Ecology is a rather young science, being more the province of the leisurely hiker than the hard-nosed sceptic. Often ecological writings are wishy-washy and vague. In contrast, this Scientific American article recounts a very specific and surprising example of the impact of a single species on a particular ecology. William J. Ripple, professor of botany at Oregon State University, has been studying the reintroduction of wolves into Yellowstone National Park.
In Yellowstone, the last wolf died out in the 1920's, which lead to the overpopulation of the elk population in Yellowstone. The engorged elk population exerted a severe pressure on the ecosystem. In 1995, to control the elk population, wolves from Canada were reintroduced back into Yellowstone.
As expected, the wolves quickly reduced the elk population. What was not expected was that the trees would come back just as quickly.
Elks, when they do not have to worry about wolves, are indiscriminate eaters, happy to munch on any vegetation they can find. Scared elks graze differently. Instead of dining lazily on delicate river-side vegatation in the Lamar Valley, scared elks must dine on higher ground where they can keep a look-out for wolves - wolves that smack their lusty lips at the thought of elk-meat.
During the 1920's, when the elks could eat indisriminately, magnificent trees, such as aspens and cottonwoods, stopped regenerating. Without the wolves running around in the park, when the elks got the pick of young juicy treelings. But now that the wolves back in town, the elks can't eat just anywhere, they have to watch their back like mafia gangsters dining on pasta in their favourite diner in Little Italy. The elks have to avoid exposed areas, the areas that treelings like to spread their leaves to grow.
Thanks to the wolves, young aspens and cottonwoods trees are sprouting all over the Lamar Valley again. And so, the moral of the story is: discriminate meat-eating is the best possible thing you could do to save the trees.
