U 5 lesson 3 integrado e.s. environmental changes

Unit 5 Lesson 3 How Do Environmental Changes Affect Organisms?

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Change Comes Naturally


• All environments change over time. Some changes happen slowly and some occur quickly.

• Climate changes, or changes to weather patterns, affect organisms.

• An ice age happens when Earth’s temperatures are colder than normal for a very long time. Large areas of land are covered in ice for thousands of years.




• What kinds of changes to the environment may have happened during the last ice age?




• Earth is now in a warming cycle, due in part to human activities. As areas become warmer, organisms will move, adapt, or disappear.

• Natural events, such as floods, mudslides, or volcanic eruptions can change the environment quickly.


Next, Please!


• The gradual change of organisms in an ecosystem is called succession.

• Primary succession begins on bare rock. The first organisms to colonize are called pioneer species.

• Lichens, common pioneers, break down rock as they grow, producing soil. When they die, their litter decays, adding nutrients to the soil.


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• Plants grow as soil develops. Mosses flourish, producing more soil. Bigger plants take hold and, eventually, trees grow.

• This establishes a mature, stable community. This process can take hundreds of years.


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• Secondary succession occurs where an ecosystem has been disturbed, but soil is still present.

• Secondary succession occurs more quickly and uses existing soil that contains seeds and roots that sprout and grow.

• Shrubs and grasses grow first, followed by larger plants. Eventually, a stable ecological community is re-established.


For Better or Worse


• Organisms living in an environment can cause both harmful and helpful changes.

• For example, beavers cut down trees that provide food and shelter for other living things in order to make a dam.

• The dam also slows the flow of water to animals. However, dams also produce wetlands, providing homes for other organisms.


Invasive Species


• Invasive species grow quickly after being introduced into a new environment.

• Invasive species take food and space away from native species, the organisms already living in an ecosystem.

• Invasive and native species compete for food.



• Human activities such as open-pit mining, cutting down forests, and building highways can harm an ecosystem.

• Humans produce waste, which ends up in landfills. These landfills can pollute soil and water.

• Pollution is the contamination of air, water, or soil by substances harmful to organisms.


Humans Change the Environment

Humans Change the Environment


• Not all changes caused by humans are harmful.

• Conservation is the act of protecting ecosystems and the organisms living in them.

• Humans practice conservation by replanting trees, cleaning up pollution, removing invasive plants and animals, and caring for injured animals.


Gone!


• Some organisms do not survive changes in the environment.

• Extinction happens when all the members of a certain species dies.

• For example, giant reptiles like the Tyrannosaurus rex lived in a time when the Earth was warm. As the environment cooled, they became extinct.


Gone!


• Could the extinction of the dodo bird have been prevented? Why or why not?


U 5 lesson 3 integrado e.s. environmental changes

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