During the Carboniferous period, plant growth was extensive but rates of decomposition slowed (probably due to the formation of vast, oxygen-poor swamp habitats). As a result, large amounts of biomass accumulated in terrestrial environments (much of this biomass is now coal). The fossil record indicates that atmospheric oxygen increased, atmospheric carbon dioxide decreased, and global temperatures dropped. Explain why.

Which of the following actions can reduce humanity's ecological footprint?a. reducing our dependence on fossil fuels;b. reducing meat consumption;c. living in higher density settlements;d. better management of human wastewater;e. all of the above

One advantage of preserving more than one population of an endangered species at more than one location is .a. a lower risk of extinction of the entire species if a catastrophe strikes one location;b. higher levels of inbreeding in each population;c. higher rates of genetic drift in each population;d. lower numbers of heterozygotes in each population;e. higher rates of habitat fragmentation in the different locations

What are 'greenhouse gases'? Why are they important to life on Earth?

The maps shown here chronicle the loss of old-growth forest (more than 200 years old) that occurred in the United States. In your opinion, under what conditions is it ethical for conservationists who live in the United States to lobby government officials in Brazil, Indonesia, and other tropical countries to slow the rate of loss of old-growth forest?

What are the causes and possible consequences of climate change? Why is international cooperation necessary if we are to solve this problem?

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.Based on what you have learned in this chapter about global trends in terrestrial ecosystems, what is currently the largest threat to the wet tropical forests in Central America?a. habitat destruction, such as the clearing of forests for coffee plantationsb. exotic species, such as the introduction of coffee berry borersc. pollution, such as the use of pesticides in coffee plantationsd. climate change, such as changes in precipitation patterns

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.a. temperate forestb. tropical dry forestc. tropical grasslandd. tropical wet forest

SCIENTIFIC THINKING 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).