Amy Crawford: Need to Rethink Alien Species


In the 19th century, European and American landscape architects expressed a patriotic pride that was sometimes tinged with nativist suspicion of “foreign” plants. In the 1930s, the Nazis took this concept to the extreme with a campaign to “cleanse the German landscape of unharmonious foreign substance.” One target was an unassuming Eurasian flower, Impatiens parviflora, which a 1942 report condemned as a “Mongolian invader,” declaring, “[A]n essential element of this culture, namely the beauty of our home forest, is at stake.”

Today’s critics of invasive species rhetoric are quick to clarify that they aren’t calling their colleagues racist. But Macalester College ecologist Mark Davis, for one, questions whether our modern campaign against non-native species has gone too far.

Davis is perhaps the field’s most notorious heretic, lead author of a widely-read 2011 essay in the journal Nature, co-signed by 18 other ecologists, that argued for judging non-native species based on environmental impact rather than origin. He believes that invasion ecology has been led astray by its central metaphor: the idea that non-native species are invading native ecosystems, and that we are at war with them. “Militaristic language is just so unscientific and emotional,” says Davis. “It’s an effective way to bring in support, but it’s not a scientific way.”