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Why do ecosystems change?
Living things
1
35
What living things are found in this habitat? Listen
and make a list.
G
E T T I N G S T A R T E D
What causes natural changes?
Natural changes in ecosystems are caused by
variations in environmental conditions, such as
seasonal changes or the natural development
of ecological communities.
In a chaparral ecosystem, winters are mild and
rainy, but summers are hot and dry. Fires are
frequent in the summer because the small bushes
that grow in this ecosystem burn easily. Often
the fires are caused by human activity, but
sometimes they are caused by lightning.
After a fire, the bushes grow again, but it may
take two years. Smaller plants predominate
in the area until the bushes grow back.
What consequences does human activity have?
Human activities such as
pollution
,
overfishing
, forest fires and
deforestation
can destroy
habitats or entire ecosystems. This destruction can lead to the extinction of many species.
Pollution
Human activities often release dangerous substances
into the air, water or soil. For example, waste from some
industries can kill
many organisms
and destroy entire
ecosystems. As a
result, many fish,
birds and other
animals lose their
habitats and may
become extinct.
Overfishing
Humans take a lot of marine animals from
the sea. This causes changes in the food
web of marine ecosystems. As a result,
the animals that feed on those fish may
become extinct.
Ecosystems change over time. Sometimes the changes are
natural, but sometimes they are caused by human activity.
Before a fire.
After a fire.
The Baiji dolphin
recently became extinct
because of shing activity
in its habitat.
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