Ecology – Page 44 – Conservation Sense and Nonsense

Another Eucalyptus Myth: Bird Death According to Audubon

As we have said in other posts on Million Trees, those who demand the destruction of non-native trees justify their demand by making many critical claims about them. One of the most disturbing of these claims is that eucalypts kill birds. Reprinted here with permission is an excerpt from an article in the April 2010 newsletter of the Hills Conservation Network which debunks this myth.

The Hills Conservation Network is a group of residents in the Oakland-Berkeley Hills who advocate for fire safety without clear-cutting non-native trees. Most of the members of the network are survivors of the 1991 fire in their neighborhood. Some lost their homes. Some lost members of their family. They are highly motivated to improve fire safety in their neighborhood and they strongly believe that fire hazard mitigation can be achieved without destroying all non-native trees.

Please visit their website to see other issues of their newsletter which is a valuable source of information on the subject of fire hazard mitigation. You may subscribe to their free on-line newsletter by sending an email to inquiries@hillsconservationetwork.org.

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BIRDS AND BLUE GUM: LOVE OR DEATH?

Brochures distributed by various agencies in northern California state that the flowers of eucalyptus trees kill birds. According to these brochures, birds feeding on insects or on the nectar of eucalyptus flowers may have their faces covered with “gum” and die of suffocation. Luckily for the birds, according to one brochure, most of them prefer native vegetation, and avoid eucalyptus groves.

These stories are, of course, extremely upsetting to all of us who love birds.

The bird-suffocation story began with a 1996 article by Rich Stallcup, a legendary birder who writes for the Pt. Reyes Bird Observatory. In the PRBO Observer, he reported that, on one day in late December, he counted, in one eucalyptus tree: 20 Anna’s Hummingbirds, 20 Audubon Warblers, 3 Orange-crowned Warblers, 10 Ruby-crowned Kinglets, a few starlings, 2 kinds of orioles, a Palm Warbler, a Nashville Warbler, a warbling Vireo, and a summer Tanager.

That was an unusually large number of birds, even for Stallcup to see in one tree, but what most surprised him, he says, is what he found under that blue gum eucalyptus tree: a dead Ruby-crowned Kinglet, its face “matted flat from black, tar-like pitch.”

Years before, Stallcup recalled in the article, he had found “a dead hummingbird with black tar covering its bill” under eucalyptus trees. This was all Stallcup needed to come up with his theory about what had happened.

This theory is now stated as fact in restorationist literature and it is stated three times as fact in the “Wildfire Plan”/EIR issued by the East Bay Regional Park District in August 2009.

Stallcup theorizes that North American birds are different from birds indigenous to Australia. He speculates that North American birds such as kinglets, warblers, and hummingbirds have evolved short, straight bills while Australian birds evolved long, curved bills. Thus, he says, when American birds with short bills seek nectar or insects on eucalyptus flowers, they have to insert their whole head into the blossom, so they get gummy black tar all over their faces.

Stallcup0001 — Misleading illustration from Stallcup article

We have great respect for Stallcup’s ability to identify birds. But we have a few problems with his theory.

weebill0001 — Australian Weebill. Credit: Stuart Harris

1. A bird-loving friend who has photographed birds in Australia points out that Australian field guides show birds with a wide variety of bill length and curvature. When he was in Australia, he saw birds with small bills just like American kinglets and warblers. “How do you suppose the Australian Weebill got its name?” our friend asked. Many of us not so familiar with Australian birds have seen parakeets and other small small-billed parrots native to Australia. Weebills and many other American and Australian birds with small bills forage on eucalyptus leaves or flowers.

To see more birds of Australia, go to this terrific website. It features photos of many small-billed birds.

euc flower0001 — Blue gum eucalyptus flowers on tree, March, 2010. Credit: John Hovland

2. Where’s the gum? The flower of a blue gum eucalyptus tree has no gum, glue, or tarlike substance on it or in it. The gum in “gum trees” refers to the sap or resin that, in some species, comes from the trunk. Other species of gum trees, such as the sweet gum (Liquidambar) are common sidewalk trees in Berkeley and Oakland. The flowers on the blue gum eucalyptus are white or cream-colored with light yellow or light green centers. There is no black, sticky, gummy or tarry substance in or on the living flower. In fact, both the Ruby-crowned Kinglet and the Australian Weebill are leaf-gleaners. They take insects off leaf surfaces, not from flowers. If the kinglet had gum on its face, the gum did not come from a eucalyptus blossom.

3. A euc flower looks most like a chrysanthemum, with longer petals. Unlike a morning glory, the euc flower is not shaped like a tube that a bird would need to poke its bill into to get nectar or insects. A hummingbird is more likely to pick up a sticky substance from inside a cup-shaped tulip, poppy, or any of the tiny tube-flowers such as California fuchsia, Indian paintbrush, watsonia, or honeysuckle that hummingbirds love. Common sense tells us that no bird, even a tiny one, could suffocate while feeding on a euc flower or leaf.

Watsonia0001 — Watsonia, Willow Walk, Berkeley, 2010. Credit: John Hovland

4. We have all seen hummingbirds poking their beaks into tube-like flowers. If you peel back these tube-like flowers, you will sometimes find a sticky substance on your finger. You’ve probably seen birds, especially tiny hummingbirds, sipping from these flowers. How do they escape getting nectar on their faces? An article in the NY Times proves truth is stranger than the fiction of suffocated hummingbirds. The article explains that a hummingbird gets nectar from a flower by wrapping its tongue into a cylinder to create a straw about ¾ inch long extending from its bill. This means that a hummingbird’s face does not touch the surface of a flat type of flower such as the flower of a blue gum eucalyptus.

After Stallcup wrote his article in 1996, it was accepted by birders and eucaphobes all across America. In January, 2002, Ted Williams, wrote about the “dark side” of eucalyptus in his opinion column called “Incite” for Audubon Magazine.

Stallcup, he wrote, had told him he had found 300 dead birds over the years “with eucalyptus glue all over their faces.” Williams wrote that the bird artist, Keith Hansen, who illustrates Stallcup’s articles, had found “about 200 victims.”(How did one kinglet and one hummingbird in 1996 add up to 500 victims by 2002 even though few if any other people have seen even a single victim?) Williams and Hansen also describe the suffocating material as “gum.”

Williams, in that same over-the-top column, dares to contradict Stallcup, claiming that he has heard only one Ruby-crowned Kinglet in a eucalyptus grove, and has never actually seen any birds in eucalyptus trees. Yet he repeats (and exaggerates) Stallcup’s story about eucalyptus suffocating birds. The National Park Service, U.C., EBRPD, and the Audubon Society have spread Williams’ interpretation of Stallcup’s story—apparently without questioning any part of it.

Stallcup and Williams are bird-lovers and writers. They are not scientists. David Suddjian, a wildlife biologist, has read Stallcup’s theory about birds suffocating on the “black pitch” of eucalyptus flowers, but in his article, “Birds and Eucalyptus on the Central California Coast: A Love-Hate Relationship,” he casts doubt on Stallcup’s claim that the kinglet (and other birds) could have been suffocated by eucalyptus flowers. Here is an excerpt from his article:

“. . . in my experience and the experience of a number of other long-term field ornithologists, we have seen very little evidence of such mortality. It has been argued that the bird carcasses do not last long on the ground before they are scavenged. However, when observers spend hundreds of hours under these trees over many years but find hardly any evidence of such mortality, then it seems fair to question whether the incidence of mortality is as high as has been suggested. Not all bird carcasses are scavenged rapidly, and large amounts of time under the trees should produce observations of dead birds, if such mortality were a frequent event. . .more evidence is needed.”

The Suddjian article is not generally favorable to eucalyptus trees. However, Suddjian notes that more than 90 species of birds in the Monterey Bay Region use eucalyptus on a regular basis. Additionally some rare migratory birds bring the total to 120 birds seen in euc groves. These include birds that use eucalyptus trees, leaves, seeds, or flowers for breeding, nesting, foraging, and roosting. A complete list of birds that depend on eucalyptus trees is too long to include here. We encourage you to click on the link to the Suddjian article so you can look for the names of the various bird species and note how they use—and depend on—eucalyptus trees.

Lynn Hovland

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Million Trees Webmaster: Shortly after this urban legend surfaced over 10 years ago, I had an opportunity to ask a local scientist about it. While attending an open house at the California Academy of Sciences in San Francisco, I was able to talk to the head of its ornithology division at the time.

He started by saying that although he had never seen a dead bird in a eucalyptus forest, there weren’t as many birds there because the eucalypts don’t offer as much food for birds as other vegetation types. (Those who bird in the eucalyptus forest without a nativist bias don’t agree with this generalization about a lack of birds, however.) He also said he hadn’t heard the claim.

Then, the scientist said that the story didn’t seem consistent with bird anatomy. He said that birds are capable of lifting their feet to their heads and clearing whatever might be accumulating there with their toes.

Ten years and many walks in the eucalyptus forest later, we have yet to see a dead bird, but the myth lives on.

Jared Diamond’s History Lesson for Us

In Collapse: How Societies Choose to Fail or Succeed, Jared Diamond reviews the histories of societies that have failed in climates as diverse as Polynesia and the Arctic North. He identifies a handful of factors that were instrumental in those failures, but only one of those factors is shared by all the examples he describes: deforestation.

In every case deforestation reduced agricultural productivity by causing soil erosion and reducing rainfall. The roots of trees hold soil in place and absorb rainfall which would otherwise wash over the surface of the soil, flushing it into watersheds where it increases turbidity and destroys fisheries. The rainfall that is absorbed by the roots of trees is transpired by the leaves into the air where it rejoins the water cycle to be returned to the land as rainfall. When the trees are destroyed, the water cycle is interrupted in that location and rainfall is reduced.

In some cases, the loss of trees had a more immediate, observable effect on the society. On Easter Island, for example, the loss of trees quickly meant the loss of their main source of food: fish. Easter Island was the most easterly of the islands inhabited by Polynesians. It was far from any other island. Therefore, when their trees were gone and their boats eventually fell apart and could not be replaced, they had no means of fishing from their rocky shores. (see video)

Likewise, the Norse population in Greenland eventually starved to death when they could no longer grow the hay needed to keep their cows alive. In this frigid climate, they had used all of their trees as fire wood for warmth and to pasteurize the milk that was their principle food source. As their fuel source diminished, they burned the peat that fed their cows.

In both cases, as well as in others, these societies made choices that eventually contributed to their demise. The failure of their societies was not inevitable. On Easter Island, for example, the Polynesians chose to cremate their dead, unlike other Polynesians who bury their dead. And they devoted much of their time, effort, and resources to building the gigantic stone tributes to their ancestors. These stone sculptures were carved in quarries and then transported many miles by rolling them on logs. These cultural uses of wood were not essential to the islanders’ physical survival.

: Easter Island, Wikimedia Commons

In Greenland, the Norse brought the cows from their homeland that were central to their culture. Their lives were devoted to keeping their cows alive by spending the brief summer growing the hay to feed the cows during the long winter in the huge stone barns in which the cows were protected from the extreme cold. The milk had to be boiled to prevent it from spoiling. As they depleted the wood needed to boil the milk, they simultaneously destroyed the land needed to grow the hay to feed the cows by burning the peat and causing erosion.

Meanwhile, the Inuit neighbors of the Norse made other choices that enabled them to survive in the harsh climate. They hunted whales and seals that were their principle food as well as the source of oil that heated their homes. The Norse considered the Inuit enemies with whom they did not interact or trade. Therefore, they were unable to learn these survival skills from them.

Diamond contrasts these histories with those of cultures that have made other choices. One of the most dramatic examples is the island of Hispaniola, shared by the nations of Haiti and the Dominican Republic. Haiti is almost entirely deforested and its ability to feed itself is destroyed by erosion. In contrast, the Dominican Republic is heavily forested because of a strong commitment to its forests made by its leadership. There are intervening factors, to be sure, but the deforestation of Haiti is a major factor in its impoverishment.

Diamond’s book intends to challenge us to look at the choices we are making for our own society. He asks and answers the rhetorical question, “Why did these societies make choices that contributed to their failure?” The short answer to that question is that long-term goals were sacrificed to short-term goals and that entrenched cultural practices were incapable of responding to changed conditions. When you are freezing cold today, you might choose to burn your last tree even if it means you don’t have any wood tomorrow. And when your entire diet is based on milk you can’t conceive that eating whale blubber may be a better choice for your long-term survival.

Million Trees sees these poor choices made by failed societies as similar to the poor choice that is now being made here in the Bay Area to destroy our non-native trees because we prefer native plants and trees.

We live in a place in which there were few trees prior to the arrival of Europeans. The landscape goal of native plant restorations is therefore grassland, scrub, and chaparral. Native trees are unlikely to survive in most of the places which are now forested by non-native trees. Native trees are being killed by Sudden Oak Death and bark beetle. Their historic ranges are changing in response to climate change. Releasing carbon sequestered in the trees and eliminating that source of carbon storage in the future will contribute to the greenhouse gases that result in climate change. Erosion is a likely consequence. Rainfall could be reduced by the absence of trees. Denuding our landscape of non-native trees is likely to result in a barren, weedy mess.

P1000017 — Grizzly Peak Blvd is being undermined by erosion resulting from clear-cutting of non-native trees

We urge native plant advocates to re-examine their demands for the destruction of non-native trees and plants in light of the changing climate which is exacerbated by deforestation. As Jared Diamond says as he concludes his book, “The other crucial choice illuminated by the past involves the courage to make painful decisions about values. Which of the values that formerly served a society well can continue to be maintained under new changed circumstances.”

We do not ask that native plant advocates abandon their preference for native plants. We encourage them to plant more native plants. We ask only that they quit destroying those that are not native.

Losing Battles to Save our Trees

In our posts “They can destroy your trees” and “KILLER TREES!! Scare Tactic #3” we told you about two efforts to save eucalyptus trees that were threatened with destruction. Today we must tell you that those battles have been lost.

In Larkspur, 25 trees that have been destroyed were on private property. The owner of that property was sued by her neighbors who demanded that the trees be destroyed because they believed them to be dangerous. The owner of the trees made every effort to save her trees, even appealing unsuccessfully to the California Supreme Court for reversal of the court order to destroy most of her trees. She organized demonstrations in a fruitless effort to interest local politicians to come to the defense of her trees. Finally, when she was cited for contempt of court, she had her beautiful trees cut down.

Yesterday we attended a memorial for her trees. We find it hard to believe that her neighbors would prefer the barren landscape that remains or the PG&E pole that was installed to hold the electrical wires that had previously been held by the trees.

In San Leandro, the neighbors worked equally hard to save the eucalyptus trees on the banks of the San Leandro Creek from being destroyed. They faithfully attended a series of community meetings which were theoretically an opportunity for them to defend the health, safety, and beauty of their trees. As is often the case when we advocate on behalf of our trees, we may be successful in demanding a public process, but that rarely seems to save our trees.

That was the case in San Leandro. Neighbors were informed at the last public meeting that 31 of the 47 trees originally in jeopardy will be removed and 2 will be “trimmed” to stumps, but allowed to regenerate (1). After months of effort, neighbors have saved only 14 of their trees and the assumption is that the remaining 1,000 eucalypts on the banks of the creek remain in jeopardy.

However, the county has made a commitment to an environmental review, which it had originally intended to avoid by destroying the trees piecemeal. This environmental review will give the neighbors another opportunity to document the negative environmental impacts of tree destruction, whether the trees are native or non-native.

As the needless destruction of non-native trees continues unabated, millions of native oaks are being killed by Sudden Oak Death, millions of native pines are being killed by bark-beetles, and the ranges of native plants and trees are shifting to higher elevations as the climate changes. Those who demand the destruction of non-native trees which are adapted to current climate, soil, and air quality conditions will doom us to a barren, treeless environment.

It is long past time for environmentalists to reorder their priorities to put climate change mitigation ahead of their commitment to native plants. Their crusade against non-native trees is contributing to climate change by releasing tons of sequestered carbon into the atmosphere. Ironically, as the climate changes, the native plants to which they are devoted are dying. In other words, they are shooting themselves and the plants they prefer in the proverbial foot.

(1) San Leandro Times, 9/2/10

SOD Update

The San Francisco Chronicle recently published an update about Sudden Oak Death (SOD) that was both misleading and inaccurate.

The article inaccurately claimed that “the mysterious pathogen…has killed tens of thousands of oak trees from Big Sur to southern Oregon.” This is a gross underestimate of the number of trees that have been killed by SOD. The California Oak Mortality Task Force reported in the announcement of their 2009 annual symposium that “Since the 1990s more than a million oak and tanoak trees have died from this pathogen and at least another million are infected.” Since there is no known cure for the disease, we must assume those trees will die.

Secondly, the article quotes Matteo Garbelotto of UC Berkeley—who is described as “the nation’s foremost expert on sudden oak death”—as recommending that “homeowners in infected areas can remove bay trees…[to] increase the survival rate of nearby oaks.” We doubt that this is an accurate quote because it is not consistent with the advice Garbelotto gave at one of his SOD workshops.

One of the many professional gardeners attending that workshop asked if he should remove the bays in the gardens in which there are also oaks to protect the oaks from infection. Mr. Gabelotto’s response was that the bays would resprout ten-fold and that the immature leaves of the resprouts would be more susceptible to infection than the mature leaves. The gardener asked if he could prevent resprouts with Roundup. Mr. Garbelotto replied that Roundup would not prevent resprouts.

In other words, removing bay trees is easier said than done. Attempts to do so can result in even more bay trees unless toxic chemicals such as Garlon are used repeatedly to prevent resprouts. Since the immature leaves of the resprouts are more susceptible to SOD infection, this is not a wise strategy.

Garbelotto may have told the Chronicle that removing bay trees already infected with SOD may prevent the spread of the pathogen to oaks. Although it seems to us a risky strategy, it is apparently being done in the Santa Cruz Mountains, according to the San Jose Mercury (“’Sorry baby, but you gotta go’,” December 17, 2009). This is an important distinction: removing healthy bay trees is likely to do more harm than good, while removing infected bay trees may make some sense, although we would prefer to avoid the use of toxic chemicals.

Journalism is a powerful tool that can strengthen democracy if used responsibly, reporting the facts faithfully and balancing competing opinions when necessary. The author of this article grossly underestimates the number of native trees killed by SOD and offers bad advice about killing healthy trees. Those who still subscribe to the dwindling San Francisco Chronicle will not be surprised by such sloppy journalism. It is an example of the death throes of the Bay Area’s local newspaper.

Eucalyptus and Poppies

Have you visited the Oakland Museum since it reopened this summer after extensive renovation? It looks pretty spiffy and continues to be a valuable resource for our community.

The museum’s collection of California art and design represents “the region’s creative output and its relationship to, and influences on, the nation and the world from the mid-1800 to the present,” according to its website. And so, as we would expect, the exhibit includes a fitting tribute to one of California’s iconic landscapes, “Eucalyptus and Poppies.”

The artworks in this exhibit were created from 1916 to 1940, a period when eucalypts were popular. They are out of fashion now, as are leisure suits and beehive hairdos. Will they make a comeback, as did bell bottoms and hip hugger jeans?

There was a time, not so long ago, when Californians thought eucalypts fit in just fine with our native poppies. Are they really the destructive intruders that native plant advocates make them out to be? We don’t think so. We believe that eucalypts are the victims of a “bad rap,” scapegoats for a fire they didn’t cause and a dwindling native landscape that is succumbing to climate change and other factors unrelated to the existence of eucalypts.

Invasion or Natural Succession?

In a recent post we considered the changes in our landscape that have occurred as a result of climate change. In this post we examine more historical sources of change in the landscape.

Native plant advocates in the Bay Area choose to replicate the “pre-settlement” landscape that existed in the late 18^th century. The arbitrary selection of this date does not take into account that Native Americans had lived in the Bay Area for approximately 10,000 years. Throughout that period Native Americans altered the landscape by setting fires to promote food production as well as to provide materials for cultural activities such as basket weaving. Fires were used to improve forage for the animals they hunted and visibility during the hunt, and to funnel animals into their hunts. Fires also promoted the growth of their food sources such as acorn production. (1)

Unlike some parts of California, fire ignition in the San Francisco Bay Area is rarely caused by lightening, making this anthropogenic (caused by man) source of fire the predominant cause of fire historically. (2)

After the arrival of the Spanish in the late eighteenth century, cattle and sheep grazing was the predominant economic activity in California and continued to be an important activity into the early 20^th century. These early ranchers also introduced non-native grasses which had greater nutritional value for their herds. The non-native annual grasses out-competed the native bunch grasses, resulting in California grassland that is 99% non-native today (3).

The fires set by Native Americans and the cattle grazing of the early Californians were both instrumental in preventing the natural succession of grassland to chaparral and scrub and subsequently to woodlands. Modern land use and management policies have suppressed fire and reduced grazing in the Bay Area. Consequently grasslands are succeeding to chaparral and scrub. Although managers of public lands often describe these changes in the landscape as “invasions,” Jon Keeley (Ph.D. biologist, USGS) considers them a natural succession:

“These changes are commonly referred to as shrub invasion or brush encroachment of grasslands. Alternatively, this is perhaps best viewed as a natural recolonization of grasslands that have been maintained by millennia of human disturbance.” (4)

Serpentine Prairie restoration. East Bay Regional Park District

So, if the succession of grassland to shrubland is natural, why do managers of public lands believe it is necessary to prevent—or even reverse– this succession?

Serpentine Prairie. 500 trees were destroyed, including many oaks.

For example, the “Wildfire Plan” of the East Bay Regional Park District is even more ambitious than halting natural progression of the landscape. In many instances it proposes to return the landscape to an earlier version of the native landscape. Here are a few examples of management actions in the “Wildfire Plan” that are intended to roll back biological time to sustain native landscapes from an earlier period:

“[Native] Grasslands and Herbaceous Vegetation…these widely-spaced trees will not cause an active crown fire because of the discontinuity of tree crowns. They could, however, provide a seed source for invasion of grassland habitats by woodland species and should be considered for removal to maintain desirable and declining grassland habitat.” (page 131)
“[Native] Maritime Chaparral…Favor chaparral community by removing oak, bay, madrone buckeye, and other trees under 8 inches diameter at breast height that are encroaching upon the maritime chaparral.” (page 136)
“[Native] North Coastal Scrub…Shift species composition towards native scrub species or consider conversion to grasslands, where appropriate on historic grassland sites…” (page 140)
“[Native] Coyote Brush Scrub…In most treatment areas, encourage conversion to grasslands by reseeding with native grasses…after brush removal.” (page 149)

Serpentine Prairie being weeded by hand. Mowing will be required during the restoration. Prescribed burns will be required to maintain it as prairie.

The return of the existing landscape to earlier, historical versions requires the removal of native trees and shrubs, as well as dangerous, polluting prescribed burns. In so doing, a permanent commitment to periodic prescribed burns is made to maintain the landscape as grassland. And what will this accomplish? If this strategy is successful the landscape would be returned to a version of the landscape in the late 18^th century, even though that landscape was actually created by the Native Americans and maintained by subsequent grazing by early European settlers.

As we often do on Million Trees, we ask the managers of our public lands to explain their strategy for artificially maintaining our landscape at an arbitrarily selected point in time. Should we run the risks of prescribed burns for the sole purpose of replicating an 18^th century landscape that was created by Native Americans? Since California grassland is now almost entirely non-native, what is the point of preventing its succession by destroying native plants? We don’t understand what would be accomplished by such artificial manipulation of the landscape.

(1) “The Use of Fire by Native Americans in California,” M. Kat Anderson in Sugihara, Fire in California’s Ecosystems, 2006.

(2) “Central Coast Bioregion,” Frank Davis & Mark Borchert in Sugihara, Fire in California’s Ecosystems, 2006.

(3) Natural History of California, Schoenherr, UC Press, 1992

(4) “Fire history of the San Francisco East Bay region and implications for landscape patterns,” Jon E. Keeley, International Journal of Fire, 2005.

Sudden Oak Death

Coast live oak, Mountain View Cemetery, Oakland

The coast live oak that is native to the Bay Area is one of our favorite trees and we would be happy to see more of them. However, the epidemic of Sudden Oak Death that is killing oaks in California and Oregon makes us question the wisdom of replacing non-native trees with oaks that may not survive that epidemic. Since any dead tree is more flammable than any living tree, we are also skeptical about claims that restoration of the oak-studded grassland will reduce fire hazard in the Bay Area.

SOD, Forest Service photo — Sudden Oak Death, US Forest Service photo

The pathogen (Phytophthora ramorum) that causes Sudden Oak Death (SOD) was reported on the UC Berkeley campus in 2002. At that time it also existed at the UC Botanical Garden and the researcher who identified the pathogen speculated that it probably existed throughout the East Bay. By 2008, the SF Chronicle reported that the infestation of SOD existed in several parks in the East Bay. The researcher estimated that about 20% of all coast live oaks in the East Bay are infected with the pathogen that will eventually kill them.

In February 2008, the California Oak Mortality Task Force estimated that ”millions of tanoak and coast live oak” have been killed by SOD in California. Thirty four other species of trees and shrubs are also infected with the pathogen, including bay laurels and redwoods. Although these species are not usually killed by the pathogen they are vectors of the disease. The bay laurel is singled out by the scientific literature as being particularly effective at transmitting the pathogen to the oaks that are then killed.

The “Wildfire Hazard Reduction and Resource Management Plan” of the East Bay Regional Park District proposes to destroy most non-native trees on over 1,500 acres of parkland. The “vegetation management goal” for most of these acres is the restoration of “oak-bay woodland.” And so we ask these rhetorical questions:

What is the probability that coast live oak will survive the deadly SOD pathogen in the Bay Area?
Does the proximity of bay laurel to the local oak population increase the probability of infection?
If the oaks are killed by SOD will the risk of wildfire in the East Bay hills increase?
If the non-native trees are destroyed and the oaks are killed by SOD will the resulting landscape be entirely treeless?

We believe these are legitimate questions and when we have asked them of native plant advocates we have not heard an adequate answer. We believe that eradicating non-native plants and trees without a clear understanding of the future of the natives, is irresponsible.

CHANGE….the only constant

The conventional wisdom amongst native plant advocates is that native plants will return to the landscape if non-native plants are eradicated. In this post, we will examine this assumption and refute it.

Several different methods are used to eradicate non-native plants, but it doesn’t matter which method is used because the results are the same: native plants do not return when non-native plants are removed.

Spraying herbicides is a popular method of eradicating non-native plants because it is considered the most cost-effective method. In addition to the obvious health risks, the downside of herbicide use is that they are as likely to kill the natives as the non-natives. This problem is illustrated by a USDA study of the effects of a one-time aerial spraying of herbicides on grassland after 16 years. Although the herbicide is assumed to “dissipate” within a few years, the negative effect on the natives persisted 16 years later: “…the invasive leafy spurge may have ultimately increased due to spraying. Conversely, several desirable native herbs were still suffering the effects of the spraying,,,”

Even when native plants are removed, non-native plants occupy the cleared ground. Environmental scientists at UC Berkeley removed native chaparral from experimental plots in Northern California to test fuel reduction techniques using two different methods (prescribed burns and mechanical), in different seasons, over a period of several years. In every test, the result was on average from 23% (for prescribed burns)to 61% (for mechanical methods) non-native plants where they had not previously existed.

Jon E. Keeley (USGS) finds the same tendency for non-natives to replace natives in forests: “Forest fuel reduction programs have the potential for greatly enhancing forest vulnerability to alien invasions.” (1)

A scientist (2) arrived at the same conclusion after attempting to restore an oak-studded grassland on Vancouver Island. He tried several different methods of removing invasive grasses for several years only to find that “…the decline of the native plant species accelerated…”

Those who observe native plant restorations in the San Francisco Bay Area aren’t surprised by these studies. We know that native plant restorations are unsightly failures unless they are aggressively planted, irrigated for several years, and fenced. Examples of successful restorations can be seen at Crissy Field and the summit of Mt. Sutro. The East Bay hills provide examples of the opposite strategy. Where UC Berkeley has clear-cut all non-native trees and vegetation, non-native weeds quickly occupied the barren ground. After a particularly wet winter, the non-native poison hemlock in the East Bay hills is 6 feet tall along the roads.

Why are non-native plants apparently more competitive than native plants? Because the conditions that supported native plants 250 years ago, prior to the arrival of Europeans, have changed. The native plants are no longer well adapted to the current conditions.

Higher levels of CO2 and the associated climate change are promoting the growth of non-native plants. A USDA “weed ecologist” (3) studied the effects of higher temperatures and CO2 on the growth of non-natives (AKA weeds) by growing identical sets of seeds in a rural setting and an urban setting with higher temperatures and CO2 levels. Seeds grown in the urban setting produced substantially larger plants with much more pollen and therefore greater reproductive capability.

Other scientists reach the same conclusions by studying the changing ranges of native plants and insects. An ecologist at UC Berkeley (4) says that “California’s flora face a potential collapse…as the climate changes, many of these plants will have no place to go.” A scientist at the California Academy of Sciences (5) predicts that redwoods will disappear from California by the end of the century.

As the plants move, so do the insects and animals that need them. A study published in Nature magazine in December 2009 found that plants and animals must move as much as 6 miles every year from now to the end of the century to find the habitat they occupy now. An ecologist at UC Davis (6) has been studying native butterflies for over 35 years. He recently reported that native butterflies are moving to higher elevations, where temperatures are lower, but that ultimately, “There is nowhere else to go, except heaven.”

The local environmental organizations and public policy-makers must wake up to this reality and reorder their priorities. Instead of demanding that all non-native plants and trees be eradicated and that native plants be restored where they are no longer sustainable, they must make climate change their highest priority. The easiest and cheapest step to take to address this issue is to quit destroying healthy trees—just because they are non-native–that are sequestering tons of carbon.

(1) “Fire Management Impacts on Invasive Plants,” USGS, Jon E. Keeley, April 2006

(2) Andrew MacDougall, University of Guelph, Ontario, Canada, NY Times Magazine, 6/29/08

(3) Lewis Ziska, USDA, Beltsville, MD

(4) David Ackerly, UC Berkeley, Los Angeles Times, 6/25/08

(5) Healy Hamilton, Cal Academy, Center for Biodiversity Research

(6) Arthur Shapiro, UC Davis, Contra Costa Times, 1/19/10

What is natural?

The branch of San Francisco’s Recreation and Park Department dedicated to the preservation and restoration of native plants to the city’s parks calls itself the Natural Areas Program (NAP). And the 32 parks or portions of parks within NAP’s jurisdiction are called Natural Areas. In this post we will visit a few of these areas to ask if they are accurately described as “natural.”

Parcel 4 1868 — Parcel 4, Balboa & Great Highway, 1868

The Natural Area known as Parcel 4 is at the corner of Balboa and the Great Highway. A photograph taken in 1868 of that location indicates that it has been continuously built upon for nearly 150 years. Long-term residents of San Francisco will remember it as the location of Playland by the Beach. After Playland was closed, the city purchased the property for $3.05 million in 1993 with the intention of putting a sewer pipe under it, then restoring it to dune vegetation. The soil was essentially building rubble, so the city had to buy $47,000 of sand and disk it down 18 inches to amend the soil in preparation for planting dune vegetation. The sand was bulldozed into simulated dune shapes and planted in 2002. The restoration was described in the newsletter of the Coalition of San Francisco Neighborhoods in April 2003, in an article entitled “Sand Francisco.” Does this sound “natural” to you?

44157_10 — Parcel 4 under construction, 2002

India Basin is a Natural Area on the east side of the city, on the bay. The east shore of the city was where most industrial development was located until industry left the city beginning in the 1960s. Much of the soil was landfill. Like Parcel 4, the landfill was bull-dozed into a simulated wetland, hoping to restore tidal action. Native pickle-weed was planted several times in the mud-filled basins. We haven’t visited this area for several years. Perhaps they have finally been successful in that effort. This is what we found there on our last visit: native plants along the trail, surrounded by plastic and woodchips to discourage weeds and huge, empty, mud basins off shore. It didn’t look natural to us.

Many of the Natural Areas in San Francisco are less artificial than these two extreme examples. Some of the Natural Areas weren’t built upon in the past, but had no native plants in them when they were designated as Natural Areas. Pine Lake is an example of such a Natural Area. Even where native plants actually existed, their populations were small and isolated in comparison to the acreage designated as a Natural Area. Over 1,000 acres of city-managed parkland have been designated as Natural Areas, 25% of all parkland in San Francisco and 33% if Pacifica is included in the calculation.

Now we will visit the Albany Bulb for contrast. Albany Bulb is also landfill that was for many years the Albany city dump. When the dump was closed, the Bulb became a park. It is a wild and wonderful place. There are few native plants, other than the ubiquitous coyote bush that seems to thrive almost anywhere. In the spring, Albany Bulb is a riot of color. These are the competitive non-natives that native plant advocates wring their hands about. They are there because they are best adapted to the current conditions in this location…the heavily amended soil, the higher levels of CO₂, the warmer climate, the use by humans and their animal companions.

Valerian and wild mustard, Albany Bulb. Both are non-native plants.

If all of these non-native plants and trees were eradicated from the Albany Bulb, would native plants magically appear? Based on our experience, we don’t think so. The conditions that supported the plants that are native to the Bay Area are gone for good. It is a fantasy that the existence of non-native plants is the only obstacle to the return of the natives. Visiting a few places where this strategy has been tried will confirm this. Unless the natives are aggressively planted, irrigated for several years, fenced for protection, weeded or sprayed with herbicides regularly, they do not return. Can such intensive gardening be called “natural?”

Restoration or Destruction?

A recent trip to the Channel Islands off the coast of California inspires us to consider the pros and cons of restorations. Islands are particularly attractive targets for restorations. They often contain endemic species that do not exist anywhere else because they have adapted to unique conditions in isolation. And the relative isolation of islands implies that once non-native species of plants and animals are eradicated, re-introduction of those species can be prevented.

Santa_Cruz_Island 2 — Santa Cruz Island, Wikimedia Commons

Some of the Channel Islands were inhabited by Native Americans as long as 13,000 years ago. Ranching by Europeans began on some of the islands in the 1850s. Europeans brought sheep, cattle, pigs, mule deer, and elk to some of the islands. Five of the eight Channel Islands were designated as a National Park about 30 years ago.

Restoration began in earnest in the 1990s when ranching operations were ceased and tens of thousands of sheep and cattle were either removed from the islands or destroyed. Black rats were eradicated from some islands after native mice were herded into protective enclosures so the rats could be poisoned. Rabbits were eradicated from another island. We don’t know how that was achieved.

The next big effort was the eradication of about 6,000 feral pigs. When this was accomplished by sharp shooters, the first unintended consequence of this ambitious restoration was revealed. It seems that the feral pigs had been the chief diet of a population of Golden Eagles, considered non-native to the Channel Islands. When the pigs were removed from their menu, they turned to the rare, endemic Channel Island Fox.

Channel Island Fox 2 — Channel Island Fox, Wikimedia Commons

The population of Channel Island Foxes plummeted. Those that remained were captured so they could breed in protected conditions while the Golden Eagles were captured and removed to a remote location. The Channel Island Fox is making a come-back, but the Golden Eagles are apparently gone for good.

The eagle considered native to the Channel Island, the Bald Eagle, has been reintroduced. It apparently lives in peace with the Channel Island Fox because it eats fish.

Mule deer and elk are next up on the eradication agenda for fauna. Non-native plants are also doomed. Ice-plant and fennel are the top priorities for eradication by 2011. Herbicides and prescribed burns are used for this purpose.

Channel Islands — Prescribed burn, Santa Cruz Island, NPS photo

We were surprised to see notice of herbicide application for Garlon 4 Ultra during our visit to this fragile place. Someone dressed from head to toe in protective clothing was spraying this chemical on a steep hillside. We have reported the toxic effects of Garlon in our post about herbicides.

This is a complex ecosystem in which simplistic solutions—such as killing all the non-natives—can result in a big mistake. For example, do we know if there are native Anise Swallowtail Butterflies on the islands that are now dependent upon non-native fennel for their survival? Do we know how the application of Garlon will impact the survival of the rare, endemic Island Jay? The US Forest Service found in its risk assessment done for the EPA that the application of Garlon had a significant negative impact on the reproductive success of birds. Are those who decided to spray Garlon aware of this study?

Herbicide application notice, Santa Cruz Island

We went to the Channel Islands with open minds. We thought the strongest arguments could be made for restorations on islands. However, when we learned of the thousands of animals who were sacrificed to this effort and the dangerous and toxic methods used to accomplish the restorations, we were not convinced. We nearly lost the Channel Island Fox because of the unforeseen consequences of killing feral pigs. Man would like to believe that he is capable of managing nature. But can he do so without causing more harm than good?