Cal-IPC Eucalyptus Reassessment: Same Result (for Different Reasons)

[Edited to Add: Cal-IPC did change the rating in its final version.]

The California Invasive Plant Council (Cal-IPC) designates eucalyptus as “moderately invasive.” Land managers all over California have used this designation as an excuse to cut down thousands of trees. Recently, people wrote to Cal-IPC citing evidence that eucalyptus forests in California are shrinking, not expanding, and they decided to revisit the assessment. However, their new Draft assessment comes to the same result – “moderately invasive.” Only the reasons are different.

They are taking public comment on this new evaluation until July 31, 2014. If you wish to comment, we provide the details at the end of this article.

mt sutro forest trail 4


Most people think Cal-IPC is a government body. It’s not. It’s a not-for-profit organization with a 501(c) 3 designation. So if it’s just another non-profit, why does it matter?

Here’s why: It’s in the business of designating plants as “invasive” (and by implication, bad.) Its assessments are repeated far and wide by land managers, repeated on the UC Davis website,  and used by government agencies as a standard. (For example: In a 2013 letter from the Fish and Wildlife Service to the CA Department of Transportation, it requires the Department to avoid planting “invasives” as determined by Cal-IPC: fws dot letter mentioning Cal-IPC) It clearly has been given a great deal of weight. Although Cal-IPC doesn’t explicitly ask land managers to eradicate “invasives,” that’s how the list is used.

Unfortunately, since Cal-IPC not a government body, it isn’t subject to the same rules or accountability to the electorate


Cal-IPC assesses plants it considers “invasive” as having a High, Moderate, or Limited rating.  All across California, land managers have used the “moderately invasive” designation as an excuse to fell hundred of thousands of eucalyptus trees.

The profile in Cal-IPC’s database says, “Eucalyptus globulus (Tasmanian blue gum) is a tree (family Myrtaceae) found throughout California, but has primarily escaped to become invasive along the coast from northern to southern California. Native plants are unable to grow underneath groves of eucalyptus. This has been attributed to either the thick litter layer that can develop, or perhaps an allelopathic effect.”

Anti-eucalyptus pamphlet from Cal IPC

Anti-eucalyptus pamphlet from Cal IPC

A pamphlet Cal- IPC distributes  uses Eucalyptus on its cover with the note: Blue gum eucalyptus (Eucalyptus globulus) invades wildlands in the San Francisco Bay Area.” Inside it says:  “Found along the coast from Humboldt to San Diego and in the Central Valley. Most invasive in coastal locations. Easily invades native plant communities, causing declines in native plant and animal populations. Extremely flammable.”

(The pamphlet’s title ‘Don’t Plant a Pest’ is ironic, because blue gum eucalyptus is no longer sold by nurseries, nor is it being planted in California – and hasn’t in years.)

So Cal IPC’s readily available public materials focus on two issues: It spreads into wildlands along the coast, and native plants can’t grow under it. Flammability is mentioned, too.


In response, we’d like to refer back to an article we recently published, Understanding Eucalyptus in the Bay Area – Dr Joe McBride. It’s  based on a talk at the Commonwealth Club by Dr Joe McBride, UC Berkeley Professor Emeritus. (The note was approved by Dr McBride.)

1) Eucalyptus DOES NOT “invade wildlands in the San Francisco Bay Area” In the Bay Area, Dr McBride found eucalyptus forest area declined between 1939 and 1997. The natural spread hasn’t increased the area of eucalyptus groves.

2) Native plants DO grow under eucalyptus. Contrary to popular belief, eucalyptus forests have as many species (or more!) growing in their understory as do oak woodlands. A 1990 survey in Tilden Park found 38 species in the understory of eucalyptus forests (24 native plants; 14 introduced plants), while the oak woodland had 18 species in understory (14 native plants; 5 introduced plants).”


When people asked Cal-IPC to remove blue gum eucalyptus from its list of invasive species – since it wasn’t in fact invasive – Cal IPC did a reassessment. What they’re come up with is the same answer for different reasons. Cal IPC’S designation of “invasive” isn’t just about spreading, it seems:  They look at ecological impact (with 4 subcategories); invasive potential; and distribution.

So what they’ve done is increase the rating under ecological impact (section 1.1) while decreasing the rating under invasive potential (section 2). And reached the same answer as they had before.

Their main argument for the increase in ecological impact rating: “Eucalyptus globulus severely alters fire regimes in grasslands and when growing in mixed stands with native tree species. Changes to groundwater consumption are also significant.”


  • Their assessment of fire danger from eucalyptus repeats all the debunked myths about eucalyptus and fire. In fact, grass fires ignite more easily and move faster; chaparral is even more dangerous. They have used data from a consultant’s report commissioned by people behind the East Bay project seeking FEMA grants to cut down tens of thousands of eucalyptus trees – certainly not an unbiased source. (Also, we have to wonder how this rating changed when the earlier pamphlet also claimed – erroneously – that eucalyptus was “extremely flammable.”)
  • The research regarding groundwater consumption is based on a misreading of the actual research they cite. There’s a good article about this here: Tracking Down the Truth About Blue Gum Eucalyptus, which discusses how drilling down to the cited research completely changes the story.
  • The eucalyptus-tree nest hole of the red-shafted flicker - San Francisco. Janet Kessler

    The eucalyptus-tree nest hole of the red-shafted flicker

    They also have a section on birds, where they repeat the myth that eucalyptus kills birds (though they report there is no supporting evidence). They acknowledge that eucalyptus provides nesting sites for hawks, cormorants, great blue herons, and greater egrets.

  • They also include a myth that Anna’s hummingbirds nesting in eucalyptus have most of their nests blown away. This is not true; in fact, these little birds thrive in eucalyptus (there’s a good article about it here: Birds and Butterflies in the Eucalyptus Forest).
  • They don’t acknowledge that a lot of other birds also use eucalyptus as a food source – either directly, eating nectar, or indirectly by eating insects attracted to flowers or hiding under the bark of the trees.


Public comment is open until July 31st. You can email your letters and comments to Cal-IPC and its Board of Directors, all of whom are in related areas and should be aware of the misconceptions about this valuable tree.

The “invasive” designation is being used as an excuse to cause huge amounts of environmental damage by felling thousands of valuable trees which would otherwise provide habitat, fight global warming by sequestering carbon, stabilize slopes by providing a living geotextile of intergrafted root systems, and fight pollution all year long. Cal IPC has an opportunity to correct a sad error from earlier years.  We hope they’ll take it.

Some points to make:

  • Claims that eucalyptus is highly flammable are exaggerated.  Forests rarely ignite, only in the most extreme weather conditions, which rarely exist in San Francisco.  Most fires in California start in grass and most wildfires are in native chaparral. In fact, eucalyptus reduces fire hazard by providing a windbreak.
  • Eucalyptus is drought-tolerant.  It uses more water early in its life, but less as it matures.  In foggy climates, it fulfills its water needs by condensing fog.
  • Scientific studies have proved that the eucalyptus forest has just as many plants in its understory as native woodlands and equal numbers of animals and insects.
  • Monarch butterflies are using eucalyptus trees for their overwintering roost and do not have the alternative of using native trees in most of the 300+ locations in which they overwinter.
  • Some species of birds prefer to nest in eucalyptus, such as hawks, owls, herons, and cormorants. Cavity-nesting birds such as woodpeckers, flickers, and western bluebirds, all of which have been found nesting in eucalyptus. As the world’s largest flowering plant, it provides a nectar food source for insects and birds in winter.
  • Eucalyptus was planted on grassland in California.  It has not displaced native forests because it does not tolerate shade. Most grasslands in California had already been transformed to non-native grass by the time eucalyptus was planted there.
  • Eucalyptus forests have not expanded in most places in California.  It has been known to spread only when planted next to streams or in very foggy and windy places.

Here are the people to send it to, and their email addresses:

  • Cal-IPC staff: Doug Johnson, Executive Director; Elizabeth Brusati, Senior Scientist; Bertha McKinley, Program Assistant;  Dana Morawitz, Program Mgr /  GIS & Regional Conservation and to the “info” email account. Here are the email addresses:,,,,

  • The Board of Directors office bearers: Jason Casanova, President; Kim Hayes, Vice-President; Shawn Kelly, Treasurer; Jutta Burger, Secretary; John Knapp, Past President. Here are their email addresses:,,,,

Please pick up those points that resonate with you and ask Cal IPC to remove eucalyptus from its list of invasive species.

mt D comparison 1927 -2010



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1 Response to Cal-IPC Eucalyptus Reassessment: Same Result (for Different Reasons)

  1. Pingback: Cal-IPC Eucalyptus Reassessment: Not So Invasive | Save Mount Sutro Forest

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