24 Feb 2011: Report

Alien Species Reconsidered:
Finding a Value in Non-Natives

One of the tenets of conservation management holds that alien species are ecologically harmful. But a new study is pointing to research that demonstrates that some non-native plants and animals can have beneficial impacts.

by carl zimmer

The tale of the honeybee is a sadly familiar one: a once-thriving species is on the ropes. After brutal bouts with mites and fungi, honeybees are now facing their most dangerous threat yet: a mysterious disease called colony collapse disorder. In the winter of 2010 alone, U.S. beekeepers reported losing 34 percent of their hives to CCD, which may be caused by viruses, pesticides, or some diabolical combination of factors. Researchers are working hard to figure out exactly why the honeybees are dying and how to save them because of their ecological importance. Honeybees pollinate many of the country’s fruit and vegetable crops, and they also carry out the same service for many species of wild plants. In Brazil, honeybees help keep isolated rain forest fragments from dying out by moving their pollen from tree to tree.

Amidst all the concern for the honeybees, it’s easy to forget an important fact about them. They’re not native to the New World.

The earliest records of honeybees in this hemisphere come from English settlers who arrived with hives aboard their ships in the early 1600s. They brought the bees to make honey they could eat and wax they could burn. Over the past four centuries, new stocks of honeybees have arrived at least eight times, from Europe, the Near East, and Africa.

Honeybees were introduced into the Western Hemisphere in the 1600s and have become an ecologically important species.
Introduced species can, in some cases, become dangerous invaders, wreaking havoc on their new homes. They may gobble up native species, outcompete them, or just infect them to cause new diseases. Much of modern conservation management is organized around keeping alien species out and killing off the ones that made it in. And yet there are no loud voices calling for the alien honeybees to be wiped out in the New World.

“It’s almost like everyone politely ignores that they’re not native,” says Dov Sax, a conservation biologist at Brown University.

Sax and some of his fellow biologists think that it’s time to give some serious consideration to this paradox. In a paper published in Conservation Biology, Sax and two colleagues argue for recognizing the ecological value of some introduced species. “We predict the proportion of non-native species that are viewed as benign or even desirable will slowly increase over time,” they write.

The fact that a journal like Conservation Biology would publish such a statement is a testament to how seriously some researchers are taking the idea. “It’s considered edgy, but it’s not considered nuts,” says Sax. Not nuts, perhaps — but certainly not innocuous. The new paper is eliciting strong responses from other conservation biologists — ranging from hearty endorsements to fierce protests.

Sax and his co-authors — Julian Olden of the University of Washington and Martin Schlaepfer of State University of New York in Syracuse and INRA in Rennes, France — point to a number of studies that have documented the benefits of introduced species. Some non-native species provide habitat and food for native animals and plants, for example. In the southwestern United States, tamarisk trees have been aggressively spreading along rivers. The trees started drawing up so much water that
Some non-native species provide habitat for native plants and animals and can promote diversity.
conservation biologists feared it might not leave enough for the native plants. If the native plants disappeared, so might the animals that depended on them, such as the endangered southwestern willow flycatcher. The government spent millions of dollars to stop the tamarisk, using bulldozers, herbicides, and even tree-munching beetles. Yet in recent years some researchers have concluded the initial worries about the threat of tamarisks to the water table were exaggerated. At the same time, conservation biologists have found the southwestern willow flycatcher nesting in tamarisk trees. Their fledglings do as well in the introduced trees as they did in the native ones. Getting rid of the tamarisk would mean getting rid of the habitat of an endangered bird.

Introduced species can also help restore native ecosystems on degraded land. In Puerto Rico, for example, much of the native forest was destroyed for farming, and in recent decades conservation biologists have been trying to nurture them back on abandoned farmland. Native trees do a poor job of pioneering this degraded landscape. Alien trees, such as African tulip trees and rose apple, have colonized them instead. These new forests remain dominated by alien trees for their first three or four decades. But the forests are also a habitat in which native trees can begin to thrive again. After 60 to 80 years of growth, Puerto Rican forests become mixes of both alien and native trees.

Introduced species can promote diversity by acting like ecosystem engineers, reworking their new habitat. Off the coast of Chile, for example, a gelatinous invertebrate called Pyura praeputialis forms massive mats, providing nooks and crannies in which other species can thrive. Juan Carlos Castilla of Pontificia Universidad Católica de Chile and his colleagues have found 116 species of invertebrates and algae living in these alien ecosystems, while nearby intertidal rocky shores were home to just 66 species.

Honeybees demonstrate another benefit that introduced species can offer. Other introduced species can pollinate plants as well, while some animals help native plants in other ways. In Hawaii, a bird called the Japanese white eye spreads the seeds of a native vine. These new partnerships between native and non-native species show that they aren’t precisely linked like a lock and key. “In reality, the world is a lot messier,” says Schlaepfer.

Schlaepfer and his colleagues stress that they’re not calling for every introduced species to be protected, or even tolerated. Instead, they hope the conservation community will at least consider the possibility that
The new paper in Conservation Biology has attracted strong criticism, some directed at its big message.
introduced species can do some good. “It’s going to cause one more round of reflection,” says Schlaepfer.

The new paper has attracted strong criticism, some directed at its big message and some at the evidence the authors marshall to build it. Thomas Gavin, a Cornell conservation biologist, sharply disagrees with the way Schlaepfer and his colleagues envision the way ecosystems work — particularly with the idea of analyzing introductions of species “as if the system were simply a collection of interchangeable parts, like some human-devised machine. I reject this notion.”

Other conservation biologists take issue with the examples that Schlaepfer and his colleagues select. To suggest that the Japanese white eye has a positive role because it pollinates a native vine is “totally ludicrous,” says David Richardson of the University of Cape Town in South Africa. “This bird is the main disperser of many non-native plants into native ecosystems,” he points out. “The net outcome of this species just has to be negative.”

Yet Richardson agrees that it’s time to think differently about invasive species. He thinks conservation biologists have to set aside purist ideas about restoring ecosystems to some pre-human state. In cases where habitats have been radically altered, he says, “removing alien species just because they are alien is futile.”

A particular passionate endorsement comes from Scott Carroll, a conservation biologist at the University of California, Davis. “My admittedly ludicrous response to the paper is ‘Yes! Go! May your sensible perspective sprout wings!’” he says.

Carroll makes a similar argument in the latest issue of the journal Evolutionary Applications, where he calls for a new kind of science he calls “conciliation biology.” Simply trying to eradicate all exotic species can be costly, he argues, and can even harm native species. Introduced cats were eradicated from Maquarie Island off the coast of Australia, after having driven two of the island’s bird species extinct. But with the cats gone, an introduced population of rabbits exploded, devouring the native plants.


Network Theory: A Key to
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Network Theory: A Key to Unraveling How Nature Works
In the last two decades, network theory has emerged as a way of making sense of everything from the World Wide Web to the human brain. Now, as ecologists have begun applying this theory to ecosystems, they are gaining insights into how species are interconnected, Carl Zimmer writes.
The failure on Maquarie Island, Carroll argues, stems from a failure to appreciate that species are constantly evolving. In the mid-1900s, scientists introduced a virus into Australia and its surrounding islands to control rabbits. Conservation biologists assumed that they could get rid of cats and the virus would still keep the rabbits at low levels. But the virus, meanwhile, had evolved to become less deadly, which enabled it to spread more efficiently but made it ineffective in controlling the rabbits.

Rather than try to restore ecosystems to their pre-industrial states, Carroll argues, conservation biologists should manage the evolution of species to make ecosystems resilient. If a vine starts to spread across a new habitat, for example, conservation biologists can help native insects to evolve mouthparts that allow them to devour the vines more quickly. Rather than signaling defeat, Carroll sees conciliation biology as a way to reach more sustainable outcomes in a human-dominated world.

POSTED ON 24 Feb 2011 IN Biodiversity Energy Policy & Politics Science & Technology North America 


Scott's book addresses similar concerns and includes numerous citations.

Invasive Plant Medicine: The Ecological Benefits and Healing Abilities of Invasives
Timothy Lee Scott

Posted by Teresa Binstock on 24 Feb 2011

Last year I read "The Lost Language of Plants: The Ecological Importance of Plant Medicines for Life on Earth" by Stephen Harrod Buhner. It dramatically expanded my view of the natural world and its immense intelligence, constant movement and adaptation. Mother Nature is far smarter than we are. It always amazes me to hear scientists speak of "managing" nature. What's that saying? "We make plans and God laughs." Homosapiens are native to Africa, not to this continent. In an effort to "manage" nature, maybe we should just all move back.

Posted by Ruth M on 24 Feb 2011

This article relies on the semantic messiness that people have around introduced species. Non-native species make up around 97% of our food, and no one has a problem with that. Many exotic species survive at low levels, but some ARE problems, and those are the only ones that should be called invasive. To point to the ones that are not, and use that to say none of them are, is a flimsy argument often trotted out. Another one making its debut is that "these native animals do well using these non-natives" which is dangerous as well--corvids and rats are super-abundant around dumps, but no one calls for more of those. The spread of sheep sorrel means more purplish copper butterflies, but the loss of lupines and the blue butterflies as well as violets and silverspots. The abundance of (native) deer mice in european beachgrass comes at great cost to an endangered dune plant.

People engineer landscapes, whether native or not. People decide what they want and what they don't. The agreement needs to come in what purpose a landscape should serve. And trying to keep some areas free of a barrage of non-natives (not necessarily "restoring" everything) seems a better compromise than the "lay back and enjoy it" exhortations of this column. We have a very poor understanding of the things we do, of the ripple effects and eventual consequences, and should be very careful every time we act (or don't).

Posted by Andrea on 24 Feb 2011

There is a perspective problem here. Honeybees are invasive and they are a problem. The author of this article simply views this issue within too small of a time frame to catch the truth.

For another perspective read Stephen Buckmann and Gary Nabhan's book - The Forgotten Pollinators.

Much has been said about how the plant and animal species, especially butterflies, of England are in decline. About how they've grown dependent upon the rural, human-made, landscape of Britain. The underlying message is that nature has adapted and grown dependent upon man. But this is short-sighted as is this article.

In England a large portion of the diverse native flora and fauna have long been extirpated or are extinct. Unlike in U.S., this extirpation occurred long before biologists or naturalists were recording species of flowers, butterflies or animals. Just because the authors of the nature-dependent-upon-man are ignorant of this doesn't make it true. What's left is a bereft landscape of the survivors of the intense, landscape changing grazing and cropping practices that have largely denuded that country's lands. Now even these survivors and the early transplants from elsewhere are having a hard time surviving.

U.S. researchers know what it is we have to lose.

Honeybees were introduced to North America in the 1500's. They were probably the first invasive species to cause havoc with this land's natural landscape. The impact they caused was largely unrecorded because it occurred ahead European settlement.

Similarly, archeologists have belatedly realized that the largely empty continent Europeans colonized was made that way by a wave of disease and death among Native Americans that preceeded settlement. Traces of extensive agricultural fields and villages show this; as do the oral histories of various tribes.

Likewise, honeybees caused waves of extinctions and extirpations that we are only now finding out about. Read the travel journal of Washington Irving as a very descriptive first hand account of how common honeybees were in the early 1800's in the western lands (Arkansas, Oklahoma). It has recently been surmised that the Carolina Parokeet went extinct not from the guns of farmers, as it died out before most of its habitat was settled. Rather, this iconic bird was killed off by competition with honeybees for its communal nesting sites in hollow trees.

We are only now realizing that some of our endangered plants are dying out because their native pollinators were killed off by competition with honeybees. There are likely many native bees, insects and plants that are extinct or are heading that way becauase of the slow motion changes in native populations that honeybees colonization has wrought.

The honeybee doesn't fit in here very well. It didn't coevolve with this continent's other plants and insects. It left its parasites and diseases behind in Europe and so for 500 years it flourished. Now its enemies have caught up with it and it doesn't have complex ecological relationships to fall back on. Relationships that would normally hit back hard on its enemies. Nor does it have the genetic diversity or cohort of similar species on this continent that would normally allow it to evolve its way out of the parasite and disease problem that threatens it with extinction in North America.

And, now the native plants who survived the loss of their coevolved pollinators hundreds of years ago will be left with nothing and a second wave of extinctions will occur.

The fossil record illustrates how continental isolation creates biotic diversity. It is expected then that the abrupt linking of the world's continents by man's transport will inevitably result in mass loss of biotic diversity.

I believe the honey bee in North America is a very eye opening and stark example of both how invasive species wreak destruction, and how the short time frame of human observation often hides nature's truths.

Posted by Andy on 24 Feb 2011

Interestingly enough, elsewhere in Australia, dingoes (which were introduced many thousands of years ago) are actually one of the best ways to control introduced cats. The effects that feral cats have on native wildlife is profound, and in areas with high populations of dingoes, specifically the northern half of the country, feral cats are held somewhat at bay. There are hundreds of thousands still roaming the countryside, but dingoes appear to affect cat home ranges significantly. It's a great example of this so-called "conciliation biology".

Posted by Ethan on 24 Feb 2011

Perhaps Andy is unaware of the fact that the European honeybee is responsible for pollinating about one-third of all agriculture crops in the United States. The native bumblebee is incapable of pollinating most agricultural crops. It is also incapable of producing honey. To prefer natives to non-natives solely because they are native, without any understanding of the function the non-native performs in our environment is to shoot ourselves in the collective foot. If Andy is aware of the importance of the honeybee to our food production and advocates for its destruction anyway, then he is an example of the extremism of the native plant movement.

The native plant movement has a death grip on our public lands. Please visit the Million Trees blog to read about the destructive affects of the native plant movement in the San Francisco Bay Area. http://milliontrees.wordpress.com.

A few articles on the Million Trees blog are devoted specifically to the impact on the honeybee: (1) “Destruction of Eucalyptus Threatens Bees” explains that non-native eucalypts in the Bay Area are one of the few sources of nectar for the honeybee during the winter months and that they are therefore essential to the survival of the honeybee hives that are collapsing in the Bay Area. This article also explains that the survival of the honeybee is also threatened by the use of toxic herbicides that are used by the nativists to destroy non-native plants and trees. These herbicides are known to be harmful to bees. (2) “Exterminating Animals: Wasted lives and money” informs our readers that the Nature Conservancy is actually killing honeybees on their “restorations” simply because they are non-native.

The native plant movement is destructive at its core. The honeybee is only one small example of the damage they are doing. Their assumption that native plants are inherently superior to non-native plants is fundamentally unscientific as Stephen Jay Gould explained in his article “An Evolutionary Perspective on Strengths, Fallacies, and Confusions in the Concept of Native Plants.” (Arnoldia, 1996)

Thank you for informing us of the forthcoming article in Conservation Biology. That is great news!

Posted by Million Trees on 24 Feb 2011

Thanks for this, Carl. My own area of research is how migrant birds use non-native fruit in urban areas during migratory stopover. It's been discouraging to me to see how little attention is given to how wildlife uses non-native species, and how these systems adapt. The level of controversy is an indication of how much more we need to learn.

Posted by Julie on 25 Feb 2011

This article is misleading: Tamarisk trees are a very Faustian bargain for Willow Flycatchers and other species.

Yes, Willow Flycatchers are nesting in them but they have to - since Tamarisk trees are creating near-monocultures in riparian habitats out west.

Willow Flycatchers would be MUCH better off if Tamarisk had never arrived here - the biological diversity (especially insect prey availability) is much reduced in the presence of such aggressive plant invaders.

It's like Chinese Tallow trees here in the eastern U.S. - sure birds eat the berries, but the Tallow trees destroy/degrade wetlands, crowd out native food + nectar sources like Tupelo, Hackberry, Viburnums, Ilex species, etc. etc. etc.

Posted by Nate Dias on 25 Feb 2011

Of course I'm aware of the importance of honeybees for crop pollination. I'm also aware of the wild claims that equate ecologists with Nazi eugenics and rascists. This is not the point of my comment. The point is that the introduction of non-native species inevitably causes a cascade of extinction of native flora and fauna and that the slow, inexorable mixing of species among continents by man is one of the main factors causing a world wide loss of biodiversity.

The introduction of new species, or removal of one whether or not it is native, should be carefully studied before action is taken.

Pollination researchers are urging farmers to plant strips of native vegetation to foster native pollinators; but they are also trying to breed honeybees and find treatments that will prevent their loss.

It is likely that the honeybee breeding will eventually have to produce a bio-pollination machine; i.e. a domesticated version of the species immune to disease and perfectly adapted to transportation and seasonal crop pollination. These breeds will may not do well outside of domestication. Therefore, it would behoove private landowners and homeowners to provide habitat for native pollinators.

There are many good resources on the web that tell how to do this as well as some good books. There are even resources that tell you how to produce honey from these native bees.

Posted by Andy on 25 Feb 2011

The attempt to eradicate tamarisk is an excellent example of the way in which "invasion biology" frequently confuses cause and effect. What created the opportunity for tamarisk to dominate native willows in the southwest was reduced water supplies: "But more importantly, eradicating the saltcedar is not likely to result in the return of the native cottonwoods [and willows] because the natural flood cycle upon which the cottonwood depends has been altered by man. The saltcedar thrives in the reduced water flow. Unless the water flow is restored, the native trees will not return no matter how many saltcedar are destroyed. Not only are we wasting our time and effort trying to eradicate saltcedar, we are also poisoning our water [with herbicides] in the process."

This is a quote from an article on the Million Trees blog: "Invasion Biology: Confusion about cause and effect." This article also describes the return of the Southwestern Fly Catcher to the Yuba Pass in California after water flow was restroed to a meadow that enabled the return of willows.

The native plant movement is always looking for scapegoats for changes in the environment caused by man. In this case, the tamarisk is not to blame. Rather it is man's demands on limited water supplies that have caused the problem. Unless or until man is prepared to address the underlying causes it is pointless to destroy plant and animal scapegoats. More importantly is often damages the environment further.

Posted by Million Trees on 25 Feb 2011

I disagree with this. For one, Honey bees may pollinate agricultural crops, but they have also displaced native bees that did a fine job of pollinating native plants, and because Honey bees need special care such as hives placed by fields, means they have a leg up on native bees. Many native bees are now rare as Honey bees outcompete them with our help.

As for tamarisk, I think we should still remove them, and we could plant native cottonwoods and willows in their stead. But that means more money and planning, and I know it is difficult for areas like the Colorado River. Where I live, in the midst of a preserve in the desert, we have a few large tamarisks but a lot of native groves of cottonwood and willow. I see willow flycatchers migrating through all trees, but I have noticed in the last nine years living here that other rare riparian breeders such as Yellow-breasted chats only use the moist thickets under native cottonwoods and willows. I have yet to see a chat in our tamarisk (which we want to remove eventually). I think the complex original habitat of cottonwood-willow riparian areas has not been duplicated by the introduced tamarisk monoculture; willow flycatchers may use them, but that does not mean other birds do too.

The paper neglects the grave impacts of introduced species such as Sahara mustard in the desert, as well as Mediterranean annual grasses over hundreds of thousands of acres of western California possibly responsible for choking out oak acorns from growing into trees because the introduced mass of annual grasses slurp up soil water that native perennial grasses did not during spring, out-competing oaks. And Red brome from Europe causing increased fire frequency in the desert, which is not adapted to this.

I would agree that helping to restore resiliency to habitats is crucial, and that eradicating introduced species in some cases can be futile (such as Mediterranean annuals in western CA), but I do not think trying to restore ecosystems to pre-industrial states is a bad thing. We do need to eliminate many exotics to allow natives to thrive.

Posted by Laura Cunningham on 26 Feb 2011

One of the implied but largely unspoken threads coursing through this discussion is species specific versus ecosystem intergrity based conservation. As a practicing restoration ecologist and PhD student in restoration ecology my persepctive, research & practice focuses on maintaining & enhancing ecosystem intergrity based on a holisitc assessment of ecosystem processes, components & functions.

I am both an ardent eradicator of invasive species and an advocate of using noninvasive, nonnative species in ecosystem repair. It is all a matter of context & goals, both anthropocentrically defined. With single species focused conservation/restoration we often do disregard as aptly pointed out, the landscape scale drivers of habitat loss e.g. hydrology and tamarisk with the willow flycatcher.

I would assert that nonnative species, invasive & not, are here to stay and that in order to most efficiently use our resources we should carefully assess the feasibility and desirability of complete eradication versus tolerable levels of suppression on a watershed scale & project scale basis. This means that we may have to balance invasive presence with single species persistence. We already live in a severely compromised, impacted world. The challenge is to manage the compromise to hold on to the biodiversity & ecosystem integrity we can with the knowledge and resources we have & develop.

Posted by Rodney Pond on 28 Feb 2011

While I appreciate having my perspective on native species issues challenged I find the closing paragraph disturbing. The notion that conservationists can "help" an insect evolve new mouthparts is naive at best.

Posted by Nancy E on 02 Mar 2011

There is an important distinction between ‘non-native’ and ‘invasive’ species that Zimmer’s article does not clearly present. As Mr. Zimmer points out, our society benefits from the presence of scores of non-native species, without disruption of the ecosystems that sustain them. ‘Invasive’ species, however, proliferate rapidly and typically displace native or established, but not invasive, non-native species, and often great modify functional components of the ecosystems they invade. Many exact substantial economic loss. Common examples include zebra mussels, Canadian thistle, buckthorn, and Asian carp.

Once established, eradication of these species is virtually impossible, yet control efforts can reduce impact. Because so many potential invasives exist, and control efforts for many are so expensive as to be impractical, risk analysis is employed to determine for which ‘invasive’ status may be realized and for which established species the benefits of control efforts would exceed the economic and ecological costs. Do, for example, the extreme economic costs of closing locks that allow shipping into and out of the Great Lakes to prevent invasion of Asian carp exceed the predicted yet uncertain costs of disruption of fisheries and ecological function that may result from this invasion? To suggest, as Zimmer does, that ‘Much of modern conservation management is organized around keeping alien species out and killing off the ones that made it in.’, without clear distinction among sub-categories of ‘alien’ species misinforms.

Beyond the inaccuracy of Zimmer’s thesis, that most conservation biologists believe that, ideally, all non-native species should be eradicated, and ecosystems should restored to ‘pre industrial’ state, the article contains statements that are blatantly incorrect. The most egregious of these was apparently paraphrased from Scott Carroll, a conservation biologist from UC Davis. Zimmer writes, ‘If a vine starts to spread across a new habitat, for example, conservation biologists can help native insects to evolve mouthparts that allow them to devour the vines more quickly.’

Many Americans, including some informed non-scientists that rely on this forum to keep abreast of issues in environmental science, misunderstand the process of evolution. The ability to make informed decisions and be able to recognize when misinformation is being used to justify legislation or environmental policy rests on access to accurate information. This accentuates the importance of ensuring that science-based articles intended for a broad audience are accurate and unambiguous.

Posted by Chris Peterson on 04 Mar 2011

I think this article is just a fact, Mr Carl should explain more briefly and shown prominent evidence that will support this article!

Posted by Ernestine Miller on 06 Mar 2011

In very sensitive ecosystems (ie fynbos SA) removing plantations and trying to restore a biome may take 200 years.

Posted by trevor on 07 Mar 2011

It's ironic and enlightening to realize that the honeybee is being attacked by other invasive species; the varoa mite and some sort of fungi. Invasive species are not usually better adapted to a particular environment. They thrive because they usually leave their predators and parasites behind in their homeland. Biologists often underestimate the importance of these in keeping an organisms population in check.

I believe the spreading of organisms from one continent to another will inevitably result in massive biodiversity loss as well as reduced ecosystem functioning. I would propose that we measure the level of ecosystem functioning by the amount of life sustained in a given area over a long period of time.

Also, I believe that engineering ecosystems based upon trophic structure and/or functional niches; where the taxonomic category of an organism is not all important, is playing with fire. We don't know enough to do this.
Posted by Andy on 12 Mar 2011

Change is in the air - and in the sea and on the land. In fact, the entire planet is undergoing a transformation called climate change.

Temperatures will rise, along with humidity and the level of the oceans. Storms will be more
severe, along with droughts and floods. Animals and plants and microorganisms will have to
adapt to survive. Some species will not make it. Others will evolve and adapt to the new,
changing ecosystem conditions.

However, despite all this change that is acknowledged and feared by governments
throughout the world, there has been no change in the way we conserve our natural resources and protect endangered species.

The goal of modern conservation goes beyond protection of forests and wild spaces from
development and pollution. Today's conservationists fight to protect and preserve
native ecosystems and native species against "invasive" species. The goal is to return
"invaded" ecosystems to their condition prior to the introductions of highly competitive "alien"
species that have altered the environmental landscape.

Essentially, conservationists and preservationists are resisting environmental change.

In the past, environmental managers introduced species into new environments to increase
biodiversity and resource values of forests and other natural areas. They valued species for
their ability to grow well in their new environments. Now, however, they call these
thriving introduced species "invasive", and introduce insects, fungi, or other biocontrol pests
to slow down their growth, or kill them with poisons, chainsaw, or bulldozers.

The hope is that by eliminating species that "don't belong" in a certain ecosystem, we can
return that ecosystem to a more natural, balanced state where native species and
endangered species can thrive without competition from introductions.

However, climate change is a deal breaker for all conservation strategies.

Climate change means that native species that once thrived in past ecosystems may be
threatened with extinction in the near future. Every species of plant, insect, mammal, bird, fungus, bacteria, and even virus will be impacted by these changes in the conditions of life. Native ecosystems existed in a different world of the past, with different conditions than we have today and will have tomorrow.

Climate change means you can never go back to the way it was centuries ago. Today's and
tomorrow's forests, coastal ecosystems, and oceans may not support yesterday's species.
And this change is now fast upon us.

Changing conditions will lead to a rebalancing of the entire food chain. Some dominant species that preferred the old conditions will fall, and new species that thrive on the change will take their place.

In short, this is a time of rapid evolution. It is a time to look forward, not backward.

As we assess species for their ability to survive and thrive in the new environmental conditions that are coming, we may discover that some species currently considered "invasive" for their ability to grow well are actually "invaluable" for being able to keep natural areas forested into the future, and our oceans vital and healthy.

The goal of environmental management should be to have healthy, vital ecosystems, regardless of the nativity of the species creating them. We cannot afford to attack introduced species for growing well and outcompeting native species. This ability to survive and thrive may make them invaluable in the future.

Those conservationists and preservationists who want to maintain native species and native ecosystems can fence, weed and manage areas that can serve as museums of the past biological world. But such natural preserve areas will require constant commitment of resources in an endless battle against the tide of climate change.

More importantly, we need to plant for the future, not weed for the past. We need to stop killing the fittest and saving the least fit, or the future forests will consist solely of weak and unhealthy trees. We need to value trees for growing well, and not just for being native, ensuring that we will still have forests to clean the air, remove carbon dioxide, and provide resources for man and wildlife as the climate changes.

Conservationism itself must change, evolving from an environmental philosophy that fights change into one that embraces and manages it.

The past is done. Climate change is now giving us a new world unfolding before our eyes. Either we fight the inevitable changes kicking and screaming for a lost past, or we plan for a better future by surfing the wave of change.

I say let's surf!

Posted by Sydney Singer on 19 Mar 2011

Trevor's comment that "I believe the spreading of organisms from one continent to another will inevitably result in massive biodiversity loss as well as reduced ecosystem functioning" is the exact situation with humans as the organisms in question. His comment about engineering and managing ecosystems as "playing with fire" is equally valid. Our best bet would be to leave as much alone and wild as possible.

Posted by Bob Goldberg on 19 Mar 2011

Comments have been closed on this feature.
Carl Zimmer writes about science for The New York Times and a number of magazines. A 2007 winner of the National Academies of Science Communication Award, he is the author of six books, including Microcosm: E. coli and the New Science of Life. In previous articles for Yale Environment 360, he has written about how ecologists are using network theory and about how global warming will cause an evolutionary explosion for animals and plants.



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Raises Concerns Over Impacts

by mike ives
Armed with new high-tech equipment, mining companies are targeting vast areas of the deep ocean for mineral extraction. But with few regulations in place, critics fear such development could threaten seabed ecosystems that scientists say are only now being fully understood.

Electric Power Rights of Way:
A New Frontier for Conservation

by richard conniff
Often mowed and doused with herbicides, power transmission lines have long been a bane for environmentalists. But that’s changing, as some utilities are starting to manage these areas as potentially valuable corridors for threatened wildlife.

With the Boom in Oil and Gas,
Pipelines Proliferate in the U.S.

by peter moskowitz
The rise of U.S. oil and gas production has spurred a dramatic expansion of the nation's pipeline infrastructure. As the lines reach into new communities and affect more property owners, concerns over the environmental impacts are growing.

How Norway and Russia Made
A Cod Fishery Live and Thrive

by john waldman
The prime cod fishing grounds of North America have been depleted or wiped out by overfishing and poor management. But in Arctic waters, Norway and Russia are working cooperatively to sustain a highly productive — and profitable — cod fishery.

A New Frontier for Fracking:
Drilling Near the Arctic Circle

by ed struzik
Hydraulic fracturing is about to move into the Canadian Arctic, with companies exploring the region's rich shale oil deposits. But many indigenous people and conservationists have serious concerns about the impact of fracking in more fragile northern environments.

Africa’s Vultures Threatened
By An Assault on All Fronts

by madeline bodin
Vultures are being killed on an unprecedented scale across Africa, with the latest slaughter perpetrated by elephant poachers who poison the scavenging birds so they won’t give away the location of their activities.

As Small Hydropower Expands,
So Does Caution on Its Impacts

by dave levitan
Small hydropower projects have the potential to bring electricity to millions of people now living off the grid. But experts warn that planners must carefully consider the cumulative effects of constructing too many small dams in a single watershed.

Why Restoring Wetlands
Is More Critical Than Ever

by bruce stutz
Along the Delaware River estuary, efforts are underway to restore wetlands lost due to centuries of human activity. With sea levels rising, coastal communities there and and elsewhere in the U.S. and Europe are realizing the value of wetlands as important buffers against flooding and tidal surges.

Primate Rights vs Research:
Battle in Colombian Rainforest

by chris kraul
A Colombian conservationist has been locked in a contentious legal fight against a leading researcher who uses wild monkeys in his search for a malaria vaccine. A recent court decision that banned the practice is seen as a victory in efforts to restrict the use of monkeys in medical research.

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