4.1 Climate
4.2 Niches and Community Interactions
4.3 Succession
4.4 Biomes
4.5 Aquatic Ecosystems
THE WOLF EFFECT
During the 1920s, hunting and trapping eliminated wolves from Yellowstone National Park. For decades, ecologists hypothesized that the loss of wolves—important predators of elk and other large grazing animals—had changed the park ecosystem. But because there were no before-and-after data, it was impossible to test that hypothesis directly.
Then, in the mid-1990s, wolves were reintroduced to Yellowstone. Researchers watched park ecosystems carefully and sure enough, the number of elk in parts of the park began to fall just as predicted. But, unpredictably, forest and stream communities have changed, too. Could a “wolf effect” be affecting organisms in the park's woods and streams?
As you read this chapter, look for connections among Yellowstone's organisms and their environment. Then, solve the mystery.
Never Stop Exploring Your World.
The mystery of the Yellowstone wolves is just the beginning. Take a video field trip with the ecogeeks of Untamed Science to see where this mystery leads.