What is Compassionate Conservation?

Matt Chew has written another guest post for Million Trees about the International Compassionate Conservation Conference that recently took place in Australia, where he gave a presentation.  Dr. Chew is a faculty member of Arizona State University’s Center for Biology and Society and an instructor in the ASU School of Life Sciences.  He has written two popular posts for the Million Trees blog about the “restoration” industry and about the controversial projects that are eradicating tamarisk trees.

Arian Wallach, Dingo for Biodiversity Project

I was introduced to compassionate conservation by one of its proponents, Arian Wallach.  Dr. Wallach is the Project Director of the Dingo for Biodiversity Project in Australia.  Dingoes were the top predators of smaller animals in Australia for about 5,000 years until Europeans introduced new predators in the 19th century.  Colonists to Australia have been killing dingoes since they arrived because dingoes are also predators of their sheep. 

Eradicating top predators has serious consequences for the entire ecosystem.  In the case of dingoes, smaller predators introduced by colonists have taken that role and are now the target of poisonous campaigns to eradicate them.  For example, Australia recently made a commitment to kill 5 million cats with poison.  Killing dingoes has put Australia on the killing treadmill. 

We have examples in the United States of similar cascading effects of killing top predators.  When wolves and bears were killed in some of our national parks, populations of grazing animals such as deer and elk exploded.  Vegetation was browsed to death and ultimately the grazing animals were without sufficient food.

Dr. Chew tells us that defending top predators is one of several tenets of compassionate conservation.  Two important themes emerge from his description of the conference:

  • Traditional conservation tends to focus on the preservation of a species, sometimes at the expense of individual members of that species. Compassionate conservation invites us to re-evaluate that emphasis, to also take the lives of individual animals into consideration.  In an extremely individualistic society such as America, this would seem an entirely appropriate approach to conservation.
  • Modern methods of conservation tend to focus primarily on rare animals, sometimes at the expense of common animals. Common animals are often blamed for the fate of rare animals.  Shooting barred owls based on the belief that endangered spotted owls will benefit is an example of such projects. 

These are ethical questions that deserve our thoughtful consideration and Dr. Chew’s guest post invites us to think deeply about them.

Million Trees

The third International Compassionate Conservation Conference took place in Australia last November. Over 100 pre-registrants represented thirteen countries of current residence. Every occupied continent and a few archipelagoes were accounted for. Nearly half of the roster bore “Doctor” or “Professor” credentials. About two-thirds were Australian, one-sixth from the USA, and the remainder distributed in single digits. The final tally, including walk-in registrants, has not been compiled.

Some Background

Traditional resource conservationists and animal welfare advocates celebrate separate histories and espouse distinct philosophies. In a given circumstance their views may coincide, but they more often conflict. Sometimes it’s a mix of both. Professionals in either discipline are more attuned and (perhaps) committed to the distinctions than are members of the general public. Some advocates on both sides are more confrontational than others. Given all that, it may be unsurprising that the concept of compassionate conservation arose in the unique context of a British charity organized by the starring actors of the 1966 film Born Free. The predicament of Elsa the lioness they helped publicize provided a unique nexus of predator conservation and captive animal welfare to build on.  Their Born Free Foundation , which at one point actually trademarked the term “Compassionate Conservation” has helped underwrite three meetings: a symposium in Oxford, U.K. (2010); a conference in Vancouver, British Columbia (2015), and the most recent conference in Leura, New South Wales.

Leura, Australia

The latter two events were co-sponsored and organized by the Centre for Compassionate Conservation (Centre) at the University of Technology in Sydney (UTS). The Centre was founded in 2013 by UTS conservation biologist Dr. Daniel Ramp, who continues as its Director. His unusual goal, succinctly (indeed, laconically) stated, is “to better conserve nature by protecting the welfare of individual animals in captivity and in the wild.” The Centre currently lists a core management team of five, plus six affiliated researchers. Five conference attendees identified themselves as Centre Ph.D. candidates, and another as an unspecified Centre student. Before organizing the Centre, Daniel and most of his present colleagues comprised something called THINKK, focused more narrowly on ethical kangaroo conservation. Coincidentally, a documentary film emerging from that effort just opened in selected U.S. theaters.

Alloying animal welfare advocates and conservationists this way requires effort.  Alloying them into a fully coherent interest group is unlikely. Conservationists, including conservation biologists, are rarely concerned with the comfort or fates of individual organisms. For example, the Society for Conservation Biology is “dedicated to advancing the science and practice of conserving Earth’s biological diversity”. It emphasizes populations, species, biotic communities and other aggregations rather than individual organisms. This view accommodates Darwinian natural selection and economic sustainability of recreational and commercial exploitation, including so-called ecosystem services. Except where the population of some species is approaching zero and every extant individual contributes substantially to its genetic diversity, whether any of them are particularly well off beyond their ability to breed or produce gametes for propagation purposes is a subsidiary concern. By contrast, animal welfare begins with sentient organisms and recognizes fewer aggregate or emergent properties. Strictly speaking, to welfare advocates, preserving a species or population is secondary to protecting individuals from experiencing pain or suffering, especially that related to human actions or influences.

California Condor with tracking tags on wings

Logically extended, the difference between conservation and compassion can be illustrated by the California condor recovery effort. Condors incapable of breeding are useless to conservation biologists other than for public relations purposes. Any “display” animal is subject to the particular dangers inherent in repeated transportation and public contact. Presented as an example or representative of the taxon Gymnogyps californianus it nevertheless becomes a named or nicknamed individual entity in the minds of the people who “meet” it.  Once transferred permanently for display to (e.g.) a zoo, the welfare of a named, non-breeding condor takes on a significance that it never had before. Should it fall ill, hundreds or thousands of people will fret. Should it die unexpectedly, they will mourn and hold its keepers responsible. Meanwhile, potential breeding condors may be released to cope with hazards of “wild” survival their captive counterparts never face. The processes of breeding contribute further stresses and risks. The value of a display condor is tallied in goodwill and monetary contributions. The value of a breeder is tallied in viable offspring, much as the value of a laying hen is tallied in eggs produced. The contentment of a named bird is judged differently from that of a numbered one. Should “recovery” succeed, individual condors will someday become as anonymous as turkey vultures, their welfare officially unmonitored. With all that in mind, a compassionate conservation conference is necessarily a coalition exercise. A stable, hybrid entity like the UTS Centre remains exceptional.

In the Event

The three-day Leura schedule included ten presentation sessions, a poster session and six workshops. Each presentation session opened with a half-hour keynote talk from an invited speaker followed by a series of shorter contributions.


Australian waterfall

Presentation sessions were organized around conservation ethics (2); novel ecosystems (2); animal welfare science and issues (2); laws and policies; agriculture and wildlife, predator-friendly ranching and finally “cultivating compassion”. Keynote speakers (six men, four women) came from the USA (5), Australia (3), Malaysia (1) and the UK (1). Nine are university faculty or affiliates; two represent independent conservation NGOs (yes, we turned it up to 11). Few of us can comfortably label ourselves without hyphenating. Our credentials include (alphabetically) Animal Science, Conservation Biology, Ecology, English, Environmental Ethics, Environmental Science, Ethnography, Evolutionary Biology, History, Humanities, Law, Natural Resources, Philosophy, Wildlife Biology, and Zoology and doubtless some that I overlooked. Our keynote talks ranged from practical legal and management case studies to aspirational exhortations. That may not be a defensible continuum, but it will have to do.

A conference program with abstracts is available for download here. Since there were about sixty presentations over two and a half days, I can hardly even list them, much less say anything pithy about more than a few. Their diversity made for an intense, eclectic, even exhausting experience. The general quality of presentations struck me as higher than the average at many more traditional, disciplinary conferences. Perhaps it takes “more” of something or another to survive the rigors of interdisciplinary or multidisciplinary work.

What I can do is highlight a couple of impressive research projects of particular interest to Million Trees followers in the western U.S.  In his keynote address, Conservation as creative diplomacy: Raven and tortoise futures in the Mojave Desert, University of New South Wales Associate Professor of Environmental Humanities Thom van Dooren looked at “new technology” attempts to dissuade the big black birds from preying on juvenile, endangered reptiles. Artificial tortoises conceived as the equivalent to exploding, joke cigars featured heavily in this thought-provoking and entertaining analysis. Understanding introduced megafauna in the Anthropocene: Wild donkeys as ecosystem engineers in the Sonoran Desert by Arizona State University graduate turned Centre Ph.D. candidate Erick Lundgren showed how “feral” burros in western Arizona create water sources used by “native” wildlife by digging down to shallow aquifers in dry washes. Photos and infrared video made the case for this completely new and gratifying application of the term “ass holes” and discussion of the demonstrable positive effects of “alien” animals. An early presentation of Erick’s findings can be viewed here.


Poster of Non-Nativist Landcare

For readers unfamiliar with poster sessions, the basic idea is to summarize a project, argument or proposal in the minimum necessary words and graphics to convey the important ideas. Posters can be perused at the convenience of conference-goers, and (as in this case) can be strategically hung in proximity to coffee and snacks; but a period is usually specified for poster authors to literally stand by their work and answer questions. What constitutes a poster is evolving rapidly. Mechanically pasted-up arrangements have been superseded by single, large format prints, which in turn may soon give way to looped or even user-navigable videos on flat screen displays. Only a handful of posters were presented at Leura. One included a description of low-disturbance riparian revegetation techniques; another explained a new proposal to legally protect captive whales, porpoises and dolphins in the U.S.A.; a third took data-driven issue with Argentina’s official over(?)-emphasis on lethally suppressing European rabbit populations; and the fourth combined a poster with a video loop to demonstrate the surprising calmness of red foxes living in proximity to dingoes, their only wild predators.


Befitting a gaggle of academics, three of the six workshops initiated collaborations meant to produce papers for peer-reviewed publication. “Welfare in the wild” focuses on the challenges of assessing the condition of free-living wild animals, a necessity for practical compassionate conservation. “The Australian Wildcat Project” seeks to reframe feral cats as wild animals and find “compassionate and effective solutions” that supersede traditional (and ineffectual) lethal culling.  “Transforming wildlife management policies” envisions a compassionate alternative to the present Australian Pest Animal Strategy.

For attendees not leashed to the “publish or perish” treadmill, “A framework for human-wildlife health and coexistence in Asia” built on the related presentation session to propose guidelines for further research and development. “Predator friendly ranching skills and technologies” demonstrated an array of time-tested, new and proposed methods for keeping livestock without resorting to lethal predator control. “Bringing ethics into conservation with argument analysis” offered an introduction to rhetorical and logical analysis of the claims underlying conservation decision-making.


Banksia in Australia

On July 31, 1947, Aldo Leopold finalized a paragraph that appeared about seven eighths of the way through his introduction to a proposed book of essays. It began “One of the penalties of an ecological education is that one lives alone in a world of wounds.” There, Leopold styled himself as “the doctor who sees the marks of death in a community that believes itself well, and does not want to be told otherwise”. Perhaps ironically, less than nine months later (at age 61) he succumbed to heart failure aggravated by the exertion of fighting a grass fire, leaving the still unpublished anthology in other hands. Nearly two decades on, editors transplanted the paragraph into the much-revised text of a Leopold essay titled “The Round River” for re-publication by Oxford University Press, where his overwrought sentiment blossomed into a gnostic axiom of conservation biology.

Practically anyone could recognize an injured animal. Only Leopold, selected colleagues and their presumptive heirs could diagnose the arcane injuries of populations, species, communities or ecosystems. The welfare of an organism didn’t “amount to a hill of beans” next to the integrity of the greater collective. It was a more than convenient fit into the value system of academic biology, where individuals are traditionally considered mere examples of taxa, available for collection, experimentation, or “scientific” interference pretty much at will.

As a group, biologists have likely devised more (and more esoteric) ways than anyone else to kill, injure or discomfit organisms. Way back in 1865, physiologist Claude Bernard, fountainhead of the indispensable idea of homeostasis, reflected, “the science of life…is a superb and dazzlingly lighted hall which may be reached only by passing through a long and ghastly kitchen.” Recipes beyond his darkest dreams have since been tested there. In that regard, conservation biology is unexceptional. Conservation biology in practice consists largely of subsidizing the (Darwinian) fitness of too-rare species by forcibly taxing that of too-common ones. The move from culinary to macroeconomic metaphors indicates only that we are now cooking on a vast, institutional scale. Both figuratively and literally, conservation biologists break a lot of eggs in service of making too-rare species more common and supposedly too-common ones more rare. Consistent with basic economic wisdom, individuals of scarce species are more highly valued than those of common species. But much of biology is still concerned with examining formerly living objects to find out what experimenting on them accomplished. The drafters of laws like the U.S. Endangered Species Act made “experimental, nonessential” individuals or populations available for scientific “take”. At best, such exceptions allow for research that might stave of extinction. At worst, they provide cover for otherwise anathema activities like “scientific whaling.”

What will become of compassionate conservation? I can’t answer that question. Its advent represents an interesting cross-pollination among otherwise ramifying points of view. I’m sympathetic to the basic aims of its proponents. My own work wasn’t really conceived to abet them; but if it does, I say “well and good.” There’s more than enough casually rationalized cruelty in the world already. 

Matt Chew

The Ecological “Restoration” Industry: Follow the money

Matt Chew is one of many professional academics that criticize invasion biology.  Unlike most, he emphasizes explaining the weaknesses of eco-nativism using scientific, historical, and philosophical methods, depending on the issue.  This has made him a useful collaborator and resource for like-minded but primarily science-oriented colleagues. Million Trees is deeply grateful for his willingness to speak publically about the fallacies of invasion biology, including the generous gift of his time in writing this guest post for us.

Dr. Chew is a faculty member of Arizona State University’s Center for Biology and Society and an instructor in the ASU School of Life Sciences.  He teaches courses including the History of Biology, Biology and Society, and a senior conservation biology course in “novel ecosystems,” described HERE on the university’s “ASU Now” news website.

He was also a speaker at the 2013 annual conference of Beyond Pesticides.  A video of his presentation is available HERE (go to 24:40).  He says that “invasive” plants are convenient scapegoats that are presenting a marketing opportunity for the manufacturers of pesticides. Invasion biology is at the core of the greening of pesticides.

In his guest post, Matt helps us to understand how he chose to pursue a multidisciplinary critique of one topic rather than adopting a single disciplinary approach and identity. He began his professional career as a practicing conservation biologist, experiencing firsthand the sometimes startling disconnects between laws, policies, aspirations, public expectations, and realities “on the ground.” 

We celebrate April Fool’s Day with Matt Chew’s article.  When we waste our money on ecological “restorations” the joke is on us!

Million Trees

Matt Chew with his class in novel ecosystems

Those familiar with my academic work know I invest most of my efforts documenting and explaining the flaws and foibles of “invasion biology.” But I got into this messy business as a practical conservation biologist, a natural resources planner “coordinating” the Arizona State Natural Areas Program during the late 1990s. I found the toxic nativism of natural areas proponents morbidly fascinating, and the practical politics of natural areas acquisition and management morbidly galling. I chose to follow my fascination. But as “Death of a Million Trees” marks the end of its seventh year as a WordPress blog, and in light of recent decisions by Bay Area authorities, it’s time for a galling reminder:  Follow the money.

Authorities responsible for suburban fire suppression and recovery necessarily view stands of living trees as liabilities. They can’t see the forest for the fuels. The prospect of eliminating them merely drives their value further into the negative. That it must be subsidized is ironic because eucalyptus and Monterey pine are plantation grown in many countries for timber or pulp. But they aren’t traditional sources of California wood products and a glut of more familiar drought-killed trees awaits salvage far from finicky neighbors.

So condemned trees can’t just be disappeared by pointing them out to eager loggers. “Concept planning” can be fairly vague, but “action planning” must be very specific. A job this big requires both general and sub-contracting. It requires hiring and training and supervising. Capital equipment will be acquired, maintained and repaired. Affected areas must be surveyed and material volumes estimated. Before trees can be felled, access routes must be surveyed and created. After trees are felled they must be sectioned, staged, loaded and hauled away for disposal. More often they are shredded in place. At every step, someone pays and someone profits.

Where “ecological restoration” is the objective, stumps must be pulled or blasted and roots must be excavated. The eucalyptus seed bank will need to be eliminated or rendered inert. Perhaps even a century’s accumulation of organic topsoil will need amending, or removing and replacing to reconstitute prehistoric substrates. Seed suppliers and nurseries will be contracted to provide plant “native” materials. After the armies of tree-fellers and stump-blasters will come waves of laborers, tractors, diggers, spreaders, and planters in an endless relay of trucks. Ecological restoration is farming, all the more so in proximity to a cityscape arrayed in exotic plants. If all goes well and the rain falls in judicious quantities at auspicious times, planting will be followed by perpetual weeding. At every step, someone pays and someone profits.

It’s hardly surprising that FEMA has no intention of underwriting restoration on that scale. Their plans envision minimally spreading shredded wood, leaving a layer up to two feet deep to gradually decompose, and hoping whatever oaks and other present understory plants they haven’t accidentally fractured or flattened will thrive in the sudden absence of big trees. Two feet of material will gradually compact, but assurances that it will rot into organic soil within a few years are pretty optimistic. Whether and when it will support anything resembling a native plant assemblage is dubious. Meanwhile, some viable stumps will require recurring treatment with the herbicide du jour and occasional supplemental felling. It’s not a reset-and-forget strategy. It’s just the first step of a long and contentious cycle of interventions. And of course, at every step, someone pays and someone profits.

Whenever public property and expenditure is concerned there should be an open procurement process with a clear data trail. A call for proposals is written and published, bids are received, contracts awarded, and work commences. But we can be certain that by the time the prospect of deforesting the Bay Area was openly discussed by policymakers, potential bidders were positioning themselves to influence the shape of the emerging policy and take advantage of it. And various interest groups who saw deforesting the hillsides as a means to their ends became a de facto coalition of advocates. Some acted more openly than others, and some to greater effect. But prominent nonprofit organizations expect returns on their investments. Nothing happens unless someone pays and someone profits.

Some of the premises underlying the logic of the program will inevitably be faulty. Should it falter at any step due to unforeseen events (e.g., meteorological, horticultural, ecological, economic or political), contingencies will be implemented… if funds are available. There are only three certainties. Firstly, no action occurs unless someone pays and someone profits. Secondly, nature, within which I include all aspects of human society, is complex and capricious. No one can predict with much certainty how a post-deforestation landscape will look or function. Finally, a coalition of the discontented will emerge and agitate for improvements that require someone to pay, and allow someone to profit.  As Nancy Pelosi recently reminded us, “we’re capitalist and that’s just the way it is.”   

Matt Chew



Are critics of invasion biology pessimists or realists?

The California Department of Food and Agriculture held a symposium about invasive pest management in the 21st Century on October 17, 2013, at UC Davis.  This second in a series was focused on insects and diseases.  The first symposium held in Oakland in June 2013, focused on “invasive” plants.

The keynote speaker at the second symposium was Professor Daniel Simberloff of University of Tennessee.  He is a prominent invasion biologist and a self-appointed defender of that scientific discipline.  When the assumptions of invasion biology are questioned by other scientists, Professor Simberloff often publishes a heated response and recruits others to join him.  (For an example, see our recent post about Ascension Island and visit his “Counterpoint” to the article on which our post was based.)

Given the many recent defections of scientists from the central assumptions of invasion biology, we anticipated that Professor Simberloff would acknowledge that invasion biology is under siege.  We were not disappointed.  He started his talk by showing a quote from a scientist on the Galapagos Islands who, after decades of trying to eradicate non-native blackberry, was admitting defeat.  To paraphrase the scientist, he no longer believes that eradication is possible.  Therefore, he is now willing to call it a native plant.

These blackberries were mowed to the ground sometime in the past year.  Herbicides haven't been used in the Sutro forest for several years, but UCSF plans to use them in the future.  Courtesy Save Sutro
These blackberries in the Sutro forest were mowed to the ground sometime in the past year. Herbicides haven’t been used in the Sutro forest for several years, but UCSF plans to use them in the future. Courtesy Save Sutro

We were reminded of Professor Matt Chew’s criterion for what species “belong” in any particular location.  If the species persists unassisted in that location, Professor Chew believes it belongs there.  Surely a corollary to that criterion should be, “if you can’t eradicate it, it belongs there.”

Professor Simberloff diagnoses this acceptance of non-native species as pessimism.  He is not alone in this characterization of people who are no longer willing to spend unlimited amounts of time and money trying to kill non-native species.  This is the standard criticism of that viewpoint.  We are called defeatists who have “given up” in the internet debates we read.

Why are we critics of invasion biology?

Although we agree that it is usually futile to try to eradicate non-native plants with large, well-established populations that have long ago naturalized in our environment, this is not the primary reason why we reject the notion that there is some benefit to trying anyway.  The main reason why we reject the fruitless crusade against non-native plants is because of the damage it does:  the herbicides that are sprayed on our public lands; the release of tons of carbon dioxide into the atmosphere when trees are destroyed; the loss of habitat for wildlife, etc.

At the same time, we acknowledge that some invasions of insects and diseases have posed such serious economic and health threats that we have no choice but to make every effort to eradicate them.  The species of mosquitoes that carry yellow fever and malaria are examples of justified eradication efforts.  We hope that those who are engaged in that effort are also mindful that the methods used are not more harmful than the targets.

Scientists defend “novel” ecosystems

We harp on these issues because they are not discussed by the scientists who either defend or critique invasion biology.  Their concerns are, so to speak, academic.

Sutro Forest is a novel ecosystem. Courtesy Save Sutro

There is an excellent description of the scientific debate about “invasive species” in the on-line newsletter of the American Society of Landscape Architecture (ASLA).  They report that novel ecosystems were featured at the recent conference of the Society for Ecological Restoration (SER) held in Madison, Wisconsin.  Novel ecosystems were defined by one of the speakers (Eric Higgs, University of Victoria) as ecosystems in which changes from historical conditions are considered irreversible: “Even if plants are removed, ‘the system will revert back immediately’ to a state of invasion.”  This is an accurate description of 15 years of effort by San Francisco’s so-called Natural Areas Program.  Non-native plants are repeatedly yanked out and/or poisoned, native plants are planted, native plants die, non-native plants return.  That cycle is repeated annually in some high-priority locations.

Apparently, we are not alone in observing this futile cycle.  The ASLA description of the conference of the Society of Ecological Restoration summarizes current thinking of practitioners of that profession:

“In the face of this overwhelming struggle against novelty, there has been a shift in values among society. Years ago, restoration ecologists wanted to restore ecosystems to their “historic fidelity” as much as possible. Now, ecologists, scientists, and landscape architects discuss the value of novel ecosystems’ services, which to some extent are plant-agnostic.”

While this viewpoint is a welcome improvement over the previous fantasies of restorationists, this information has not yet reached managers of public lands in the San Francisco Bay Area.  Nor does it acknowledge the very real damage that is being done by those who cling to the fantasy that non-native plants can be eradicated and replaced with native species, particularly in an urban setting such as the Bay Area.

The mission of Million Trees is not an academic exercise.  Our objective is to stop the damage being inflicted on our environment and the animals that live in it.  And we don’t intend to shut up until the damage has stopped.  We hope to be put out of business within our lifetime.

Implications of climate change for ecological restorations

The Intergovernmental Panel on Climate Change (IPCC) is a committee of hundreds of scientists from all over the world that has been reporting since 1990 to the United Nations its consensus predictions of the future of climate change.  They made their latest report recently and these are their primary findings:

  • They report with 95% certainty that current climate change is being caused by the activities of humans, particularly burning fossil fuels.
  • They predict that sea level could rise as much as 3 feet by the end of this century if current levels of greenhouse gas emissions continue.
  • During the same timeframe and in the same conditions, the temperature is expected to rise between 2.7 to 8.1 degrees Fahrenheit.
  • If carbon dioxide emissions double by the end of the century, as the current trajectory predicts, the IPCC says current climate trends will be irreversible.

The Earth’s constantly changing climate

The public is preoccupied with the current round of climate change as well as predictions of its trajectory and consequences partly because it may be within our power to stop the trend by reducing greenhouse gas emissions.  But we should not lose sight of the fact that the 4.5 billion year history of the Earth is a history of a constantly changing climate which humans did not influence.  Conventional wisdom is that current climate change is unique in that it is a more rapid change than past changes, making adjustment to the change more difficult for the Earth’s inhabitants.  In fact, many historical changes in the climate occurred even more rapidly when they were precipitated by cataclysmic events such as the impact of huge asteroids or volcanic eruptions.

Our readers may wonder where we are headed with this train of thought.  We hasten to preview our point lest our readers think our goal is to dismiss the seriousness of the current round of climate change.  Our intention in this article is to invite our readers to consider the absurdity of the concept of “native plant and animal species” in the context of the dynamism of nature, climate changes being one of the many factors in producing that dynamism.  We will use the last ice age as an example to illustrate this point, drawing from an excellent book on that subject:  After the Ice Age.  (1)

Glaciers in the US in past 100,000 years.
Glaciers in the US in past 100,000 years.

The Last Glacial Age

In the past billion years, there have been many glacial periods, popularly called ice ages.  It’s worthwhile to consider their cause to understand that they are as likely to occur in the future as they did in the past.  They are thought to be a consequence of the constantly shifting tectonic plates that change ocean currents as well as cycles in the rotation of the Earth and its orbit around the sun.  The former pattern is unpredictable, even random, and the latter is a more predictable sequence.  There are intervening variables that make this an oversimplification of the causes, but this is a sufficient explanation to make the main point: 

At no time has there been a return to ‘things as they were.’  It is true that there must have been times when average temperatures were similar to those of the present.  Thus, before the beginning and after the end of the warmer-than-now hypsithermal interval [the warmest time interval between glacial periods], the average annual temperature must, for a while, have been much the same as now.  But in other respects, conditions would have been radically different, as there were still extensive ice sheets that would have cooled their immediate neighborhoods, and sea level was still about twenty-to twenty-five meters lower than at present” (1)

In other words, the changes in the Earth are always moving forward.  To suggest that a past period represents some ideal to be reified, is to treat nature as a still life painting rather than the motion picture it is.  Particularly at a time of rapidly changing climate, attempting to replicate a landscape that existed 250 years ago on the West Coast and 500 years ago on the East Coast is a fool’s errand (the pre-European landscape is selected by native plant advocates to define “native”).  The naturalized landscape that exists presently is surely better adapted to current conditions than whatever landscape existed hundreds of years ago.  As Matt Chew (Arizona State University) says, “belonging” is when the organism is capable of persisting. (2) The Natural Areas Program in San Francisco has demonstrated in the past 15 years that the plants that existed here 250 years ago are not capable of persisting here without intensive gardening.  Therefore, using Matt Chew’s definition, we might say they no longer “belong.”

The last ice age on the North American continent

Mendenhall Glacier, Alaska.  Creative Commons
Mendenhall Glacier, Alaska. Creative Commons

The most recent ice age in North America was at its height 20,000 years ago and a tiny fraction of those glaciers persist in the Arctic today.  The climate oscillated many times in the past 20,000 years, but the over-all pattern was a gradual melting.  As the glaciers receded, they left a barren landscape, scraped of all vegetation and sculpted by the enormous weight of the ice and the eroding action of the rocks carried within the ice.  The ice was so heavy that it actually weighed down the land, lowering its elevation relative to the ocean.  As the ice melted, the land returned to its previous elevations when relieved of the weight of the ice.

As the ice melted, the land was slowly vegetated by seeds blowing onto the bare land, germinating, and growing.  The strength and direction of the wind was therefore an important factor in the process.  Which seeds blow in depends upon what plants are close by and the mobility of the seeds which varies by species.  Which seeds germinate depends upon the soil conditions where they land as well as the resource requirements of the seed species.  Local climate conditions will also determine which seeds survive:  the temperature, the hours of light, the amount of moisture and precipitation, etc. 

Add to this complexity of variables, the interaction of the plants as they grow, some hindering the growth of their neighbors by shading them, for example.  In other words, there are many different factors at play as the bare land is vegetated and those factors vary enormously from one place to another.  The outcome is random, largely unpredictable, and outside the control of human witnesses to the process. 

The initial vegetation of the bare ground as the ice melts is only the beginning of the story.  The rocky surface lacks nutrients initially.  Nitrogen-fixing plants are needed to begin the process of building soil from which subsequent species of plants will benefit.  Bacteria and fungi slowly populate the soil, contributing to its fertility for later plant arrivals.   Animals participate in the process by distributing seeds as well as selectively eating vegetation.

This is a severely truncated version of a far more complex story none of which humans could control.  We hope we have not exhausted your patience, but have given sufficient background to help you understand the most important point as explained by After the Ice Age:

 “There is a wealth of evidence, however, showing that climatic change is never ending.  Even if major climatic ‘steps’ are comparatively quick, it is almost certain that the climate in the intervals between steps undergoes continual lesser changes.  In the light of present knowledge, therefore, [Margaret] Davis’s view, that disequilibrium in ecological communities is much commoner than equilibrium, is the more acceptable.  It should lead, in time, to a much needed change in popular thought.  The notion espoused by so many nonprofessional ecologists—that the living world is ‘marvelously’ and ‘delicately’ attuned to its environment—is not so much a scientifically reasonable theory as a mystically satisfying dogma.  Its abandonment might lead to a useful fresh start in environmental politics.” (3)

We conclude with a nota bene:  this remarkable book was published in 1991!!!   Isn’t it long past time for the public to be aware of scientific information that has been available for over 20 years?  When will we abandon the mystical fiction that there is some ideal landscape that may or may not have existed hundreds of years ago that we must attempt to re-create?  Even if we thought such an effort would be of some benefit, what makes us think that it is physically possible, given the changes that have occurred in our environment?


(1)    E.C. Pielou, After the Ice Age:  The Return of Life to Glaciated North America, University of Chicago Press, 1991

(2)    Matthew Chew, “Anekeitaxonomy:  Botany, Place and Belonging,” chapter in Invasive & Introduced Plants and Animals:  Human Perspectives, Attitudes, and Approaches to Management, editors Ian D. Rotherham and Robert A Lambert, Earthscan, 2011

(3)    Margaret Davis is “one of North America’s leading palynologists,” who studied the development of eastern forests after glaciers melted.