A love-hate relationship with eucalyptus

Illustration of California state and eucalyptus trees
Olivia Staser/Senior Staff

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“The chilly air smelled of eucalyptus in a way that will always remind me of Berkeley,” wrote geochemist Hope Jahren in her acclaimed memoir “Lab Girl.” Indeed, the pungent, medicinal smell of Tasmanian blue gum, Eucalyptus globulus, has permeated my memories and given both campus and the Bay Area a personality like no other. The mottled, peeling strips of bark, the tapered leaves, the proud trunks standing tall — there is no doubt that the eucalyptus is a magnificent tree. But it is also known as the most hated tree in California. What is it about this Australian tree that is so polarizing, and which side should we take?

Eucalyptus is an invasive species that was introduced to California in response to the 1850’s Gold Rush population boom. Originally conceived as a fast-growing lumber source, eucalyptus wood soon proved to be too brittle and gnarled to work with. Eucalyptus trees have since taken over native vegetation and ecosystems to become one of the most prevalent trees within California’s coastal fog belt, however. Free to expand without the constraint of natural predators such as the koala, eucalyptus both outcompetes native plant species and fundamentally changes its surrounding environment to be unsuitable for said species. This is how Eucalyptus Grove on the west side of campus bordering the Life Sciences Addition has become such a distinctive monoculture. It is now the largest, densest stand of eucalyptus in the world.

The most critical ecosystem impact of eucalyptus is its dangerous flammability. On the scale of one to 10 for ignition potential, eucalyptus scored a one: the highest possible ignition potential. The oily resins it produces cause fires to burn for longer times and at higher intensities. Eucalyptus also accumulates more fuel loads and propagates fires quicker than other native grass and tree species. According to the National Park Service, eucalyptus trees accounted for an estimated 70% of the energy released in the combustion of vegetation in the deadly Oakland firestorm of 1991.

The frightening California wildfires just two years ago — which killed several civilians, burned countless homes (costing government agencies more than $3.5 billion) and rendered air quality dangerous for all — are still fresh in our memory. It is painfully clear why the flammability of eucalyptus is a major concern. Many environmentalists want to see this species removed because it is a potent fire hazard, as well as a non-native invasive tree that destroys habitats and outcompetes native tree species.

But not everyone supports the removal of eucalyptus. Another faction of environmentalists, including the Hills Conservation Network and the Forest Action Brigade, points out that native species may also be flammable, that eucalyptus trees may also provide valuable habitat and that eucalyptus trees sequester carbon and provide shade, beauty and recreation. These advocates are especially opposed to killing off eucalyptus trees because doing so generally requires large amounts of possibly carcinogenic glyphosate herbicides. Dousing the environment with these harmful chemicals could potentially be even worse than simply letting the eucalyptus thrive.

In 2015, this faction of environmentalists successfully stopped a plan to fund the eradication of eucalyptus trees in the Oakland Hills for fire management. Supporters included protesters from The TreeSpirit Project, who stripped naked and hugged trees in UC Berkeley’s Eucalyptus Grove.

This long-standing debate over the removal of eucalyptus is politically charged because it is a difficult issue with science backing up both sides. I wonder, however, why this debate remains so binary. It is clear that both groups have the same goal of a productive wildland-urban interface; the conflict lies in their differing values, which dictate their methods for achieving this vision. We should try to understand both sides in order to develop a more moderate approach.

One possible solution is to seek advice from independent third parties such as the National Academy of Sciences, which isn’t perceived as being tainted by industry ties. The East Bay Regional Park District has also adopted the middle approach to fire prevention by thinning eucalyptus groves from as much as 1,700 to 100 trees per acre to create shaded firebreaks that slow down fires. The downside to this method is that it is extremely expensive in terms of time and money. Some may say this human intervention would essentially reduce the eucalyptus population to a wild zoo that is dependent on constant and costly maintenance. Yet, perhaps this trade-off is worth the alternative removal method of toxic herbicides. Whatever the proposed action, it is always important to realize that the management of eucalyptus must be site- and context-specific, as well as goal-oriented. Government agencies need to take into account both cultural and ecological considerations when developing methods in order to ensure community safety.

It is always easier to categorize the other side as wrong rather than try to find a compromise. But only through increased cooperation can we ensure the health of our ecosystems and the nature that we love so much.

Fionna Lee is an undergraduate studying molecular environmental biology at UC Berkeley.