More Skewed Logic on Invasive Species--Bradford Pear

Soon after writing a critique of the NY Times article that demonizes those of us who are concerned about invasive species, I received an email saying "They've done it again!" The email pointed to a NY Times oped by a science writer, Gabriel Popkin, about the Bradford Pear. Called The Ups and Downs of the Bradford Pear, most of the oped tells the standard story of how this tree, introduced by the nursery industry with great fanfare, became an ecological problem years later. Only at the end does the oped take a bizarre turn, using strange math and selective pessimism to conclude that, in a world full of bigger problems, we need not take any action.

The Bradford Pear turns our towns, and increasingly our countrysides as well, white with its intense, incandescent blooms in the early spring. It seems like a beacon after the long voyage of winter, telling us that the comforts of spring are close at hand.

But like many species introduced to our continent with great hopes,

Skewed Logic Thrives in NY Times Article on Invasive Species

One expects quality from the NY Times, but for some reason it periodically weakens its standards to publish an oped or article attacking native plant advocates and biologists who study biological invasions. (See list and previous detailed critiques here.) The tactics are always the same: a blurring of important distinctions, a failure to explain to readers the basic concepts of invasive behavior in plants and animals, the creation and tearing apart of strawmen, an embedding of bias in word choice and sentence structure, and a lot of mean-spirited pejoratives. This curious, recurrent smearing of those who seek to understand and tend nature's garden is fueled, as best I can tell, by a never-ending stream of resentment emanating most stridently from a couple California-based websites, then given undeserved validation by journalists who lack training and field experience in biology and ecology.

The latest, by veteran science writer Erica Goode, is a polemic loosely disguised as an article in the Science section. Entitled "Invasive Species Aren’t Always Unwanted", it portrays invasion biology as a xenophobic, militaristic, quasi-religious cult that has invented a false enemy and caused people and governments to behave in violent ways. We are asked to accept this dark psychological portrait largely on faith.

Like attacks on climate science, the article claims to shake the foundations of a major area of scientific study

Going Negative On Natives--The Latest Example in the NYTimes

The New York Times is one of the bedrocks of news, which makes it hard to understand why its opinion page would show a weakness for ill-informed attacks on native plants and their proponents. The latest is by Verlyn Klinkenborg, a point-by-point rebuttal of which can be found further down in this post, but his is just one in a series.

First in my memory is George Ball, president of Burpee Seed Company and former president of the American Horticultural Society, who despite these distinguished labels launched an error-filled broadside (Border War, 3/19/06) against people who promote the planting of native flora. In his words, people who promote natives are xenophobic, narrowminded, the horticultural equivalent of radical fundamentalists, utopian, elitist snobs, anti-exotic partisans, and (last but not least) dangerous to a free society.

Then there was Sean Wilsey, (High Line, Low Aims, 7/9/08) who spoke disparagingly of the proposal to plant a ribbon of native species on Manhattan's High Line. Apparently lacking any botanical or ecological knowledge that might have heightened his appreciation of the plan, he made it sound like the High Line would be little more than a linear patch of weedy sumac--a species he may have confused with the ubiquitous non-native Tree of Heaven. Time, and the spectacular congregation of native plants that now thrive on the very popular elevated walkway, have proven him wrong.

(Update, 11.29.13: Another which I forgot to mention when writing this piece appeared on April 3, 2011. In “Mother Nature’s Melting Pot,” Hugh Raffles, an immigrant who had just received citizenship, characterizes native plant advocates as nativists with the same core fear of aliens as the Tea Party. After cherry picking a few beneficial aspects of some introduced species, he calls for an "inclusive" approach, which presumably would include disease pathogens and agricultural pests. As with Klinkenborg's piece, he mentions eucalyptus, climate change, claims that most efforts to control invasives are futile, believes the term "native" to be arbitrary, characterizes any "mythic time of past purity" as an artificial construct, and implies that the rapid introduction of new species from other continents is a natural phenomenon and nothing new. Letters rebutting Mr. Raffles' logic can be found here.)

The latest installment of this attack on native plant advocacy, as mentioned, arrived this past week (Hey, You Calling Me an Invasive Species?, 9/7/13), written by a member of the Times' editorial board, Verlyn Klinkenborg. Avoiding George Ball's name-calling and Sean Wilsey's dismissive tone, his thesis is that the distinction between native and nonnative species is now an arbitrary one, given the passage of centuries and the ever-expanding influence of humans on the natural world.

Klinkenborg's opinion piece was prompted by recent public protests against a plan to thin out a dense forest of non-native eucalyptus trees growing on Mount Sutro in San Francisco. The University of California San Francisco (UCSF) owns the property, which the local fire department has said is in urgent need of thinning in order to protect nearby buildings from the highly combustible eucalyptus. Reducing the dense shade will improve the health of the trees while providing some light for native vegetation to grow beneath them. Sounds benign, yet locals who walk in the forest are calling the proponents of the plan "plant facists" who want to impose the tyranny of nativism on a woods that is perfect just the way it is.

Joining the chorus of protest, Nathan Winograd, an animal rights advocate who blogs on the Huffington Post wrote a post about the Mount Sutro tree-thinning plan entitled "Biological Xenophobia: The Environmental Movement's War on Nature". Adopting the strident tone of George Ball, he has nothing but contempt for the concept of native plants, preferring that "every life that appears on this Earth is welcomed and respected." Apparently, he's never grown any plant he valued enough to save from the weeds.

The most informative report, as opposed to opinion, on the San Francisco controversy that I could find is here. The university describes the plan this way: "Under the guidance of an outside licensed arborist, UCSF will remove approximately 1,250 trees, each less than 6 inches in diameter, while also thinning shrubs and mowing non-woody perennial plants in the 100-foot buffer zone. All told, the work will encompass approximately 15.6 acres of the 61-acre Reserve."

Here is a point by point rebuttal of Mr. Klinkenborg's opinion piece:

"Since the 1880s, there have been blue gum eucalyptus trees growing on San Francisco’s Mount Sutro, which lies just south of Golden Gate Park. Recently, the University of California, San Francisco, which owns most of Mount Sutro, has been trying to thin the dense eucalyptus forest. The reason is fire control — eucalyptus trees are “fire intensive,” shedding a lot of debris and burning with unusual volatility. But the effort to cull the Mount Sutro forest has been met with strident protest by residents who want to see the eucalyptus left untouched."

Mr. Klinkenborg only mentions fire once in the oped, but fire hazard is a big deal in the California landscape, and the planting of Eucalyptus trees close to structures has doomed many a building when the trees' high flammability causes them to explode. The link he offers, another opinion piece in a distinguished scientific journal, Science, actually offers compelling reasons to alter the forest. There's the current fire hazard to reduce, and the opportunity to improve habitat for the resident great horned owls by re-establishing some native flora. 

By the standard of the California Native Plant Society, eucalyptus, which were brought from Australia, are officially nonnative trees because they were introduced after the first European contact with the New World. But the trees on Mount Sutro have been there within the memory of every living San Franciscan, and to the generations who have grown up within view of them, it seems almost perverse to insist that they are aliens.

No science here, just an anthropocentric view that wishes the rest of nature to conform to the human sense of time.

To keep a clear distinction between native and nonnative species requires nearly geologic memory. 

No, one hundred and thirty years, or even three or four hundred, is not even close to a geologic scale.

But humans, like most species, don’t live in the past, where the distinction originates. In the present, the difference is largely immaterial. 

This isn't true. Though wildlife don't literally live in the past, their tastebuds do. Herbivores tend to be extremely conservative in their food preferences. Whether it be deer or the larvae of moths and butterflies, they continue to reject exotic species introduced hundreds of years ago. They still prefer to eat the native species, which gives exotics a competitive advantage, which makes native plants rare, which then limits wildlife's food options. 

Native or nonnative, California’s eucalyptus trees, like the starlings of Central Park, have come to seem original just because they predate us.

Again, he imposes an anthropocentric view on nature.

Of course, the vast majority of nonnative species have not been intentionally introduced, as the Mount Sutro eucalyptus were, but have been distributed accidentally, unnoticed baggage in the wanderings of our species.

Whether a species is introduced intentionally or unintentionally has no bearing on the potential harm the species can do, just as the impact of human-caused global warming will bear no relation to whether we have intended to change the climate or not. 

Some species — invasive ones like kudzu, Japanese knotweed, rabbits and rats — find almost unlimited room for expansion in their new environs, often overwhelming native species. But not all introduced species are invasive, and pose a threat only when they outcompete native species.

Excellent! It's so important to make the distinction between invasive and non-invasive species. 

It’s important to remember that the distinction between native and nonnative depends on an imaginary snapshot of this continent taken just before European contact. 

Not so imaginary, really. Though American Indians transformed the landscape, spreading some plant species along trade routes, favoring some species through cultivation or burning, or denuding the landscape, e.g. around Teotihuacan to heat the plaster for their pyramids, the massive influx of species from other continents did not begin until Western colonization. It's well known which species are or were part of a particular plant community. The bur oak savannas of the midwest, which had disappeared due to the invasion of buckthorn and other exotics, were pieced back together through research and restoration, and now flourish once again. Whole books describe in detail the various plant communities of a given region, such as this one detailing the plant communities of North Carolina. 

               That distinction is becoming even harder to make as climate change alters the natural world.

A new study from the University of Exeter and Oxford University finds that plant pests and diseases have been migrating northward and southward an average of two miles a year since 1960. This suggests that the plants on which they prey have been moving at similar rates. In places like the Adirondacks, for instance, you can follow the boundary between southern and northern tree species as it shifts northward, year by year. As plants and their pests adjust their range, under the influence of global warming, what becomes of the distinction between native and nonnative? 

Plants and animals have been shifting their regional boundaries throughout the last four hundred thousand years, as glaciers advanced and receded. Human-caused climate change is happening much more rapidly, which is one reason why it is proving so destructive, but most plant species have broad geographic ranges. Climate change doesn't mean that plant communities developed over millenia suddenly have no integrity. 

To any individual species, it doesn’t matter whether it’s native or not. The only thing that matters is whether its habitat is suitable.

 Again, because herbivore food preferences tend to remain unchanged hundreds of years after the introduction of exotic species, suitable habitat tends to equate with native plant species. 

And this is where we come in.
For the most part, we don’t have an immediate impact on the species that surround us. But we do have an immediate impact on their habitat, which determines whether they survive or, in some cases, shift their ground.
Nearly every habitat on this planet has been affected by humans, no matter how remote it is. In the past decade, for instance, the habitats of grizzly bears high in the Rocky Mountains — places most of us never get a chance to visit — have been significantly altered by global warming. As the climate warms, the mountain pine beetle has managed to winter over and destroy vast tracts of whitebark pine trees, which produce pine nuts that bears eat.

When I visited a hillside in Smokey Mountain National Park where hemlock had been wiped out by the exotic wooly adelgid, growing beneath the dead trunks was a riot of native wildflowers and brambles, representing a plant community that deep shade had suppressed. The devastation of whitebark pine trees in the Rockies is tragic, and the loss of that important species may have broad ramifications over time for that ecosystem, but that doesn't mean that native landscapes suddenly lose all meaning and relevance because one species drops out.

CONSIDERED in this light, the natural world as a whole begins to look like Central Park — an ecosystem where human influence is all pervasive. Parts of the park seem almost wild, but every creature in Central Park, native or not, has adapted to a world that is closely bounded by human activity. It is nature bordered by high-rises, intersected by paths and roadways, basking under artificial light at night.

In late August, a group of scientists and students from the City University of New York’s Macaulay Honors College spent the day cataloging all the nondomesticated life forms living in the park. It will take a while to compile and compare the data, but even the anecdotal reports from that single day show how diverse and surprising the park’s ecosystem can be. It isn’t all squirrels and pigeons. The group reported sightings of several unexpected species — a diamondback terrapin in Turtle Pond, a Wilson’s warbler in the North Woods, a bullhead catfish in the Harlem Meer. And though it might seem like a stretch to talk about ecosystems in Central Park, that is exactly what the group found — a healthy mix of species, overlapping generations within many species, and a sense of balance, especially within the aquatic zones.

Actually, a lot of work has been done to restore native species and habitat in Central Park, and it's the only sizable green space for miles for wildlife like birds and insects to gravitate to, so it's not surprising it would exhibit some diversity.

Nature in Central Park can’t be neatly divided into native of nonnative species, and neither can it be on Mount Sutro. The eucalyptus trees that grow there may be naturalized rather than native, but try telling that to all the other creatures that live in those woods or the people who hike there.

 This would be more convincing if it actually described what diversity resides on Mount Sutro. In Princeton, we had a woods that was densely planted in the 1960s with white pine and spruce--species whose native range lies farther north. The woods had considerable charm and a nice mood to it, but it was an ecological desert, with little more than garlic mustard growing in the deep shade and thick mulch of the evergreens, and reportedly an owl or two making use of the dense canopy for protection. (Mount Sutro, from what descriptions I could find, looks to be similarly slim on diversity, dominated by the eucalyptus, with an understory of English ivy and poison ivy, and a stifling and highly flammable thick mulch of eucalyptus litter.) 

Their trunks weak from age and crowding, most of the pines and spruce in the planted woods in Princeton fell during several ice and wind storms, leaving an impenetrable mess that will become a fire trap as the debris dries out. Ash trees, the only seedlings that the too-numerous deer didn't eat, are now taking over, and before long, the introduced Emerald Ash Borer will arrive to kill all the ash.  

A similar fate could await the planted woods on Mount Sutro, in the form of a cataclysmic fire. That, though far more destructive than what the university is trying to do, would not be as controversial, because it would occur due to inaction rather than action. I'm well aware of the capacity for good intentions to go awry, but sometimes inaction can be the most destructive action of all.

And when it comes to the distinction between native and nonnative, we always leave one species out: call us what you will — native, naturalized, alien or invasive.

I don't want to read too much into this, but Mr. Klinkenborg seems to be suggesting here that because we are a species that invaded the American continent, we therefore cannot be judging other invasive species. With such logic, our compromised position brings into question our capacity to understand nature and act upon what we know. 

The attempt to blur the distinction between native and non-native depends on a highly simplified view of nature and evolution. It ignores the deep interconnections species develop while co-evolving over thousands of years.  It sees no symbiotic relationship between soil fungi and plant roots, between an insect and its obligate host plant, between a particular species of ant and the plant that depends upon it to disperse its seeds. Some species, like humans, are highly adaptable to new circumstances. Others are not. Embracing non-native landscapes may give people the comforting illusion of being open-minded, but it closes the door on those more conservative, less adaptable species. 

Related Writings by Verlyn Klinkenborg

It's long been my observation that environmental issues get marginalized on the opinion pages of the news media, likely because columnists and editors tend to lack training in the life sciences. If environmental issues come up, they tend to be treated in isolation rather than seen in the broader context of economics and political concerns. On the New York Times editorial board, Mr. Klinkenborg appears to represent the sum total of biological expertise. His doctoral degree from Princeton University is in english literature. I'm all for self-education, and hopefully he took some biology-related courses along the way. 

Some of his writings for National Geographic appear to contradict his opinion piece dismissing the relevance of native habitats. For instance, an essay on the Endangered Species Act states that people

"discovered, too late, how finely attuned to its home in the cordgrass the dusky seaside sparrow really was. That last bottled sparrow is what a species looks like when its habitat has vanished for good."

In an essay on the tallgrass prairie, rather than downplaying the importance of native plant communities, he seeks a deeper understanding of them:

"The hard part here in the Flint Hills—and in any of the few remaining patches of native prairie—is learning to see the tallgrass ecosystem for itself. It is a study in the power of modesty."

Rather than giving simplified plantings like the eucalyptus on Mount Sutro equal status with native plant communities, he states:

"In most of America, agriculture has meant replacing the incredible complexity of a natural ecosystem with the incredible simplicity of a single crop growing on bare ground."

That incredibly complex prairie ecosystem, however, is threatened by an invasive non-native plant called Sericea lespedeza (Lespedeza cuneata). Rather than showing concern about the impact of that invasion, Mr. Klinkenborg worries about the human intervention to counter the invasion:

"There is also a worrying trend toward ground and aerial spraying to control a highly invasive weed called sericea lespedeza, introduced decades ago to curb erosion around mines and provide forage and cover for wildlife around reservoirs."

Now, I happen to know Sericea lespedeza well. I've seen how it moves in and eventually replaces a richly diverse native meadow with a monoculture. Though originally touted as a good wildlife food, both its seeds and foliage provide little nourishment. Its roots release toxins that discourage other plant species. If you're looking for an example of intolerance, of a refusal to "play well with others", Sericea lespedeza is Exhibit A. When it invades new territory, land managers have a choice--either let the noxious weed continue to degrade native habitat, or attempt to limit the weed's destructive impact by intervening, often with selective herbicides.

The objections of Klinkenborg and others to intervention are in part a failure to make distinctions. They want to blur the distinction between native and non-native species. The toxicity of herbicides varies according to type and method of application, but its easier for protesters to demonize them all. Nathan Winograd, in his broadside against native plant advocates, wishes to obliterate all distinctions and treasure every living thing equally. More broadly in national discourse, we see a trend towards accepting all opinions as worthy, whether they are founded on fact or fancy.

Saying that we don't need to make these distinctions, nor intervene to restore native plant communities, sounds less to me like open mindedness than a convenient way of letting ourselves off the hook.