Briefly explain how the increase in elk population affected the river banks

Elk are vegetarians and they bring down the willows on the bank affects the quality of soil in the river banks.

EXPLANATION:

Elk mainly eat grasses and also shrubs. Recent studies in Yellowstone National Park have shown that an increase in elk population causes the willows on the banks of the river to come down. As a result of which soil was not stabilized and the quality of water was decreasing.

So, to save the ecosystem, wolves were brought back to Yellowstone National park. Wolves eat the elk and therefore reduces their population in the ecosystem. This increases the vegetation by improving the quality of soil at the banks. Finally, the water in the banks are free from the willow deposit.