“When we try to pick out anything by itself, we find it hitched to everything else in the Universe.” – John Muir
The game Okami is a beautiful title that puts you in control of Amaterasu, the Shinto goddess of the sun, who comes to earth in the guise of a white wolf. Throughout the game your goal is to heal the world around you, giving life to plants and animals. The actions of the game, in essence, involve nature fixing itself. While Okami was not necessarily created with the purpose of displaying the importance of biodiversity in ecosystems, the wolf-like goddess affects her environment much like real wolves do in their natural world. Wolves have such a massive impact on eco-systems, in fact, that their very existence changed the geography of a landscape.
This geographic change in a landscape is due to where wolves fall in a natural phenomenon called a Trophic Cascade: a pattern that follows the interruption of the flow of a food chain from top-to-bottom. Top predators of the cascade, such as wolves, have the largest effect on the environment. This means that if a top species is removed from an eco-system, it could have drastic effects.
When wolves were removed from Yellowstone National Park, the biodiversity of its 3,468 square miles dwindled. Small predators began to dominate, killing rodents and fish while leaving the elk population entirely free to grow–their only population control now relying on human hunting. As a result, the elk, too big in number to be supported by the park’s resources, destroyed what little lush vegetation there was. Without vegetation, river banks became unstable and eroded. Trees couldn’t grow. As a result of the lack of nutrients, the animals that relied on the vegetation of the park left in search of food or died of starvation.
In 1995, scientists reintroduced wolves to Yellowstone in order to study their behavior–and they received far more than just behavioral data. The studies revealed that, as wolves spread through the park, elk populations began to decline. The wolves sprang quickly on the heavy elk populations, increasing their own numbers while selectively killing their prey and driving them away from areas that were at high-risk for vegetation loss (e.g., river edges, open valleys, and meadows). This herding allowed Aspens and willows to grow, which attracted songbirds to nest. Beavers returned and built dams, which supplied habitats for otters, ducks, and fish.
The wolves also killed coyotes, which made room for rodents to return. The rodents then attracted ducks, Bald Eagles, weasels, and badgers. And lastly, after a few years, the rivers themselves began to change their structure and activity–their banks calmed by the vegetation. The rivers slowed and stabilized because the plants around them prevented soil erosion. That action, in turn, created more pools which, in turn, created even more habitats for the animals. The situation in Yellowstone is eye-opening because it shows us how fragile and connected things are. A single species, just one, changed the geography of an area simply by existing in it. By removing and reintroducing a species, we bear witness to the direct correlation of cause and effect in ecosystem chains. It echoes the words of naturalist John Muir, who said, “When we try to pick out anything by itself, we find it hitched to everything else in the Universe.”