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?

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?

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?

Drought: 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?

Diseases can harm an ecosystem. Dutch elm disease

(DED). It 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

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?

How does Elm disease spread? 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?

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?

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?

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?

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?

Dingos A wild dog that

hunts kangaroo. 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?

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?

Pollution It happens when

harmful substances are added to Earth’s water, air, or land.

Humans and other living things need a clean place to live.

How can people change ecosystems?

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?

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.

www.video.yahoo.com/video/play?vid=1091686304&fr=yfp-t-501

How can people change ecosystems?

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?

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?

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?

Smog 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

People who have trouble breathing should say inside during a smog alert.

What the difference between fog and smog?

It is pollution. Waste gases and

smoke from cars, homes, and factories.

Smog Fog

It is condensation. It is created by warm

water moist air moving over cold water.

How can people change ecosystems?

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?

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?

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?

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?

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

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

Science Packet due tomorrow

Appointment Assignment

What types of things can you do everyday to help prevent harmful changes in the environment?

Experiment