1. Chapter 1 Lesson 4: Changes in ecosystems pgs. 58-63
EQ: How can a change to an ecosystem affect living things?

2. Vocabulary
Succession: an order, or sequence, in which an ecosystem recovers from a change

3. What causes an ecosystem to change?
Ecosystems are always changing. It makes it difficult for living things to survive.
Most ecosystems change due to natural causes or patterns.
Volcanoes can fill a valley with ash, hurricanes can destroy wetlands, rain can cause landslides, or too little rain can cause a drought.
It takes a long time for an ecosystem to recover from changes.

5. Mount St. Helen This is a volcano in Washington.
In 1980 it erupted, the ash and lava destroyed nearby plants.
It took many years to recover.

6. Living Things Living things can also change an ecosystem.
A locust is a kind of grasshopper and in large numbers they are dangerous.
Swarms of locusts can gather together eating many plants leaving a community without food.

7. Living things helping the ecosystem
Have you ever seen a gator hole in a wetland?
An alligator uses its feet, tail, and snout to churn up muddy water and these movements create a hole.
Slowly, the hole fills with water.
Gator holes help alligators survive during a drought, but the effect doesn’t stop there.
Birds and other animals move to gator holes when their habitats get dry.
They find their food, water, and shelter there.

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9. What happens when ecosystems change?
Fires can destroy the main food supply of animals in a forest.
Some animals, like deer, can change their diet.
Instead of eating green leaves, they may eat the bark of trees.
Other animals may use different plants or new materials for shelter.

10. Moving Away
Some animals may not be able to change their behavior and may instead have to move away to meet their needs.
The search for food, water, and shelter may lead them far away.

11. Fires
Fires can be good for a forest. A natural fire forces some individuals to leave.
This helps the population from becoming too large.
There is less competition and enough resources for all to use.
Fire in the longleaf pines forest are important because the scrub oak would take over.
This has already happened in many forests of the southeast U.S.

12. Role of Soil The upper part of soil is called topsoil.
Here live all kinds of insects, worms, plants, and bacteria.
This is also where decomposers do their job.
Roots of plants keep topsoil from coming apart and bind bits of soil together.
If the ecosystem changes and the plants die, the soil might not stick together.
Then wind and rain would wash away topsoil leaving all the organisms homeless.
This could change the whole food web!

13. How do ecosystems come back?
There is an order, or sequence, in which an ecosystem recovers from a change. This name of this sequence is succession.
Succession can take place after a forest fire.
Sometimes succession occurs on bare ground after a volcano erupts.
It can take as many as 50 years for a full recovery!

14. Stages of Succession
The area may start out empty, with little life or soil.
Small bits of dust and seeds blow from nearby areas.
Mosses and lichens (organisms) begin to grow on the rock
Together they break down the rock and form soil as they grow.
When they die, decomposers add their nutrients to the soil.
After time, grasses and shrubs sprout and plants attract insects and birds.
The animals help spread the seeds and then small mammals move in and then larger animals come.

17. Study Jams
es-ecosystems.htm