Scientists around the world are collaborating to understand how deforestation, climate change, and natural processes will interact to affect one of the most productive and biodiverse ecosystems on Earth.
Researchers have measured the effects of periodic forest fires on primary productivity in Amazon rain forest plots, comparing years with average precipitation and years with severe drought. Propose which controls would be necessary for such studies.

The human-generated increase in greenhouse gases (see Module 38.3) provides many opportunities to study the effects of climate change. For example, snowshoe hares are adapted to the climate of their habitat in the taiga of the high mountains and northern regions of North America. One adaptation is seasonal changes in fur color—a white winter coat that turns brown in the spring—that camouflage hares from a long list of predators. These color changes are triggered by day length. As increasing spring temperatures cause earlier snowmelt in the taiga, biologists have observed many white hares sitting on brown earth. Suggest how this natural experiment could be used to investigate the effects of climate change on populations and communities in the taiga ecosystem (assume historical data are available).

Do you drink coffee? A lot of people do—coffee is a major tropical crop, valued at over $100 billion per year. The most popular species of coffee, Coffea arabica, originated in Africa and is now planted extensively in Central and South America. The pest called the coffee berry borer beetle (Hypothenemus hampeii) moved along with the coffee and is a major problem for coffee farmers, sometimes destroying half of the coffee crop in mature plantations.

Pesticides are generally ineffective in killing coffee berry borers. Ecologist Daniel Karp and colleagues conducted a study in Costa Rica to determine if natural predators like birds reduce the beetle population. The researchers selected 12 control plots and used nets to exclude birds from 12 similar treatment plots. What is the take-home message of the graph? (Remember, * means P < 6 0.05)

Scientists around the world are collaborating to understand how deforestation, climate change, and natural processes will interact to affect one of the most productive and biodiverse ecosystems on Earth.

Select True or False for each statement about the effects of clear-cutting on the Amazon rain forest, then explain your reasoning.

T/F Nutrient export is likely to decline.

T/F Atmospheric CO₂ is likely to decline.

T/F Soil moisture is likely to decline.

T/F Species diversity is likely to decline.

Do you drink coffee? A lot of people do—coffee is a major tropical crop, valued at over $100 billion per year. The most popular species of coffee, Coffea arabica, originated in Africa and is now planted extensively in Central and South America. The pest called the coffee berry borer beetle (Hypothenemus hampeii) moved along with the coffee and is a major problem for coffee farmers, sometimes destroying half of the coffee crop in mature plantations.

Look at the graph. Why did the researchers bother to collect data from the coffee shrubs before adding the nets to treatment plots to exclude birds?

Researchers studied active and abandoned pika colonies at two sites (one in southeast Oregon and one in northwest Nevada) to understand how elevation might influence pika range (see Module 38.0 and Module 38.11). Sites were classified as old (no longer occupied) or current. How would you summarize the findings?

Does this study support the hypothesis that pika ranges are shifting to higher elevations due to climate change?

What are some limitations to describing patterns in nature as compared to doing a controlled experiment?

Do you drink coffee? A lot of people do—coffee is a major tropical crop, valued at over $100 billion per year. The most popular species of coffee, Coffea arabica, originated in Africa and is now planted extensively in Central and South America. The pest called the coffee berry borer beetle (Hypothenemus hampeii) moved along with the coffee and is a major problem for coffee farmers, sometimes destroying half of the coffee crop in mature plantations. The abundance of birds and other predators of borer beetles depends on how much natural forest is left within and around the coffee plantations. What is the approximate percentage increase in borer predators per hectare if forest cover is doubled from 15 to 30 percent?

Scientists around the world are collaborating to understand how deforestation, climate change, and natural processes will interact to affect one of the most productive and biodiverse ecosystems on Earth.

This box-and-arrow model summarizes some of the feedback links observed in the Amazon rain forest. Select True or False for the statements that follow, based on whether they are represented by the model. (Note that the boxes and arrows in this model are used differently than those in the nutrient cycle models).

T/F The burning of fossil fuels increases atmospheric CO₂.

T/F Tree growth reduces atmospheric CO₂.

T/F The death of trees promotes the invasion of grasses.

T/F An increase in CO₂ increases the frequency of droughts.

T/F Drought increases the frequency of forest fires.

Do you drink coffee? A lot of people do—coffee is a major tropical crop, valued at over $100 billion per year. The most popular species of coffee, Coffea arabica, originated in Africa and is now planted extensively in Central and South America. The pest called the coffee berry borer beetle (Hypothenemus hampeii) moved along with the coffee and is a major problem for coffee farmers, sometimes destroying half of the coffee crop in mature plantations. Draw a simple model to compare the relative species richness and species diversity of these two coffee plantations: one is clear-cut and planted with only coffee shrubs, the other retains some natural forest. For symbols, use a few letters to represent different species of plants and a few numbers to represent different species of animals in a square 1-ha plot.