Author: Conservation Sense and Nonsense

Doug Tallamy refutes his own theory without changing his ideology

In our debates with native plant advocates, the scientist who is most often quoted to support their beliefs is Doug Tallamy who wrote an influential book, Bringing Nature Home:  How Native Plants Sustain Wildlife in our Gardens.    Professor Tallamy is an entomologist at the University of Delaware.

Professor Tallamy’s hypothesis is that native insects require native plants because they have evolved together “over thousands of generations.”  Because insects are an essential ingredient in the food web, he speculates that the absence of native plants would ultimately result in “ecological collapse” as other animals in the food web are starved by the loss of insects. (1)

Professor Tallamy freely admits that his theory is based on his anecdotal observations in his own garden, not on scientific evidence:  “How do we know the actual extent to which our native insect generalists are eating alien plants?  We don’t until we go into the field and see exactly what is eating what.  Unfortunately, this important but simple task has been all but ignored so far.”  (1)

This research has now been done to Professor Tallamy’s satisfaction by a Master’s Degree student under his direction.  The report of that study does not substantiate Professor Tallamy’s belief that insects eat only native plants.  In his own words, Professor Tallamy now tells us:

“Erin [Reed] compared the amount of damage sucking and chewing insects made on the ornamental plants at six suburban properties landscaped primarily with species native to the area and six properties landscaped traditionally.  After two years of measurements Erin found that only a tiny percentage of leaves were damaged on either set of properties at the end of the season….Erin’s most important result, however, was that there was no statistical difference in the amount of damage on either landscape type.” (2)

Corroborating Evidence

This finding that insects are equally likely to eat native and non-native plants may be new to Professor Tallamy, but it isn’t new to the readers of Million Trees.  We have reported many studies which are consistent with this finding.

Anise Swallowtail butterfly in non-native fennel
The English garden, where plants from all over the world are welcome

Specialists vs. Generalists

When debating with native plant advocates, one quickly learns that the debate isn’t ended by putting facts such as these on the table.  In this case, the comeback is, “The insects using non-native plants are generalists.  Insects that are specialists will not make that transition.”  Generalists are insects that eat a wide variety of plants, while specialists are limited to only one plant or plants in the same family which are chemically similar.

Professor Tallamy offers in support of this contention that only “…about 10 percent of the insect herbivores in a given ecosystem [are not specialists],” implying that few insects are capable of making a transition to another host plant.

However, categorizing insects as specialists or generalists is not a dichotomy.  At one extreme, there are some insects that choose a single species of plant as its host or its meal.  At the other extreme, there are insects that feed on more than three different plant families.  It is only that extreme category which has been estimated at only 10% of all phytophagous (plant-eating) insects.  The majority of insects are in the middle of the continuum.  They are generally confined to a single plant family in which the plants are chemically similar.

Putting that definition of “specialist” as confined to one plant family into perspective, let us consider the size of plant families.  For example, there are 20,000 plant members of the Asteraceae family, including the native sagebrush (Artemisia) and the non-native African daisy.  In other words, the insect that confines its diet to one family of plants is not very specialized. 

Soapberry bug on balloon vine. Scott Carroll. UC Davis

Professor Tallamy offers his readers an explanation for why specialist insects cannot make the transition from native to non-native plants.  He claims that many non-native plants are chemically unique and therefore insects are unable to adapt to them.  He offers examples of non-native plants and trees which “are not related to any lineage of plants in North America.”  One of his examples is the goldenrain tree (Koelreuteria paniculata).  This is the member of the soapberry (Sapindaceae) family to which the soapberry bug has made a transition from a native plant in the soapberry family in less than 100 generations over a period of 20 to 50 years.  Professor Tallamy’s other examples of unique non-native plant species are also members of large plant families which probably contain native members.  Professor Tallamy is apparently mistaken in his assumption that most or all non-native plants are unique, with no native relatives. 

The pace of evolution

Even if insects are “specialists” we should not assume that their dependence on a native plant is incapable of changing over time.  Professor Tallamy’s hypothesis about the mutually exclusive relationships between native animals and native plants is based on an outdated notion of the slow pace of evolution.  The assumption amongst native plant advocates is that these relationships are nearly immutable.

In fact, evolution continues today and is sometimes even visible within the lifetime of observers.  Professor Tallamy provides his readers with examples of non-native insects that made quick transitions to native plants:

  • The hemlock wooly adelgids from Asia have had a devastating effect on native hemlock forests in the eastern United States.
  • The Japanese beetle introduced to the United States is now eating the foliage of over 400 plants (according to Professor Tallamy), some of which are native (according to the USDA invasive species website).

These insects apparently made transitions to chemically similar native plants without evolutionary adaptation. If non-native insects quickly adapt to new hosts, doesn’t it seem likely that native insects are capable of doing the same?  That is both logical and consistent with our experience.    For example, the native soapberry bug mentioned above has undergone rapid evolution of its beak length to adapt to a new host.

Although Professor Tallamy tells us that the relationship between insects and plants evolved over “thousands of generations,” he acknowledges much faster changes in plants when he explains why non-native plants become invasive decades after their arrival:  “Japanese honeysuckle, for example, was planted as an ornamental for 80 years before it escaped cultivation.  No one is sure why this lag time occurs.  Perhaps during the lag period, the plant is changing genetically through natural selection to better fit its new environment.”  Does it make sense that the evolution of plants would be much more rapid than the evolution of insects?  Since the lifetime of most insects is not substantially longer than the lifetime of most plants, we don’t see the logic in this assumption.

Beliefs die hard

Although Professor Tallamy now concedes that there is no evidence that insects are dependent upon native plants, he continues to believe that the absence of native plants will cause “ecological collapse.”  In the same book in which he reports the study of his graduate student, Professor Tallamy repeats his mantra:  “…our wholesale replacement of native plant communities with disparate collections of plants from other parts of the world is pushing our local animals to the brink of extinction—and the ecosystems that sustain human societies to the edge of collapse.”

This alarmist conclusion is offered without providing examples of any animals being “pushed to the brink of extinction.”  In fact, available scientific evidence contradicts this alarmist conclusion. (3)

Here are more articles about the mistaken theories of Doug Tallamy:

  • Doug Tallamy claims that non-native plants are “ecological traps for birds.”  HERE is an article that disputes that theory.
  • Doug Tallamy claims that native and non-native plants in the same genus are not equally useful to wildlife, but he is wrong about that.  Story is HERE.
  • Doug Tallamy advocates for the eradication of butterfly bush (Buddleia) because it is not native.  He claims it is not useful to butterflies, but he is wrong about that.  Story is HERE.
  • Doug Tallamy publishes a laboratory study that he believes contradicts field studies, but he is wrong about that.  Story is HERE.
  • Doug Tallamy speaks to Smithsonian Magazine, Art Shapiro responds, Million Trees fills in the gaps:  HERE
  • Doug Tallamy’s Nature’s Best Hope perpetuates the myth that berry-producing non-native plants must be eradicated because they are less nutritious than the berries of native plants.  Available HERE. 
  • Doug Tallamy believes we must prevent hybridization.  Hybridization is a natural process that increases biodiversity and enables plants and animals to adapt to changes in the environment.  Available HERE.
  • There is NO evidence to support Doug Tallamy’s claim that insect populations are declining because of the existence of non-native plants.  Available HERE.

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(1)    Tallamy, Doug, Bringing Nature Home, Timber Press, 2007

(2)    Tallamy, Doug, “Flipping the Paradigm:  Landscapes that Welcome Wildlife,” chapter in Christopher, Thomas, The New American Landscape, Timber Press, 2011

(3)    Erle C. Ellis, et. al., “All Is Not Loss:  Plant Biodiversity in the Anthropocene,” http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0030535

Biological Control: Another dangerous method of eradicating non-native species

We were recently reminded of the use of biological controls to eradicate non-native species when we learned that Australian insects may have been illegally imported to California to kill eucalyptus, which had been virtually pest free until 1983.  So, an article in the New York Times about the development of a fungus for the purpose of killing cheatgrass (Bromus tectorum) caught our attention.  The fungus has been given the ominous name, Black Fingers of Death, for the black stubs of cheatgrass infected with the fungus.

Cheatgrass, Bromus tectorum

Cheatgrass is one of the non-native grasses that have essentially replaced native grasses throughout the United States.  It was probably introduced with ship ballast and wheat seed stock in about 1850.  As we have reported, native grasses were quickly replaced by the non-native grasses which tolerate the heavy grazing of domesticated animals brought by settlers.    Native Americans had no domesticated animals.

Biological controls have frequently caused more serious damage than the problems they were intended to solve.  Therefore, we would hope that their intended target is doing more damage than the potential damage of its biological control.   We must ask if the cure is worse than the disease.  And in this case, we don’t think the damage done by cheatgrass justifies inflicting it with the Black Fingers of Death.

The track record of biological control

Biological control is the intentional introduction of animals, pests, microbes, fungi, pathogens, etc., for the purpose of killing a plant or animal which is perceived to be causing a problem.  The ways in which some of these biocontrols have gone badly wrong are as varied and as many as the methods used.

Introduced species of plants are said to have an initial advantage in their new home because their pests and competitors are not always introduced with them.  This is the “enemy release hypothesis” popular amongst native plant advocates to explain the tendency of non-native plants to be invasive.  However, this is usually a temporary advantage which is exaggerated by native plant advocates who do not seem to recognize the speed with which native species can adapt to new species, and vice versa.

Therefore, a popular method of biological control is to import the predator or competitor of the non-native species which is considered invasive.  This is only effective if the pest is selective in its host.  There are many examples of such introductions which did not prove to be selective:  “For the United States mainland, Hawaii, and the Caribbean region, Pemberton (2000) listed 15 species of herbivorous biocontrol insects that have extended their feeding habits to 41 species of native plants…” (1)  Although most of the unintended hosts were related to the intended hosts, some were not.

Similar shifts from target to nontarget species have occurred for biocontrol agents of animal pests:  “For parasitoids introduced to North America for control of insect pests Hawkins and Marino (1997) found that 51 (16.7%) of the 313 introduced species were recorded from nontarget hosts.  For Hawaii, 37 (32.3%) of 115 parasitoid species were noted to use nontarget hosts…biological control introductions are considered to be responsible for extinctions of at least 15 native moth species [in Hawaii].”  (1)

There are also several cases of biological controls escaping from the laboratory setting before they had been adequately tested and approved for release.   A virus escaped the laboratory in Australia and killed 90% of the rabbits in its initial spread through the wild population.  Very quickly, the virus evolved to a less fatal strain that killed less than 50% of the rabbits it infected.  A second virus was then tested and also escaped its laboratory trial and has spread through the rabbit population throughout Australia.

A fly being considered for introduction to control yellow starthistle apparently escaped and damaged a major cash crop of safflower in California according to a study published in 2001, illustrating the risks of biocontrols to agriculture.

This is but a brief description of the diverse ways in which nature has foiled the best efforts of the scientists designing biological controls for non-native species of plants and animals.  The source of this information (1) therefore concludes, “…many releases of species have inadequate justification…The first goal of research must be to show that the introduced biological control agent will not itself cause damage.”  Given this wise advice, we will return to the question, “What damage is being done by cheatgrass and does that damage justify the introduction of The Black Fingers of Death?”

Why is cheatgrass considered a problem?

Cheatgrass is one of the many non-native annual grasses which have replaced the native grasses which were not adapted to the grazing of domesticated animals.  Cheatgrass is a valuable nutritional source for grazing animals when it is green and loses much of its nutritional value when it dries.

Grazing is only one of the types of disturbance which create opportunities for non-native grasses to expand their range into unoccupied ground.  Fire is another disturbance which gives cheatgrass a competitive advantage over native grasses because it uses available moisture and germinates before native grasses can gain a foothold on the bare ground cleared by fire.

Cheatgrass is said to increase fire frequency by increasing fuel load and continuity.  Unfortunately, increasing levels of CO₂ (carbon dioxide) in the atmosphere is increasing the fuel load of cheatgrass:  “…the indigestible portion of aboveground plant material [of cheatgrass] …increased with increasing CO₂.” (2)

Carbon dioxide is the predominant greenhouse gas which is contributing to climate change.  And increasing frequency of wildfires is one of the consequences of the higher temperatures associated with climate change.  Therefore, one of the causes of the expanding range of cheatgrass is increasing levels of the greenhouse gases contributing to climate change.  Rather than address the underlying cause, we are apparently planning to poison the cheatgrass with a deadly fungus.

If we are successful in killing the cheatgrass, what will occupy the bare ground?  Will native grasses and shrubs return?  Will whatever occupies the bare ground be an improvement over the cheatgrass which has some nutritional value to grazing animals?  The US Forest Service plant database gives us this warning, “Care must be taken with methods employed to control cheatgrass so that any void left by cheatgrass removal is not filled with another nonnative invasive species that may be even less desirable.” 

Recapitulating familiar themes

The project to develop a deadly fungus to kill cheatgrass is another example of the issues that we often discuss on Million Trees:

  • Are the risks of the methods used to eradicate non-native species being adequately assessed and evaluated before projects are undertaken?
  • Are the underlying conditions—such as climate change–that have contributed to an “invasion” being addressed by the methods used to eradicate them?  If not, will the effort be successful?
  • Is the damage done by the “invasion” greater than the damage done by the methods used to eradicate the invader?  Is the cure worse than the disease?

We do not believe that these questions are being addressed by the many “restoration” projects we see in the San Francisco Bay Area.  Consequently, we believe that these projects often do more harm than good.

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(1)    Cox, George W., Alien Species and Evolution, Island Press, 2004

(2)    Ziska, L.H.; Reeves III, J.B.; Blank, R.R. (2005), “The impact of recent increases in atmospheric CO2 on biomass production and vegetative retention of cheatgrass (B. tectorum): Implications for fire disturbance.”, Global Change Biology. 11 (8): 1325–1332,

The futility of eradicating non-native species

We tend to focus on the native plant “restorations” in our neighborhood, but we should not lose track of the fact that similar efforts are taking place all over the world.  The native plant movement is international and if it loses momentum, we should expect to see loss of support for its destructive projects elsewhere.  So, today we will tell our readers about several recent developments that suggest that scientists all over the world are having second thoughts about invasion biology, which is the scientific underpinning of the native plant movement. 

Second Thoughts:  The Hawaiian Case

We have reported to our readers about the many “restoration” projects in Hawaii.  There is some logic to focusing such efforts on islands, because they are the places most vulnerable to the loss of native species attributed to introduced species and theoretically they are also the places where re-invasion should be easiest to control.

Scientists have recently published the results of a ten-year effort to return an “invaded” forest to its native origins.  They spent about 5 years clearing the forest of all non-natives.  They planted the scorched earth with natives and then they walked away from it to observe the long-term sustainability of their effort.  Five years later they report that the composition of the forest—with respect to its nativity—has essentially returned to its original state.

They tested several hypotheses while observing the changes in the forest during the second half of the project.  Conventional wisdom had been that the more densely natives occupied the ground, the less vulnerable it would be to re-invasion.  Much to their surprise, this was not the outcome of their experiment.  The more densely natives occupied the ground, the greater the population of non-natives in the final analysis.  They conclude that the same conditions which encouraged the growth of native plants were equally beneficial to the growth of non-native plants.

This study was conducted by the US Forest Service.  We hope they learned something from this experience.  Specifically, we hope that the US Forest Service now understands that native plant “restorations” are not a one-shot deal.  They are a permanent commitment to garden that restoration with the same amount of effort.  That’s why scientists—such as Professors Arthur Shapiro and Peter Del Tredici—tell us that large scale projects are not sustainable in the long term.  A small scale native plant garden as an historical illustration is a worthwhile effort.  Gardening our vast public lands is like “plowing the sea,” as Professor Shapiro told us recently.

Second Thoughts:  The New Zealand Case

New Zealand has made herculean efforts to save its native species from “invasions” by non-native species:  “New Zealand is a very weedy country.  Indigenous plant species are matched in number by naturalized exotic species and about 20 new invaders are discovered each year.  Thus, a weed eradication program has been under way for the past 10 years, but eradicating an unwanted plant species is much more difficult than it might seem.” (1)

Eradicating yellow tree lupin, New Zealand Dept of Conservation

How successful have these efforts been?  According to a recent study, they have had very little success:  “The current issue of the journal Invasive Plant Science and Management assesses the progress of 111 weed eradication programs carried out by New Zealand’s Department of Conservation.  Only four of these programs have met with success, while 21 have been discontinued and the rest remain an ongoing challenge.”

The report concludes, “After a decade, New Zealand’s weed eradication strategy has yet to yield significant results.”  Anyone who has been watching similar efforts all over the San Francisco Bay Area will not be the least bit surprised by this conclusion.  With the exception of small gardens which are irrigated and intensively gardened, these projects are weedy messes, usually behind fences.

Second Thoughts:  The Australian Case

Scotia Sanctuary, Australia

Emma Marris interviewed the manager of one of many “restoration” projects in Australia for her book, Rambunctious Garden.  He told her about the 18 month process of killing all non-native animals in a 15-square mile sanctuary enclosed by a prison-like fence, “sturdy, tall, and electrified.”  (This was half of the Scotia Sanctuary)

“He was able to shoot out the goats in a matter of days.  Rabbits were harder…he put out carrot bait…the rabbits…would learn to trust the new food source…[then] the carrots would be poisoned…[He] repeated this routine three times, running through 12,500 pounds of carrots…For each fox, he learned its habits and was eventually able to find perfect places to trap or poison them.  He also trapped cats…The key to making it work, he says, was ‘perseverance, perseverance, perseverance.’” (2)

It was necessary to kill all the non-native animals before taking on the more difficult task of returning the land to native plants because of the interaction between the plants and animals.  The non-native animals are considered a continuing and permanent threat to the sanctuary.  The expectation is that this 250 acre restoration will require human intervention indefinitely into the future.

Australia is a huge place, so the prospect of this labor-intensive process being replicated on a nationwide basis is absurd.  Therefore, it seems inevitable that Australian scientists would begin to question the efficacy of such efforts. 

Just two months ago, an Australian scientist, Angela Moles, gave a TED (Technology, Entertainment, and Design) presentation suggesting that it is time to grant Australian citizenship to introduced species.  Click here to see the video.

Her reasoning is based on the relatively new understanding of the speed with which evolution occurs.  Her laboratory used the collection of a university herbarium to measure the changes in the plants that were introduced to Australia.  The herbarium had samples of the same species of plants collected over a 60 year period from the same location.  They found that the plants had changed in significant ways.  In a sense, they were becoming Australian plants in response to the biotic (other plants and animals) and abiotic (climate, soil, etc) conditions of their new home.  She predicted that if they weren’t yet genetically distinct from their ancestors, they soon would be.   In other words, they are becoming distinct, new species…..Australian species.

She showed a slide of her son who is a 2nd generation Australian.  He is considered an Australian by law and custom.  Then she showed a slide of clover which has changed significantly since its introduction.  After 130 generations, it is still not considered Australian.  After showing a few of the massive eradication projects and describing the scale and futility of those efforts, she suggested that it is long past time to accept the clover and other introduced species as Australian.

And, of course, we agree.  Let us abandon the destructive and futile war on non-native species.  The sooner we do, the less damage will be done to the environment and to the animals that live in it, including us.  

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(1)    “Eradicating Weed Species in New Zealand Poses a Larger Challenge Than Expected,” Science Daily, July 21, 2012

(2)    Emma Marris, Rambunctious Garden, Bloomsbury, 2011

The “Look, don’t touch” approach to environmental education

Environmental education plays an important role in the native plant movement.  Young people are indoctrinated with the native plant ideology and recruited as volunteers in native plant restorations. 

We were introduced to the relationship between environmental education and the native plant movement on our first visit to the Randall Museum in San Francisco.  The Randall is operated by San Francisco’s Recreation and Park Department.  According to its website it “…offers youth and adults opportunities for active involvement and recreation in an integrated program of arts and sciences…The Museum strives to inspire creativity, curiosity, and appreciation of the world around us.”

On our first visit, the main room of the museum was decorated with posters that had been drawn by the children visiting the museum.  The posters covered the perimeter of the room.  Each poster featured an animal, a plant, and the message “Save California’s native plants for the [pictured animal].”

Poster at the Randall Museum

The relationship between each animal and the pictured native plant seemed tenuous at best.  Here is a picture of one of those posters, which claims that the Snowy Plover requires a particular native plant.  In fact, Snowy Plovers make no use of this plant or any other. 

According to The Sibley Guide to Bird Life and Behavior, “Plovers…are specialized feeders that rely on vision to locate their prey, which includes all manner of invertebrates such as earthworms, adult and larval insects, amphipods, isopods, tiny crabs…” etc.  They don’t eat plants nor do they require plants—let alone native plants—for nesting because they nest on the bare sand.

In addition to being misinformation, this approach to environmental education struck us as rather sterile.  It reminded us of a public hearing about San Francisco’s Natural Areas Program at which a native plant advocate explained her objective for the education of children in San Francisco.  She said that children should be required to memorize the names of 30 native plants each day.  How boring, we thought.  Would children be inspired to love nature by such a rote exercise?

Separating children from nature

“Stay on designated trails” Signage in San Francisco’s “natural areas”

We are apparently not the only ones who have reacted to such an uninspiring approach to environmental education.  In a recent article in Orion Magazine (1), a parent tells the story of taking his children to a class at the Happy Hills Nature Center.  The nature center is surrounded by a meadow blooming with wildflowers, but instead of wandering through that meadow to explore, the children are required to go inside on a sunny day and watch 27 slides of wildflowers.  They are bored stiff.  When the class is over, they want to get outside, but they are told to stay on the trail and not to pick the flowers, even the non-native dandelions. 

This is typical of the experiences that children are now getting in our parks.  They are prohibited from wading in the creek or lake. They are prohibited from climbing the rocks or trees.  Fences and signs require that they stay on the trails.  They are told that nature is fragile and will not tolerate their presence.  They are effectively prevented from interacting with nature.  They may look, but they may not touch.

 The Orion article concludes that this approach to environmental education will not foster an interest in or respect for nature.  If children are alienated from nature, they will not have an interest in protecting it.  The article cites two research studies in which early experiences with nature are found to correlate with an interest in nature as adults. 

One study surveyed environmentalists to determine if there were any similarities in their childhood experiences.  It found that “Most environmentalists attributed their commitment to a combination of two factors, ‘many hours spent outdoors in a keenly remembered wild or semi-wild place in childhood or adolescence, and an adult who taught respect for nature.’”

Another study interviewed two thousand adults in a wide range of occupations chosen at random in one hundred urban areas around the country.  They found that “Childhood participation in ‘wild’ nature such as hiking or playing in the woods, camping and hunting or fishing, as well as participation in ‘domesticated’ nature such as picking flowers or produce, planting trees or seeds, and caring for plants in childhood have a positive relationship to adult environmental values.”

Of course, we couldn’t help but think of our own early experiences with nature.  Vivid memories of building forts in the trees and dams in the creek came to mind.  Both activities would be prohibited in today’s parks.

Defeating the purpose of environmental education

Memorizing lists of plants or looking at slides of them in a darkened room is not a substitute for interacting with nature.  And that interaction will not take place behind a fence.  The result of such childhood experience will be adults who are not interested in nature and therefore don’t care about protecting it.  Ironically, those who claim to be devoted to saving nature are defeating their purpose by separating children from nature.

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(1)    David Sobel, “Look, Don’t Touch,” Orion Magazine, July/August 2012

Permaculture takes the long view of the big picture

What is permaculture?

“The primary agenda of the [permaculture] movement has been to assist people to become more self reliant through the design and development of productive and sustainable gardens and farms. The design principles which are the conceptual foundation of permaculture were derived from the science of systems ecology and study of pre-industrial examples of sustainable land use.“(1)

What does the permaculture movement have in common with the native plant movement?

Both have an interest in the preservation of native habitats and animals and both want to reduce the negative impact of human habitation on the Earth’s ecosystems.

How is the permaculture movement different from the native plant movement?

The permaculture movement has a broader view of ecology including the impact modern agriculture has on the Earth’s ecology, taking into account that modern crops are almost entirely non-native.  Permaculture considers both the costs and benefits of native plant “restorations”—such as the use of pesticides—and also puts the question of how realistic the goals of the project are into that equation.  Permaculture respects the complexity of nature and the shortened time perspective of man.  It therefore does not assume that man is capable of foreseeing the consequences of his manipulation of nature.  The humility of permaculture is a stark contrast to the sweeping generalizations and dogmatic edicts that we often hear from native plant advocates. 

What do the principles of permaculture tell us about “invasion biology?”

The principles of permaculture were eloquently expressed in a recent blog dialogue about the potential for introduced species to be invasive, in this case the kiwi vine.  The author of this comment is Toby Hemenway, who has given us permission to reprint his comment.  Mr. Hemenway is the author of a book (Gaia’s Garden:  A Guide to Home-Scale Permaculture, Chelsea Green Publishing, 2009) and a website about permaculture.  Reading the entire comment thread in which this comment appears will help you to understand the difference between the native plant movement and the permaculture movement.   

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Hardy Kiwi. Creative Commons

“I have said several times that the shade-tolerant vines are very challenging species, so I’m not surprised to see Mr. Lautzenheiser’s report [about the kiwi vine]. And I’ll repeat that all of New England is a highly disturbed landscape…

The vines will come, and they will go. After all the alterations in the landscape Euro-Americans have made, it’s going to be centuries before we stop seeing things like these kiwi amphitheaters. We cannot predict when a species will turn rampant – next time it might be string beans – so we have two choices: never, ever introduce a new species, or accept that we are dealing with new types of ecosystems that are going to make us miserable if we keep thinking about the impact of new species as a disaster. The first is impossible.

Very relevantly, I spent last Saturday in the Beartooth Mountains with a retired local ecologist. We stopped at a disturbed site in the sagebrush above Red Lodge and he harvested two bouquets of plants, one of natives, one of exotics. The exotic bouquet had at least twice as many species in it, including a number that he was pretty upset with. He is no fan of invasive species. Later we stood in a mixed-conifer grove high in the much less disturbed mountains, and he showed the immense damage from the pine beetle, a native insect that is devastating millions of acres in the west. It seems to have burst out of control because of decades of Smoky the Bear fire suppression – our way of saving the ecosystem – that has left the forest full of crowded trees that are perfect beetle food. This is a native species that has gone rampant. This happens all the time: many thousands of acres of lodgepole pine in Idaho and eastern Washington are dying from native honey-mushroom infestation, but ecologists are starting to understand that this may be a way of returning nutrients to the soil after old-growth forests have sequestered them above ground for too long. We hate to see these forests die. And we don’t know what’s going on.

When someone asked what we can do about all this, the ecologist answered that we can preserve very small areas in special projects, but that anything beyond that is simply impossible. The impact of non-native species, he said, brought here in the massive quantities that they were and still are, combined with our alterations in the landscape of a whole continent, make any return to previous conditions out of the question. We don’t like this, he said, because it holds a mirror up to us and shows us how out of balance with the rest of nature we are. And now we’re stuck with the consequences, so we demonize the other species instead of facing what he sees as the real problem: there are too many of us, moving around far too much. Asking people not to plant species that they like is a losing game, not with a hundred million gardeners in this country shopping at nurseries.

We’re going to have to learn to live with this new landscape, as much as we don’t like it, and take it as a stunning opportunity to learn about ecosystem development, was his conclusion. It is a colossal experiment in hybridizing whole ecosystems, and to say “this species is bad, or this one” misses the point completely. We have altered a continent and there is no undoing it, no return to before. We cling to the hope of preservation and restoration because we can’t accept that we have to live with what we have done. It’s time to move on, he said, accept that these species are here, and stop interfering. We didn’t know enough to keep this from happening, and we surely don’t know enough to “fix” it. The attempted cures are doing even more harm, the way fire suppression did. Thinking it is a problem is the problem.

He struck me as a wise man, in many ways, and I learned a lot from him. I’ve been spending many days in Yellowstone this summer, and see that one simple restoration act, re-introducing the wolf, has slammed through that nearly undisturbed, enormous ecosystem in hundreds of unforeseen ways. The elk have been driven out of the valleys into the hills. The bison are exploding through the valleys, along with once-scarce pronghorns. Species mixes of all kinds are shifting in totally unforeseen ways. It was a profoundly radical act that has totally altered the landscape, all because of one management decision. And we think we know that hardy kiwi is wrong to be there? We need to stop deciding we know better than nature, even nature with kiwi in it.

Am I saying we should do nothing? Well, we can do what we want, and I’m sure we will. But it won’t make much difference at all, except where we’re able to target especially vulnerable species and habitats and freeze some of them where they are (in ways nature never does). Nature is just too big, the process too far along.

I was at a conference a while ago called “Native Plants and Permaculture” where those two groups came together to make peace and learn from each other. We did an exercise where everyone lined up where they thought they fell along a spectrum from “Only plant natives” to “Plant whatever you want.” There were 3 people in the first category, and one in the latter. Everyone else, permies and nativists, were mixed in a perfect bell curve with most right in the middle. Our differences are tiny. Let’s stop focusing on them.

Again, I think that against all the good that permaculturists are doing, it makes little sense to focus on the tiny minority of us who don’t think before we plant. That’s a minuscule drop in the bucket compared to corn, GMOs, nursery owners, developers, and all the others who alter land and plant exotics. It’s a classic case of making our firing squad in a circle, as Che claimed the Left was prone to do. The discussion of all this is very fruitful, but the accusations that permaculturists are doing significant harm, compared to all the others, don’t hold up.

Most states have invasive species lists in the several hundreds, which to me says we’re either completely doomed or there is an error in our way of thinking. In another 5 years another hardy kiwi-like enemy will appear, and then another, and another, with no one able to predict, like the native pine beetle, what it will be. You can be miserable about this if you want; I’m going to watch it and learn from it. We have no choice but to wait out the next few hundred years until this terribly unbalanced landscape finds some new, always-dynamic set of equilibriums. Meanwhile I’ll be using the best tools available (and they won’t include hardy kiwi in New England!) to create healthy designed ecosystems in the places people are settled in, and if nature chooses to use something I’ve planted for her own purposes, in a way that I don’t understand, I will accept that she knows what she is doing instead of thinking, always wrongly, that I know better.”

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Oliver Holmgren (1997). “Weeds or Wild Nature”. Permaculture International Journal. http://www.holmgren.com.au/frameset.html?http://www.holmgren.com.au/html/Writings/weeds.html

Vandalism by native plant advocates

In 2010, Timothy Paine, an entomologist at University of California, Riverside, published an article (1) about the introduction of Australian insect predators of eucalyptus into California.  Eucalyptus is native to Australia.  It was introduced to California in about 1850 and was virtually pest free until 1983.  Since then 15 insect predators of the eucalyptus have been found in isolated locations in California. 

Professor Paine observes that, “The spatial and temporal patterns of introductions [of these insect pests] do not seem to be random, particularly when taken in perspective of the geographic distribution of the insects in Australia.”  For these and other reasons explained in his publication, Professor Paine speculates that “…with no definitive proof, we suggest that the multiple patterns may be nonrandom; instead they suggest the possibility of intentional introductions.”

In a recent interview  Professor Paine explains, “We took all of the available information we had on the introduction of eucalyptus pests into California and the conclusion we drew is that there is a very high probability that someone was intentionally introducing [the insect pests of eucalyptus]…There is likely intentional movement of insect pests of eucalyptus into the state.  The patterns suggest that.”

Professor Paine agonized about publishing his study.  Responsible people are appropriately reluctant to make accusations in the absence of proof.  He decided to publish because of the implications of his findings: 

“Intentional introductions of insect herbivores onto crop plants, or organisms pathogenic to plants or domestic animals, represent an insidious threat that could severely damage the national agricultural economy, endanger a safe and abundant food supply, threaten water quality or quantity, increase the risk of wild fires, or degrade environmental quality across massive areas.” 

Professor Paine has had some success with finding biological controls of these insect pests of the eucalyptus.  However, as fast as he can find an effective antidote species of insect, a new pest arrives to attack the eucalyptus.  His research is controversial because the native plant advocates who despise eucalyptus and demand its eradication are opposed to any attempt to control the insect infestation.  Jake Sigg, our local, prominent native plant advocate is quoted as saying, “I think the University ought not to be going ahead with this research without considering all of the ramifications and hearing from all parties.” 

Jake Sigg is a big fan of biological controls to eradicate non-native plants, so we find it ironic—even hypocritical–that he is opposed to research needed to save the eucalyptus from its insect predators.   In his Nature News of February 18, 2011, he said, “On this scale, biological control offers the most promise, and–take note–would obviate the need for herbicides.  Unfortunately, it is inadequately funded.  The beauty of biocontrol is that if the necessary rigorous (and expensive) research is successful the problem of that plant is taken care of for all time–which means it is really inexpensive in the long run.”

So apparently biological controls are highly desirable if they are used to eradicate non-native plants and trees.  If they are used to save non-native trees, they are verboten, in Mr. Sigg’s opinion.

The long track record of vandalism by native plant advocates

We can’t prove that Australian insects were intentionally imported to California to kill eucalypts.  However, if they were it would not be the first time that native plant advocates have used vandalism to eradicate our eucalypts.

The historical record of vandalism of non-native trees in San Francisco goes back nearly 20 years.  In 1994, the Sacramento Bee published an article (2) about non-native Monterey pines and eucalyptus being cut down in public parks by a native plant advocate by the name of Greg Gaar.  According to the Sacramento Bee, Mr. Gaar had planted these trees and then changed his mind some 20 years later. (For the record, we note that we don’t approve of such unauthorized plantings any more than unauthorized destruction.)  

The California Native Plant Society apparently convinced Mr. Gaar that the trees were a threat to San Francisco’s “natural heritage.”  He cut down trees on Mount Davidson and Tank Hill in San Francisco and was sent a bill for $10,996.27 by the Recreation and Park Department.  The Bee reported that Mr. Gaar was unemployed and had no intention of paying the bill.  Getting caught was apparently the end of that particular method of destroying non-native trees. 

Native plant advocates then found a more surreptitious method of destroying the trees. They began girdling the trees in the public parks of San Francisco.  Girdling is a method of killing a tree slowly.  A band of bark is hacked off the circumference of the trunk with an axe or chainsaw.  This prevents water and nutrients from traveling from the roots of the tree into the tree.  The tree slowly starves to death.  The bigger the tree, the longer it takes to die.

Girdled trees, Bayview Hill, San Francisco

After girdling the tree, native plant advocates stacked up vegetation around the scar so that it was not visible to the public.  Even if the public noticed the scar, they didn’t know what it meant until the tree began to die.  By the time the trees started to die several years after the girdling began, about 1,200 trees had been girdled in the parks of San Francisco.  Most of them were on Bayview Hill, and many are still visible on Mount Davidson. 

According to an article in The Independent, some of the girdling was done by city employees of the Natural Areas Program in the Recreation and Park Department, but much of it was done by native plant advocates, described as “volunteers” by their supporters and “vandals” by their critics.  The Independent quotes the head of the urban forestry division of the Recreation and Park Department as saying that trees were also being killed by dousing them with pesticides.

There was a noisy outcry when the public figured out what they were doing.  The native plant advocates paid a public relations price for their vandalism and they quit doing it.  They are no less dedicated to destroying all of our eucalypts.  Perhaps they have moved on to even more nefarious methods such as introducing deadly insects.

We wouldn’t be at all surprised.  One of our more memorable debates with a prominent local nativist was about the plan of the Natural Areas Program to reintroduce a legally protected native turtle to a local park that is heavily forested with eucalypts.  We knew that rare turtle requires unshaded nesting habitat within 500 feet of its water source.  Providing that habitat to this legally protected turtle would have required the destruction of all the trees in that park.

When we objected to the reintroduction of that turtle, the nativist smirked and said, “You know nothing can stop us from putting that turtle in that park whenever we want.  And the law provides the same legal protection to that turtle whether it is found there naturally or put there by man.”

Some of these people will stop at nothing.  They are appropriately called eco-terrorists.

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(1)    Timothy Paine, et. al.,  “Accumulation of Pest Insects on Eucalyptus in California:  Random Process or Smoking Gun,”  Journal of Economic Entomology, 103(6): 1943-1949, 2010

(2)    “San Francisco garden guerrillas axing alien plants in San Francisco,” Sacramento Bee, February 19, 1994.  This article is not available free on-line.  However, it can be purchased inexpensively from Sacramento Bee Archives.

More evidence that eucalypus is not flammable

Last week there was a fire in Stern Grove, in San Francisco.  Stern Grove is heavily forested in eucalyptus which did not ignite, providing more evidence that eucalypts are not as flammable as native plant advocates want the public to believe.  The claim that eucalypts are highly flammable is one of many arguments native plant advocates use to justify the eradication of eucalypts.  And like most of their claims, it is quite simply not true that eucalypts are highly flammable.

Location of fire in Stern Grove

The fire in Stern Grove was reported by a local television station.  You can view photos and videos of the fire on their website.  They report that the fire was started by homeless campers.  Nearly 40 firefighters battled the blaze which they described as challenging because it was the middle of the night and visibility was low.  The fire moved up a steep hill which has a tendency to accelerate the spread of fire.

This fire in Stern Grove was a particularly rigorous test of the flammability of eucalypts because many of them are shrouded in ivy.  The ivy creates a fire ladder to the canopy of the tree, which increases the risk that the tree will ignite.  But they did not ignite.  The understory of the trees was completely engulfed in flames.  The trunks of the trees were badly scorched by the fire in the understory.  The fire did not travel up the trees and ignite the canopy.

Aftermath of fire in Stern Grove

Let’s talk about ivy

This is an opportunity to talk about the ivy that we find growing up the trunks of the trees in San Francisco.  The ivy was planted at some time in the past and in fact, the Recreation & Park Department is still planting ivy when it renovates the parks, believe it or not.  It’s a popular groundcover because it thrives with no care and it grows almost anywhere.

Another absurd argument that nativists use to advocate for the destruction of eucalypts in San Francisco is that they are covered in ivy.  This seems an extreme case of cutting off your nose to spite your face.  Why kill the tree when it’s the ivy that is the problem?  It’s not the tree’s fault that it’s covered in ivy.  It’s the fault of the Recreation and Park Department that it provides so little maintenance in the parks that the ivy grows out of the control.  How does destroying the tree solve the problem?  The ivy will overwhelm anything that grows there.  Trees aren’t the exclusive target of ivy.

Our personal experience with ivy

We know from personal experience that it’s not that difficult to control ivy.  We’ve never planted ivy but we have inherited it in our gardens from previous owners.  My spouse complained bitterly about the ivy. But as the primary gardener in the household, I knew we did not have the fortitude to eliminate it.  We don’t use pesticides in our garden so without the physical stamina or the resolve to eliminate it, our only option was to manage it.  It wasn’t that hard to do.  With an annual “haircut” our ivy was never out of control.

Ivy management in Dracena Park, Piedmont, CA

We have also had the experience of watching ivy being successfully managed in a public park.  In the City of Piedmont’s beautiful parks, ivy is the predominate ground cover.  It doesn’t crawl up trees or overwhelm shrubs because it is managed.

Another case of eucalyptus being scapegoated

The eucalypts in San Francisco’s parks are shrouded in ivy because the Recreation and Park Department does almost no maintenance in our parks.  Watering and mowing the lawns is about the limit of their maintenance.  Why would we expect maintenance to improve just because the trees are destroyed?  We certainly haven’t seen any evidence of improved maintenance in the 1,100 acres of “natural areas” in which non-native plants and trees are repeatedly destroyed, native plants are planted and are quickly overwhelmed by foxtails and other non-native weeds.

The money being wasted on these unsuccessful “restorations” would be much better spent maintaining the landscape that exists.  It would certainly be less destructive.

Regretting the use of pesticides

Spraying Milestone in Glen Canyon Park, June 2012

Recently visitors to Glen Canyon Park in San Francisco spotted a Pesticide Application Notice in their park, which states that Milestone herbicide was used on “sweet pea.”  Sweet pea is not classified as an invasive plant by the California Invasive Plant Council.  Milestone herbicide is classified as Tier I “Most Hazardous” pesticide by San Francisco’s IPM program because it persists in the ground for a long time.  The City’s IPM policy states that it is approved for use on “invasive species.”  Since sweet pea is not an invasive plant, we assume this pesticide application violated San Francisco’s IPM policy.

The federally mandated Material Safety Data Sheet (MSDS) for Milestone advises users to, “Prevent [Milestone] from entering into soil, ditches, sewers, waterways and/or groundwater.”  The MSDS also says that Milestone “is not readily biodegradable according to OECD/EEC guidelines.”

For these reasons, the manufacturer of Milestone herbicide withdrew its application to sell Milestone in the State of New York, after the State of New York determined, “The [New York State] Department [of Environmental Conservation] could not ensure that the labeled use of aminopyralid [the active ingredient in Milestone] would not negatively impact groundwater resources in sensitive areas of New York State.”  In other words, the sale of Milestone herbicide is banned in the State of New York.

Kid playing in Glen Canyon Park. Courtesy San Francisco Forest Alliance

Since Glen Canyon is a watershed to Islais Creek, we believe it is irresponsible to use Milestone in that park.  And clearly there is no justification for using this persistent herbicide on a plant as benign as sweet peas.  Since Glen Canyon park is the home of a year-round day care center as well as a summer camp which leads children throughout the park, it is outrageous that these pointless risks were taken there.

We have learned nothing….

As we celebrate the 50th anniversary of Rachel Carson’s ground-breaking book, Silent Spring, there is renewed media interest in this issue.  We welcome this reminder that Rachel Carson informed the public in 1962 that DDT was having a devastating impact on wildlife.  DDT had been used for about 20 years, but it took that long for us to notice that some species of birds had been poisoned nearly to extinction.  And it took another 10 years for DDT to finally be banned in 1972.

Rachel Carson was vilified for her revelations, just as critics of the so-called Natural Areas Program are being vilified by supporters of that program.  We have been called “chemophobes” and “anti-chemical crazies.” 

Frank Graham, editor of Audubon Magazine, recently wrote an article for Yale University’s “environment 360” blog about the abuse that Rachel Carson endured after the publication of Silent Spring.  He recounts several anecdotes about the attacks on her character.  For example, “An official with the federal Pest Control Review Board drew laughter from his audience when he remarked, ‘I thought she was a spinster.  What’s she so worried about genetics for?’”

Forty years after DDT was banned in the United States we have a local example of the persistence of this dangerous chemical in our environment.  From 1947 to 1966, several companies on the harbor in Richmond, California formulated, packaged, and shipped pesticides, including DDT.  The site was designated a State Superfund site in 1982, and in 1990 the EPA placed the site on a national priorities list for clean up.  “Remedial actions took place on the site from 1990 to 1999.”  Twelve years later, the EPA tells us, “Although actions were taken to reduce the risk from the pesticides found on site…sediments and the water [in that location] are still contaminated with pesticides, primarily DDT and dieldrin.”

In other words, we fouled our water with dangerous pesticides; we then spent many years and probably a lot of money trying to clean up after ourselves, and 40 years later we are still living with the consequences of our foolishness.

What have we learned from that experience?  Now we are using a very persistent chemical (Milestone) on a benign plant (sweet pea) in our public parks.  We have learned nothing.  And those who have some economic gain from poisoning our parks—or are clueless about the risks they are taking—are defending the use of pesticides and trying to shut us up, just as they tried to shut Rachel Carson up 50 years ago.  We are proud to be in her company and we are inspired by her leadership.

Some people have learned

Peaches at “Organic U-Pick” Courtesy Arnita Bowman

We prefer to end our stories on a positive note when we can, so we turn to a book we read recently about a fruit farmer in California’s Central Valley.  David Mas Masumoto wrote Epitaph for a Peach to tell us about his transition from the traditional farming methods used by his father to organic methods.  He has abandoned rigorous weed and pest control and he is learning to live in harmony with his orchards rather than fighting against nature.  He tells us about the difficult decision to quit using pesticides:

“I am reminded that in some valley wells they have found traces of a chemical called DBCP in ground water aquifers.  DBCP was linked to sterility in males and is now banned in the United States.  My dad used some DBCP years ago…No one knew it would contaminate drinking water.  Neighboring city folks are angry with farmers for damaging their water supply.  ‘How could you farmers poison the water?’ they ask.  My dad didn’t choose to pollute the water table.  He did nothing illegal.  He simply trusted the chemical company and the governmental regulatory agencies. “

Mr. Masumoto has learned from bitter experience.  What we know about pesticides today is not necessarily what we will learn about them tomorrow.  We often look back on our use of pesticides with regret.  So, shouldn’t we at least avoid using them when we don’t need to—such as on flowers just because they aren’t native—or in places where the risks are great—such as public parks occupied by children?

Let’s turn that rhetorical question into the affirmative statement that it deserves to be:  We should not be using pesticides in our public parks or on plants that aren’t doing any harm.  We will live to regret it when we do.  And let’s express our gratitude to Rachel Carson for inspiring us to keep informing the public of the needless risks that are being taken in their parks. 

The Ruth Bancroft Garden where plants from all over the world are welcome

The Ruth Bancroft Garden in Walnut Creek, California, is a 3-acre remnant of a 400-acre fruit farm started in the 1880s by Hubert Howe Bancroft.  Bancroft is a familiar name in the Bay Area because Mr. Bancroft was also a famous historian and publisher who amassed a huge collection of documents about the American West.  He donated that collection to University of California at Berkeley, which is the origin of the Bancroft Library there.  The Bancroft Library is California’s greatest repository of California history.

Valley Oak, Bancroft Garden

When Mr. Bancroft purchased his property, it was oak woodland.  These were the venerable valley oaks (Quercus lobata), the largest oak in Northern California.  Only one of these oaks remains in the garden.  It is estimated to be 350 years old.  Its contorted branches create an enormous tent of shade, reaching to the ground.  There is not a more beautiful tree, in our opinion.

Quercus lobata, named for its deeply lobed leaves

Mr. Bancroft’s granddaughter-in-law, Ruth Bancroft started planting her garden in 1972.  She had a life-long interest in cactus and succulents, so it wasn’t a good year to begin that venture. The hard freeze of the winter of 1972-73 killed many of the young plants which are not hardy in temperatures below freezing.  Fortunately, such hard freezes are rare in the Bay Area and the garden has suffered significant losses only once since then, in winter 1990.

Ghost Gum. Courtesy Cynthia Clampitt, Waltzing Australia

There are several eucalyptus trees in the garden, but one is a stand-out.  The ghost gum (Eucalyptus pauciflora) is aptly named for its white bark.  Coincidentally its ancestral home is the Snowy Mountains in Australia where it is often found standing in the snow.  It is one of the few cold-tolerant species of eucalypts.  Our opinions of eucalypts are heavily influenced by one particular species, the blue gum eucalyptus, because it is the predominant eucalypt in California.  We often forget that there are actually 700 species of eucalyptus and therefore there are a wide variety of forms and horticultural characteristics.  The ghost gum in the Bancroft Garden was flowering and swarming with bees collecting pollen and/or nectar.  The flowers were close to the ground so we were able to confirm that the nectar was not at all sticky, as critics of eucalyptus often claim.

Flowers of Ghost Gum with visiting bee

Touring the garden, we were reminded of many of the themes of the Million Trees blog.

Planting species outside of their range is insurance

The plants in the Bancroft Garden are from all over the world, particularly similar climates such as Australia, South Africa, and Mediterranean countries.  Many of the plants come from drier desert climates.  Several of the plants in the garden are extinct or nearly so in their native ranges.  They continue to exist in the world only because they were exported to new locations before they disappeared from their ancestral homes. 

Agave franzosinii is no longer found in the wild in Mexico
Golden Barrel cacti are endangered in the wild due to unscrupulous collectors and the flooding of their habitat by a hydroelectric project,

This is one of many reasons why we do not share the purist vision of the native plant movement, that only plants native to a particular location be allowed to exist in that location.  In a changing climate, it is particularly important that plants and animals be allowed to remain where they have been introduced.  Their new homes are insurance against their extinction from the Earth.

The characteristics that native and non-native plants have in common

Although most of the plants in the Bancroft Garden are not native to California, there is a section of the garden that is devoted to native plants.  Ruth Bancroft had some difficulty establishing that portion of the garden:  “When Ruth Bancroft decided to experiment with native California penstemons…many of her plants died.  She added even more rock to the bed and planted again.  In the improved drainage, that this rocky bed now provides, penstemons thrive alongside such other California native perennials as woolly blue curls and…buckwheats.”

Mitilija poppy, Bancroft Garden

Matilija poppy (Romneya coultera), is another California native in the Bancroft garden, but one which must be watched closely because, “…its major problem is that it spreads underground and can be invasive.”   This is a description often applied to non-native plants.  However, when the author is a horticulturalist, rather than a nativist, it is sometimes applied to native plants as well.

There is also a native Manzanita in the garden which is a hybrid descendent of two unrelated Manzanita species which have long since disappeared from the garden.  Hybrids of native plants are often eradicated by native plant advocates who want to freeze all native species into place.  Hybridization represents change and abhorrence of change is a basic tenet of nativism.  The existence of this hybrid in the Bancroft Garden is an example of why we are opposed to nativism in its purest form.  The hybrid survives, but its two ancestors are gone.  Aren’t we better off with this survivor in the Bancroft Garden than with no Manzanita at all?

The Bancroft Garden was an opportunity to revisit these themes of the Million Trees blog:

  • Native plants are as likely as non-native plants to require tending in the garden, such as soil amendments
  • Both native and non-native plants are sometimes invasive
  • Hybridization is another means of insuring the survival of plant genes

This is a particularly good time to visit the Bancroft Garden.  There is an exhibit of sculpture by artists from all over the West Coast in the garden until July 14, 2012.  It is an interesting and lovely garden which is rich in California history.

Sculpture in the Bancroft Garden

California Academy of Sciences: “Evolution in the Park”

In 2003, when the great debate with native plant advocates about the future of San Francisco’s public parks reached a fever pitch, the California Academy of Sciences stepped into the fray by publishing this article in their quarterly publication, California Wild.  This article was written by Gordy Slack, free lance science writer and former editor of California Wild. 

Golden Gate Park in 1880. The trees are about 10 years old. In the distance, looking south, we see the sand dunes of the Sunset District. That’s what most of Golden Gate Park looked like before the trees were planted.

As you will see, “Evolution in the Park”  (1) urges the public to consider that the parks of San Francisco have been transformed over the past 150 years from predominantly barren sand dunes to green oases of non-native trees and plants.  Using Golden Gate Park as an example, Mr. Slack reminds us that the non-native trees provided the windbreak needed to protect the entire landscape which we admire today.  The park has changed and it will continue to change, because nature is dynamic.  The forces of evolution are stronger than human desires to freeze-frame our world.

At the time, we were deeply grateful to Mr. Slack and to the Academy of Sciences for taking a position on the controversy.  We remember thinking that the opinion of this prestigious institution would surely settle the controversy.  But we were mistaken, because native plant advocates would not even read this article, let alone heed its message.

As the Environmental Impact Report for the Natural Areas Program undergoes revision and the controversy heats up again, we reprint “Evolution in the Park.”  We can only hope that someday reason will prevail.

Tree ferns from New Zealand are one of many species of non-native trees that make Golden Gate Park the beautiful place it is today. Creative Commons

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“When San Francisco officials asked the great nineteenth-century landscape architect Frederick Law Olmstead how to turn the wind-scoured dunes of the western half of the city into a green, rambling park, he was happy to offer advice: Don’t bother, he said, it’ll never work.

They went ahead anyhow, establishing three-mile-long, 1,107-acre Golden Gate Park on April 4, 1870. The decades that followed saw an almost unbelievable transformation under the strong hand of the park’s first superintendent, William Hammond Hall. He shaped glades and grew forests, dug lakes and planted lawns, until people nearly forgot that under the acres of grass and trees and shrubs lay mountains of sand.

The invention of Golden Gate Park was an amazing engineering and horticultural accomplishment, but it was not an environmental one—at least not in the sense of conserving native natural resources. If the California Native Plant Society (CNPS) had existed then, it would never have allowed Hall to spread tons of exotic barley seed over the dunes as part of his plan to “reclaim” them. The barley achieved what Hall wanted—to create favorable conditions for the thousands of alien trees and shrubs he would soon plant. And yet the CNPS now meets in Strybing Arboretum and botanists love the park. Everyone does. It would seem as silly to criticize the park’s blue gum trees for being out-of-towners as it would be to criticize most of us for being exotics. The park is as much an urban invention as the parking lot or the shopping mall, only much better. There is nothing wild about it…except what goes on there.

Nancy de Stefanis is the Director of San Francisco Nature Education, a group that leads nature studies in Golden Gate Park. She is perhaps best known for her discovery in 1993 that great blue herons were nesting in the park’s Stow Lake, and for her efforts to protect those nests from raccoons and other threats (California Wild, Summer 2002). A few days ago, on an early morning walk in the park, she saw a great blue plucking endangered red-legged frogs out of a pond. She saw feral cats, gray squirrels, and a three-foot-long box turtle. All this, and she had intended to look for birds! She saw those, too: an albino robin, varied thrushes, ravens, white- and gold-crowned sparrows, and a courting pair of red-tail hawks doing loopty-loops and dives. She saw a bevy of seven California quail running through Strybing Arboretum, the only population of quail left in the park. “It was incredible,” she said. “We saw 25 bird species easy.”

Anyone who’s spent much time in Golden Gate Park has wild stories to tell. My own favorite took place a few years ago, after I’d pulled an all-nighter at the magazine and was tired enough to sleep dangling off of Half Dome. Half Dome was too far away, so I walked a few hundred yards east on Middle Drive and up a tiny path back to Lily Pond. I walked the perimeter looking for a place to sleep. The pond had steep vegetated banks all around except for a small, reasonably sloped patch of dirt on the east side. I kicked away some guano, put a newspaper under my head, and fell asleep.

I woke up half an hour later; something soft was tickling my arm. I raised my head slowly to find myself surrounded by mallards. There must have been 20 and they filled every inch of the dirt patch around me. One nestled comfortably between my outstretched arm and my torso.

Each duck had its head swiveled and tucked into the feathers on its back. When I lifted my own head, the birds next to me raised and turned theirs as well, and a couple of them stirred, causing a chain reaction of awakenings in the ultimate morning-after surprise. No one lost his or her cool, though. I tiptoed out of their realm and headed back to work, downy feathers clinging to my sweater and my hair. That was how I became the Man Who Sleeps with Ducks.

Raymond Bandar, a field associate in the Academy’s Department of Ornithology and Mammalogy, grew up in Golden Gate Park and has a thousand wild stories to tell. He says that in the 1940s, when he was a boy, it was a “biologist’s paradise.” He spent long summer days hunting for garter snakes, alligator and fence lizards, bush rabbits, Pacific pond turtles, weasels, and red-legged frogs. Peacocks roamed free in the park, and there Bandar courted his wife, Alkmene. They took long, moonlit walks from the beach to the park’s entrance on Stanyan, stopping to spoon in the Valley of the Moon.

Most old-timers like Bandar long for the good old days, when the park was “less manicured.” It’s hard to tell if this is because the park used to be wilder, or because the old-timers were. But there’s no doubt that the park refuses to cooperate by holding still. As Heracleitus said, “You can’t step into the same river twice.” (Or as Cratylus, Heracleitus’s follower, trumped, ‘You can’t step into the same river once.’)

The park’s “ecosystems” are a moving target, changing with park administrations and larger cycles of growth and death. In recent years, the Parks Department has cleared away much of the undergrowth that had been protecting ground-nesting birds—and homeless humans. Other forces originate outside the park but have an influence by increasing, diminishing, or eliminating the animals that live within. If there are no peregrines anywhere else in California, there aren’t going to be any in Golden Gate Park either.

Late Academy ornithologist Luis Baptista used to talk about the 1980s in the park. California quail were common then, running here and there on urgent business. Native bush rabbits lived here, too. The rabbits are now gone and the quail nearly so. I’ve heard speculation that the rabbit population may have collapsed partly under predation by humans, too. But both are most likely victims of the park’s shifting food web.

Raptors returned when their populations rebounded from the DDT poisoning that largely ended four decades ago. Recently, red-tailed, red-shouldered, and Cooper’s hawks have moved in, according to Douglas Bell, a biology professor at California State University in Sacramento. The park is now “probably a sink for white-crowns” he says. “It draws them in, but because of the intense predation, their survivorship is very low.” But even bigger players in the songbird and quail equation are the park’s resident feral cats. According to Baptista and Bell, white-crowned sparrow deaths in the park are probably due mostly to cats.

In addition to feral cats and other predators, floral changes affect park wildlife as well. Many of the Park’s trees are reaching climax now, says Peter Dallman, who is writing a natural history guide to Strybing Arboretum. The big trees are falling or are being cut down in anticipation of their natural collapse. The pygmy nuthatch, a bird that nests in the park’s climax Monterey pine forest, will likely flee the park when those trees come down.

Today, raccoons are plentiful. So are ravens, though Bell remembers that not long ago no ravens nested here. Exotic cowbirds have arrived, too; they lay their eggs in the nests of other birds, which then raise ravenous cowbird chicks, often at the expense of their own young. Squirrels are multiplying out of control, says Dallman.

Cat populations are strong, but not as strong as their political lobby. The bison herd, introduced to the park in 1894, remains stable at eleven. But the reintroduced grizzly bears (Bandar remembers when there were at least two sad grizzlies in cages in the park’s southeast corner) are long gone. The last Golden Gate grizzly, Monarch, is now stuffed and on exhibit in the Academy’s Wild California Hall.

These changes and conflicts raise some uncomfortable questions about the park and its mission. By what standard can the costs or benefits of these changes be measured? Should we be trying to restore Golden Gate Park systems and populations that are at bottom artificial? Should we simply maintain the species we prefer, and get rid of, or let slip away, the unpopular ones? Should “maximum diversity” be the goal, and mandate mediations of conflicts that arise between incompatible species, such as cat and quail?

To maintain quail in the park for the long term, for instance, would require “intensive and sustained human intervention,” says Bell. “We’d have to rely on the full range of wildlife management techniques.” Predation would have to be monitored and protective habitat cultivated. New quail stocks would have to be introduced, and electrically charged wire cages (through which the quail could fit, but not cats or ravens or raptors) could be built around nesting areas. But without heroic and constant human support, the quails’ days in the park are numbered.

Like its creation, the park’s future will be shaped by human invention, its progression determined by our priorities.”

Golden Gate Park, aerial view. Gnu Free Documentation

(1) Gordy Slack, “Evolution in the Park,” California Wild, Spring 2003 [reprinted with permission of author]