Humans change Ecosystems - Marana Unified School District

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Transcript Humans change Ecosystems - Marana Unified School District

Humans change
Chapter 3 Lesson 3
People change ecosystems all the time,
sometimes in harmful ways
• Air pollution can cause smog, a visible
layer of haze close to the ground.
• Introducing exotic species, that can
help or hurt ecosystems.
– How do you think that introducing an exotic species would hurt
an ecosystem? How could it help it?
• People have caused the
extinction of many
• Extinction- loss of an
entire species
• The greatest cause
of extinction today is
habitat loss.
• Pollution, hunting, and
competition from exotic
species also causes
• The government keeps
track of the number of
many species of plants
and animals. It lists
those that are
threatened or
• An endangered species
is one with so few
individuals that it
could die out.
• A wetland is an area of land covered
by water.
• The Everglades were once a huge
wetlands in Florida but have been
drained and filled by people over the
• People change Earth’s surface to
meet their needs. Some examples are:
– draining wetlands
– cutting down forests
– Change natural grasslands into farms
How can humans help?
• Laws have been passed in order to cut
back on pollution and protect the
• The U.S. government passed the
Endangered Species Act to protect
the habitats of endangered and
threatened species. Several species
have been saved from extinction.
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