"Competition": Perceptions & Preconceptions (1 of 2)
On the "struggle for life" as handed down from Darwin
The most common accusation leveled against “invasive” plant species is that they “outcompete” native species; that they “aggressively” and “ruthlessly” “encroach on,” “choke out,” “push out,” “bully,” and “displace” native plants and that they “take over” ecosystems, “degrading,” “disrupting” and “destroying” them, causing “ecological havoc.” Our response must be a declaration of “war” where we “push back,” “stem the influx,” and “turn back the tide” by “fighting,” “battling,” and “combating” them, in order to “wipe out,” “purge” and “eradicate” them. We’re given a picture of monsters we must kill in order to save helpless victims from being gobbled up. As an image to incite fear and enmity against supposed villains, it’s very effective. But as a way of understanding ecological interactions, it’s misleading, and as a starting point for making intelligent choices, it’s counterproductive.
Many of us have heard the horror stories about remote islands where, say, a population of native ground-nesting birds was driven to extinction by rats who escaped from a colonizer ship. Such events are tragic, certainly—and also rare—but is that how it works in the plant world? We wonder if people think so, given all that militant verbiage. Obviously though, plants are not analogous to animals in terms of either mobility or appetite.
Do introduced plant species have effects in their new environments? Yes, because all plant species have effects in their environments, no matter how long they’ve been there. Do introduced plants “compete” with native plants? They can, but this is where it gets complicated. Though “competition” is considered a major factor in the make-up of plant communities by biologists, they are not in agreement about its definition, mechanisms, measurement, or how to differentiate its effects from other processes. In other words, the question, “Did x outcompete y?” is not easy to answer.
Before we get into the science of competition, however, we must take a look at how the current conversation started, with the work of Darwin.
Keep reading with a 7-day free trial
Subscribe to Speaking for the Trees, No Matter Where They're From to keep reading this post and get 7 days of free access to the full post archives.