“Environmentalism” has been hijacked by nativism

Our family contributed to several mainstream environmental organizations for decades.  We were Sierra Club members because we wanted clean water and clean air.  We were Audubon Society members because we care about birds and other wildlife.

About ten years ago, we learned that these organizations were actively participating in projects demanded by native plant advocates to destroy our non-native urban forest and fence the public out of its public parks in order to turn our parks into native plant museums.  When we learned about the huge quantities of pesticides used by these projects that was the last straw.

The Berkeley Meadow is a 72-acre native plant garden on a former garbage dump on landfill.
The Berkeley Meadow is a 72-acre native plant garden on a former garbage dump on landfill.

We spent several years trying to convince these organizations that they were making a mistake by supporting projects that are doing far more damage to the environment than any theoretical benefit of native plants.  Much of our effort was directed to the Sierra Club because they claim to be a democratically run organization.  After several years of futile attempts to change the policies of these organizations, we quit because we did not want to contribute to the damage they are doing to the environment.

Logo of The Nature Conservancy.
Logo of The Nature Conservancy.

The Nature Conservancy was the only environmental organization to which we were still contributing.  Below is our “resignation” letter to The Nature Conservancy, which explains why we finally gave up on them as well.  This was not an easy letter to write because we care deeply about the environment and the animals who live in it.  We believe that environmentalism has an extremely important role to play in society and we would like to participate in an organization that is focusing on the environmental issues of our time, particularly climate change.

September 2016

Mark Tercek, Executive Director
The Nature Conservancy

Dear Mr. Tercek,

We have been contributors to The Nature Conservancy for decades.  In the past few years we increased our donations because of the publications of TNC’s former Chief Scientist, Peter Kareiva.

While other mainstream environmental organizations were actively supporting destructive and restrictive ecological “restorations,” Mr. Kareiva was questioning that conservation strategy.  In his publication, “What is Conservation Science?” Mr. Kareiva said, “Our vision of conservation science differs from earlier framings of conservation biology in large part because we believe that nature can prosper so long as people see conservation as something that sustains and enriches their own lives.  In summary, we are advocating conservation for people rather than from people.”  Mr. Kareiva was also articulating that revised mission for conservation in presentations around the country (which we attended), in TNC’s publications, and in mainstream media.

As you know, Kareiva’s viewpoint was in conflict with the old guard of conservation biologists who subscribe to the tenets of invasion biology.  This conflict resulted in a confrontation of the old guard against TNC that was reported by the New Yorker in 2014.   TNC resolved that conflict by making a commitment to quit publishing Mr. Kareiva’s viewpoint in mainstream media and by restoring eradication of “invasive” plants to its budget.  That agreement foretold Kareiva’s departure from TNC.  Not publishing is tantamount to career suicide for scientists.  Mr. Kareiva has left TNC, as any self-respecting scientist would who has been deprived of his freedom to publish.

While this battle between competing visions of conservation played out, the country’s foremost invasion biologist, Daniel Simberloff, conducted a survey of TNC project managers to determine what, if any, impact Kareiva’s leadership was having on TNC’s conservation strategies.  Most survey respondents (95%) reported that they “manage” non-native species and nearly all reported that they would devote more effort to that task if more resources were made available.  Project managers devote a “substantial proportion” of their resources to “managing” non-native species and they expressed skepticism about “academic research and the invasion management controversy in particular.”  Simberloff did not ask project managers what methods they are using and so we have no insight into the use of pesticides by TNC.  This is probably information that Simberloff would rather we not have. Invasion biologists prefer to ignore the destructive methods that are used in the fruitless attempt to eradicate non-native plants.

Ecological “restorations” are damaging the environment by destroying useful habitat, poisoning open spaces with pesticides, and killing animals perceived to be competitors of native animals.  These projects are usually futile because the plants and animals that are being eradicated are adapted to current environmental conditions that are not reversed by their elimination.  The “native” ranges of plants and animals must change in response to changes in the environment, most notably climate change.  So-called “invasive” species are symptoms of change, not causes of change.

Here in the San Francisco Bay Area, our urban forest is being destroyed because it is predominantly non-native.  Native plant advocates have fabricated an elaborate cover story to mask nativism because widespread destruction of plants and animals does not appeal to the public.  Our public lands and open spaces are being poisoned with pesticides to kill vegetation and prevent trees from resprouting after they are destroyed.  We are unwilling to support that agenda by contributing to organizations that engage in these projects.

Therefore, we will not renew our TNC membership and we will not contribute further to TNC.  If and when TNC abandons its attempts to eradicate plants and animals that are performing valuable ecological functions, we would gladly renew our contributions.


[Former Members of The Nature Conservancy]

Referenced sources:

  • D.T. Max, “Green is Good,” New Yorker, May 12, 2014
  • Sara Kuebbing and Daniel Simberloff, “Missing the bandwagon:  Nonnative species impacts still concern managers,” NeoBiota , April 14, 2015


The Economist: “You can garden in a garden. You cannot garden nature.”

For those who may not be familiar with The Economist magazine, let us introduce this venerable publication to you.  The Economist is a weekly news magazine published in Britain continuously since 1843.  It has a readership of over 1.5 million and about half of its readers are in America.  Its viewpoint is fiscally and politically moderate (it endorsed Ronald Reagan and Bill Clinton) and socially liberal (it supports same-sex marriage and immigration).  It is widely read by the business community and public policy makers.  In other words, it is an influential, mainstream source of information.

Therefore, The Economist’s recent articles about invasion biology represent a significant step forward in the effort to stop the pointless and damaging crusade against harmless non-native plants and animals.  The following is an excerpt from the editorial version of a longer article in the December 5, 2015 edition of The Economist.  We have added emphasis and a few photos.

“In Defense of invaders”

“EVERYBODY loves to hate invasive species. Americans battle rampant plants such as kudzu, a Japanese vine; Europeans accuse the American grey squirrel of spreading disease and damaging forests. As The Economist went to press, a scientific committee was expected to sign off on Europe’s first invasive-species blacklist. Cross-border trade in 37 species will be banned (the list is bound to grow longer as conservationists add more troublemakers). Where it is not already too late to wipe out these alien invaders, EU member states will be required to do so.

“Europeans are restrained in comparison with other countries. The international list of invasive species—defined as those that were introduced by humans to new places, and then multiplied—runs to over 4,000. In Australia and New Zealand hot war is waged against introduced creatures like cane toads and rats. In 2013 New Zealand used helicopters to drop a poison known as 1080 on 448,000 hectares of land—an area about the size of Yosemite and Sequoia national parks put together. Just four public objections were recorded.

“Some things that are uncontroversial are nonetheless foolish. With a few important exceptions, campaigns to eradicate invasive species are an utter waste of money and effort—for reasons that are partly practical and partly philosophical.

Rhodedenron ponticum, one of only a dozen plants considered invasive in Britain. Wikimedia Commons
Rhodedenron ponticum, one of only a dozen plants considered invasive in Britain. Wikimedia Commons

“Start with the practical arguments. Most invasive species are neither terribly successful nor very harmful. Britons think themselves under siege by foreign plants like Japanese knotweed, Rhododendron ponticum and Himalayan balsam. In fact Britain’s invasive plants are not widespread (see article), not spreading especially quickly, and often less of a nuisance than vigorous natives such as bracken. The arrival of new species almost always increases biological diversity in a region; in many cases, a flood of newcomers drives no native species to extinction. One reason is that invaders tend to colonise disturbed habitats like polluted lakes and post-industrial wasteland, where little else lives. They are nature’s opportunists.

Honeybee in non-native wild mustard
Honeybee in non-native wild mustard

New arrivals often turn out to be useful, even lovely. Americans fret about the decline of a vital crop-pollinator known as the American honey bee. Apis mellifera is actually an invader from the Old World: having buzzed from Africa to Europe, it was brought to America by colonists and went wild. Invasive plants provide food and nests for vulnerable natives; invasive animals can help native species by killing their predators, as the poisonous cane toad has done in Australia.

Another practical objection to the war on invasive species is that they are fiendishly hard to eradicate. New Zealand will not get rid of its rats any more than Britain could wipe out its grey squirrels. Culls tend to have a short-term effect at best. It is, however, sometimes possible to get rid of troublesome immigrants on tiny oceanic islands. Because the chances of success are higher, and because remote islands often contain rare species, efforts there are more worthwhile.

“The philosophical rationale for waging war on the invaders is also flawed. Eradication campaigns tend to be fuelled by the belief that it is possible to restore balance to nature—to return woods and lakes to the prelapsarian idyll that prevailed before human interference. That is misguided. Nature is a perpetual riot, with species constantly surging, retreating and hybridising. Humans have only accelerated these processes. Going back to ancient habitats is becoming impossible in any case, because of man-made climate change. Taking on the invaders is a futile gesture, not a means to an achievable end.

“No return to Eden”

“A rational attitude to invaders need not imply passivity. A few foreign species are truly damaging and should be fought… It makes sense to keep out pathogens… Fencing off wildlife sanctuaries to create open-air ecological museums is fine, too….You can garden in a garden. You cannot garden nature.”


Adventures in the Anthropocene

Adventures in the AnthropoceneAdventures in the Anthropocene:  A Journey to the Heart of the Planet We Made is, indeed, a journey. (1) Its author, Gaia Vince, traveled the globe for two years to witness first-hand the impact of human civilization on the planet.  It is an even-handed account, in which grim realities are described but are balanced with optimistic predictions of the innovations that will ultimately enable us to cope with them.

Ms. Vincent takes us to remote corners of the Earth where undeveloped communities are further impoverished by climate change and related changes in the environment.  Rising temperatures and reduced rainfall have forced many agricultural communities off their ancestral lands and into a more marginal existence.  In Bolivia, for example, former farmers have been displaced into brutal mines where life span is typically shortened by health and safety hazards.  Some Pacific and Indian Ocean islands have been drowned by rising sea levels, forcing mass evacuations onto those that remain.  Their protective reefs are dissolving in the increasingly acidic ocean.

Meanwhile, enterprising people are responding to threats their communities are facing.  In the Indian Himalayas, for example, artificial glaciers are being created to replace those that are melting.  Glaciers were the irrigation system that enabled agriculture in marginal conditions.  Torrential downpours caused by climate change are frozen on dammed, flat plains to create artificial glaciers that perform the same function.  In a remote village in Nepal, a villager returns from his Western education to bring his impoverished community into the 21st century by creating a wi-fi network that provides internet access.  The internet brings education to a village that could not afford teachers.  It is powered by a small hydroelectric generator in a glacial stream.  The stream is expected to disappear when the glacier melts in a decade or two, a problem yet to be solved.

These stories and a multitude of others are both sobering and inspiring, but we will focus on the issues relevant to Million Trees.

Harvesting fog with trees

The coast of Peru is one of the driest places on the earth.  There are places in Peru where no rain has been recorded.  The city of Lima is near the coast and its climate is similar to San Francisco.  There is little rain, but there is a great deal of fog.  Lima, like many cities in undeveloped countries, is surrounded by shanty towns in which poor people build make-shift shacks and live without modern services such as water, power, and sewage systems.

Demonstrating once again, that poverty is sometimes the mother of invention, the people of one of these shanty towns are attempting to grow a forest on their sand dune.  The trees are being irrigated with water harvested by huge fog nets, which are also supplying the community with drinking and washing water.  Within four years, the community expects the trees to be large enough to harvest the fog without the help of the fog nets, “producing a self-sustaining run-off that will replenish ancient wells and provide water for the community for the first time in 500 years.” (1)

Sutro forest on a typical summer day. Courtesy Save Sutro Forest.
Sutro forest on a typical summer day. Courtesy Save Sutro Forest.

This is a familiar scenario to the readers of Million Trees.  Fog drip in the eucalyptus forests in San Francisco has been measured at over 16 inches per year.  In the driest months of the year, soil moisture in San Francisco’s eucalyptus forest has been measured at over 10%, while soil moisture in grassland was only 2% and 4% in shrubs.  (2)

The value of forests and the dangers of deforestation

Each chapter of Adventures in the Anthropocene is devoted to a different ecosystem.  Each ecosystem is introduced with a description of the importance of that ecosystem and the way in which is it being compromised by the activities of humans in the Anthropocene.  Here are a few excerpts from the chapter about forests, which will be familiar to the readers of Million Trees.

  • “Forests play an important role in local and global climate. The world’s forests absorb 8.8 billion tonnes of carbon dioxide each year through photosynthesis—about one-third of humanity’s greenhouse gas emissions.”
  • “…their canopies provide shelter from the sun and wind, making forests much wetter, cooler environments than surrounding treeless areas. This nurtures streams and rivers, provides habitat for a range of amphibians and other life, helps cool the regional and global atmosphere, and recycles water.”
  • “Although forests help create the climate, they are also exquisitely sensitive to it—and the smaller a forest gets, the less resilient it is. When trees are chopped down, sunlight enters in the gap and dries the soils. Drought upsets the forests’ delicate water cycle—trees start to die and the entire ecosystem can tip from rainforest to grass-dominated savannah.”
  • “Deforestation emits carbon dioxide from soils and decaying plant matter, and is responsible for around 20% of all carbon dioxide emissions.”

One point bears repeating because it is relevant to our local version of deforestation.  In some cases, native plant advocates have succeeded in their demand to destroy 100% of our urban forest because it is predominantly non-native.  In other cases, they have only been able to convince land managers to “thin” the forests, although “thinning” does not seem an accurate description of destruction of 90% of the trees.  In any case, we should all understand that the ultimate likely outcome of the “thinning” strategy is an eventual clear-cut because “when trees are chopped down, sunlight enters in the gap and dries the soils….trees start to die and entire ecosystem can tip” from forest to grassland.  The drying of the soil is only one factor in this prediction.  The remaining trees also will be vulnerable to wind throw.  And the herbicides used to prevent the destroyed trees from resprouting are mobile in the soil and are likely to damage the trees that remain.  Plans to “thin” the forest are either based on ignorance or are a strategy designed to achieve the same goals as a clear-cut with less public opposition.

Are invasive species a problem?

We were gratified that there was barely a mention of “invasive” species in the detailed accounts of the impact of human civilization on the planet.  The conventional wisdom that “invasive” species are one of the primary causes of species extinction is waning and this book reflects that fact. 

Galapagos Islands
Galapagos Islands

The pros and cons of introduced plant species are debated in the context of the Galapagos Islands, where biodiversity is worshipped because it was instrumental in Darwin’s theory of evolution.  Ms. Vince interviewed the conservationist who has been battling invasive plant species on the Galapagos for 20 years.  He recently decided that attempts to eradicate introduced plants are futile and he now calls them native plants.  His surrender to this reality is controversial, but he is resolute.  He is supported in this decision by scientists who have studied novel ecosystems and find ecological value in them.  The rebuttal to such defense of novel ecosystems is that the globalization of ecosystems is homogenizing the world’s biota.

Ms. Vince concludes that proponents of eradicating non-native plants are losing the battle against the “McDonaldization” of nature:  “From the Galapagos to Hawaii, conservationists are switching tack and starting to embrace the introduced species of Anthropocene ecosystems…” because “In some places, invasives have enhanced the landscapes, reducing erosion, providing handy cash crops or food and habitat for other wildlife.”

We can only hope that our local version of “conservation” in the San Francisco Bay Area will catch up with this new realistic perspective in time to save our urban forests from being needlessly destroyed.


The final chapter of Adventures in the Anthropocene is an epilogue, which takes place in 2100 in London.  The author’s son muses at the age of 87 about which of his mother’s many predictions occurred in the 21st Century.  As we would expect, it was a tumultuous century, one in which drastic changes were made to accommodate the changing climate.

We notice that 22nd Century vegetation of London is tropical:  “Now, carpets of sedges and mosses fill the spaces, interspersed by grasses grazed by capybara, and the planted fig and mango trees, noisy with wild birds.”     We marvel that people claiming to be environmentalists are blissfully unaware of the fact that the native plants they are demanding we restore are not adapted to current climate conditions, let alone the climate foreseen in the near future.

We conclude with the final paragraph of Adventures in the Anthropocene, because it is the most optimistic prediction in this excellent book:

…the world has become a kinder place.  The terrible wars, the famines, the terrorism, extremism and hate, the drownings and deaths of hundreds of thousands of migrants the humanitarian crises…they seem to be over now…The great global mix-up of people that has occurred as a result of climate migration, urbanization, and online networks has produced a new, socially mobile, egalitarian society.  The world’s giant cities force people to live together in close but diverse communities, and it has generated a spirit of cooperation.”

We look forward to a time of greater equality for humanity as well as for the natural world, when the meaningless and unnecessary distinction between native and non-native will be retired from our vocabulary.


(1) Gaia Vince, Adventures in the Anthropocene:  A Journey to the Heart of the Planet We Made, Milkweed Editions, 2014

(2) Kevin M. Clarke, et. al., “The influence of urban park characteristics on ant communities,” Urban Ecosyst, 11:317-334, 2008

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 Amazon.com 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 Amazon.com 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 Amazon.com.  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

2014 Wrap-Up and 2015 Preview

Our last post of 2014 will summarize wins and losses in our effort to save our urban forest and preview the local issues that remain unresolved.  2014 has been a year of many accomplishments, but there have been disappointments as well.

2014 Accomplishments

Good news always comes first!  We are most grateful for the hard work of the San Francisco team with whom we collaborate.  After herculean effort, they completed most of the presentations to the members of the Board of Supervisors about the forthcoming approval process for the Environmental Impact Review of San Francisco’s Natural Areas Program, which has been in the works for eight years…and still counting.  We are advocating for the Planning Commission and the Board of Supervisors to approve the “environmentally superior” Maintenance Alternative, which would enable the Natural Areas Program to maintain the native gardens they have created in the past 15 years, but would prohibit expansion of those gardens.  The Maintenance Alternative could save about 18,500 healthy non-native trees from being needlessly destroyed and significantly decrease herbicide use in our parks.

Because native plant advocates have succeeded in convincing many politicians that their projects are “science-based,” the San Francisco team was particularly glad to have three lectures at the Commonwealth Club by academic scientists, which challenged the unfounded assumptions of the native plant ideology:

These presentations were very well attended, including by native plant advocates.  They were entirely successful from our standpoint, though they seem to have had little influence on the opinions of native plant advocates, many of whom seemed not to understand the scientific information being presented.

The dense and healthy Sutro Forest
The dense and healthy Sutro Forest

 In March 2014, UCSF announced that they have put their plans to destroy most trees on Mount Sutro on indefinite hold.  This decision was made in response to the public’s overwhelming opposition to these plans during the public comment period for the Draft Environmental Impact Report in March 2013.  However, UCSF has destroyed about 1,200 trees during the past 18 months which they claimed would mitigate immediate hazards.  UCSF has also made a commitment to not using herbicides on Mount Sutro.  UCSF has provided no estimated time frame for announcing a new plan. Please visit Save Mount Sutro Forest for a more detailed description of that announcement.  We consider this a “holding pattern” because we know that UCSF is under constant pressure from those who want the Sutro Forest to be destroyed.

Invasion biology is being revised by academic scientists who inform us that empirical studies do not support the hypotheses of invasion biology.  Here are a few of the highlights from the scientific literature:

Likewise, mainstream media has become more even-handed in its coverage of invasion biology and native plant “restorations.”  Here are a few specific examples:

2014 Disappointments

The publication of the final Environmental Impact Statement for FEMA projects in the East Bay Hills was the biggest disappointment of 2014.  There were over 13,000 public comments on the draft and they were overwhelmingly opposed to the proposed projects.  Yet, the projects are fundamentally unchanged by the final EIS, which will be officially approved by a “Decision of Record” on January 5, 2015.  We are grateful to the Hills Conservation Network for their continuing opposition to these projects and we urge our readers to support their effort.

Some of the hundreds of trees destroyed by UC Berkeley in August 2014
Some of the hundreds of trees destroyed by UC Berkeley in August 2014

We were outraged by UC Berkeley’s destruction of hundreds of non-native trees on their property in August 2014, prior to the approval of these FEMA grants.  And we were also appalled by the letters sent to FEMA by elected officials in the East Bay in July, demanding that funding be immediately released and approved for use to destroy all non-native trees on their properties.

In San Francisco, our biggest disappointment of 2014 was the approval of the revised Recreation and Open Space Element (ROSE) of the city’s General Plan, which has committed the city to managing all open space as “natural areas.”  The ROSE defines “natural areas” so broadly that it includes not only areas that currently contain existing remnants of SF’s pre-settlement habitat, but also areas that could support native plants if they were planted there, or, in other words, nearly all open space in SF, including people’s back yards. This policy commits the city to managing nearly ALL open space in San Francisco, including that in private hands, the same way as the Natural Areas Program manages its lands.  As disappointing as that decision was, it was also instrumental in producing one of the biggest accomplishments of 2014.  We were successful in convincing the State of California to decline to fund a grant application which would have implemented the plans to convert all open space in San Francisco to native plant gardens.  That so-called “biodiversity program” continues, but is presumably handicapped by the loss of that fund source.

Looking forward in 2015

In the past six months, the San Francisco team has devoted a great deal of time and effort to influencing the city’s Urban Forestry Council (UFC) to adopt “best management practices” that would discourage the destruction of healthy trees.  The UFC has hosted a “listening series” of presentations by those who advocate for the eradication of eucalyptus forests as well as those who are opposed to that destruction.  Native plant advocates have introduced new justifications for destroying the eucalyptus forests:

  • They claim that eucalyptus forests are dying of disease, drought, old-age, etc. We have sought the advice of many professional arborists and academic ecologists who assure us these claims are inaccurate.
  • They claim that the health of the eucalyptus forests would be improved by radical “thinning.” The scientific literature informs us that mature forests do not benefit from thinning because mature trees are unable to respond positively to increased light and wind.  Thinning is only beneficial to young trees and even then, the disturbance can damage the trees that remain.  Radical thinning of the mature eucalyptus forest is likely to destroy the few trees that will remain.

The UFC has completed its listening series and will probably reach its conclusions in 2015.  Based on the meetings we have attended and the conversations we have had with members of the UFC, we are not hopeful about the outcome.  They seem to be sympathetic to the demands of those who want the non-native forests of San Francisco to be destroyed.   In that case, their “best management practices” could be specifically supportive of the plans of the Natural Areas Program to destroy 18,500 trees in San Francisco and Pacifica.  If you would like to express your opinion to the Urban Forestry Council, you can write to them here:  SFUrbanForestCouncil@sfgov.org.

We also expect the final Environmental Impact Report for San Francisco’s Natural Areas Program to be published in 2015.  We will make our best effort to convince the Planning Commission and the Board of Supervisors to approve the Maintenance Alternative.  However, we should all understand that the lack of an approved EIR does not seem to have prevented the Natural Areas Program from destroying trees whenever and wherever they wish.  Many trees (perhaps a few hundred) in Glen Canyon Park, McLaren Park and Pine Lake in Stern Grove have been destroyed without an approved Environmental Impact Report.  In other words, the Environmental Impact Report seems increasingly irrelevant to what is actually being done in our parks.

A few of the trees destroyed recently in Pine Lake "natural area"
A few of the trees destroyed recently in Pine Lake “natural area”

The President of the San Francisco Forest Alliance, Carolyn Johnston, ran for a seat on the Executive Committee of the San Francisco Group of the Sierra Club.  If you follow the controversy about the Natural Areas Program in San Francisco, you may be aware of the Sierra Club’s role in supporting the nativist agenda (HERE is an example of their role).  Carolyn lost by only 6 votes.  If everyone in San Francisco who abandoned the Sierra Club because of its support for turning urban parks into native plant gardens, would renew their membership, maybe we could win a seat next year.  We are grateful to Carolyn for running.

We also expect a final response from the California Invasive Plant Council to our request that Blue Gum eucalyptus be removed from its list of “invasive” plants.

In summary

Science is rapidly revising the unfounded assumptions of invasion biology and climate change is making the concept of “native” meaningless.  But these realities are having no apparent influence on public policy, which seems to be immune to such facts.  Popular culture always lags behind science.

Million Trees is changing its emphasis in response to these political realities.  In 2015, we will focus on the science that is revising invasion biology because that’s where progress is being made.  This type of research is both difficult and time-consuming for us because we do the background reading to understand the scientific literature and produce accurate reports that are accessible to the layperson.  We therefore expect to publish new articles only once each month in 2015.  As always, we invite guest authors to step forward with news of new developments that we are not covering.

Thank you for your readership in 2014 and for any help you gave us in 2014 on our various initiatives.  We wish you all a Happy New Year in 2015.

Another lame attempt to defend invasion biology

The Editor of an academic journal, Diversity and Distribution, wrote and published a defense of invasion biology (which he prefers to call “invasion science”) entitled, “Misleading criticisms of invasion science:  a field guide.” (1)  We recently critiqued a similar defense by other invasion biologists, so we’ll “cherry-pick” a few issues from this publication which weren’t covered in our earlier critique.

“Costs and Benefits?”

The authors begin by describing their academic discipline:  “Invasion science is the study of the causes and consequences of the introduction of organisms to the areas outside their native ranges.  It concerns all aspects relating to the transport, establishment, and spread of organisms in a new target region…and the costs and benefits of invasion with reference to human value systems.”  However, the publication makes no mention of any benefits of non-native species nor does it mention the costs to the environment associated with the attempts to eradicate non-native species, such as herbicide use.  Non-native species are said to be “far more likely to cause substantial ecological and socio-ecological damage” than to benefit ecosystems and, in any case, if there are any benefits they are said to be “transient.”

Zebra mussels, open underwater with siphons out.  Creative Commons
Zebra mussels, open underwater with siphons out. Creative Commons

Actually, there is empirical evidence that the negative impacts of non-native species are transient.  For example, the population of zebra mussels in the Great Lakes began to decrease significantly within three years when the population of migrating ducks discovered them and altered their migratory route to take advantage of that new food source.  And the negative effects of garlic mustard on forest regeneration were significantly decreased within 50 years of its arrival in North American forests.

Monarch butterflies roosting in eucalyptus tree.
Monarch butterflies roosting in eucalyptus tree.

Evidence of the benefits of non-native species is too voluminous to enumerate, so we will just offer our local example of the services to wildlife provided by eucalyptus in California.  It is one of the few sources of nectar in the winter and is therefore essential to the survival of honeybees and hummingbirds.  Eucalyptus is the over-wintering roost of 75% of monarch butterflies in the California migration.  It is the preferred nesting habitat for raptors.

We see no evidence in this publication that “costs and benefits” of non-native species have been considered.

Are most “invasions” benign?

The authors respond to the defenders of non-native species who say that most non-native species are benign:

  1. “The impacts of most invasions have not been studied, and so important effects may remain undetected,
  2. Invaders that are apparently innocuous in one region can be disruptive in other regions,
  3. Subtle impacts that may be unrecognizable without careful technical study can produce enormous ecosystem changes over time, and
  4. Many non-native species that currently appear innocuous may become damaging many years later—when it is no longer feasible to eradicate them.” (1)

Here’s how we paraphrase this defense:  “We may not have much evidence that non-native species are doing any harm, but we are sure they are doing harm and even if they aren’t doing any harm, we’re sure they will eventually do a great deal of harm.”  Does this seem an adequate defense of projects that are eradicating all non-native plants on thousands of acres of public land, using harmful methods such as herbicides and prescribed burns?  We think a higher standard of proof is needed to justify such damage to our public lands.

Invasion biologists chastise critics

Invasion biologists are angry that their academic turf is being challenged by other academic scientists:

“In our view, the escalation of cavalier bashing of the discipline is undermining systematic science-based efforts to improve the efficiency of management of problematic non-native species and invaded ecosystems.” (1)

We have seen no “cavalier bashing” of invasion biology.  What we have seen, and provided to readers of Million Trees, are many scientific studies which show that the hypotheses of invasion biology are often not supported by evidence from the field.  Most of the papers don’t even mention “invasion biology,” they just present their evidence in scientific journals.

We wish it were true that these studies were “undermining management” of non-native species.  Unfortunately, we see no evidence that criticisms of invasion biology by academic scientists have any impact on public policy.  Every project in the San Francisco Bay Area which is eradicating or proposing to eradicate all non-native species on our public lands is moving inexorably forward.  There is no apparent connection between the revision of the hypotheses of invasion biology by academic scientists and the practical application of those out-dated hypotheses by managers of public lands.  If the primary goal of invasion biologists is to eradicate non-native species rather than to defend their academic discipline, they seem to have nothing to fear.  They would be wise to shut up and let the destruction continue quietly under the public’s radar.

A new round of criticism of invasion biology

Where do camels belongMeanwhile, the angry reaction of invasion biologists to criticism of their discipline has not stopped that criticism.  Hardly a day goes by without the publication of new critiques of invasion biology by other scientists.  Where do camels belong? by Ken Thompson was published in September 2014.  It is a full frontal assault on the unfounded assumptions of invasion biology.  It is a hard-hitting, often amusing summary of the flaws in the reasoning on which invasion biology was constructed.  Although Mr. Thompson is a British academic scientist, his book is written for the general public, drawing on the scientific studies of his colleagues who share his opinion of the fallacies of invasion biology.  The book is also unique in mentioning the damage that is done by the fruitless attempts to eradicate firmly entrenched non-native species.

Mr. Thompson was recently interviewed by Canadian public radio.  Here is a choice excerpt from that interview:

“He also cautions that our efforts to control or eliminate invasive species can be tremendously expensive, are rarely successful, and often have damaging unintended consequences. For example, the herbicides used to try to eliminate invasive plants often have devastating impact on vulnerable native species. The cure, in some of these cases, is worse than the disease, he says.  Professor Thompson says the invasive species we might worry about most is actually us. Humans have spread to every corner of the globe, and altered a huge amount of the planet.  ‘We’ve chopped down forests, built dams and turned the whole world into a giant cattle pasture, and then we’re surprised that some species quite like what we’ve done. We shouldn’t be surprised.’”

The publication of Where do camels belong? is one of the few bright spots in 2014, a year full of disappointments for those who value our urban forest in the San Francisco Bay Area.  We recommend it to our readers.  It may cheer you up as it did us.

Update:  Professor Richardson recently published (February 11, 2015) an article in Ensia, an on-line science blog, which was written in response to an earlier article(January 21, 2015)  in Ensia by Daniel Simberloff.  Professor Simberloff’s article defended “invasion biology” and criticized any acceptance of “novel ecosystems.”  Professor Richardson’s response seems to defend “novel ecosystems.”   It seems that Professor Richardson has altered his views regarding novel ecosystems since writing his article two years ago about “Misleading criticism of invasion science.”  Welcome to reality, Professor Richardson.  Updated 4/8/15


  1. David Richardson and Anthony Ricciardi, “Misleading criticisms of invasion science: a field guide,” Diversity and Distribution, 19: 1461-1467, 2013

What is the goal of ecological “restorations?”

In the not-so-distant past, the goal of ecological “restoration” was usually described as the re-creation of an historical landscape that was believed to have been undamaged by humans, presumed to be “in balance” and therefore sustainable after “restoration” without further human management.  In North America, the pre-European landscape is usually selected as the ideal landscape to be replicated, based on the assumption it had not been radically altered by Native Americans.  New knowledge has overturned this model:

Native Americans setting grass fire, painting by Frederic Remington, 1908
Native Americans setting grass fire, painting by Frederic Remington, 1908

Oddly, many invasion biologists accept these new understandings of ecological science without changing their deep commitment to eradicating all non-native plants and animals.  Daniel Simberloff published an article about the current status of the concept of “balance of nature” simultaneously with the publication of his defense of invasion biology.  He described the current thinking about this concept: “…a widespread rejection of the idea of balance of nature by academic ecologists, who focus rather on a dynamic, often chaotic nature buffeted by constant disturbances.”

Invasion biologists have therefore revised their goal for ecological “restorations” to accommodate their new understanding of the dynamic nature of ecosystems.

The revised goal of ecological “restorations”

If the return to an equilibrium state is no longer the goal of ecological “restorations,” what is the new goal?  This is how invasion biologists writing in defense of their discipline described their goal: “…we should seek to reestablish – or emulate, insofar as possible – the historical trajectory of ecosystems, before they were deflected by human activity, and to allow the restored system to continue responding to various environmental changes…” (1)

In this post we will deconstruct this new definition of the goal of ecological “restorations.”  Our first problem with this new definition is that we don’t know the “historical trajectory” of a landscape because it is fundamentally unknowable.  We would have to reconstruct all the events and changes in the environment in the Bay Area in the past 250 years in the imagined absence of any Europeans.  Even if we knew what would have happened without our presence, we cannot then ensure the continuation of that imagined environment because, the fact is, WE ARE HERE AND WE AREN’T GOING AWAY!

Because we cannot reconstruct an imagined environment that has not been “deflected by human activity,” restorationists—who are the practitioners of invasion biology–focus on the one element in the environment of which there is sufficient historical knowledge, i.e., plants.  Most local restoration projects eradicate all non-native plants and trees, usually using herbicides to accomplish that task.  They rarely plant anything after this eradication attempt because they don’t have the resources to do so.  Those few projects that re-plant after non-natives are eradicated usually irrigate the new landscape for several years.  Here is an incomplete list of everything these projects do not do to replicate an historical landscape:

  • Soils are not restored for many reasons:
    • We have no way of knowing the composition of soil 250 years ago.
    • Soils have been altered by the plants that have been growing in them and by the herbicides used to kill those plants.
    • Urban soils have high nitrogen levels resulting from exposure to fossil fuel exhaust.
  • The atmosphere is not restored:
    • There are much higher levels of ozone and carbon dioxide than there were 250 years ago.
  • The climate is not restored:
    • The temperature is higher than it was 250 years ago.
    • The timing of seasons has therefore changed.
    • Precipitation and fog have changed in known and unknown ways.
  • The disturbance events that sustained historical landscapes or set them on another evolutionary course are not restored:
    • We cannot set fire to urban landscapes annually without polluting our air and endangering our lives.
    • We cannot allow our creeks and rivers to overflow in urban areas without damaging our properties.
  • Most occupants of the historical landscape are not reintroduced:
    • The grazing animals that helped to sustain grassland are gone and cannot be returned to urban landscapes.
    • The top predators such as bears and wolves that kept grazing and other animals in balance with available resources cannot be returned without threatening our safety in an urban setting.
    • Many insects that lived in these historical landscapes are unknown to us and some are extinct.
The El Cerrito Plaza with the Albany Hill in the background, centuries ago.  Oil painting by Laura Cunningham, with permission
Bears roamed the grasslands in the Bay Area, preventing over-population of grazing animals. The El Cerrito Plaza with the Albany Hill in the background, centuries ago. Oil painting by Laura Cunningham, with permission

In other words, destroying plants will not “restore” an historical landscape.  Nor will it return that landscape to its “historical trajectory” even if that trajectory were known or knowable.  Plants live in complex communities in which they are interacting with everything in the environment.  Local “restoration” projects do not “restore” an historical landscape because they do not and cannot change anything other than the plants that occupy the space.  Because most environmental variables have not been altered by these projects, the landscape will quickly return to its unrestored state unless it is intensively gardened.  In that case, the landscape will be continuously “deflected by human activity,” which violates the original goal of invasion biologists.

Misanthropic premise of invasion biology

The revised goal of invasion biology is unattainable because the absence of humans is a prerequisite for its attainment.  We cannot know and we cannot replicate a theoretical historical trajectory for ecosystems in which humans were not present.  And when we modify ecosystems in an attempt to do so, human activities will determine their future trajectory. The premise of invasion biology is that success of ecological “restorations” depends upon the absence of humans. Therefore, invasion biology has no practical application in the real world.   


  1. Carolina Murcia, James Aronson, Gustavo Kattan, David Moreno-Mateos, Kingsley Dixon, Daniel Simberloff, “A critique of the ‘novel ecosystem’ concept,”Trends in Ecology and Evolution, October 2014, Vol. 29, No. 10

A defensive tirade from invasion biologists

Pesticide use by land managers in California.  Source California Invasive Plant Council
Pesticide use by land managers in California. Source California Invasive Plant Council

An international team of invasion biologists has just published a defense of their academic turf, invasion biology.  (1) Daniel Simberloff, an American member of the team, is the most relentless defender of the crusade to eradicate all non-native species, wherever they are found, all over the world.  Their publication acknowledges the mounting criticism of this crusade and attempts to respond to that criticism, but what is most notable is what is missing from their attempt to defend their opinions.  They make no mention of the harmful methods used to eradicate non-native species:

Keep these damaging methods in mind as we visit the hypocritical and contradictory arguments used to justify the projects for which these invasion biologists advocate.  They set up “novel ecosystems” as the straw man to which they compare the goals of invasion biology.  They define novel ecosystems as “a new species combination that arises spontaneously and irreversibly in response to anthropogenic land-use changes, species introductions, and climate change, without correspondence to any historical ecosystem.”

“Lack of rigorous scrutiny”

Their primary criticism of the concept of “novel ecosystems” is that it has not been “subjected to the scrutiny and empirical validation inherent in science” and its definition is “impaired by logical contradictions and ecological imprecisions.”   These criticisms apply equally to invasion biology.

Hypothesis n % of supporting studies % of decline in support
Invasional meltdown




Novel weapons




Enemy release




Biotic resistance




Tens rule




Island Susceptibility




Although support is strongest for the invasional meltdown hypothesis, recent studies are less supportive than early studies, indicating substantial decline in supporting evidence.  Declining evidence of invasional meltdown is consistent with the fact that exotic species are eventually integrated into the food web which reduces their populations, stabilizing their spread. There is apparently little evidence that islands are more susceptible to invasion than continents and few studies have been done to test the hypothesis.

If empirical validation and semantic precision are required to establish the credibility of scientific hypotheses, invasion biology has failed that test.

“Precautionary principle of conservation and restoration”

These invasion biologists define the precautionary principle of conservation and restoration as follows:  “we should seek to reestablish –or emulate, insofar as possible—the historical trajectory of ecosystems, before they were deflected by human activity.”  This is an unusual use of the precautionary principle, which is more typically defined as avoiding damage to the environment by not using potentially harmful methods, even in the absence of solid evidence of such harm.  The precautionary principle was not used when the following “restoration” projects were defined or implemented:

Ivy in the Conservatory in Central Park, New York City
Ivy in the Conservatory in Central Park, New York City

In 1996, Daniel Simberloff made this statement in his publication about the hazards of biological controls:  “…are there any protocols for biological-control introductions that would prevent all disasters?  Probably not…” (2) Yet, in 2013, he expressed his support for the introduction of non-native insects to control cape ivy at a conference at UC Davis sponsored by the California Department of Food and Agriculture.  Although cape ivy is despised by native plant advocates, it is not an agricultural pest and therefore causes no economic damage to ecosystems, unless money is wasted on attempts to eradicate it.

“All ecosystems should be considered candidates for restoration”

In response to those who find value in novel ecosystems, these invasion biologists find none.  They reject the possibility that there is ever a point at which it may not be possible to re-create a historical landscape.  They continue to believe that ANY and ALL radically altered landscapes CAN and SHOULD be considered candidates for restoration.  Their only caveat to this universal goal is that “damaged ecosystems…should be evaluated for feasibility, desirability, and cost-effectiveness, on a case-by-case basis, so that informed and science-based policy decisions can be made, in consultations with scientists, restoration practitioners, stakeholders, and advisors.”

These criteria for potential “restoration” have nothing to do with reality:

  • Most projects in the San Francisco Bay Area have not provided cost estimates when they were planned. The public demanded cost estimates for the projects of the Natural Areas Program in San Francisco, but these demands were ignored.  Therefore, “cost-effectiveness” is not usually considered when these projects have been shoved down the public’s throat.
  • We consider the public to be “stakeholders” in decisions to radically alter our public open spaces. We are the visitors to these areas and our tax dollars pay for their acquisition, maintenance, and “restoration.”  Yet, managers of public land are consistently making those decisions without taking the public’s opinion into consideration.  Most projects are planned and executed without any public participation.  In the few cases in which there are environmental impact reviews, the projects are implemented regardless of overwhelming opposition of the public.

 “Human-damaged ecosystems can be at least partially restored”

The demonstrated futility of “restoration” projects is one of many reasons why there is waning public support for attempting them.  Yet, invasion biologists who authored this diatribe claim that “restored sites recovered on average 80-86% of biodiversity and ecosystem services…and showed improvements of 125-144% over degraded ones.”  This claim is contradicted both by other scientific studies and by experience with local projects:

  • “…this paper analyses 249 plant species reintroductions worldwide by assessing the methods used and the results obtained from these reintroduction experiments…Results indicate that survival, flowering and fruiting rates of reintroduced plants are generally quite low (on average 52%, 19%, and 16% respectively). Furthermore, our results show a success rate decline in individual experiments with time.  Survival rates reported in the literature are also much higher (78% on average) than those mentioned by survey participants (33% on average).” (3)
  • Dunnigan Test Plot, Augusst 2011.  The result of an eight-year effort to restore native grassland.  Does it look "biodiverse?"  ecoseed.com.
    Dunnigan Test Plot, August 2011. The result of an eight-year effort to restore native grassland. Does it look “biodiverse?” ecoseed.com.

    There is frequently a discrepancy between the success rates claimed in papers and those actually observed. For example, Cal-Trans gave researchers at UC Davis $450,000 to restore 2 acres of non-native annual grassland to native grassland.  UC Davis researchers spent 8 years and used multiple methods to achieve this transition.  When they ran out of money, they declared success in their published report.  They defined success as 50% native plants which they expected to last 10 years before being entirely replaced by non-native annual grasses again.  Do you consider that a success?

  • On a more anecdotal level, we watch established landscapes that have required no maintenance in the past being transformed into weedy messes by failed “restoration” projects. Then, adding insult to injury, we hear those who are responsible for these failures tell us how successful they are.

“Inadequate political will”

The authors of this publication conclude:

“No proof of ecological thresholds that would prevent restoration has ever been demonstrated.  Often the threshold that obstructs a restoration project is not its ecological feasibility, but its cost, and the political will to commit to such cost.” (1)

We are reminded of an old football adage:  “The best defense is a good offense.”  In other words, invasion biology is under fire, but the reaction of invasion biologists is to demand more….more money, more effort, and the commitment of public land managers to “restore” all ecosystems, regardless of what the public wants.  And in support of that aggressive strategy, they refuse to acknowledge the damage that is being done to the environment and the animals that live in it, by the projects they demand.

The authors of this defensive tirade have hammered another nail in the coffin of invasion biology.

  1. Carolina Murcia, James Aronson, Gustavo Kattan, David Moreno-Mateos, Kingsley Dixon, Daniel Simberloff, “A critique of the ‘novel ecosystem’ concept,” Trends in Ecology and Evolution, October 2014, Vol. 29, No. 10
  2. Daniel Simberloff and Peter Stiling, “How Risky is Biological Control?” Ecology, 77(7), 1996, pp 1965-1974
  3. Sandrine Godefroid, et. al., “How successful are plant species reintroductions?” Biological Conservation,   144, Issue 2, February 2011

Evolutionary advantage of introduced species

We have often wondered why so many plants and animals introduced to North America become invasive, compared to species introduced to Europe.  In California, there are about 200 plants on the inventory of “invasive” plants.  In Britain, there are only about a dozen plants considered “invasive.”  In past articles, we have speculated that Americans are using different standards to determine invasiveness and that may be a factor.  But now scientists, Jason Fridley and Dov Sax have recently reported the empirical evidence that suggests some regions are more vulnerable to invasion than others because of competitive advantages of species from regions with longer evolutionary histories.  In fact, Charles Darwin is the original author of this theory:

“Darwin (1859) observed that because ‘natural selection acts by competition, it adapts the inhabitants of each country only in relation to the degree of perfection of their associates, such that, we need feel no surprise at the inhabitants of any one country…being beaten and supplanted by naturalized productions from another land.’  Darwin’s view, one of the earliest on biological invasions, presents invasion as an expectation of natural selection – a view largely absent from modern invasion biology.  Darwin further suggested that species from larger regions, represented by more individuals, has ‘consequently been advanced through natural selection and competition to a higher stage of perfection of dominating power’ and therefore be expected to beat ‘less powerful’ forms found in other regions.” (1)


Based on Darwin’s speculation, Fridley and Sax formulated the evolutionary imbalance hypothesis, based on three postulates:

  • Evolution is essentially an infinite series of experiments as each generation is tested by the conditions they encounter. The more tests the species passes by surviving and reproducing, the more fit the species is to face the next test.
  • The number of such experiments vary by region that differ in size and biotic history, which influences the intensity of competition each species encounters.
  • “Similar sets of ecological conditions exist around the world” thereby facilitating the movement of species from their native ranges to new ranges.

It follows from these postulates that when species from previously isolated habitats are mixed, some species will be more fit than others for any given set of conditions.  In other words, they have an evolutionary advantage by virtue of having faced more competition for a longer period of time.   These are the environmental conditions that are likely to confer such an evolutionary advantage:

  • Larger regions with large expanses of habitat usually have larger populations of species. Larger populations have more genetic variation, which provides more opportunities for natural selection to choose a “winning” genetic combination.
  • Also, more stable environments enable lineages to survive for longer periods of time. The longer the opportunity for natural selection to operate, the more fit the surviving lineage.
  • The greater the competition each species experiences, the more fit the surviving species is likely to be. Therefore, species occupying diverse habitats are likely to be more fit than species in less diverse habitats.

The authors of this new study tested these hypotheses in three geographic areas that have well-documented non-native floras, including Eastern North American, the Czech Republic, and New Zealand.  For example, the climate of the Northeast of America is similar to East Asia.  Some of the most destructive invasive species in the Northeast are from East Asia, such as the emerald ash borer.  Yet species from North America do not become invasive when introduced to East Asia.  Species from East Asia have a much longer evolutionary history than species native to the Northeast because much of the United States was buried in glaciers during the Ice Ages, while East Asia was not.  (2)  The longer evolutionary history of East Asia makes East Asian species “fitter” and more likely to be successful in North America, while North American species are less successful in East Asia.

Kudzu evolved in Japan.  USDA
Kudzu evolved in Japan. USDA

Failure of the competing theory

Invasion biology is the competing theory of why introduced species become invasive when introduced outside their native ranges.  It is a theory that turns its back on evolutionary theory by assuming that plants and animals are incapable of adapting to changed conditions.  Invasion biology assumes that introduced plants become invasive because they leave their predators behind.  This is the predator release theory which also implies that introduced plants are not useful to native animals.

The problem with the predator release theory is that there is no empirical evidence that supports it.  For example, equal numbers of insects are consistently found in native and non-native habitats.  And when empirical studies claim to have found evidence of predator release, sampling errors have discredited those studies:

“For example, one study found fewer parasitic worms in introduced starlings in North America than in the entire native range of Europe and Asia.  But once allowance was made for the actual local source of the starlings, the difference disappears:  various evidence suggests starlings arrived in North America via Liverpool, and American starlings have most of the parasites of Liverpool starlings, plus quite a few others, either American natives or European parasites introduced with other birds.  In fact, American starlings have more parasites than are found in the likely source population.”  (3)

Starling in breeding plumage.  Creative Commons - Share Alike
Starling in breeding plumage. Creative Commons – Share Alike

“Resistance is futile”

And so we add the evolutionary imbalance hypothesis to the long list of reasons why we are opposed to fruitless attempts to eradicate well established non-native species of plants and animals:

And now we know that many invasive species have evolutionary advantages over the native species they have displaced:  “The evolutionary imbalance hypothesis…could have a grim implication for conservation biologists trying to preserve native species:  They may be fighting millions of years of evolution.  If that’s true, the phrase ‘Resistance is futile’ comes to mind.” (2)


  1. Jason Fridley and Dov Sax, “The imbalance of nature: revisiting a Darwinian framework for invasion biology,” Global Ecology and Biogeography, 23, 1157-1166, 2014
  2. Carl Zimmer, “Turning to Darwin to Solve the Mystery of Invasive Species,” New York Times, October 9, 2014
  3. Ken Thompson, Where do camels belong?, Greystone Books, 2014

Polarized views of nature mirror our politics

We recently posted an article about our on-going debate with the Audubon Society regarding its misguided support for the projects that are destroying the urban forest in the San Francisco Bay Area.  That article provided a few examples of our widely divergent views of nature:

  • We don’t see how birds will benefit from the destruction of tens of thousands of trees and countless plants that provide food and cover for birds and animals.
  • We don’t enjoy walking in nature with a judgmental eye, which points fingers at plants and animals that others claim “don’t belong there.” We are unwilling to divide nature into “good” and “bad” categories.
  • We don’t think humans have the right to pass a death sentence on wild animals because they prefer another animal, which they claim will benefit from the death of a potential competitor.
  • We don’t consider a “managed” forest a “more natural forest.” We don’t think humans are capable of improving what nature can accomplish without our interference.  We don’t think a public park that is routinely sprayed with herbicides can be accurately described as a “natural area.”
English sparrow.  US Fish & Wildlife photo
English sparrow. US Fish & Wildlife photo

However, these widely divergent viewpoints about nature are not inconsistent with the extremes of our polarized politics in America.  Just as we don’t expect to change the minds of those at the opposite end of the political spectrum, we don’t expect to change the minds of those who view nature through the darkly colored lens of nativism.  Just as elections for public office are decided by the independents in the middle of the political spectrum, the debate about the future of our public lands will be decided by those who have not yet formed an opinion about what is best for nature.  Today’s post is addressed to them.  We will tell the “independents” about two recent op-eds published by The New York Times which represent the two extreme viewpoints about nature.  Both op-eds use sparrows as representatives of the natural world, which we hope will make the differences in these viewpoints starker and therefore clearer.

First a word about how important the “independents” are to the debate about the ecological “restorations” which are dictated by invasion biology.  Political independents are usually not more than a third of the electorate.  But, a survey conducted by University of Florida suggests the majority of the public are still open to learning more about “invasive species.”  They report that 62% of Floridians they surveyed said they are not knowledgeable or only slightly knowledgeable about invasive species.  Ironically, the same survey claimed that “a majority voiced support for raising sales tax to combat invasive species.”  One wonders why voters who acknowledge that they know nothing or next to nothing about invasive species would be willing to tax themselves to combat something they don’t understand.  In any case, if Floridians are typical, the majority of the public needs to know more about invasion biology.  We hope they have access to balanced information that is not written by those who make their living killing animals and poisoning our public lands.  Million Trees was created over four years ago for that purpose.

“The Truth About Sparrows”

Some time ago, we told the story of how sparrows were brought to America in the 1850s by people who believed they would eat the insects that were killing trees.  We concluded that article by saying that 150 years later house sparrows are no longer despised as alien intruders.  We were wrong.

In May 2014, the New York Times published an op-ed entitled “The Truth About Sparrows.”  The op-ed was written by Peyton Marshall, whose mother was an exterminator of house sparrows.  This was no idle pastime for Ms. Marshall’s mother.  It was her mission.

Eastern bluebird, public domain
Eastern bluebird, public domain

Mom’s crusade against house sparrows began when Ms. Marshall was a child.  Mom loved bluebirds at a time when their population was dwindling in the east where they lived.  Mom decided that house sparrows were to blame and so she took it upon herself to kill every house sparrow that had the misfortune of entering her yard or within reach of it.

Mom began by trapping the house sparrows.  “Good” birds caught in the traps were freed, but the house sparrows were put into plastic garbage bags and asphyxiated.  Mom started the family car in the garage and wrapped the open end of the garbage bag around the tailpipe.  When the birds did not die, she consulted her husband who informed her that the car was a diesel and would not produce enough carbon monoxide to kill the birds.

So, mom took her operation on the road.  She helped elderly ladies with their groceries in the parking lot in exchange for a shot at their tailpipe.  When dropping off her children for play dates and birthday parties, she asked their parents if she could make brief use of their cars to kill birds.  Polite parents watched in horror as they became accessories to this execution.

Ms. Marshall concludes her story by noting that the population of bluebirds has rebounded since she was a child.  But mom continues to trap house sparrows in her yard and now uses a less public means of killing them:  “Now, she uses a carving knife and cutting board, at her leisure, in the privacy of her own kitchen.”

Although Ms. Marshall doesn’t say so, we doubt that the recovery of the bluebird population has much to do with the extermination of house sparrows in her mother’s backyard.  The recovery of the bluebird population is attributed to building nest boxes that substitute for the dead trees which are their preferred nest sites.  There are few dead trees in urban and suburban areas because people consider them hazardous and unsightly.  Once again, animals pay the price for the choices of humans.

“What the Sparrows Told Me”

The New York Times published “What the Sparrows Told Me” in August 2014.  It is a fitting antidote to the grisly tale of the sparrow exterminator.

Trish O’Kane, the author, was a human rights investigative journalist in Central America for 10 years before moving to New Orleans to teach journalism.  Less than a month after arriving in New Orleans, she and her family were displaced by hurricane Katrina in 2005.  Four months after the hurricane, she rented a room in a dry part of town so that she could return to her teaching job.  It was a hard time for everyone in New Orleans, but her gloom was deepened by learning of her father’s terminal cancer which would kill him in a matter of months.

Ms. O’Kane had never had an interest in birds before, but she knew she needed “to focus on something beautiful, something positive, something alive,” and so she did:

“I bought two bird feeders.  Each morning I sat on that back stoop and watched those sparrows.  Instead of wondering what was going to happen to the city, to the Gulf Coast, to the planet, I started wondering why one sparrow was hogging all the seed.  I started thinking about their resilience, their pluck, their focus on immediate needs.  If they couldn’t find food, they went somewhere else.  If they lost a nest, they built another.  They had no time or energy for grief.  They clung to the fence in raggedy lines heckling one another like drunken revelers on Bourbon Street.  Their sparring made me laugh.“

Audubon Park, New Orleans.  Public domain
Audubon Park, New Orleans. Public domain

Ms. O’Kane started holding her classes in Audubon Park, named for John James Audubon.  Her students began to find the same solace in watching the birds going about their business, finding a way to survive, carrying on.  And that gave her and her students the strength and the will to do the same at a time when life was hard in New Orleans.

Ms. O’Kane is now a doctoral student in environmental studies at University of Wisconsin, Madison.  She has found a way to connect her interest in human rights with her new found interest in birds.  She teaches an undergraduate course in environmental justice in which she pairs undergraduate students with middle school students in a mentoring program called Nature Explorers.  Many of the middle school children are immigrants from Central America.  She finds that they enjoy learning about the birds that migrate between Central America and Wisconsin, just as their families did.  The birds, like the people of America, are citizens of the world.

Ms. O’Kane tells us that many of her undergraduate students are frightened of the future of our planet.  She likes to start each new class with the story of the sparrows in New Orleans:  “I tell them that the birds are a gift to help them get through each day, a way to enjoy the world while we change it so that young people, everywhere, have a chance.”

Whose eyes do you choose to look through?

It’s no secret that our viewpoint regarding nature is more closely aligned with Ms. O’Kane’s.  If you haven’t yet taken a stand on the issue of what plants and animals are welcome in your ideal nature, think for a moment.  Which of these starkly different viewpoints do you prefer?