Letter From Discover

Tough love for aliens

Sunday, July 24, 2005

Our May cover story, “Are Invasive Species Really So Bad?” by Discover senior editor Alan Burdick, clearly hit a hot button with a lot of readers. Setting aside the labels of “good” and “bad”—which are inescapably human judgments—Burdick sought to view invasive species with more objectivity and to explore what they have taught scientists about how ecosystems work. Many readers instead interpreted this approach at best as a missed opportunity to firmly reiterate the negative consequences of invasive species and at worst as a moral failure to denounce the “anything goes” school of environmental management. Some readers were appalled at Burdick’s proposal to “love” alien species; others, at his suggestion that the real crime is against “self-serving ideas of what nature is supposed to be.”

With all due respect, these readers seem to have missed some of what was written in our pages. The damage inflicted by some invasive species has been well documented. Noting that many or most invaders do no visible harm does not negate the fact that, as Burdick acknowledged, a handful can and do. As for “loving” alien species—why not? Studying them has yielded insights into the workings of nature, including the surprising fact that the composition of ecosystems may be influenced far more by propagule pressure—the persistence with which new species are introduced—than by the life-history traits of organisms or by competition between species. That observation will no doubt complicate ecosystem management, but it at least merits discussion. Moreover, as Burdick pointed out, we already love aliens—that’s part of the problem. We actively import and spread exotic plants and animals (and whatever smaller organisms they carry). That doesn’t explain all invasions; nobody actively invited the zebra mussels to the party, or the brown tree snake. But it’s true often enough that it bears keeping in mind.

Meanwhile, we’ve made it fashionable to discuss nature in the third person, as something to be preserved for its own sake. But the truth is, no matter how much we care about nature’s more attractive artifacts, it does not care for us, or even for itself. Only we care. Expressing it thus does not alter the mandate to preserve, only the rationale for doing so.

In the end, what seems to have most offended readers was the mere asking of the question: Are invasive species really so bad? The editors of Discover believe it is a valid one, deserving to be asked aloud even by people who know where they stand.

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