“INVASIVE” SPECIES

Competition between Plants: What Biology Says

It’s not as simple as two boxers in a ring

Russian Olive (Elaeagnus angustifolia) foliage and berries, as observed on a tree growing by an irrigation ditch in Fruita, Colorado

The following is a draft chapter from the book that Nikki Hill & I are writing, tentatively entitled, “Don’t Blame the Messengers: A critique of the ‘invasive plant’ narrative.”

The most common accusation leveled by the “invasive plant” narrative is that introduced plants “outcompete” native species. As the story goes, they “aggressively” and “ruthlessly” “encroach on,” “choke out,” “push out,” “bully,” and “displace” native plants and that they “take over” ecosystems, thereby “degrading,” “disrupting” and “destroying” them, causing “ecological havoc.” The human response must be a declaration of “war” in which 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 presented with a picture of horrible monsters we must slay 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 how does it stand up as way of understanding ecological interactions?

Turning to science, let’s look at how biologists define “competition.”