The Great Eucalyptus Debate

A grove of eucalyptus trees, viewed at trunk level, with whitish bark
Eucalyptus globulus at Reyes National Seashore, Marin County, California. Reproduced under a CC license. Charles (Chuck) Peterson

The Tasmanian blue gum, Eucalyptus globulus, is a magnificent tree. That is perhaps the only thing that everyone agrees on. It is, as Jake Sigg puts it, “a big, grand, old tree.” Tall, gnarled, stripey-barked, with white flowers like sea anemones, blue gum eucalyptus are characteristic of the San Francisco Bay area, despite being native to an Australian island half a world away. They just happen to thrive in the Bay climate, and many were planted either for timber of for scenery from the 1850s onwards.

There is, to put it mildly, widespread disagreement about what to do with these trees. The argument is as complex and tangled as the bark streamers that hang from the blue gum’s trunks. In the most general terms, there is a faction of environmentalists that want to see many of these eucalyptus trees removed, because they are a fire hazard close to homes, or because they are non-native and make poor habitat for native species, or both. In this group, place native plant enthusiast Sigg (who nevertheless loves the species and would like to see more of them planted in landscaped, irrigated parks). This faction also includes the local chapter of the Sierra Club.

There is another faction of environmentalists that dispute that the trees are more of a fire hazard than what might replace them, see them as decent or even very valuable habitat, and want to retain them to sequester carbon, provide shade, beauty, and recreation, and to avoid the use of the herbicides that are generally necessary to thoroughly kill them off. This faction includes a longtime correspondent of mine, Mary McAllister, and allies in different groups, including the Hills Conservation Network and the small-but-fierce Forest Action Brigade.

Those are the basic contours, but getting a fuller understanding requires a walk deeper into the woods.

This fight is many years old. There have been lawsuits and there have been letters to the editor pro and con. There have been protests and postcard campaigns and blog posts and newsletters and lots and lots of official public comment on management plans for various eucalyptus forests and groves. It is a classic Bay Area dispute: greens vs. greens, experts vs. experts, and committed amateurs vs. committed amateurs. And it has gotten very hot.

One recent summary of the dispute was this feature in Bay Nature by Zach St. George. The piece seemed pretty even-handed to me, but McAllister sent me a four-page memo with counter arguments against a hypothetical fire scenario described in the article. And that’s not surprising. McAllister, a retired university administrator, is very much engaged in the eucalyptus debate and always ready to rumble. And she and her allies can chalk up some recent wins. The Hills Conservation Network recently settled with the Federal Emergency Management Agency, who, as a result of the settlement, cancelled grants to remove eucalypts in the East Bay.

I became interested in the Great Eucalyptus Debate several years ago. In 2011, I wrote a book, Rambunctious Garden, that reported on new exciting directions in conservation. Among these was a reassessment of non-native species. Maybe not all of them were terrible. In fact, maybe we had been spending too much time and money removing non-natives in a quest for an unobtainable purity, money we could have spent on something else, like land acquisition or climate change mitigation. McAllister read my work and got in touch. People were trying to cut down all the eucalyptus trees just because they were non-native, she said. All the talk about fire risk was just “a cover story.” Recently we spoke on the phone. “They learned that the public is not interested in killing trees or eradicating plants just so it can look like it did 250 years ago,” she says. “They learned that they have to use fear tactics, and their main response is fire.”

McAllister has “reams” of studies that she says shows that the trees aren’t a fire hazard—or any more of one than the native shrubs and trees. She points in particular to the “fog drip” that these large, lanceolate-leaved trees collect and retain making them, in her opinion, a lovely defense against fire.

Sigg actually agrees that fire isn’t the main reason to remove eucalyptus. His central motivation has always been “the importance of saving natural ecosystems”–in this case the  oak woodland-grassland that predated the eucalyptus at many sites around the Bay.

Sigg and McAllister have tried to remain cordial over the many years that they and their allies have disagreed about the blue gums. They haven’t always managed to stay on speaking terms. And both sides naturally see science as supporting their own position.

So which side does science support? Well, it is complicated.

A botanical illustration showing the leaves, seeds, and flowers of the tree
licensed under cc.

According to Doug Johnson, executive director of the California Invasive Plant Council, whether the Tasmanian blue gum deserves to stay depends a lot on one’s goals for a particular site. That is, much of the disagreement is not on how to achieve a shared goal, but what the goals should be. And that’s an issue of differing values. “There are a number of competing visions for the wildland-urban interface,” he says. And then he ticks off just a few: “the safety aspect of wildfire protection, the cultural and recreational aspect of the beauty of large trees, the practical greenhouse gas storage aspect, the habitat aspect.”

It is Johnson’s belief that while“intelligent people and well-meaning people” are working on each side, positions have unfortunely become calcified, unbending no matter what any new study says.  “People fit the information to the narrative,” he says.

Over the course of his career, Johnson has seen interest in native plants move from a hip, counterculture movement to becoming the establishment position. These days, questioning “nativism” has become hip itself—and much of the questioning is led by scientists. Even invasive species conferences now feature panels on how to work with exotics to achieve restoration goals, Johnson says. The embrace of eucalyptus may be part of this pendulum swing.

As far as the public perception is concerned, the herbicides used to kill exotics certainly don’t help sell the idea of removing the trees. “When it comes to using herbicides to control invasive plants, there is a strong underlying narrative of fighting authority and any kind of synthetic product, especially something made by a large corporation and especially if that company is Monsanto,” Johnson says.

As we talk, I ask Johnson whether having an independent third party weigh in on some of these questions might be useful, and he perks up. When it comes to working with the horticultural plant trade—often the entry point for non-natives that go on to spread beyond home gardens—he’s had luck with using research by botanical gardens as a “trusted messenger” for science that all sides can believe. “We trust them to be scientifically based and horticulturalists know they love plants and don’t think they will be overly cautious and restrictive without good reason.”

So who would the trusted independent third party be on issues like the relative fire danger posed by eucalyptus vs. whatever would grow up where they were removed vs. a complete native restoration? Or the danger posed by herbicides used to remove eucalyptus? Johnson thinks universities are perceived as tainted by industry ties. But what about the National Academy of Sciences (NAS)? Could a study on the relative risks and benefits of removing, thinning, or retaining these Australian giants be explored for a number of different goals, from safety to habitat to beauty? (Most NAS studies are paid for by federal agencies, but a California state agency could fund a study, or the NAS could use some of their internal funding to take it on themselves.)

Macalister isn’t 100% sure she could trust a NAS report, but she likes the idea better than charging a local university with studying these issues. “I would say it is a roll of the dice, but if you must put the dice in particular hands, the Academy is certainly better than local options,” she says.

Science can’t tell us what to do, whether to hone the axe and ready the glyphosphate or simply spread a picnic blanket under the canopy and relax. But in an ideal world, there would be an agreed-upon set of facts. From there, the differences of opinions would flow from different values, and there’s always hope that opposing values can expand and melt into each other—that compromise and compassion can be achieved. Until then, the magnificent Tasmanian blue gum is in some sense, a prisoner of dueling realities.

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11 thoughts on “The Great Eucalyptus Debate

  1. Another article by a wildfire risk denier. The 1923 Berkeley fire burned 580 homes in two hours, the 1970 burned 75 homes in one hour, and the 1991 Oakland/Berkeley fire burned 790 homes in one hour and 3,800 homes in one afternoon. See website for more information

  2. There is so much to be said about Eucalyptus, but what really decided me was watching them and seeing how they seemed to be the tree of choice for Golden Eagles, Great Horned Owls, Red Shoulder Hawks, and other raptors to nest. There is something about their height and open canopy that makes them particularly safe for the young birds to begin to learn to fly as well providing safety. Then I found out about so many other native animals who use Eucalypts, from hummingbirds drinking their nectar to Monarch butterflies who rest in them.

    Another deciding factor was finding out that our native trees may all be dying of disease and infestation, which the Eucalyptus, Acacias, and other exotic trees are healthy and resistant to the same problems. We’re lucky to have these trees who may end up being the only trees we have left.

  3. Yes, they’re nonnative and grow like weeds, but I have never yet heard anyone who was urging cutting down large areas of eucalyptus offering to reforest the area with an equivalent quantity of native trees – a balanced community of redwood, madrone, oak, buckeye, and so on. Desertification is not an improvement. Until people can afford and are committed to replant with a sufficiency of native trees, I wish they would direct their energies toward eradicating pampas grass and star thistle instead. By the way, eucalyptus provides excellent bat habitat.

  4. Here’s a thought, why not just leave the eucalyptus trees where they are and leave them alone.
    For those on the non-native bandwagon a question is raised as to what is the cut off point in time that defines a species as non-native. The giant blue gums are older than anyone of us and have survived longer than we ever will.
    Oh and by the way, wouldn’t the removal also be the destruction of existing habitat that has developed through the past century and longer?
    Move on folks, quit trying to bring back what didn’t survive. If it was native. wouldn’t it still be here? And if you bring something in that hasn’t been here, isn’t that introducing a non native species?

  5. The sheer audacity of this so-called debate is just too much. How do these pseudo-environmentalists have the nerve to talk about ‘invasive species’ without looking at the catastrophic invasion of the human species, of which the eucalyptus trees are but a proxy for and byproduct of. And as usual, the so-called environmentalists invisibilize the abject terror unleashed by the human species by reframing the threat as one against themselves. The ‘trees’ threaten human communities that have wreaked havoc on bay ecologists? Climate change is a concern not because nearly every aspect of human existence is ecological genicide, but is reframed as a threat to human society? Enough already. Time to take a hard look at Anthropocene and de-center the interests of the real invasive species – one that has destroyed every available oceanic, terrestrial and atmospheric biome on the planet. On the list of species deserving protection, humans are at the very bottom. In the meantime, I suggest a close reading of Eileen Crist’s ‘paper. ‘On the Poverty of Our Nomenclature’.

  6. It looks to me like BayNature is becoming a source for nature gossip and not a source for sound resource and urban environmental sciences. The Marris and St. George articles were filled with opinions and factual errors on matters of significance for people living in the East Bay Hills. In my opinion, eucalyptus and pine forests are problematic in a high-fire risk environment filled with homes on narrow streets. During the first hour of the 1991 Oakland Berkeley fire, 790 homes were burning at a rate of one home ignited every 11 seconds. By the end of the day 25 people died and 3,000 homes were burned in a 1.5 billion dollar fire. Forty mile per hour Diablo winds were blowing embers into flammable grass, brush, eucalyptus and pine trees, and unprepared homes creating a wildfire that could not be controlled until the winds slowed in the late afternoon. Let’s see something in BayNature that is worthy of this dilemma and provides science and environmental based information to its readers.

  7. I always say that the nativists who want to destroy the homes and food of the native animals because the plants they need are not native should first remove their non-native selves.

    Killing trees will not prevent future fires, especially since trees, including Eucalyptus and pine, help prevent fire (because of their substantial inches of fog drip and by creating windbreaks), but leaving us with flammable, barren grasslands will definitely cause fire.

    The 1991 one fire started in grassland, and because the fire department had not adequately put out the fire the first day, when they returned the next day, they kicked the embers up , where the disaster spread to trees and houses. The situation was made worse by the fire hose couplings not fitting the hoses brought by other fire departments.

    Native Bay trees are the most flammable, but no one is killing them.

    This wonderful blog has a lot of information refuting the fire risk claims by those who are likely to benefit from destroying our parks.

    There is no reason to do anything to our trees in our parks. Anyone want to see the effects of the increase in flammable grasses, poison hemlock and thistles after Eucalyptus have been clearcut, I can show you. It’s also easy to see the landslides in the hills where trees have been killed.

  8. This is a subject that I can see both sides. Still I like to walk in the small groves where they still stand. If for no other reason then the smell.

  9. While I agree that there is room for debate either way, I have to say, the number of fires that are in the Oakland/Berkeley hills, and the number of homes that burned with them, have FAR more to do with the fact that the residents refuse to do basic fire control, and that they fight tooth and nail to prevent remaking streets so that fire trucks can actually get UP there. How do I know this? I spent many summers working as a brush hazard remover in those very hills. The trees and brush thoughout the area made a perfect fire ladder in an estimated 75% of the properties up there. Further evidence? Watch the film of the 1991 fire, showing the threatened Claremont Hotel. See the large property just northeast of there that is NOT burning? That refused to burn for hours, while all the resources in the area were dedicated to saving the historic Claremont? Yeah, paid to have real fire control done…. Lots of eucalyptus on that property, too…
    However, Eucalyptus are not native, and they do present hazards to nearby structures. We lost parts of roofs several times when branches would twist off the trees and crash below. When the area freezes, these large, majestic trees die back..and when they come back from the roots, they creat huge brushlands. These trees DO prevent other plants from growing under them in many cases..they exude, as do many Australian/New Zealand area plants, an oil that inhibits seed viability underneath them.

  10. I’ve read a great deal on psychology and am well aware of the existence of cognitive biases. I myself tend to lean a bit towards the side of non-natives. Some non-natives tend to do better in anthropogenic environments or in general (when natives are perrishing), others are just very unique. I value the autonomy of nature foremost and see in non-native species evolutionary potential. That are the reasons I give for liking them. However that does mean I am a bit biased towards the non-native side.

    Not to say they do not bring problems. But be aware that such a thing is still a value-judgement. In my country we have one native crayfish which doesn’t seem to do so well in our rivers due to some pollution (but fine in a Northern part of Europe). Meanwhile, we have several, 3-5 non-native crayfish. In that case, I do honestly prefer those several crayfish doing well, than one doing badly. It is similar with a native harvestman, which is being replaced by a non-native harvestman from the south.

    On the other hand, while I do appreciate the autonomy of nature, monocultures of plants are hard to swallow. As well as the fact that, non-native plants, especially the unique ones I am fond of, usually do not support much insects at all, if any. There are exceptions, the dreaded non-native black cherry (Prunus serotina) now has more insects on it as the native bird cherry (Prunus paddus). I can also understand how people living in unique environments such as Australia or New Zealand loathe most non-natives. But I have to say I’ve yet come accross an invader in Europe that has been as damaging as those in New Zealand or Australia. That is my interpretation of what I know. But I do acknowledge that interpretation is likely biased.

    So I acknowledge that I am biased. But I also honestly think that some non-native species, and I focus on Europe, are unfairly judged. When I read about the northern red oak (Quercus rubra) I must conclude that its introduction is more negative as positive. It supports few insects, cast much shade thus leaving little room for undergrowth, has a tendency for monoculture and so on. The only positive side is that woodpeckers prefer this tree for their cavities. But when I read about raccoon dogs the verdict seems to be towards neutral and only negative in specific cases, the latter which is similar as the native red fox. Yet there is a lot of negative talk about this raccoon dog, even action, when it doesn’t seem to be negative.

    It does seem at times that values get in the way of the facts. And that concerns both sides. Even with facts, you could still argue what to value. I can understand that people value a older state of the landscape and others the new landscape, or a bit of both. Maybe we should just acknowledge our values, first and foremost, instead of hiding behind the facts that support our position. And when it concerns the facts, only looking at the non-native species from a negative perspective is bound to give you negative aspects.

    Concerning the eucalyptus. From the little that I know it seems both eucalyptus and pines are fire sensitive, so if that is indeed the case, I would focus on that.

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