August 1, 2011 | 8:22 AM | By

Rethinking the war on invasive species

FILED UNDER: Adaptation

N Sloth / Biopix

Purple loosestrife (Lythrum salicaria) is an aquatic plant that is native to Europe and Asia. It was introduced to the U.S. in the early 1800s via ships' ballast and as an ornamental plant. It is considered a pest because it crowds out native species.

The Ideas section of the Sunday Boston Globe included a thought-provoking article by Leon Neyfakh about organisms that have come to be known by the epithet “invasive species.” These are plants and animals that have been introduced by human activity into areas where they aren’t native. In recent decades, these immigrants have become a prime target of environmentalists.

The reasons to fight invasive species may be economic, or conservationist, or just practical, but underneath all these efforts is a potent and galvanizing idea: that if we work hard enough to keep foreign species from infiltrating habitats where they might do harm, we can help nature heal from the damage we humans have done to it as a civilization.

In a nutshell

Two essays in the journal Nature sum up the arguments for and against fighting invasives:

This war on invasive species has come under fire in recent months, and not just from politicians. Neyfakh points to essays authored by scientists in the field and published in both Science and Nature – the two most prestigious scientific journals – as well as the New York Times.

This flare-up has reawakened a debate over non-native species that goes back more than a decade. And while it would appear that the two sides are badly mismatched – those who oppose the targeting of non-native species are still very much a minority – their disagreement highlights questions about mankind’s relationship to nature that are far from settled. If we’re going to help restore a more natural environment, how do we decide what in the world is “natural” and what is the result of artificial forces? Why do some species get to stay, while others get pulled out by the roots? Their clash points up the fact that as humans take upon themselves the job of managing a changing natural world, there’s no obvious way to know which version of nature we should be aiming for.

Nehfakh’s article is highly recommended reading. But he doesn’t mention what I’d argue is the elephant in the room – climate change. Rising temperatures and changing precipitation patterns are fundamentally altering the areas that plants and animals find habitable. Just one example: over half of all commercially exploited fish and shellfish species in the northeast have shifted northward (not to mention deeper) in the past forty years to stay within comfortable water temperatures. By mid-century, lobster and cod may live only in the memories – not the waters – of Cape Cod.

But, as lobster and cod are departing, blue crab and Atlantic croaker will likely be moving up from their traditional Mid-Atlantic ranges. And herein lies the rub: the vast majority of scientists agree that climate change is largely the result of human activities (a.k.a. fossil fuel burning). So, technically, these climate migrants could be considered invasive species – introduced into non-native areas by human activities.

Attempting to block the wholesale shift of species is futile. Besides, there’d be quite an ecological void if departing native species weren’t replaced with something.

This might seem to be an argument for ending the war on invasive species and just letting un-nature take it’s course. That’s not really the intention. In my mind, what the climate change angle does is put traditional environmental issues, like invasive species, on a larger stage and force examination of the root issue: what role should humanity play in the global ecosystem? Should we – and can we – hold ourselves and “nature” as two separate things to be, respectively, reigned in and preserved untouched? Or should we envision humans as part of nature and search for the most responsible ways to behave accordingly?

  • http://www.theflotsamdiaries.org Harold Johnson

    For me, this ties in with the question of, at what point does a “non-native” species become, for all intents and purposes, “nativized”? I learned recently about the huge Colombian exchange in the 15th-17th Cs, and how much of our everyday, ordinary foods, plants, and animals actually weren’t in North America before Europeans got here. Like horses. Or wheat! Fields of wheat grain are quintessentially American. But they’re also a human-brought “invasive.”