Don't judge species on their origins

They’re treated as outsiders, as opportunity-stealing intruders who ought be greeted with government crackdowns rather than open arms.

They’re immigrants — immigrant species, that is. And some ecologists say it’s time to declare amnesty, demilitarize our environmental borders and accept the inevitable reality of non-native invasion.

“People like to have an enemy, and vilifying non-native species makes the world very simple,” said ecologist Mark Davis of Macalester University. “The public got sold this nativist paradigm: Native species are the good ones, and non-native species are bad. It’s a 20th century concept, like wilderness, that doesn’t make sense in the 21st century.”

Davis is one of 18 ecologists to sign a June 9 Nature essay entitled, “Don’t judge species on their origins.” They argue that while some non-natives are indeed destructive, such as Guam’s brown tree snakes and Great Lakes zebra mussels, they’re the exception.

Most are actually benign, relegated to a lower-class status that reflects prejudice rather than solid science, write the authors. Non-natives are assumed to be undesirable, and their benefits go ignored and unstudied.

‘To value the nature we actually have, and are creating, we need to think broadly…. Nature is something we create now.’

Sitka Spruce plantation - Galloway

As examples of unfairly maligned invaders, the authors mention Australia’s devil’s claw plants, subject to a 20-year-long plant hunt that’s done little to contain a species that may cause little ecological disturbance. In similar fashion, tamarisk trees in the U.S. southwest have been targeted for 70 years by massive eradication programs, but are now seen as providing important bird habitat.

“Classifying biota according to their adherence to cultural standards of belonging, citizenship, fair play and morality does not advance our understanding of ecology,” wrote the essay’s authors. They also consider ecological nativism to be hypocritical — nobody’s complaining about lilacs or ring-necked pheasants — and a form of denialism: In a globalized, human-dominated world, plants and animals will get around.

“Most human and natural communities now consist both of long-term residents and of new arrivals,” they wrote. “We must embrace the fact of ‘novel ecosystems.’”

 Matt