By Dawna Matthews:
“When we try to pick out anything by itself, we find it hitched to everything else in the Universe.” – John Muir
Can one species completely alter an ecosystem? After reintroducing wolves intoYellowstone National Park, it appears to be true. At the time wolves were brought back to the park, it was quite controversial: many did not believe it would improve conditions or make any impact at all. Years later, we have been able to study the effects of this reintroduction and now understand that wolves have created quite a benefit to the park and its life force.
The Ripple Effect
The effect of the wolves on the ecosystem in Yellowstone is known as a trophic cascade. Historically, ecosystems were believed to be created from the ground up — from the plants, and then insects, rodents and various wildlife, leading up to predators. A trophic cascade is the reverse theory, literally like a cascade of water falling from the top and branching off into smaller tributaries to the bottom. It means that animals at the top of the food chain can cause a series of behavioral changes in the animals they prey upon (middle) that can lead to changes in plant growth (bottom) and even in geography.
In the instance of grey wolves being reintroduced to Yellowstone National Park, they restored equilibrium to the ecosystem as well as added biodiversity. Yellowstone National Park was established in1872, and at that time wolves were a part of life there. The wolves were eradicated early in the 1900s, as they were seen as a threat to the environment and many people saw them as “bad.” The role of the wolf and the importance they played in the life of the park was unknown.
Many decades passed without the wolf. As a result, the northern range elk population eventually skyrocketed. This large number of elk needed a large food supply so, in turn, they overgrazed and decreased vegetation.
The wolf was reintroduced into the park in 1995 after being gone for almost 70 years. Since the wolves’ presence in the park, the overpopulation of elk has been regulated and returned to historic normal levels, as the wolves hunt them for food. And the behavior of the elk has shifted. A report from Oregon State University further supports this by claiming the wolf has been the primary factor in the improved health and vegetation of plants and trees such as the aspen, willow, and cottonwood in Yellowstone National Park. The rejuvenation of these plants has benefitted wildlife in the area and enhanced the habitat for animals such as beaver, bison, raptors and trout.
The wolves’ trophic cascade has been a powerful, relatively quick, yet subtle success story of how we can restore what may have been lost, and how we can heal what we have hurt. We humans are at the top of the food chain. We play a great role in the impact of the earth; and we have the power to change a variety of habitats as diverse as kelp beds, mountain forests, tropical rain forests, salt marshes, and more. If one wolf pack can provide all these amazing benefits to its surrounding environment, just imagine what one of us can do.
“In wildness is the salvation of the world.” – Thoreau
For more information on the wolves and other wildlife in Yellowstone, visit: