Take a few minutes to watch this interesting short showing the effects that one change to an ecosystem can have on the environment as a whole.
Trophic cascades occur when predators in a food web suppress the abundance or alter the behavior of their prey, thereby releasing the next lower trophic level from predation.
Just 14 wolves were re-introduced into Yellowstone back in 1995 after being extinct in the national park since 1926. They slowly and steadily increased in number, but the effects on the park seemed to be evident much sooner. It became readily apparent that these few animals were having a rather obvious, dramatic, and positive impact on the regional ecosystem. Take a look at the video for more information.