Big Idea: Nature is very complex, and small actions by people can make a big difference.
1.
Suppose you wanted to learn more about the behaviors of Pacific Tree Frogs in the forest ecosystem, and decided to set up a terrarium as shown below:
Describe two ways the model might be unable to reliably predict the behaviors of frogs in the forest.
In your description, be sure to a.
Identify two ways the model is different from the forest. b.
Describe how each way prevents you from making reliable predictions about the behaviors of the Pacific tree frog in a forest ecosystem.
2.
Snakes eat frogs. When the population of frogs increases, the population of snakes increases. This in turn causes the frog population to decrease. Is this an example of a positive feedback system or a negative feedback system? Explain your answer.

3.
Pollution from people’s cars can affect animal and plant life in the forest ecosystem. Describe why adding car exhaust to the forest model you constructed in question #1 may be unable to predict the consequences of car pollution in the surrounding forest ecosystem.
In your description, be sure to
 Identify a way that car exhaust could affect the forest ecosystem.
 Describe why the forest model may be unable to reliably predict the consequence.
4.
Population density is a measure of how many individuals animals or plants there are in a particular area.
For example, if there were ten worms in a square foot of topsoil, the population density would be 10 worms per square foot. What would be the population density of…. a.
2 owls in 5 square miles of forest? _________ owls per square mile. b.
6 crayfish in 150 square meters of a stream. ___________ crayfish per square meter.
5.
Sometimes invasive animal or plant species come to Washington State from elsewhere by hiding in cargo ships, trains, or trucking containers. An example would be the Eastern gray squirrel, which originally came from the east coast and compete for food with Western gray squirrels. Local wildlife biologists want to solve the problem of increased eastern gray squirrels in our area.
One criterion for measuring the success of a solution to this problem would be a reduction in the population of Eastern gray squirrels. Describe a different criterion for measuring the success of a solution to the problem.

6.
One way to solve the Eastern gray squirrel problem is to trap and move them to another location.
Describe one unintended consequence of trapping or moving the squirrels other than the possible death of the squirrels.
7.
Two possible solutions to the squirrel problem are
 Solution A: Use a natural predator of the eastern squirrel.
 Solution B: Educate shipping and trucking companies about how to check more carefully for invasive species.
Describe a way to test whether Solution A or Solution B is more effective at reducing the eastern squirrel population.
Be sure your description includes:
 A method for testing each solution.
 The data to be collected to determine whether Solution A or Solution B is more effective at reducing the eastern squirrel population.