Retreat from invasion biology becomes a stampede

The New Wild by Fred Pearce (1) is the third book to be published in three years which challenges the conventional wisdom that native species are inherently superior to non-native species and the closely related corollary assumption that all non-native species are competitors of native species.  These are the assumptions that underlie invasion biology.  Each book has been progressively more pointed in its criticism of this ideology, masquerading as a scientific discipline.

Rambunctious Garden

Rambunctious GardenThe first book to be published in 2011—Rambunctious Garden by Emma Marris (2)—was timid in its approach in comparison to The New Wild.  Ms. Marris visited “restoration” projects all over the world.  She described unsuccessful efforts to eradicate non-native plants and animals as well as extreme attempts to “rewild” that are often a mishmash of plant and animal species from different native ranges and time periods.  She implied that these projects were futile as well as artificial, but she was not explicitly critical.  Despite her cautious approach, she has been subjected to intense criticism from both academics and practitioners of invasion biology.   The following excerpt of a reader’s review of Marris’s book found on is typical of the criticism:

“Earth as cookie jar”

“Emma Marris, the author of Rambunctious Garden (RG), loves the nature hiding in back street alleys and along the highway median strip. Marris believes it’s time to abandon (or de-emphasize) what she sees as outdated and naïve conservation strategies such as creation of national parks and wilderness reserves. She feels the biggest obstacles to a bold new world of “designer” and “novel” ecosystems is the “wilderness cult” that naively wants to preserve “natural” landscapes–which she says do not exist anymore.

Marris espouses the anthropocentric perspective that the Earth is more or less a resource cookie jar for humans–to be used carefully to be sure–but she doesn’t really question whether ethically or ecologically this is ultimately a good idea…

However, by moving the goalposts to vacant city lots as an acceptable desired future condition of the landscape, she implicitly, if not explicitly, provides cover for all manner of environmental degradation.”

Most of the 35 readers’ reviews about Rambunctious Garden on are equally critical.  This particular review was rated as “helpful” by 141 other readers and 21 comments were also posted in support of the critical review.  Marris and her book have been thrashed in many other venues, including conferences where she is called out by name as an enemy of nature by invasion biologists.

Where do camels belong?

Where do camels belongThe second book, which challenges the assumptions of invasion biology, was published in September 2014.  Where do camels belong? by Ken Thompson, a British academic, (3) is much more explicit in its criticism of invasion biology.  One of its strong suits is the examples of the ambiguity and absurdity of the often muddy distinction between native and non-native.  As we might expect, this distinction is less clear in Britain because it has a much longer history of “invasion” than North America (only because invasion biologists have chosen to define “native” in North America as any species that precedes the arrival of Europeans).  Professor Thompson offers some comic examples of how status as a native has been conferred in Britain and the contortions that are required to provide preferential treatment to these “natives.”

Despite kicking up the level of criticism of invasion biology a notch, reviews of Professor Thompson’s book are far more positive than those of Ms. Marris’s book.

The New Wild

The New Wild was published in the US in April 2015.  Fred Pearce does not pull his punches in The New Wild.  He methodically lays out all the reasons why invasion biology no longer deserves the status of a scientific discipline.  The readers of Million Trees are familiar with all of these arguments, so we will summarize them here and provide links to articles on Million Trees that illustrate each issue:

Although The New Wild is a full frontal assault on invasion biology, it has been very favorably received by reviewers on  Here is a review by a reader for whom the book was an epiphany:

“An important—even essential—look at our global challenges”

“Let me cut to the chase: read this book. I want to follow that statement with several exclamation points, but I’m trying to control my enthusiasm. Perhaps the book seems so important to me because I was so ignorant when I first started reading it. Perhaps my level of ignorance is extraordinary, but I just checked the websites of several environmental organizations I respect and it looks to me like they too need to read the book. Certainly it is provocative, controversial, and challenging. It will anger some, but it is not an ad hominem attack against anyone. Whatever you think of Fred Pearce, Daniel Simberloff, and others on either side of this debate, it is clear that the debate is important, even urgent. It made clear to me that I have put too much faith in environmental organizations to ferret out the facts and explicate the issues for me. Clearly, I have allowed myself to be misled. Even more important, scientific standards are not being rigorously followed. Have you noticed the headlines about all the “invasive” species that “need” to be eradicated? About the billions of dollars that are required to do this purportedly important work? I have been asking why so much killing is necessary. Pearce states that it isn’t. In fact, he goes further and suggests that the species targeted for eradication may be our salvation precisely because they have the adaptability and resilience to survive in environments disturbed and dramatically changed by mankind. His arguments are articulate and persuasive.

Environmental writers and organizations sometimes make conclusory and inflammatory claims about the damage done by those species they choose to characterize as invasive. And supporters such as myself accept those claims unquestioningly. As Pearce points out in his eye-opening treatment of the subject, too often one environmentalist repeats or even amplifies the unsubstantiated claims of another, and when this happens again and again with no one questioning the science along the way, dangerous, counterfactual conclusions are spread and soon become gospel. Pearce’s probing, incisive exploration into several of those claims in his seventh chapter, “Myths of the Aliens” is alone worth the price of the book.

Pearce woke me up. I respect the scientific method and believe it must be adhered to without fail in environmental writings. I have naively accepted that other environmentalists feel the same. We cannot make intelligent decisions if we are uninformed about true facts. False allegations have no value for any of us. “Invasive” species need new, clear-eyed, unbiased consideration by environmentalists. We need to look again at our underlying assumptions. What does “native” really mean? Which species are natural to an area? Which can survive in the “wild”? Pearce asserts that there is a “New Wild” and that we will do better to respect it sooner rather than later, to work with it rather than against it. I learned so much from Pearce not only about the facts of our situation, but also about new ways of looking at our extremely challenged world. I highly recommend this book and hope you get the opportunity to read Pearce’s insightful and creative ideas.”

This reader understands for the first time that the environmental organizations he/she had previously trusted had misled him/her into believing that non-native species are the cause of environmental damage rather than symptoms of that damage.  He/She was always uncomfortable about all the killing that was motivated by that viewpoint, which is perhaps what opened his/her mind to Pearce’s message.  This sequence of realizations describes my own journey to the other side of invasion biology.  I was initially appalled by the killing, but I did not realize that the justification for the killing was entirely bogus until I began to do my own research.  I initially assumed that they knew what they were doing.  After reading innumerable books and studies, I began to understand that there is little evidence supporting their claims that non-native species are damaging the environment.  Quite the opposite is true.  We hope that Pearce’s book will start many other readers on the same journey of discovery.

(To be fair, the first critique of invasion biology was Invasion Biology:  Critique of a Pseudoscience by David Theodoropoulos, published in 2003.  Although it was ahead of its time, virtually every criticism of invasion biology in that book remains true to this day.  However, at that point in time there were few empirical studies testing the hypotheses of invasion biology and few “restorations” based on those hypotheses.  It was therefore more difficult to make the case against invasion biology.  Theodoropoulos foretold the fate of invasion biology as a discredited ideology based primarily on his personal observations in nature.)


In just three years, three hard-hitting books have been published which confront the unfounded assumptions of invasion biology.  Although each book is progressively more aggressive and explicit in its criticism, the reaction of the public has been progressively more positive.

We admired all three of these books, so we are reluctant to conclude that the more favorable reaction to the more recent books is because of improved quality.  Perhaps the more explicit criticism of the more recent books makes it easier for readers to appreciate the strength of the argument.  Although we are deeply grateful to Emma Marris for leading the way, Rambunctious Garden requires the reader to reach the conclusion she only implies. The New Wild makes no such demands on the reader’s judgment.

However, we have our own optimistic theory about why readers are welcoming The New Wild.  The more experience the public has with the destructive projects which attempt to eradicate non-native species, the more likely they are to understand the futility and the damage being done to the environment.  We choose to interpret the positive reception for The New Wild as an indication that the public is ready to abandon the fantasy of returning our public lands to some mythical ideal landscape.

  1. Fred Pearce, The New Wild, Beacon Press, April 2015
  2. Emma Marris, Rambunctious Garden, Bloomsbury, 2011
  3. Ken Thompson, Where do camels belong?, Greystone Books, 2014

Professor Arthur Shapiro’s Review of Emma Marris’ Rambunctious Garden

Rambunctious GardenProfessor Arthur Shapiro is Distinguished Professor of Evolution and Ecology at University of California Davis and a renowned expert on the butterflies of California.  His public comment on the Draft Environmental Impact Report for the Natural Areas Program is one of the most popular articles on Million Trees.

Professor Shapiro has written a review of Emma Marris’ Rambunctious Garden and given us permission to reprint it here.  We share his high opinion of Ms. Marris’ book and we urge you to give it the careful read it deserves.


Rambunctious Garden: Saving Nature in a Post-Wild World by Emma Marris

Review by: Arthur M. Shapiro

The Quarterly Review of Biology, Vol. 88, No. 1 (March 2013), p. 45

Published by: The University of Chicago Press

Stable URL: .

“Several years ago, I attended a seminar on the psychology of the animal-liberation movement. The speaker observed that although very few animal-lib activists were actually religious, most such people scored very highly on the “religiosity” scale in personality inventories. He suggested that animal liberation served the same functions for such people as religion did for many more: it gave life meaning and conferred a group identity centered on shared moral superiority over others. After years of interacting with “weed warriors”—people who spend their free time trying to eradicate “invasive species” from parks and public lands—I would advance the same hypothesis about most of them. They tend to be absolutely convinced of the righteousness of their cause and highly resistant to any suggestion that naturalized exotics might not be all bad. They also tend to be oblivious to the disconcerting degree to which their rhetoric converges to that of racists and xenophobes, and highly defensive if you point that out to them. After all, they are on the “green” side, right?  

In the face of such popular enthusiasm for the alarmist viewpoint on exotics, Emma Marris, a professional science writer, has produced an eminently reasonable, well-researched, and engagingly written defense of the notion that human beings have changed the world and the most sensible way to deal with that is to manage it for the greatest good. She demonstrates very convincingly that communities and ecosystems have always been in flux as the physical world changes around them. The idea of freezing them at some arbitrary moment in time is as wrongheaded as it is impractical. Some naturalized exotics present serious threats to human beings or their support systems: we call them pests, pathogens, and vectors, and they are not what is at issue. Some are such radical ecological gamechangers that they need to be assessed with an eye to the full scope of their impacts (think cheatgrass in the desert and its impact on fire ecology). Most, however, are trivial, and in a world of limiting resources where we must assign priorities to our actions, they do not merit serious attention. But it is not merely a matter of using our management resources effectively. Much of our “invasive species” discourse simply ignores the evolutionary creativity consequent on community reorganization.

Yet we know both in theory and from the fossil record that precisely such creativity is essential for long-term survival in a changing physical context. Ecotypes or ecological races arise in response to novel challenges, both biotic and abiotic. The future of endangered species is likely to depend on such processes. Failure to appreciate this is the single biggest flaw in the “climatic envelope” or “niche modeling” approach to conservation biology. Much of California’s lowland butterfly fauna is now dependent on nonnative larval host plants. When I tell garden clubs—or public land managers—that successful eradication of invasive “weeds” would drive their beloved backyard butterflies to extinction, they stare at me in disbelief. But it is true and emblematic of the larger problem explored very well in this volume.

Shortly after Marris’s book appeared there was a flurry of articles in the professional literature advancing precisely the same ideas. Among the best are by Carroll (2011. Evolutionary Applications 4:184–199) and Thomas (2011. Trends in Ecology and Evolution 26:216 –221). But Marris got there first, and with luck her wise words will be read and acted upon far and wide.”

Arthur M. Shapiro, Center for Population Biology, University of California, Davis, California

Scientists reject the notion of “Balance” in nature

"Delicate Balance of Nature" Painting by N. Robert Wagstaff, Maui, Hawaii

The recently published book by Emma Marris, Rambunctious Garden,* is getting the attention it deserves from conservationists and the managers of public lands.  If you read widely in this field, as we do, you won’t find much new in her book, but you will find a comprehensive and comprehensible overview of the emerging scientific consensus that it is time to revise the assumptions of invasion biology.

If you haven’t the time or inclination to read this book, you can take a short cut to two recent interviews with Ms. Marris, published by the American Society of Landscape Architects and the magazine of the Nature Conservancy.  The published interview by the Nature Conservancy is another indication that this prestigious organization is shifting its emphasis to embrace the realities of nature as we know it, rather than as we imagine it was in the distant past.

Ms. Marris methodically revisits the original assumptions of invasion biology and offers us the growing evidence that they have not been confirmed by the science that tested them in the field.  In a recent post, we reported that the assumptions that ecological “niches” are exclusive and therefore new species will displace former occupants, are not consistent with the fact that introduced species far outnumber the loss of native species.  In fact, there is little evidence that introduced species have resulted in extinctions. 

“Nature has no ‘Balance’ for us to keep”

Matt Ridley, in his weekly column “Mind & Matter” for the Wall Street Journal, invites us to revisit the concept of the “balance of nature” with the help of Ms. Marris’ book.  Mr. Ridley is a British scientist who has written many popular books about human genetics and evolution. 

In our interminable debate with native plant advocates, we find that the concept that nature achieves an equilibrium state that is, by definition, balanced, is central to their ideology.  Their argument is that man has disrupted this balance and that he is therefore obligated to right this wrong.  Furthermore, when this balance has been achieved, theoretically, nature sustains itself without further interference from man. 

This is a powerful narrative with much intuitive appeal.  Particularly for those who feel some guilt for the damage that man has inflicted on nature, the obligation to heal those wounds is strong.  However, the scientific evidence is mounting that there is no such thing as a “balance” of nature, as Mr. Ridley tells us in his column:

Academic ecologists have abandoned such a static way of thinking for something much more dynamic.  For a start, they now appreciate that climate has always changed, and with it, ecology.  Twenty thousand years ago the spot where I live [in the UK] was under a mile of ice.  Then it was tundra, then birch forest, then pine forest, then elder, linden, elm and ash, then most recently oak, but beech was coming.”

Mr. Ridley goes on to lament that although science tells us that a stable balance in nature cannot be achieved, particularly at a time of rapidly changing climate, the notion still dominates practical conservation management, which he describes as:  “preserve this rare species, maintain this habitat structure, freeze in time this ecological moment, return this degraded land to a particular state, whatever the weather and whatever the novel arrivals of exotic species.”  These goals sound very familiar to those of us who follow the various “restoration” projects on our public lands in the San Francisco Bay Area. 

We are grateful to Ms. Marris for bundling the recent science that dismantles the mistaken assumptions of invasion biology into a readable package that is being reported by the mainstream press.  We anticipate that the public will eventually realize that the destructive native plant “restorations” in which the managers of our public lands are engaged are unnecessary and ultimately futile. 

It’s just a matter of time!


“Emma Marris, Rambunctious Garden, Bloomsbury, 2011

Conservation Refugees: The misanthropy of ecological “restorations”

Hawaiians protest confiscation of public lands

We recently told our readers about the controversial “restoration” projects in Hawaii.  Now our colleagues in Hawaii have sent us photographs of a public protest in Hawaii and The Hawaii Reporter tells us why they are protesting.  Hawaii’s Department of Land and Natural Resources (DLNR) is fencing the public out of another 17 square miles of prime forest on the Big Island.  All the non-native animals—sheep, goats, pigs—will be exterminated and all their non-native food—strawberry guava, passion fruit, etc—will be eradicated in that fenced enclosure.   The people who hunted the animals and gathered fruit in the forest are protesting the loss of this source of food. 

In addition to the loss of food, the protestors also object to the loss of an activity that is central to the Hawaiian culture of foraging and hunting for food.   DLNR’s response to that particular complaint is that the historical record indicates that Hawaiians didn’t hunt prior to the arrival of Europeans because they raised animals as their own. 

In other words, not only does DLNR wish to stop the biological clock, they also wish to freeze-frame the Hawaiian culture to a pre-European standard.  They don’t seem to have considered that the Europeans essentially confiscated the land of the Hawaiians when they arrived, which deprived the Hawaiians of the land needed to raise animals.  That’s too bad.  The Hawaiians are not allowed to hunt now because they didn’t hunt 250 years ago.   As absurd as creating botanical museums seems to us, the suggestion that culture must also be prevented from evolving strikes us as utterly ridiculous.

Hawaiians protest loss of access to public lands

Conservation Refugees

Hawaii’s cost of living has always been one of the highest in the country because virtually all of its food must be imported.   And now Hawaiians are being deprived of an important source of food by the confiscation of public lands.  Will these Hawaiians join the ranks of the millions of conservation refugees all over the world who have been displaced in the name of conservation?

We were introduced to conservation refugees by Mark Dowie in 2004.  He told us that the belief that wilderness is not compatible with human community originated with John Muir, who demanded that Native Americans living in Yosemite be removed from the valley.  Native Americans were also removed from Yellowstone when the National Park was created.  These Native Americans were the first conservation refugees, but not the last.

Dowie told us that the worldwide official protected areas—parks, reserves, wildlife sanctuaries, biodiversity corridors—had expanded from 1,000 in 1962 to 108,000 in 2004.  The total number of indigenous people displaced by the creation of these protected areas is not known because most countries make no attempt to quantify the impact.  In Chad an estimated 600,000 indigenous people became conservation refugees when the amount of protected areas increased from 0.1 to 9.1 percent of total national land in the 1990s.  India admits to creating 1.6 million conservation refugees as a result of creating new protected areas and the Indian government estimates that 2 or 3 million more will be displaced in this decade.

Dowie visited some of the communities that have been displaced by the confiscation of their ancestral land.  The loss of their land is also the loss of their way of life.  Hunters/gatherers are deprived of their source of food.  Likewise, farmers lose their croplands.  They wander into shanty towns where they lack the skills to survive in the modern world.  They create shabby squatter camps on the perimeter of their homeland where they live without sanitation or water.  The fabric of their communities is shattered.

Emma Marris* observes the irony of these evictions of traditional cultures which have tended these remnants of the wilderness for generations.  These places were targets for conservation because they had been preserved by traditional cultures that had learned to co-exist with nature.  This is how they are rewarded for their stewardship of the land.

What is accomplished?

What is gained when Hawaiians are thrown out of their public lands, depriving them of a source of food?  Are these projects successful?  Are the plants and animals that existed in Hawaii several hundred years ago returning to the fenced reserves that have been created for them?

Emma Marris visited one of these projects in Hawaii.  A small test plot was cleared of all non-native plants, requiring the removal of about half of all the vegetation.  That process took about a week per thousand square feet and then “epic bouts of weeding thereafter.”

 The theory was that the removal of all the non-natives would enable the natives to thrive without the competition for sunlight and water.  Five years later, there is little evidence that native plants have benefited from the eradication of all non-native plants:

“Disappointingly, the mature native trees had grown very little.  As [the project directors] put it, ‘The native trees may either be responding to the treatments very slowly and still undetectably, or they may be unable to respond at all.’”

The directors of this project also told Marris, “I think that people that are interested in protecting Hawaii’s flora and fauna have resigned themselves to it being in postage-stamp sized reserves.”   Apparently Hawaii’s Department of Land and Natural Resources hasn’t gotten this message.  They are now creating another 17 square mile reserve with the intention of eradicating everything non-native in it.  Nothing is likely to be accomplished by all that death and destruction and some Hawaiians will also go hungry.

The slippery slope of nativism

Perhaps we should be grateful that the “restoration” projects in the San Francisco Bay Area aren’t depriving us of our homes and our livelihoods.  We are just being fenced out of our public parks.  We are just losing our trees.  Our public parks are just being poisoned with pesticides.

But we watch these projects all over the world and we listen to the demands of local native plant advocates and we wonder where this is headed.  In San Francisco, for example, native plant advocates are demanding that all of the public lands in the city be managed as “natural areas.”  In addition to destroying the trees in our parks, would we lose the trees on all our public properties?  We also know that native plant advocates want plant nurseries to quit selling to the public the approximately 200 plants that they have categorized as “invasive.”  Will we lose the right to plant what we want in our own backyards?  Given what we see happening around the world, it doesn’t seem farfetched. 

* Emma Marris, Rambunctious Garden, Bloomsbury Publishing, 2011