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Essay Instructions: Please separately explain the answers to these questions. It is preferred to explain them in simple terms than to quote extensively from research material.

1. We hear the word ecosystem used frequently in the news today. In your own words, explain what an ecosystem is. Be specific.

2. Is the biosphere a single ecosystem or an aggregate of many ecosystems? Explain the reasoning behind your answer.

3. Select an ecosystem (pond, salt marsh, deciduous forest, old field, etc.) and explain a food web that occurs in that ecosystem. You may use a diagram if you wish. Label plants and animals as specifically as possible and indicate the trophic level they occupy. Make sure you include decomposers.

4. It is intuitively obvious that there are few large predators in an ecosystem; there is even a book about why large, fierce animals are rare. The grizzly bear requires any where from 11 square miles to 1000 square miles of habitat for its home range. The average in the Brooks Range of Alaska where there is minimal human interference is 521 square miles. Range size seems to be at least a factor of richness of food supplies. From your knowledge of energy flow, trophic structure and ecological pyramids, explain why the grizzly bear needs such a large range to survive, or , as it is put in Asia, why there is only one tiger to a hill.

5. Using nitrogen as an example, explain how biogeochemical cycles work. How is nitrogen "lost" from ecosystems and how is it "replaced"?

6. When a farm is abandoned, as has frequently happened in most parts of the country, the land goes through a series of changes. Assuming this has happened near where you live, describe what would happen to the ecosystem--be specific. How does this differ from primary succession?

7. A corn or cotton field has very little biotic diversity; that is intentional in this case. Farmers spend a great deal of time money, and energy maintaining this "simple" ecosystem. Compare this type of ecosystem with a mature forest ecosystem in terms of stability and identify the factors which account for this difference.

8. Select one of the human interactions that you investigated in the module and discuss the following:

How has this particular interaction affected the environment.?

What attempts have been made to counteract the negative affects?

What do you think the future results will be of this continued interaction?

Essay Instructions: Essay 1

Read the following Articles then answer the questions provided below:

a. http://kanat.jsc.vsc.edu/student/callahan/mainpage.htm

b. http://www.mongabay.com/brazil.html

Question 1

Logging and slash and burn agriculture are two major contributors to deforestation. Three other major factors are?

Question 2

List five major negative impacts of deforestation on forest ecosystems:______,________,__________,
________ and _____________?

Question 3

What are two ways you could slow down the rate of forest deforestation considerably: __________ and ___________.



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Essay 2


Review the following newspaper article on deforestation. This is a news article without data: "Farming in the rainforest can preserve biodiversity, ecological services"., located at http://news.mongabay.com/2007/0305-sulawesi.html

a. Name two types of data you would like to know regarding the situation in order to academically assess the situation. Be specific and academic. Additonally, explain why these types of data are important.

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