Friday, April 15, 2011

Invasive Species: Melting Pot or Natural Disaster?

Two very different articles on invasive species appeared in my email box recently. Mother Nature’s Melting Pot* encourages us to “embrace the impurity of our cosmopolitan natural world.” In contrast, Should Biological Invasions Be Managed as Natural Disasters?** promotes building “a culture of safety and resilience,” requiring a “national and international commitment to prevention, preparedness, and vulnerability reduction.”

A similar contrast is evident in two recent local events. The Oregon Invasive Spiecies Council (OISC) held a statewide summit on invasive species last fall to highlight the importance of invasive species issues in Oregon. A few months later, the Public Interest Environmental Law Conference (PIELC) held a conference on “Environmentalism Gone Awry: The war on invasive speces – the need for a rational assessment of the costs and benefits of invasive species control.” Clearly some people see invasive species as one of the worst environmental problems we face; while others wonder, What’s the big deal? They’re going to get here sooner or later anyway, so why should we fight it?

How can people see this issue so differently? The first problem is a matter of definition. Invasive species doubters point to all the beneficial plants and animals that are not native. It is true that most of the food we eat comes from non-native plants and animals. It is also true that the grass in our lawns and the plants in our yards are mostly not Oregon natives either. This argument is a red herring (not native?). I think we can agree that lots of exotic species are beneficial and integral to modern society. Going completely native is not possible in this day and age, nor is it desirable.

Second, it is easy to find examples of invasive species response programs that didn’t work. Perhaps the most famous was the attempt to eradicate imported fire ant, Solenopsis invicta, from the Southeast using Mirex. Rachael Carson’s book, Silent Spring, was published during this project, and shined a spotlight on the ecological dangers of wide-area use of persistant pesticides. Sudden oak death, Phytophthora ramorum, provides a less dramatic example from right here in Oregon. Starting in 2001, a consortium of state and federal agencies attempted to eradicate this disease from the forest just north of Brookings. It didn’t work, though we did dramatically slow down the spread of this invasive disease.

The arguments that invasive species are no big deal or not worth fighting fall away if you focus not on all non-native species but on the small percentage that are really pests or weeds – the real invasive species. Oregon statute (ORS 570.750 (2)) recognizes: “invasions by harmful nonnative species are damaging to the environment and cause economic hardship. . .” The key word is harmful. There are hundreds of non-native species in Oregon that don’t fit this definition. We’re not talking about those.

Secondly, you can’t talk about the failed programs while ignoring the successes. There are many, many examples of successful invasive species response programs that get very little recognition. It is easy to write a book or hold a conference about about the big in-your-face failures because the consequences are obvious. It is much harder to interest people in the success stories. Anyone for a conference on why we don’t have gypsy moths in Oregon? Would you buy a book entitled; “Kudzu, The Worst Weed That Doesn’t Occur Here”? Yet Oregon has a proud history of successful early detection and rapid response against gypsy moth, kudzu, and many other invasive species.

I suspect that there is another factor common to people that don’t believe invasive species are a serious problem. I’ll bet they don’t get out much and/or they wouldn’t know a native plant from an invasive weed if they tripped over one. Many people are pretty well divorced from nature these days. Do you know which of the birds at your feeder are native? Exotic? Invasive? Congratualtions if you do -- if you don’t, you should borrow a field guide from the library or Google a local bird list and learn the common birds (ditto for trees, wildflowers, butterflies, etc.). Knowing what you’re looking at adds a great deal to one’s appreciation of nature and makes it easy to understand the importance of keeping invasive species out of places where they don’t belong.

Dan Hilburn
*Raffles, H. 2011. Mother Nature’s Melting Pot. The New York Times op-ed April 3, 2011 on page WK12 of the New York edition.
**Ricciardi, A., M.E. Palmer, and N.D. Yan. 2011. Should Biological Invasions Be Managed as Natural Disasters?  BioScience. Vol. 61(4) 312-317.


  1. Excellent post and very well said. To me, the recent spate of "invasive apologetics" smacks of apathy. Disregarding economic costs, no true outdoors-man or woman, whether butterfly enthusiast, duckhunter, or timbercruiser would, "...embrace the impurity..." which has negatively transformed many of their favorite wild areas into weedy deserts.

  2. Three very strong points.