One of nature’s most interesting concepts is the idea of a trophic cascade.
Essentially, a trophic cascade is a top down cascade—where the food chain and subsequent ecosystems are changed by removing the top predator from the area. The consequences can be grave. However, when that predator is reintroduced some amazing things can occur.
This was witnessed most miraculously in Yellowstone National Park when wolves were reintroduced back into the landscape in 1995. For 70 years wolves had been absent from the park, which caused the deer population to grow to an unmanageable degree. The deer were grazing everywhere and had devastated the vegetation in the park to almost nothing.
Once wolves were reintroduced to the area they had an immediate and rippling effect. Yes, the wolves did kill some deer, but more importantly they changed the behavior of the deer. The deer could no longer roam wherever they wanted, so now the valleys and gorges the deer used to eat from started to be reborn. Entire hillsides and valleys rejuvenated and vegetation flourished. Even some tree heights quintupled in only 6 years.
As a result of the trees coming back, songbirds as well as beavers, which like to eat the trees, came back. The beavers built dams and helped foster smaller ecosystems for abundant amphibian life.
The wolves also killed coyotes, and as a result mice and rabbit population grew which meant more hawks, foxes, and weasels. Even bear populations grew and began to feed on carcasses the wolves left, or the berries of the rejuvenated trees. Wolves were changing the entire ecosystem and landscape of the park.
The most interesting result however was the fact that wolves actually changed the behavior of the rivers. The rivers now didn’t need to meander so much, so they grew stronger and more centralized. With the growth of trees and added vegetation, the riverbanks became stronger and more reinforced. Larger pools of water started to form, which helped entire groups of animals.
Nature is amazing for many reasons, one of which is this ripple effect, and the notion that the entire way nature works revolves around deep relationships and connections to something else.
Just a simple act of reintroducing wolves changed an entire landscape, and an entire ecosystem.
The wolves didn’t just help grass grow and animals to flourish, they also changed the way rivers flowed, and brought back a variety life to the park.