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Ecosystem Formation
Ecosystems tend to change over a long period of
time until a stable ecosystem is formed.
Both the living (biotic) and nonliving (abiotic) parts of
an ecosystem change.
The replacement of one kind of community with
another is called ecological succession.
The kind of stable ecosystem that develops in a
particular geographical area depends on climate.
Mrs. Degl
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Pioneer Organisms
Succession begins with pioneer organisms,
which are the first plants to populate and area.
Lichens and algae are usually the
pioneer organisms on bare rock,
found on a newly emerged
volcanic island. Lichens on volcanic rock
New York State typical plant succession is:
1. Lichens
2. Grasses
3. Shrubs
4. Conifers (pine trees)
5. Deciduous (beech and maple trees) forest
Mrs. Degl
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Climax Communities
Succession ends with the development of a climax
community. This is when plants and animals exist
in balance with each other and the environment.
The climax community remains stable until a
catastrophic change. Examples of such changes
are volcanic eruptions or forest fires.
After this event, succession begins again and
ends in another climax community which can
either be the same or different than the previous
one.
Mrs. Degl
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Biodiversity
A stable ecosystem requires biodiversity. Biodiversity is
the presence of a wide range of different species of
organisms living and interacting with each other and the
environment.
The removal of one species from the ecosystem may have
profound negative effects on the overall health of the
ecosystem.
Biodiversity increases the probability that some organisms
would be able to survive a catastrophic event and
reestablish a community.
Mrs. Degl
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Stable ecosystems with many different species
contain a wealth of genetic material that may
have beneficial uses in medicine, agriculture, or
other areas.
Today tropical rain forests, wetlands, coral reefs,
and other ecosystems with biodiversity are being
destroyed at alarming rates.
Once a species is lost to extinction, it cannot be
brought back.
Careful protection of these places should be a
priority for the planet. Mrs. Degl
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Mrs. Degl
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Overall, the tropical rainforests that we have come to
know and love are disappearing at a fast and seemingly
unstoppable rate. Brazil and Indonesia, which contain some
of the world's largest surviving regions of rain forest, are
being stripped by logging, fires, and land-clearing for
agriculture and cattle-grazing. To date, we are losing
approximately 150 acres of rainforest every minute. If this
rate of deforestation continues, we could lose all the world's
rainforests within 100 years, causing unknown effects on
the climate and destroying the majority plant and animal life.
International efforts are being made to preserve the forestsin Costa Rica, for example, more than 35% of the country is
a national park - but in many countries deforestation is
continuing at a fast rate.
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Besides destroying
species and possible
medicines, what
effect does
deforestation have on
global warming?
Mrs. Degl
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