Is it time to challenge the conventional wisdom about alien or exotic species? Not surprisingly, a growing number of biologists are questioning whether aliens are truly detrimental to ecosystems and whether pristine ecosystems actually exist.
Fred Pearce, a freelance author and journalist based in the United Kingdom (U.K.) and environmental consultant for New Scientist magazine, asks, “Are our ideas about what we label as pristine nature faulty?”
Pearce reminds us that, “The good news is that nature emerges as resilient and adaptable, able to bounce back from the worst we can throw at it.”
The general public has been indoctrinated to believe that non-native species are inherently bad and when they show up in an ecosystem they must be removed regardless of the costs of doing so.
Mark A. Davis, chair of the biology department at Manchester College in St. Paul, Minnesota and author of a book titled Invasion Biology, holds the view that we should learn to love most exotic species because they are here to stay and many of them do no harm. In fact, an exotic species that truly fits the definition of an exotic or an alien species is the honeybee.
British settlers brought bees with them in the early 1600s for the honey and the wax they produced. No one questioned their first entry to North America or the regular arrival of new stock to replace those that have died in vast numbers, probably because of pesticides.
Davis states that the belief that the spread of exotic species will drive native species to extinction rarely happens except in insular environments such as lake ecosystems or islands. He claims that the opposite occurs--that the introduction of an exotic species adds to species richness in an ecosystem.
Does the presence of exotics signify a “degraded” ecosystem? Davis claims that there is no such thing as a healthy ecosystem or a sick ecosystem. Ecosystems are just where we find them and they have no particular goal or purpose. “They’re just the species and the physical and chemical processes taking place.”
The late Stephen Jay Gould, evolutionary biologist, scientist, professor at Harvard University, and author argued that the movement of species around the world should be seen as part of the evolutionary process rather than a destructive force. In 1998, Gould claimed that the discussion of native plants “encompasses a remarkable mixture of sound biology, invalid ideas, false extensions, ethical implications and political usages.”
Dov Sax, biologist in the Department of Evolutionary Biology at Brown University, Providence Rhode Island, believes that the human population will be unable to control the exotics that reach ecosystems everywhere through global trade and travel.
Sax suggests that our future landscapes and waterscapes will be home to “novel ecosystems.” agglomerations of species that have never been seen before.
The human population likes to think that nature was pristine and untouched until a couple hundred years ago, but that idea has been refuted by Erle Ellis, a geographer at the University of Maryland Baltimore County and some colleagues who have calculated that one-fifth of the landscapes around the world were first modified by humans some 5,000 years ago rather than in more recent times, as is the common belief.
Does any of the foregoing information matter to those of us who live in the Boundary region where the management of the watershed is in sharp focus? Is there any better time than the present to examine the way we define healthy ecosystems and what the flora and fauna they contain, if we need to define them at all? Will we change our minds about how ecosystems work?
Now may be a good time to heed the words of Mark Davis: “It’s very important to distinguish harm from change.”