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Name: _____________________________________________
Ecosystem Balance
Environmental Science
E4
Stability in the Ecosystem
Stability is a measure of how ______________ an ecosystem is affected by a disturbance and how
_________________ it returns to its original condition after a disturbance
• The original condition for an ecosystem includes its ________________ and ________________
components as well as the ___________________ of energy flow and nutrient cycling
• _______________________ structure is also an important aspect of ecosystem stability
• A more ________________ ecosystem will return to a steady pattern of energy flow and nutrient
cycling with ______________ evolutionary, food-web, and abiotic environmental _____________
• Averaged over longer periods and larger areas, even __________________ disturbed ecosystems
can show ____________ ________________ of stability
Stability and Food Webs
Ecosystem stability may be related to the complexity of the ____________ ____________
• More connections in this web may _____________________ the overall ___________________ if a
single species is lost or one part of the system is disrupted
• Changes would be counteracted by changes in _______________ parts of the system, such as the
________________________ of adaptations to cold weather
• The disrupted ecosystem will return to a state of balance, called ______________________
Disruptions in the Ecosystem
_____________ disruptions can cause _______________________ changes as the ecosystem adjusts to
new conditions
• Some disruptions can even destroy ______________ ecosystems
• But a ___________ ecosystem will develop to replace the one destroyed
• The evolution of ________________ after the extinction of the ________________________ is an
example of a changing ecosystem
The general rule is: Species and whole ecosystems _______________ and may _________________,
but __________ species and ecosystems can evolve to __________________ them
Using Math to Understand the Ecosystem
Scientists do not understand every _____________ of how even ______________ ecosystems function
• They do understand that, like falling dominoes, ______________________________________ of a
system can _________________________________________________________________
• But they cannot always _________________ ________ changes in one part will _______________
another part
Ecosystem Balance
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•
E4
Recently, a few scientists have tried to apply a kind of mathematics called ___________________
to the problem
Chaos theory suggests that ecosystems may be sensitive to very ____________ changes, and that
the ________________ state of an ecosystem is crucial to its _______________ development
Extinction Rates
At present, species are becoming extinct at the _________________ ___________ since the extinction
of the dinosaurs
• The growth of the _______________ population may be ________________ more extinctions than
any other factor
• Major human __________________
• _______________ destruction
• Introduction of _________________ species to new ecosystems
• ______________________ of fresh water
• It is very difficult for scientists to predict the __________ ____________ ______________ of these
disruptions on the biosphere and its ability to support the human population
Section Review (15 Points)
1. Why is the study of ecosystems so complex? (1 points)
2. Besides humans, what are 6 factors that can influence the stability of an ecosystem? (6 points)
3. Why is an ecosystem stable? How does it react to a change in one of its parts? (4 points)
4. When scientists say that the balance in an ecosystem is dynamic they mean that (1 point)
a. niches are unstable
b. change is constant
c. animals migrate
d. humans alter habitats
5. If an ecosystem is disturbed, goes out of balance, and cannot return to a state of equilibrium, the
species living there will most likely (1 point)
a. become extinct
b. find new resources
c. become a climax community
d. move
6. When applied to ecology, what does the new field of mathematics called chaos theory imply?
a.
b.
c.
d.
Ecosystems are really not balanced
Organisms are constantly changing to meet new conditions
Interactions in ecosystems can never be understood.
One small change in an ecosystem can lead to drastic results.
7. Stability returns to disrupted ecosystems because (1 point)
a.
b.
c.
d.
organisms remain stable
conditions return to normal
ecosystems adjust to new conditions..
ecosystem disruptions are never catastrophic.