Transcript Changes in Ecosystems

CHANGES IN ECOSYSTEMS
Chapter1
Lesson 5
Objectives
Students will:
 Explore factors that change ecosystems.
 Discuss different types of pollution and how they
harm ecosystems.
 Discuss ways people can fight pollution.
What causes ecosystems to change?
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A resource is a material
that helps support life on
Earth.
To survive within an
ecosystem, organisms
need many resources
such as:
 Water
 Sunlight
 Soil
 Air
What causes ecosystems to change?
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Some resources, such as
water, can run out or dry
up.
Others such as sunlight,
never run out.
Sometimes events occur
that cut off or destroy a
resource.
Ventura County, California
What causes ecosystems to change?
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Drought:
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A long period of time with little or no precipitation, such as rain.
During a drought, plants may turn brown and die.
When plants die, the consumers that need them for food can also
die.
Animals also need water to drink.
Lake Powell, Paige, AZ
Corn fields affected by a drought.
What causes ecosystems to change?
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Diseases can harm an
ecosystem.
 Dutch
 It
elm disease (DED).
is a fungus.
 It affects the trees by
blocking the vascular
system and preventing
the transport of water
and nutrients to the
leaves.
 The leaves wilt and
eventually the tree dies.
What causes ecosystems to change
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In 1930 it arrived in N.A. in wood crates made of diseased elm
wood.
Over time DED spread from tree to tree.
It killed more than half of all N.A. elm trees.
Between 1945 and 1976, 43 million trees died from DED.
Elm trees add to the oxygen we breathe.
They can also prevent soil erosion.
What causes ecosystems to change?
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How does Elm disease
spread?
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European Elm bark-beetle.
Root contact between trees.
Humans transporting infected
wood around (either with fungus
or beetles in it).
What causes ecosystems to change?
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DED harms more than just elm
trees.
Trees are home to many
insects and other animals.
When a tree dies, these
animals homes are destroyed.
What causes ecosystems to change?
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Fire can also change an
ecosystem.
How would a fire in a rain
forest affect the animals that
live and feed on trees?
What causes ecosystems to change?
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Overpopulation is another
factor that changes
ecosystems.
 Overpopulation
happens
when an ecosystem has
too many of at least one
kind of living thing.
 In many crowded cities,
people have left little or
no space for other animal
to live.
What causes ecosystems to change?
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Overpopulation reduces the resources that all living
things must share.
In Australia, overpopulation of kangaroos has become a
big problem.
What causes ecosystems to change?
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Dingos
A
wild dog that hunts
kangaroo.
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As the number of dingos
decreased, the number of
kangaroos increased.
Kangaroos compete with other
livestock on farms for food
and water.
They also knock down fences
and cause erosions.
What causes ecosystems to change?
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How has the Australian
government dealt with this
problem?
 They
have allowed a
certain number of
kangaroos to be hunted.
 They are used for
leather, pet food, and
even human food.
How can people change ecosystems?
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Pollution
 It
happens when harmful
substances are added to
Earth’s water, air, or land.
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Humans and other living things
need a clean place to live.
How can people change ecosystems?
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Water Pollution
 Waste from homes or factories are
dumped into rivers, lakes, and
oceans.
 Water pollution is a problem for
everyone.
 It makes the water too dirty to use.
 It can be dangerous.
 Plants and animals that live in the
polluted water can die.
 Living things can get sick.
How can people change ecosystems?
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Water Pollution
 In 1989 the oil tanker
Exxon Valdez ran aground
in Alaska’s Prince William
Sound.
 It spilled 11 million gallons
of oil.
 The oil polluted the water
and coastline for 600 miles
from the ship.
 Many animals became sick
or died.
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www.video.yahoo.com/vi
deo/play?vid=1091686
304&fr=yfp-t-501
How can people change ecosystems?
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Water Pollution
Between 300,000 and
675,000 animals were
killed.
 Sadly, pockets of oil can
still be found in the water
today.
 This oil spill also harmed
the people of Alaska.
 In some villages people
could no longer catch fish.
 They lost their jobs and
money.

http://video.yahoo.com/video/
play?vid=1094032167&fr=
yfp-t-501
How can people change ecosystems?
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Air Pollution
 It
can come from forest
fires or volcanoes.
 Most of it comes from
cars and factories.
 Burning gasoline, coal,
and other fuels can
pollute the air.
How can people change ecosystems?
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Acid Rain
 Burning
gasoline, coal,
and other fuels release
compounds of sulfur and
nitrogen called acids.
 This acid mixed with
water in the air then falls
to the Earth as acid rain.
 Acid rain can ruin our
lakes, forests, soils, and
crops.
 Too much acid rain can
harm many plants and
animals.
How can people change ecosystems?
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Smog
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Waste gases and smoke from
cars, homes, and factories may
join with water in the air to form
smog.
It hangs in the air like a cloud.
It can make the air harder to
breathe.
It can sting the eyes.
Smog Alerts
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People who have trouble
breathing should say inside
during a smog alert.
What the difference between fog and smog?
Smog
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It is pollution.
Waste gases and smoke
from cars, homes, and
factories.
Fog
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It is condensation.
It is created by warm water
moist air moving over cold
water.
How can people change ecosystems?
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Land Pollution
 Acid
rain, chemical
wastes, smog, and trash
can also pollute our soil.
 Soil or land that is
polluted can harm the
plants and animals that
live on it.
 It can also make
everything look
unattractive or ugly.
How can human fight pollution?
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In order to keep ecosystems
healthy, we must use resources
wisely.
Using energy wisely can help
keep our air clean.
 Shut off televisions and
radios when not in use.
 Turn off lights in an empty
room.
 Ride a bus or train.
 Carpool when possible.
How can human fight pollution?
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The U.S. government has
written laws to control air
pollution.
 Clean Air Act.
 It sets limits on different
kinds of air pollution.
 The laws in California
are stricter.
 Cars sold here must meet
tough tests that help
keep pollution low.
How can human fight pollution?
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Littering
 We can help by:
 Cleaning up litter when
we see it.
 Recycling and reusing.
 Keeping the land clean
helps everyone.
How can human fight pollution?
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Water Pollution
 It is a problem in thousands
of lakes, rivers, and other
bodies of ocean.
 Clean Water Act
 It tells states to clean
polluted waters and to
stop further pollution.
 We can help by:
 Not dumping waste that
could harm our water.
 Don’t throw things into
rivers, lakes, or oceans.
Questions
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A new factory opens in your area. Suddenly, dead
fish are found in the local stream.
 What
can you infer?
 How can you determine if your inference is correct?
Homework
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Science Packet
due tomorrow
Appointment Assignment
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What types of things can you do everyday to help
prevent harmful changes in the environment?
Experiment