Trophic Cascades and Ecosystem Dynamics in Yellowstone National Park

The video discusses the concept of trophic cascades, using the reintroduction of wolves in Yellowstone National Park as a case study. Wolves, absent for 70 years, were reintroduced in 1995, leading to significant ecological changes. They controlled deer populations, allowing vegetation to recover, which in turn supported diverse wildlife. The presence of wolves also affected river behavior, stabilizing banks and reducing erosion. Overall, the wolves transformed both the ecosystem and physical geography of Yellowstone.

What is a trophic cascade?

• A process where top predators are removed from an ecosystem.

• An ecological process starting at the top of the food chain and affecting the entire ecosystem.

• A method of controlling animal populations through hunting.

• A type of waterfall found in national parks.

What was the primary effect of reintroducing wolves to Yellowstone on the deer population?

• The deer population was unaffected by the wolves.

• The deer population increased significantly.

• The deer population remained stable.

• The deer population decreased due to hunting by wolves.

How did the presence of wolves affect tree growth in Yellowstone?

• There was no change in tree growth.

• Trees were cut down to make space for more wolves.

• Trees grew taller and more abundant as deer avoided certain areas.

• Tree growth was stunted due to increased grazing.

Which animal's population increased due to the wolves' impact on the ecosystem?

• Coyotes

• Lions

• Deer

• Beavers

What role do beavers play in the ecosystem as mentioned in the video?

• They are predators that hunt small mammals.

• They are ecosystem engineers that create habitats for other species.

• They are scavengers that feed on carrion.

• They are primary consumers that only eat grass.

How did the reintroduction of wolves affect the population of smaller mammals like rabbits and mice?

• Their population was unaffected by the wolves.

• Their population decreased due to increased predation.

• Their population remained unchanged.

• Their population increased as wolves reduced coyote numbers.

What change occurred in the rivers of Yellowstone due to the wolves?

• The rivers flooded more frequently.

• The rivers became more stable and less prone to erosion.

• The rivers dried up completely.

• The rivers changed color due to increased sediment.

Why did the rivers in Yellowstone become more stable?

• The wolves built dams in the rivers.

• The deer population increased, reducing soil erosion.

• The regenerating forests stabilized the riverbanks.

• The rivers were artificially modified by humans.

What was the overall impact of the wolves on Yellowstone's ecosystem?

• The ecosystem remained unchanged.

• The ecosystem deteriorated due to increased predation.

• The ecosystem was transformed, including its physical geography.

• The ecosystem became less diverse.

How did the reintroduction of wolves affect the physical geography of Yellowstone?

• It had no impact on the physical geography.

• It caused the rivers to dry up.

• It led to changes in river courses and reduced soil erosion.

• It resulted in the formation of new mountains.