Alien invaders!

Just posted this reponse to the lengthy discussion on Grist over an article questioning whether invasive species really are as evil as we think they are. Short answer: probably. Long answer:

As someone who spent one hot summer waging a futile battle against exotic invasives plants (Japanese honeysuckle and tree of heaven, mainly) in a national park, and a semester studying the effects of goats on the flora and fauna in the Galapagos, it would be fair to say I think exotic invasive species are a serious threat.

I also think it's fair to say that the best policy is to "keep them all out", as burger suggests, provided burger means preventing any new exotic species from entering an ecosytem. And I agree with NJD that the "wait-and-see" approach is irresponsible; if newly introduced population is still small enough that eradication is feasible, better to be safe than sorry.

I don't think it's fair, however, to dismiss Erik's arguments as they apply to established exotic invasive species. It's easy to say, yes, let's get rid of kudzu. Not so straightforward if we bring herbicides into the picture. Or when we have to kill golden eagles to protect the foxes on California's Channel islands. (The eages are protected under the Eagle Protection Act but are not native to the islands).

We have a limited number of resources with which to manage exotic species and it's not cheap or easy. So it makes sense to evaluate the costs and, yes, the benefits, of an established invasive species to an ecosystem, as well as the costs and benefits of trying to eradicate it. That way we can make the most out of the limited resources we have.

At the national park, my two coworkers and I barely made a dent in cutting back the exotic invasive plant species, and I'm sure most of plants grew back the following year anyway. Perhaps if we had focused on just getting rid one of the most noxious species, we could've successfully eradicated it from the park. Perhaps if we'd also focused more restoring disturbed areas and preventing further disturbances, rather focusing solely on the symptoms--invasive population explosions, we'd have been more successful.

That said, I think Erik is right on to question whether a "pristine" ecosystem ought to be our ideal. The vast majority of forests in this country are not virgin forests and are constantly changing due to forces of nature and man. Deeming one moment in history as an ecosystem's "pristine" state to aim to replicate seems rather arbitrary and silly. Perhaps "healthy" is a better adjective to work towards.

As a side note, what about native invasive species? Whitetail deer, juniper, red maple...