Chapter 2: Principles of Ecology

Ch. 18 Notes-Part II
Succession
What is succession? Changes over time. Succession can occur in decades or even centuries.
It can take a really long time.
If you didn’t cut the grass, what would happen to it?
1) It would grow larger
2) Weeds would start to grow
3) The area will look like a meadow
4) Bushes will grow
5) Trees will appear
6) Less light will reach the ground b/c
of the trees
7) The grass will slowly disappear
8) The area will become a forest
Stages of succession
1) Primary succession – colonization of new sites by organisms
Example) Lava from a volcano, an avalanche makes new territory for organisms
2) Climax Community – A stable, mature community that undergoes little or no change in
species
3) Secondary succession – sequence of community changes that takes place after a
community is disrupted by natural disasters or human actions (occurs in areas that
previously contained life, and on land that contains soil)
Example) Forest fire, hurricanes, farmers abandon a field, a building is demolished
BIOLOGICAL DIVERSITY & CONSERVATION
Biodiversity – variety of life in an area (More biodiversity in the warmer environments)
Threatened species-Endangered species-Extinct species
Threats to Biodiversity
1) Habitat loss – when rainforests and coral reefs are wiped out
2) Habitat fragmentation – separation of wilderness areas from other wilderness areas
(like islands)
3) Edge effect – when climate is changed along the edge of an ecosystem
4) Habitat degradation – damage to a habitat by pollution
5) Introduction of exotic animals – introducing a new species into an ecosystem
Conservation biology – new field that studies method and implements plans to protect
biodiversity
How to conserve
1) Legal protection – no one can hunt or kill any animal on the endangered species list
2) Preserving habitats – installing national parks
3) Reintroduction programs – bringing species back to where they once lived
4) Captivity – people holding onto organisms in a zoo
Cycles in nature
There is only a limited amount of resources (water, oxygen, nitrogen, carbon) on the earth
In order to keep these resources available to organisms, they must be recycled after they
are used
Cycle: a process that recycles a resource so that you end up with what you started with
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