George Monbiot explains how reintroducing wolves to Yellowstone National Park after a 70-year absence set off a “trophic cascade” that altered the movement of deer, sent trees soaring to new heights, attracted scores of new animals to the area, and stabilized the banks of rivers making them less susceptible to erosion.
Worth watching just to hear the howling of the wolves!
(Source: https://www.youtube.com/)
Key and Teeth 