
and antelope
• Run quickly
 Grasshoppers
• Feed on seeds and leaves of grasses
 Mice, gophers, prairie
dogs
• Burrow underground
• Active mostly at night (avoid predators…)
 Coyotes, foxes, snakes, birds
• Top consumers in North American Prairies
 Burn
away layer of dead grass
• Converts to fertilizer for soil
 Grasslands
contain species of grass that
fire actually aids in its germination
 Different
rainfall amounts results in
different grasses grown.
• United States has both tall and short grass
prairies
 Drier climate: shorter, fine grass
 Mainly used for cattle grazing
 Wetter climate: taller, thick grass
 Most cleared for crop farming
 Cycles
of rain
• Heavy period of rain (rainy season)
• Little or no rain (drought season)
 Trees
and shrubs are able to survive the
drought season due to adaptations
 1. where
are grasslands located in
relation to deserts and forests?
 2. Suggest
reasons for the relationship
between grass size and climate.
 Tall grasslands:
• have very tall grass, up to 5 feet tall
• get almost 30 inches of rain a year.
 Mixed grasslands:
• grasses that grow around 2-3 feet high
• gets about 15-25 inches of rain in a year
 Short grasslands:
• almost a desert
• very short grass
• only receives 10 inches of rain each year
 Grasslands
are becoming as extinct as
the animals that are missing from them
today.
• In Africa, national parks are being set up to
preserve the grasslands.
• This will help the animals such as lions and
elephants as well.
• The United States is starting to preserve the wild
grasslands, too. It is even replanting grass where
it has been cleared for farming.
 Steppes:
• short, bunched together grass
• Less than 50 cm of rainfall annually
• Located on the western edges of grassland (that
nearest the desert)
 Prairies:
• Make up most of land in United States
• Rolling hills and plains
• Fertile land provides base for crop growing
 Generally a lot of wheat and grains
 Receive
more than 25 cm of rainfall
• Prairies usually get 50-75 cm of rain
 High
winds and high temperatures
 dry
environment so most of the rain
evaporates quickly (doesn’t get deep in soil)
 Temps: 23-86
degrees fahrenheit
 Prairies
• Soil holds moisture very well
• Sod-forming grasses: form a mat of soil and roots
 Example: Grass in our lawns
 Holds soil together  decreases amount of evaporation
• Humus: layer of organic matter formed from the
decomposition of plants and animals
 Also helps to retain moisture and provide nutrients
 Steppes:
• Short grasses
• Bunchgrasses: short, fine-bladed grasses that
grow in a clump
 Clumps retain water
 Adaptations:
• Migrate, hibernate, or burrow
• Plants use the wind to aid in dispersal of seeds
• Colder areas:
 Hibernate or migrate
• Warmer areas:
 Burrow-nocturnal
 Overgrazing
 Replacing
native grasses with ones less
suitable for the area
 1. Why
are prairies called breadbaskets
of the world?
 2. How
might desertification occur in
steppe and prairies?
Jan
Feb Mar Apr Ma
y
Jun
e
July
Aug
Sept Oct
Nov
dec
Temp
-3
-3
-2
0
6
18
22
20
14
6
3
-2
Precip
0
0
2
4
6
5
5
4
3
2
1
1.5
 Tropical
 Range
 In
or subtropical grasslands
from dry to wet, open grasslands
Asia, Africa, and South America
 Rainy
seasons
• As much as 150 cm of rainfall
• From January to April
• Usually falls in heavy thunderstorms
 Drought
seasons
• May to December
 Grasses, shrubs, trees
• Must be resistant to:
 Drought, fires, grazing animals
 Runners:
• Long stems above ground
• Used by some plants to reproduce
 Rhizomes:
• Roots underground
• Protected from fires
 Tufts: large
clumps of tall, coarse grasses
 Adaptations:
• Trees and shrubs have thorns/sharp leaves
 Protect them from predators
• Grow rapidly
 Recover quickly from damage by animals and fire
• Make use of the vertical feeding pattern
 Animals eat different vegetation at different heights
 Decreases the competition for food
 More animals can live in a smaller area
 Larger
animals migrate to areas where
rain has fallen
 Habitat
loss due to human activity has
lead to disruption of some animals
migrating patterns
• Affects the predators that feed on those animals
 1. How
have plants adapted to savanna
life?
 2. What
could happen to the migrating
animals in a savanna if they were fenced
in a large wildlife park for protection?