Hungry Hyaena draws attention to a post by Swarthmore history professor Timothy Burke on the issue of invasive species and our attitudes toward them. Though Burke’s post is about six months old, it contains some statements that I think bear continued comment.
Burke tells of a trip to the Canadian Rockies in which he found poor fishing in some streams, due in part to a Parks Canada policy against stocking fish. From Burke’s post:
The purpose behind Parks Canada policy appears to be two-fold. First, to remove trout from aquatic environments within the National Parks where non-native predatory fish are deemed destructive in their impact on the ecosystem; second, to protect native species like the bull trout and the cutthroat trout.
The first objective I can see—it’s easy to forget that the introduction or repeated re-stocking of trout into waters that wouldn’t normally support a trout population has a significant impact on other organisms, like amphibians, particularly if the water is cold enough for the trout to reproduce.
The second objective I feel a bit more ambivalent about. If rainbow trout elbow out bull trout, then that’s a problem from the standpoint of losing a species of trout, but on the other hand, rainbows pretty well occupy the same niche as bull trout, only more successfully and possibly voraciously. The vision here isn’t just the preservation of a species — it’s the larger antipathy towards “invasive species” that’s become an orthodoxy of environmental science.
The statement that rainbows are appropriate replacements for bull trout in Alberta trout streams is trivially easy to debunk, so let’s save it and deal with that last, rather inflammatory statement first.
There’s a nascent if not growing tendency on the part of non-scientific observers of the sciences to speak in terms of “orthodoxy,” or “dogma,” to portray scientists as members of a bureaucratic herd who are largely opposed to independent thought.
You see this most often, of course, among creationists who oppose the teaching of evolution in the schools (or anywhere else for that matter), but it also comes to the surface in cases like the recent debacle over the unfortunate Terry Schiavo, in which people who couldn’t diagnose a fractured femur on an x-ray declared that the panel of neurologists who declared Schiavo’s persistent vegetative state were acting out of some sort of obligatory pro-death sensibility. In my line of work, I hear such statements coming from the environmentally concerned, most often when they criticize researchers for failing to support notions like Multiple Chemical Sensitivity or health hazards from EMFs, or when they defend homeopathy and other pseudosciences.
One can easily write off such people as “kooks,” but Burke is no kook. Tim Burke is a friend of the sciences and a thoughtful and careful writer, so that fact that this notion appears in his writing is worth study.
And, as it turns out, Burke is using the phrase “orthodoxy” in a context that gives many friends of the sciences similar misgivings. He continues:
I do wonder about that attitude a bit, not just in the context of fishing, but as a whole. When I read some of the material on the dangers of invasive species, its rhetoric and tropes sometimes seem uncannily familiar, reminding me very much of ideas about race, miscegenation and nativism in modern colonialism, in post-colonial nationalism, and in identity politics.
This is, of course, not a new idea, as almost anyone who has worked to restore native plants to a patch of land will tell you. Many people react near-violently to the thought of removing even the most invasive and destructive plants from a piece of landscape: broom in the California coast, feijoas in Hawai’i and Florida. In Virginia, I even heard strong argument for allowing kudzu to grow unimpeded.
We who have torn out invasive plants to plant local natives have been called Nazis, compared to Serbian “ethnic cleansers,” accused of racism and genocide. And that response pales by comparison to that received by those who suggest housecats might not be the best addition to wild landscapes.
This response is not limited to the grassroots, but is occasionally echoed in statements by the mainstream media and representatives of local government. In San Francisco, for example, defenders of native species have come under sustained attack on three fronts. There are the feral cats, which especially in Golden Gate Park have wiped out most of the ground-dwelling birds, including native quail. In the Presidio, there are attempts to cut down invasive eucalyptus tress — which far from being passive catchers of wind and rain, have been implicated in the direct killing of native bird species due to sticky nectar that seals hummingbirds’ nostrils — in favor of plantings of endangered species once native to the site. And there are the plovers, endangered beach-nesting birds that are particularly vulnerable to disruption by free-roaming dogs, and in whose interest the National Park Service is attempting to enforce a leash law on a section of Ocean Beach. All three issues have earned defenders of native species regular and scientifically illiterate criticism from San Francisco Chronicle columnist Ken Garcia and County Supervisor Leland Yee.
If the charge of hewing to orthodoxy is to be made, it’s as defensible to level it at opponents of efforts to control exotic species as it is to criticize environmental scientists for it.
And though the notion of a scientific herd mentality is not wholly without merit, science at its best carries the seeds of self-correction. It’s worth noting that a century ago, the scientific community was more or less persuaded that introducing exotic species into ecosystems was a value-neutral event, if not actually a beneficial action for the ecosystem as a whole. It was agricultural scientists who introduced kudzu to the southeast, for instance, choosing it for the very characteristics of fast growth and hardiness that make it anathema today.
In fact, Burke’s very language underlines the fact that ecological science has shifted away from a previous consensus in favor of introductions, where he mentions that Parks Canada has stopped stocking non-native fish. Which means that at one point Parks Canada did stock exotic fish, presumably on the advice and with the consultation of the best wildlife biologists to which Government Canada had access.
All this raises the question: why has the science shifted so radically in a relatively short period? Answer: because we have learned about the damage such introductions can cause.
When you use words such as “orthodoxy,” the clear connotation is of inflexibility, of hewing to a dogma despite evidence to the contrary. What scientists concerned about invasive species display may, in some cases, be unwarranted concern. It is far from being orthodoxy.
That’s a lot of analysis of one word in Burke’s piece, but it’s a pivotal word. I by no means intend this allusion as a slight to Burke, but his argument is remarkably like that Michelle Malkin used recently in condemning the recent salad-dressing attack on Pat Buchanan. Malkin decried the attack, and rightly so, but then went on to allege that this violence was the exclusive province of the left, ignoring that fact that violence from the right is higher by several orders of magnitude. Similarly, Burke ascribes “orthodoxy” to scientists and others concerned about invasive species, while giving a free pass to those who would impose the jargon and definitions of wholly unrelated social sciences onto the discipline of wildlife biology.
That’s not to say that native species defenders haven’t been flagrantly insensitive to the connotations of the loaded language they often use carelessly to describe invasive species. I’ve met a few California native plant activists who regard Central American laborers in much the same way they do invasive star thistle. This is problem enough that I’ve written on the subject, as for example in this piece, which when it was first published in the Contra Costa Times won me a fair bit of hate mail from the racists at vdare.com.
Executive summary of the piece: Not all exotic species are invasive. Origin of the species isn’t the issue; behavior is. And though the language some use to describe invasive species is redolent with horrible memory, that doesn’t mean we ought to fall into the trap of metaphor. People coming from other places increase diversity, while invasive species decrease it.
As illustration of the warning against conflating “invasive” and “exotic,” a mistake that many die-hard native plant activists make staggeringly often, consider the raven. The raven is native to the Mojave Desert. The raven is an invasive species in the Mojave Desert. Ecosystem disruption and human presence have encouraged an increase in raven numbers in the desert, and this increase comes at a catastrophic cost: the seemingly inevitable extinction of the desert tortoise, whose young are a favorite raven snack.
It’s behavior, not origin, that concerns wildlife biologists.
Burke continues:
There’s some similar desires to stop the forward motion of change, to fix environments (human or natural) in their tracks, the same suspicion of dynamism.
This is definitely true among some sectors of the environmental movement. It’s largely untrue among wildlife biologists — especially in the arid Western states, where change is stochastic rather than continuous — and almost completely untrue among paleobiologists and paleontologists, whose work is based almost entirely on recording and analyzing evidence of past ecosystems radically different from those in which we now live.
Popular understanding of the environmental sciences seems to lag a generation or more behind the actual state of the science. A lay environmentalist may believe that preserving an ecosystem at status quo, in situ, in perpetuity is a laudable goal. A freshman undergraduate student in the environmental sciences knows this is an impossibility. Not only do species migrate and their populations fluctuate, but the species themselves change, through speciation, genetic drift or depauperation, random acts of carnage, and the occasional natural advent of new species into their habitat. Extinction is a normal process taking place at a background level that may occasionally spike, due either to disaster or to the vagaries of chance.
Dynamism is the normal state of affairs in an ecosystem, which after all functions to disperse and use up solar energy as completely and efficiently as possible. The question, as Timothy himself readily admits, is scale. How much additional strain does the current rate of destructive species introductions add to an ecosystem burdened with damage from human society? And how much does the damage from human society accentuate the success of invasive species — many of which are disturbed ecosystem colonizers?
Resume fisking:
What is particularly striking to me is that the arguments against “invasive species” even from scientists sometimes seem not so much technical or scientific (when they are, they usually rest on the relatively weak assertion that there is a burning necessity for general biodiversity that trumps all other possible principles of ecological stewardship) but mostly aesthetic.
This is the key point in Burke’s essay, and the key controversy in the whole range of subjects relating to environmental protection. That “relatively weak assertion” about biodiversity is the foundation of the ecological sciences. Because one of the outmoded metaphors long ago abandoned by scientists but still revered by lay enthusiasts is “the balance of nature,” there seems to be a general sense that a few judicious extinctions are no real problem. If the bull trout goes extinct, at least there’s a rainbow trout of about the same size to “keep the balance,” as if we were replacing one literal fish with another on a literal balance scale.
But the “balance of nature” — as I’ve written before — is misconception based on a tautology. A complex system is beset by disruptive events generated from within and without, internal instabilities, long-term and erratic fluctuations, and other forms of unanticipated and largely unquantifiable change. The notion of the “balance of nature” stems from the fact that the complex ecological systems we live in wander over time into what seem to us to be stable states. And since “stable” is defined as “lasting a long time,” these states by definition characterize a significant part of the system’s timeline. Nature no more “seeks balance” than a slinky seeks the stair tread on which it happens to stop.
Instead, the characteristic tendency of the living world is one of reacting to disruption. Intertidal organisms react to — and have in many cases evolved dependency on — the twice-daily flooding of their habitat with salt water and desiccating air. An old tree falls and another, spurred to growth by the new bright light penetrating the canopy, grows to take its place. Plants in the coastal California landscape push new shoots through incinerated soil after a fire, their seeds or roots having weathered the conflagration.
We need not resort to thought experiment to see that species diversity in an ecosystem is often directly proportional to the facility with which that ecosystem adapts to disruption. Bulldoze an acre in Pennsylvania, one in western Kansas, and one in the Mojave, and see ten years later which site has the most obvious damage still remaining. There’s a degree to which this risks a “correlation is causation” argument; you could argue that the Mojave’s aridity causes both the low biodiversity and slow rate of “recovery.” So do a second experiment. Bulldoze four acres: one in the woods on the ridge outside Williamsport PA and one in central Philadelphia; one in the wild margins of the Antelope Valley and one in Lancaster, CA, a few miles down the road. Barring other influences, the tracts with neighboring wild biodiversity will “heal” faster.
That land’s “healing” does not mean “regaining its previous state.” Each blading and regrowing of that Pennsylvania forest will result in a different patch of woods, with different species concentration in both plants and animals. Colonization of disturbed habitat does not proceed on a fixed schedule, but rather varies with absolute random chance: is the first plant to colonize a dandelion or a patch of timothy? Do the crows move in, or the blue jays?
And yes, this defense of the value of biodiversity can be boiled down to “biodiversity is good at ensuring continued biodiversity.” Burke’s point about the value of biodiversity being essentially an esthetic one has some merit. Similarly, it is difficult to discuss the state of global human rights without a shared assumption that wantonly and callously causing unnecessary pain to other people is to be avoided, though there is no real hard-science reason to avoid torture. Most people presume that democracies are better than dictatorships, though there are plenty of rational arguments that dictatorships are more efficient. To some extent, Burke is correct: valuing biodiversity is an esthetic choice.
But there are marked utilitarian arguments as well. For example: with pesticides, habitat disruption, destruction of food plants, and introduction of competitors, we’ve killed off a huge proportion of the native pollinating insects in the US. We’ve been able to weather this severe depletion of biodiversity due to our importation of efficient, tractable Eurasian honeybees. But honeybees have one life strategy: large colonies. Their lifestyle makes them vulnerable to brood parasites such as the varroa mite, to which native pollinators such as solitary bees, who do not maintain hives, are resistant.
Varroa mites are currently marching through the honeybee populations of North America. So are tracheal mites, which are pretty much what they sound like. Though innovative control measures are being used, there is some question as to whether we can assume the continued existence of honeybees for many more decades.
Oh, and if the honeybees go, so do four-fifths of our food crops.
We rely for our very lives on the intricate interplay of the global ecosystem, containing perhaps a hundred million species. We exist by consuming a portion of that ecosystem. The stability of that ecosystem is a benefit to us. Biodiversity functions as a set of redundant systems to ensure ecosystem function: If one pollinator fails in the course of a year or a decade, others can fill in for it. And — as any crop-diversified farmer will tell you — biodiversity in and of itself helps prevent certain kinds of ecosystem failures.
Burke continues:
I readily agree that an introduced species which might appear harmless or inoffensive can have unpredictable effects on an ecosystem. It’s a classic source of emergent change. But what’s interesting to me is that the strongest general attacks on all invasive species frequently concede that it’s impossible in general to predict the full long-term consequences of a species introduction, and indeed in many ways impossible to predict or manage the long-term arc of change in any ecosystem even assuming that all introductions of new species could be prevented. I wonder then why there is such certainty, therefore, about the horror of any and all species introductions.
I would be interested to see some of these attacks on introductions of “all” new species. Even in New Zealand, the most invasives-conscious nation on the planet (it’s socially acceptable there to shoot kitty cats, for crying out loud) furor over introductions is limited to species shown to have been invasive in other locations, or their close relatives. (Which, by the way, counters the “impossible to tell” argument. You can’t anticipate every problem, but you can make some pretty damned accurate educated guesses.)
There simply is no group of people advocating a ban on imports of all species not native to, or established in, their region. If this were proposed, the howls of the nursery industry would be heard as far as Alpha Centauri. Not even the Kiwis are talking about banning tulips, or maize, or daffodils.
In fact, the social momentum is heading the other way. Between 90 and 99 percent of the biomass in San Francisco Bay is made up of invasive species, but the EPA is still trying to evade its legal responsibility to ban dumping of ballast water under the Clean Water Act. Free trade agreements ensure that potentially disastrously destructive wood-boring insects enter the US each year in wood pallets of sweatshop clothing and video came cartridges.
At most, what environmentalists and environmental scientists propose in the US is not a ban, but merely actions to stop the worst introductions from being carried out inadvertently, and for deliberate introductions (such as of beneficial insects) to be done with some forethought given to the effects and the social benefit — which benefit is hopefully more than a few hours of distraction for anglers.
And we’re losing.
I wonder then for the same reason whether it is really so terrible if rainbow trout displace bull trout in waters that support trout populations. There are consequences to that—loss of genetic resources of the bull trout population, possibly pressure on prey populations due to the more voracious appetites of the rainbow trout, and loss of the unique “character” that bull trout provide, whatever that might be…
A place to start looking is in the very success of the rainbow trout. If the rainbows are faring better than the bulls, it may be due to resistance to a disease that kept bull trout numbers in check, or ability to take advantage of a helpful resource that was inaccessible to the bulls. That success relative to the native trout means that the stream will have more trout in it in the short term, and despite the biases of anglers, this is not necessarily the best thing for the stream ecosystem as a whole. What of the effect mentioned above on prey populations? When those are depleted, what of the effects on less-preferred prey? If the trout population crashes as a result of the rainbows eating themselves out of house and home, what becomes of the animals that rely on a steady supply of fish?
but the intrinsic, instinctive horror at the idea of a “native” species displaced by a very similar “non-native” one seems to me to come largely from the same place that modern ideas about race, identity and nationality in human beings have come from, somewhere deep in the cultural and ideological foundations of modernity and not from a cleanly rational scientific principle. There’s a rich potential intellectual history lurking in there somewhere—in fact, I strongly suspect that it’s already been written, and I’m simply not aware of it.
Though some misguided enthusiasts, as I’ve mentioned, do resort to sloppy metaphor — perhaps as a sign of their own xenophobia — this sentiment is pretty much limited to the fringes.
There is, however, a wonderful existing work on invasive species ecology that draws parallels with the regrettable human history of the last millennium, and I think Burke would find it valuable — though the ideas it proposes are 180 degrees counter to the ones Burke offers in his piece. The book is Ecological Imperialism; The Biological Expansion of Europe, 900-1900 by Alfred Crosby.
Posted by: Chris Clarke
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