Date ______
Energy in Ecosystems
Name ____________________
Go to http://www.learner.org/courses/envsci/interactives/ecology/producers.php and open simulator.
Part 1: The Producers Competition
Imagine the ecosystem is newly forming—the
previous ecosystem has been destroyed by
fire or flood—and the first colonizers of the
successive ecosystem are, of course,
producers. Given the two species of plants in
the simulator (Plant A & Plant B), predict
what will happen in this young system. Then
run the simulator to 100 time steps and
record the population numbers for both
plants.
1. Describe what happened to the populations of Plant A and Plant B by the end of the simulation.
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2. Explain why one species of plant may be more successful than another species of plants.
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Part 2: Primary Consumers
Reset the simulator. Now you'll introduce an herbivore into the environment. In theory, an herbivore native
to the ecosystem should feed primarily on the dominant species. In this system, the herbivore may consume
enough of the dominant species to give the
non-dominant species a chance for
proliferation and survival. Click on herbivore
A (the rabbit) and choose "eats plant A."
Predict and record what will happen to the
population numbers in the ecosystem. Then,
run the simulator and record your results.
3. Record your results in the space below.
Date ______
Energy in Ecosystems
Name ____________________
4. Looking at the graph above, what happens to the plant populations when the rabbit population is at
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its highest point?
5. Why must the rabbit population always be less than the population of plants A and B?
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6. Explain why adding an herbivore is necessary for Plant B to survive.
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Part 3: Food Chains
Choose only one organism from each trophic
level and make sure that the food chain goes in
a straight line from one trophic level to the
next, i.e., Herbivore A eats Plant A, Omnivore A
eats Herbivore A, and the Top Predator eats
Omnivore A. Run the simulator to see how the
population changes after 100 time units.
7. Record your results in the space below.
8. What trend did you see when looking at the population size and the trophic level of each organism?
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9. Remove the top predator from this food chain and re-run the simulation. Did the top predator have a
large effect on other populations? Explain. _____________________________________
_________________________________________________________________
Energy in Ecosystems
Date ______
Name ____________________
10. What would happen to this imaginary ecosystem if the producers were to die out?
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Part 4: Food Webs
Now try a more "real-life" scenario and
experiment with what might happen in an
ecosystem that is more like a food web. This
time click the "all on" button. The model
shows who eats who and the paths by which
energy is transferred. Run the simulation once
and record the results in your Data Table.
(HINT: move your cursor over the lines on the
graph to show the exact population size)
11. Complete the data table.
Species
Ending
Population
12. Why do you think that the ominvores were unable to survive?
Plant A
Plant B
Plant C
13. Why do you think that Plant C was unable to survive?
Herbivore A
Herbivore B
Herbivore C
Omnivore A
14. Explain why the top predator was able to survive even after
both omnivores died out?
Omnivore B
Top Predator
Part 5: Creating a food web
Use the simulator to create a food web where every organism survives. Use lines to show the feeding
relationships in the diagram.