The Encyclopedia Britannica tells us “Trophic Cascade” is the ecological phenomenon triggered by the addition or removal of top predators and involving reciprocal changes in the relative populations of predator and prey through a food chain, which often results in dramatic changes in ecosystem structure and nutrient cycling.
Said another way, trophic cascades are powerful indirect interactions that can control entire ecosystems; they occur when predators limit the density and/or behavior of their prey, which enhances the survival of the next lower trophic level.
Normally I don’t write about things circulating on the Internet (unless they’re light-hearted and somewhat humorous topics) but an email with an attached link to a particular video describing the impact of wolves in Yellowstone National Park piqued my interest.
Man began hunting wolves in Yellowstone National Park in the early 1900s. By 1926 the grey wolf had ceased to exist there (as well as in many other areas throughout the U.S.) Then, in 1995, wolves were reintroduced into the park and amazing things began to occur.
At the time, deer and elk were overrunning Yellowstone and the abundance of these ungulates was causing much of the park to be over-grazed and vegetation was beginning to disappear.
But soon after their reintroduction the wolves began to thin the deer and elk herds. As a matter of survival, these certivae started to avoid certain parts of the park, especially the valleys and gorges where they could be trapped most easily.
Before long the areas where the deer and elk had abandoned began to rejuvenate and in some areas the number of trees quintupled. By the early 2000s spaces that had been barren for decades began to grow willow and aspen forests.
As the forests spread, migratory birds and songbirds began to increase. The beaver population also increased and these semi-aquatic rodents not only ate these new trees but also cut many of them down. Beavers are the engineers of the animal world and the dams the beavers built created habitat for muskrat, otters, ducks, fish, reptiles and other amphibians.
The wolves also killed coyotes, which meant the number of rabbits and mice began to increase, which created food for hawks, weasels, foxes and badgers. Additionally, bears, eagles and ravens began eating the carrion from the wolf pack kills. The bear population further benefitted due to the nutrient-rich berries on the park’s regenerated shrubs.
The regenerating forests also meant less erosion, which stabilized the banks of the rivers, which then became more fixed in their course, which further resulted in permanent pools of water that in turn created even more habitat for wildlife. In essence, the reintroduction of wolves changed not just the eco system but also the physical geography of Yellowstone.
We can all learn valuable lessons from Yellowstone. A hundred years ago some rancher said, “Wolves kill livestock and must eliminated” and a series of deleterious unintended consequences was set into motion.
Unintended consequences are outcomes not intended by a particular action. All of us experience this to varying degrees in everyday life. Your wife decides to paint the bedroom and when it’s finished, the adjacent hallway suddenly looks dingy; so off you go next Saturday to buy paint for the hallway. You try a new fish recipe and the house smells of halibut for a week, or you get a raise and come April 15th you find you’re in a higher tax bracket.
Planet earth may be fragile, but it’s also resilient and sometimes something as simple as reintroducing a predator (in this case, wolves) can make enormous differences.
Predicting nature with absolute certainty is dangerous, and this is especially so regarding the topic of climate change. In his State of the Union Address the president said the “science is settled.” But there is nothing more anti-scientific than the notion that “the science is settled.” The president would have been more accurate had he said, “the ideology is settled.”
To paraphrase Charles Krauthammer, even worse than the pretense of “settled-ness” is the politically convenient attribution of any natural disaster to climate change. When snowstorms clobber the East coast repeatedly, blame it on climate change. Hurricane Sandy, of course it was due to climate change. The California drought—once again, it must be climate change. In fact I’m certain the sky is falling crowd would have us believe the Broncos Superbowl debacle was caused by climate change.
After the president’s visit to drought-stricken California in mid-February even the ever-liberal NY Times contradicted him pointing out that far from being supported by evidence, “the most recent computer projections suggest that as the world warms, California should get wetter, not drier in the winter.” So what was the president talking about? It sure wasn’t science!
No one argues the need to protect the environment. But before our government makes dubious proclamations that include wholesale ‘solutions’ to our changing climate, we should remember that a hundred years ago, people thought eliminating wolves was a good idea.
Quote of the day: “Only the wisest and stupidest of men never change”—Confucius