Pesticides are the primary tool of the “restoration” industry

Over 20 years ago, my initial reaction to native plant “restorations” was horror at the destruction of healthy trees.  It took some years to understand that pesticides are used by most projects to prevent the trees from resprouting and to control the weeds that thrive in the sun when the trees are destroyed.  Herbicides are a specific type of pesticide, just as insecticides and rodenticides are also pesticides.

Because pesticide application notices are not required by California State law for most of the herbicides used by “restoration” projects, the public is unaware of how much herbicide is needed to eradicate non-native vegetation, the first step in every attempt to establish a native plant garden.  California State law does not require pesticide application notices if the manufacturer of the herbicide claims that their product will dry within 24 hours.

Herbicides used to eradicate non-native plants

In 2014, the California Invasive Plant Council conducted a survey of 100 land managers to determine what methods they use to kill the plants they consider “invasive.”  The result of that survey was a wakeup call to those who visit our parks and open spaces.  62% of land managers reported that they frequently use herbicides to control “invasive” plants.  10% said they always used herbicides.  Only 6% said they never use herbicide.  Round Up (glyphosate) is used by virtually all (99%) of the land managers who use herbicides.  Garlon (triclopyr) is used by 74% of those who use herbicide.

Pesticide use by land managers in California. Source California Invasive Plant Council

Land managers in the Bay Area use several other herbicides in addition to Garlon and Round Up.  Products with the active ingredient imazapyr (such as Polaris) are often used, most notably to kill non-native spartina marsh grass.  Locally, the San Francisco Estuary Invasive Spartina Project (ISP) “defines a need for a zero tolerance threshold on invasive Spartina in the San Francisco Bay.” 2,000 acres have been repeatedly sprayed with herbicides on East and West sides of the San Francisco Bay since the project began.  The result of this project has been bare mud where the imazapyr was aerial sprayed from helicopters the first few years of the project with annual spot spraying continuing 15 years later.  Imazapyr is very mobile and persistent in the soil.  That is the probable reason why attempts to replace the non-native species with the native species were unsuccessful. The loss of both native and non-native marsh grass has eliminated the nesting habitat of the endangered Ridgway rail, decimating the small population of this endangered bird in the Bay Area.

Pesticide Application Notice, Heron’s Head, 2012

Aminopyralid (brand name Milestone) is also used.  Although it is considered less toxic than other herbicides, it is the most mobile and persistent in the soil.  New York State banned the sale of Milestone because of concern about contaminating ground water.

With this knowledge of widespread use of herbicides by land managers, we followed up with specific land managers in the Bay Area to determine the scale of local herbicide use.  East Bay Regional Park District significantly reduced their use of Round Up for facilities maintenance in 2018, in response to the public’s concerns after multi-million dollar product liability settlements of lawsuits from users who were deathly ill after using glyphosate products.  In 2019, the Park District announced that it would phase out the use of Round Up in picnic areas, camp grounds, parking lots, and paved trails.

Source: East Bay Regional Park District

At the same time, the Park District restated its commitment to using herbicide to control plants they consider “invasive.”  Unfortunately, the Park District’s use of herbicide for “resource management projects” has skyrocketed and is by far its greatest use of herbicides.  “Resource management project” is the euphemism the Park District uses for its native plant “restorations” that begin by eradicating non-native vegetation such as spartina marsh grass and 65 other plant species.

These trends in pesticides used by East Bay Regional Park District continued in 2019.  Glyphosate use continued to decline by 82% since reduction strategies began in 2016.  Use of Garlon (active ingredient triclopyr) to control resprouts of non-native trees and shrubs increased 23% since 2017.  Use of Polaris (active ingredient imazapyr) to eradicate non-native spartina marsh grass increased 71% since 2017.  “Resource management projects” have been renamed “ecological function.”

San Francisco Recreation and Parks Department (SFRPD) reduced use of herbicide briefly in 2016, after glyphosate was classified as a probable carcinogen.  However, herbicide use has since increased, particularly in the 32 designated “natural areas” where SFRPD is attempting to “restore” native plants by eradicating non-native plants. In 2019, SFRPD applied herbicides 243 times, the most since 2013.  Of these, 144 applications were in the so-called “natural areas” (this includes properties of the Public Utility Commission, San Francisco’s water supplier, managed in the same way; i.e., eradicating plants they don’t like).  Though the “natural areas” are only a quarter of total city park acres in San Francisco, nearly half the herbicides measured by volume of active ingredient were used in those areas.

Data source: San Francisco Recreation and Parks Department. Graphic by San Francisco Forest Alliance

San Francisco’s Parks Department has been using herbicides in these areas for over 20 years.  Plants that are repeatedly sprayed with herbicides eventually develop resistance to the herbicide, just as over use of antibiotics has resulted in many bacteria that are resistant to antibiotics.

Spraying Garlon on Twin Peaks in San Francisco, February 2011

UC Berkeley recently announced a temporary ban on the use of glyphosate on playing fields and similar landscaped areas.  The use of glyphosate to kill non-native plants considered “invasive” was specifically exempted from UC’s temporary ban.

The more pressure the public puts on land managers to restrict the use of herbicides, the more vociferous native plant advocates have become in defense of herbicides.  In October 2017, California Invasive Plant Council published a position statement regarding glyphosate that justified the continued use of glyphosate, despite its classification as a probable human carcinogen by the World Health Organization.

Mounting public pressure to ban the use of glyphosate has also pushed land managers to try newer herbicides as substitutes (e.g., Axxe, Lifeline, Clearcast).  Less is known about these products because less testing has been done on them and we have less experience with them.  It took nearly 40 years to learn how dangerous glyphosate is!

Why are we concerned about herbicides?

The World Health Organization classified glyphosate (the active ingredient in Round Up) as a probable human carcinogen in 2015.  That decision suddenly and radically altered the playing field for the use of glyphosate, which is the most heavily used of all herbicides.

Since that decision was made, many countries have issued outright bans on glyphosate, imposed restrictions on its use or have issued statements of intention to ban or restrict glyphosate-based herbicides. Countless US states and cities have also adopted such restrictions. Locally, the Marin Municipal Water District (MMWD) made a commitment to not using pesticides—including glyphosate—in 2015.  MMWD had stopped using pesticides in 2005 in response to the public’s objections, but engaged in a long process of evaluating the risk of continuing use that resulted in a permanent ban in 2015.

Several jury trials have awarded plaintiffs millions of dollars as compensation for their terminal medical conditions that were successfully attributed to their use of glyphosate products by product liability lawsuits. There are an estimated 125,000 product liability lawsuits in the US against glyphosate awaiting trial. 

In 2020, plaintiffs in a class-action suit against Monsanto alleging that it falsely advertised that the active ingredient in Roundup only affects plants were awarded $39.5 million.  The settlement also requires that the inaccurate claim be removed from the labels of all glyphosate products: “…[plaintiff] says Monsanto falsely claimed through its labeling that glyphosate, the active ingredient in Roundup, targets an enzyme that is only found in plants and would therefore not affect people or pets. According to the suit, that enzyme is in fact found in people and pets and is critical to maintaining the immune system, digestion and brain function.”

It took lawsuits to establish the toxicity of glyphosate because the “studies” that are used to approve the use of pesticides in the US are done by the manufacturers of pesticides.  The studies are manipulated, often with the active participation of government employees who are responsible for regulating dangerous chemicals.  The lawsuits succeeded by revealing the fraudulent studies used to exonerate glyphosate.

What little research is done on the effect of pesticides on wildlife indicates that pesticides are equally toxic to animals.  New research finds that western monarch milkweed habitat contains a “ubiquity of pesticides” that are likely contributing to the decline of the iconic species:  “’We expected to find some pesticides in these plants, but we were rather surprised by the depth and extent of the contamination,’ said Matt Forister, PhD, a butterfly expert, biology professor at the University of Nevada, Reno and co-author of the paper…’From roadsides, from yards, from wildlife refuges, even from plants bought at stores—doesn’t matter from where—it’s all loaded with chemicals. We have previously suggested that pesticides are involved in the decline of low elevation butterflies in California, but the ubiquity and diversity of pesticides we found in these milkweeds was a surprise,’ Dr. Forister said.”

Damage to the environment

In addition to harming humans and other animals, herbicides used by native plant “restorations” are damaging the soil, undoubtedly contributing to the failure to successfully establish native plants. (1)

  • Both glyphosate (Round Up) and triclopyr (Garlon) are known to kill mycorrhizal fungi that live on the roots of plants and trees, facilitating the transfer of moisture and nutrients from the soil to the plants.  The absence of mycorrhizal fungi makes plants more vulnerable to drought because they are less able to obtain the water they need to survive.
  • Glyphosate is known to bind minerals in the soil, making the soil impenetrable to water and plants more vulnerable to drought.
  • Both glyphosate and triclopyr also kill microbes in the soil that contribute to the health of soil by breaking down leaf litter into nutrients that feed plants.
  • Because herbicides are mobile in the soil and the roots of plants and trees are often intertwined, non-target plants are often harmed or killed. 
Pesticides kill the soil food web.

Despite knowing that glyphosate probably causes cancer in humans and that many herbicides cause significant environmental damage, native plant advocates continue to push land managers to use toxic chemicals to kill non-native plants and trees.  They do so because herbicides are the cheapest method of eradicating vegetation.  They do not have the person-power to eradicate all the vegetation that is being killed by herbicides.  Using herbicides enables native plant advocates to claim larger areas of parkland and open space than they would be able to without using herbicides.

(1) Montellano, et.al., “Mind the microbes: below-ground effects of herbicides used for managing invasive plants,” Dispatch, newsletter of California Invasive Plant Council, Winter-Spring 2019-2020.

Conference of the California Invasive Plant Council: Fallacies and Failures

The California Invasive Plant Council held their 27th annual conference in Monterey in November.  It was their biggest conference, with about 400 attendees and more sponsors than ever before.  Clearly the industry that promotes the eradication of non-native plants is alive and well.  However, a closer look at the conference presentations suggests otherwise.  Eradication efforts are growing, but eradication success is not and establishing a native landscape after eradication is proving elusive.

A few common themes emerged from the presentations:

  • Eradication cannot be accomplished without using pesticides.
  • When eradication is achieved with pesticides, non-natives are rarely replaced by native plants.
  • Planting natives after non-natives are eradicated reduces re-invasion, but secondary invasions of different non-native plants are common.
  • “Managing” forests with prescribed burns did not result in more biodiversity than leaving the forest alone.

Goals of these eradication projects have shifted in response to these failures to achieve original goals:

  • Replacement plantings after eradication are sometimes a mix of natives and non-natives.
  • Inability to establish native grassland has given way to different goals.
  • Language used to describe the projects are evolving to be more appealing to potential volunteers.

Here are a few examples of presentations that illustrate these themes:

Eradicating beach grass in Point Reyes National Seashore

About 60% of sand dunes in the Point Reyes National Seashore were covered in European beach grass when the eradication effort began in 2000.  The goal of the project was to restore native dune plants and increase the population of endangered snowy plovers that nest on bare sand.

The project began by manually pulling beach grass from 30 acres of dunes at Abbott’s Lagoon.  The grass grew back within one year, presumably because the roots of the beach grass are about 10 feet long.  Manually pulling the grass from the surface does not destroy the roots.

A new method was devised that was more successful with respect to eradicating the beach grass.  The grass and its roots were plowed up by bulldozers and buried deep in the sand.  The cost of that method was prohibitively expensive at $25,000 to $30,000 per acre and the barren sand caused other problems.

The barren dunes were mobile in the wind.  Sand blew into adjacent ranches and residential areas, causing neighbors of the park to object to the project.  The sand also encroached into areas where there were native plants, burying them.  The bare sand was eventually colonized by “secondary invaders.”  Different non-native plants replaced the beach grass because they were more competitive than the desired native plants.

In 2011, the National Park Services adopted a third strategy for converting beach grass to native dune plants.  They sprayed the beach grass with a mixture of glyphosate and imazapyr.  At $2,500 to $3,000 per acre, this eradication method was significantly cheaper than the mechanical method.

However, it resulted in different problems that prevented the establishment of native dune plants.  The poisoned thatch of dead beach grass was a physical barrier to successful seed germination and establishment of a new landscape.  Where secondary invaders were capable of penetrating the dead thatch, the resulting vegetation does not resemble native dunes.

Presentation at California Invasive Plant Council conference regarding attempt to eradicate European beach grass at Point Reyes National Seashore

The concluding slides of this presentation were stunning.  They said it is a “Restoration fallacy that killing an invader will result in native vegetation.”  My 20 years of watching these futile efforts confirm this reality.  However, I never expected to hear that said by someone actually engaged in this effort.  The presenter mused that such projects are like Sisyphus trying to roll a boulder up hill. 

Presentation at California Invasive Plant Council conference regarding attempt to eradicate European beach grass at Point Reyes National Seashore

Attempting to plant Douglas fir after eradication of broom

Over a period of 5.5 years, broom was eradicated in plots in Oregon by spraying glyphosate.  The plots were then planted with Douglas fir seedlings that soon died.  They were replanted the following year and died in the second year.

There were two theories about why the plantings failed, both broadly described as “legacy” effects in the soil left by the broom.  One theory is that nitrogen levels were too high for successful growth of Douglas fir.  That theory is consistent with the fact that broom is a nitrogen fixer.  That is, broom—like all legumes—have the ability to transfer nitrogen in the atmosphere to nitrogen in the soil with the help of bacteria that facilitate that transfer.  Nitrogen generally benefits plant growth, but there can also be too much nitrogen.

The second theory is that Douglas fir requires a specific suite of mycorrhizal fungi for successful growth.  Mycorrhizal fungi live in roots of plants and trees.  They transfer moisture and nutrients from the soil to the plants.  Plants with a healthy suite of mycorrhizal fungi are more drought tolerant because they extract more moisture from the soil.

Neither of these theories has been successfully proven by this project.  They remain unanswered questions.  We were struck that the researchers had not considered the possibility that the repeated use of glyphosate could have been a factor in the failure of the Douglas fir.  Glyphosate is known to kill bacteria in the soil.  Could it also kill mycorrhizal fungi?  (We know that triclopyr kills mycorrhizal fungi.) That possibility was not considered by this project. Did the project consider that glyphosate also changes the consistency of the soil by binding certain minerals together?  It is more difficult for roots and water to penetrate the hard soil.  Were soil samples taken before and after repeated applications of glyphosate to determine how the soil had been changed by pesticide applications?

The published abstract for this project made this observation:  “It is typically assumed that once an invasive species is successfully removed, the impact of that species on the community is also eliminated.  However, invasive species may change the environment in ways that persist, as legacy effects, long after the species itself is gone.”  In fact, it seems likely that the pesticides used to eradicate the “invasive” species could also be the source of the “legacy effects.”

Does “managing” a forest result in greater biodiversity in the understory?

California State Parks tested that hypothesis by conducting prescribed burns in some of their forests in the Sierra Nevada 20 years ago, while leaving other portions of the forest “unmanaged.”

The abstract for this presentation describes the goals and expectations for the prescribed burns:  “Prescribed fire is a tool used to reduce fuels in the forests in the Sierra Nevada and mimic the low and moderate severity wildfires that burned before the onset of fire suppression.  A manager’s hope is that prescribed fire will create the disturbance necessary to stimulate the development of species rich understory communities and increase species richness, compared to unburned forests, which are often viewed as species depauperate.”

Twenty years after the burns, abundance and species composition of the understory in the burned areas were compared to the unburned areas.  They found little difference in the biodiversity of the understory of burned areas compared to unmanaged forests:

  • “Species richness was highly variable within burned and passively managed areas but was not statistically different.”
  • “Passively managed areas did not appear to be depauperate in understory species diversity compared to areas managed with prescribed fire.”
  • “Fire did not appear to reduce or enhance species richness numbers in burned areas, as compared to passively managed areas.”

No fires occurred in either the burned areas or the unmanaged areas during the 20-year period.  Therefore, this study did not test the theory that prescribed burning reduces fire hazards in forests.  This study found no significant differences in diversity of forest understory resulting from prescribed burns.

There are significant risks associated with prescribed burns.  They cause air pollution and they frequently escape the controlled perimeter of the fire, becoming wildfires that destroy far more than intended.  This study does not provide evidence that would justify taking those risks.  In fact, available evidence supports the “leave-it-alone” approach to land management.

Moving the goal posts

If at first you don’t succeed, you have the option of redefining success.  Here are a few of the projects presented at the conference that seemed to take that approach.

Make projects so small that success can be achieved

Eric Wrubel introduced himself as the National Park Service staff who is responsible for prioritizing invasive plants for removal in the National Parks in the Bay Area (GGNRA, PRNS, Muir Woods, and Pinnacles).  His work is based on the premise that the most successful eradications are those that are small.  The bigger the infestation, the greater the investment of time and resources it takes to eradicate it and the smaller the likelihood of success.  This is illustrated by a graph showing this inverse relationship between the size of the invasive population and the success of eradication.

Source: Rejmanek and Pitcairn, “When is eradication of an exotic pest plant a realistic goal?,” 2002

The process of prioritizing eradication projects began over 10 years ago with a survey of over 100 species of plants considered invasive.  Cal-IPC’s “watch list” was used to identify the plants that are not yet widely spread in California, but considered a potential problem in the future.  Cal-IPC’s risk assessment was the third element in the analysis.  Plants with “High” risk ratings by Cal-IPC were put higher on the priority list than those with “Moderate” or “Limited” ratings.  Plants that did not exist elsewhere in the region or watershed were also given higher priority, based on the assumption that re-invasion was less likely.

This is the list of eradication projects in the National Parks in the Bay Area that was presented at the conference of the California Invasive Plant Council. The projects marked with the red symbol for crossing out are completed projects. Nearly half of the plants on this hit list are not considered invasive in California.

The priority list showed that the highest priority eradication projects were quite small.  Some were just a few acres.  Buddleia jumped out as the 7th highest priority on only 13 acres.  Buddleia was recently added to a new category of plants on Cal-IPC’s “invasive” inventory.  It is not considered invasive in California, although it is considered invasive elsewhere.

In placing buddleia on its “hit list,” Cal-IPC illustrates one of the fundamental weaknesses of its evaluation method.  Cal-IPC does not evaluate pros and cons of non-native plants.  Only traits considered negative are taken into consideration.

Monarch sanctuary in Monterey, California. November 2018

Buddleia is one of the most useful nectar plants for pollinators in California.  We took the time to visit the monarch butterfly sanctuary in Monterey while attending the conference.  The monarchs are arriving now to begin their winter roost in the eucalyptus, Monterey pine and cypress in this small grove.  At the entrance to the sanctuary a sign instructs visitors to plant only native milkweed as the monarch’s host plant and only native flowers for nectar.  Fortunately whoever planted the flowering shrubs in the sanctuary didn’t follow the advice of the sign-makers.  They planted buddleia and other flowering non-natives such as bottle-brush.  Several species of butterflies and hummingbirds were enjoying those plants in the Sanctuary. Strict adherence to the native plant agenda is not beneficial to wildlife because animals do not share our prejudices.

Monarch nectaring on butterfly bush. butterflybush.com

Acknowledging the difficulties of converting non-native annual grass to native perennial grass

Pinnacles National Park acquired 2000 acres of former ranchland in 2006.  The park wanted to convert the non-native annual grasses and yellow-star thistle on the former ranch to perennial bunch grasses and oak woodland.  They were able to reduce the amount of yellow-star thistle by burning and spraying with herbicide, but cover of native species remained low.  Conversion of grasses from non-native annuals to native perennial grass has been tried many times, in many places, and for long periods of time.  These projects were notoriously unsuccessful.

The project at Pinnacles has changed its goal to plant forbs (herbaceous flower plants) instead of grasses and they report that they are having some success.   They justify that shift in goal on soil analysis that suggests forbs were more prevalent than perennial grasses in inland valleys in California than previously thought.

This change in goal could be described as “adaptive management,” which adjusts methods and goals in response to observable outcomes of existing methods.  You could also call it “trial and error.”  We would like to see more land managers make such adjustments to their strategies, rather than doing the same thing over and over again and expecting a different outcome.

Recruiting volunteers with appealing messages

There were several presentations about effective methods of recruiting volunteers to participate in restoration projects.  Some of their messages seem to acknowledge that the language used in the past may have alienated some potential volunteers.  Speaking from personal experience, I can confirm that observation.  Here are just a few of the cringe-worthy native plant mottos that I hope have been abandoned in favor of a more positive message:

  • “That plant doesn’t belong here.”
  • “That is a good plant and the other is a bad plant.”
  • “The invasive landscape is sick and requires chemotherapy.” (to justify the use of pesticides)
  • “That’s a trash bird.” (said of common, introduced birds, such as starlings and house sparrows)

The speaker advised those who work with volunteers to focus on why an unwanted plant is a problem rather than where it comes from.  Unfortunately, the list of problems is heavily influenced by the preferences of native plant advocates.  If their criticisms are not accurate, or they don’t acknowledge the advantages of the plant, little has been achieved by using euphemisms.  Here are a few of the inaccurate criticisms made of eucalyptus:

What was missing?

Ecological restoration is a major industry. Thousands of people are employed by the industry, which is funded by many different sources of public money.  Whether individual projects are successful or not, the industry will survive and thrive as long as it is funded.  Greater care should be taken to design and implement projects that will be successful.

Stepping back from the conference presentations of specific restoration projects, here are a few issues that were conspicuously absent from the conference. 

  • Pesticides are being widely used by the restoration industry. When projects don’t achieve desired outcomes, pesticides should be considered as a factor.  Did pesticides alter the soil?  Were beneficial microbes and fungi killed? How persistent was the pesticide in the soil?  How mobile was the pesticide in the soil?  Was pesticide applied in the right manner?  Could aerial drift account for death of non-target plants?  There are many other useful questions that could be asked.

Update:  The California Invasive Plant Council has published “Land Manager’s Guide to Developing an Invasive Plant Management Plan.”  It says very little about the disadvantages of using herbicides to eradicate plants they consider “invasive” other than a vague reference to “unintended consequences,” without discussion of what they are or how to avoid them. 

However, it does give us another clue about why eradication efforts are often unsuccessful. When herbicides are used repeatedly, as they have been in the past 20 years, weeds develop resistance to them:   “The International Survey of Herbicide Resistant Weeds (2018) reports there are currently 496 unique cases (species x site of action) of herbicide-resistant weeds globally, with 255 species…Further, weeds have evolved resistance to 23 of the 26 known herbicide sites of action and to 163 different herbicides.”  The Guide therefore recommends that land managers rotate herbicides so that the “invasive” plants do not develop resistance to any particular herbicide.  The Guide gives only generic advice to use “herbicide X” initially and “herbicide Y or Z” for subsequent applications.

In other words, the California Invasive Plant Council continues to promote the use of herbicides to kill plants they consider “invasive.”  They give advice about ensuring the effectiveness of herbicides, but they do not give advice about how to avoid damaging the soil, killing insects, and harming the health of the public and the workers who apply the herbicides.  May 20, 2019

  • Are workers who apply pesticides being adequately trained and supervised by certified applicators? The safety of workers should be one of many goals of restoration projects.
  • When non-native plants are eradicated, serious thought should be given in advance to the probable outcome. Will native plants return?  Will wildlife be harmed?  Will the risks of failure outweigh the potential benefits of success?
  • Is climate change taken into consideration when planning the replacement landscape? Are the plants that grew in the project location 200 years ago still adapted to that location?  Is there enough available water?
  • If new plantings require irrigation to be established, what is the water source? Is it recycled water with high salt content that will kill many plants, including redwoods?
  • Are the new plantings vulnerable to new infectious diseases, such as phytopthera or infestations of new insects such as shot-hole borer?
  • Does the project team have sufficient horticultural knowledge to choose plants that can survive in current conditions? Does the project team know the horticultural needs of the plants they are planting?  Is there enough sunlight, water and wind protection for the trees they are planting?

The public is investing heavily in the “restoration” of ecosystems.  We can only hope that our investment is being used wisely and that projects will not do more harm than good.  Cal-IPC can play a role in raising the questions that have the potential to improve projects and enable them to succeed.  The long-term survival of the “restoration” industry depends on it.


Most quotes are from abstracts of presentations published in the conference program.

Digging In: Nativists aggressively defend their use of herbicides

The trial of DeWayne Johnson vs. Monsanto began early in July.  This is the first trial of about 4,000 lawsuits against Monsanto for “product liability.”  Mr. Johnson is dying of non-Hodgkin lymphoma.  He believes that the glyphosate that he sprayed as an employee of the Benicia School District from 2012 to 2015 has caused his terminal cancer.  His lawyer will present evidence at the trial that Monsanto knew the health risks of the glyphosate they manufactured and hid that information from the public. 

This trial could be the turning point that will determine the future of glyphosate in America.  Therefore, this is a suitable opportunity to explain how we got here and why the fate of glyphosate may also determine the fate of the native plant movement.


Update August 10, 2018:  BREAKING NEWS!!!

”A San Francisco jury has found in favor of a school groundskeeper dying of cancer whose lawyers argued that a weed killer made by the agribusiness giant Monsanto likely caused his disease.

“Dewayne Johnson was awarded nearly $290 million in punitive damages and another $39 million in compensatory damages.

“Johnson’s lawsuit against Monsanto was the first case to go to trial in a string of legal complaints alleging the glyphosate-based Roundup herbicide caused non-Hodgkin’s lymphoma.

“He sprayed Roundup and another Monsanto product, Ranger Pro, as part of his job as a pest control manager at a San Francisco Bay Area school district, his attorneys have said.

“He was diagnosed with lymphoma in 2014, when he was 42.

“Monsanto, for its part, vehemently denies a link between Roundup and cancer.

“But jurors at San Francisco’s Superior Court of California, who deliberated for three days, found that the corporation failed to warn Johnson and other consumers about the risks posed by its weed-killing products.

“The outcome of the trial will not have a direct affect on the slew of other Roundup-related suits in state and federal courts. But it could serve as a bellwether for other cases in the queue.”  https://www.nbcnews.com/news/us-news/jury-orders-monsanto-pay-290m-roundup-trial-n899811

This could be the beginning of the end for glyphosate.  There will be many appeals of this decision, but there are also many other lawsuits in line by people who believe they were harmed by glyphosate.  This is a significant step forward.


The story begins

I have followed the native plant movement in California for over 20 years.  I knew that herbicides were used by land managers to eradicate plants they consider “invasive” only because I made the effort to inform myself of what they were doing.  It wasn’t easy to figure out that they were using herbicides because many land managers do not post notices of their pesticide applications and even fewer report their pesticide use to the public.  State law does not require posting of pesticide application notices if the manufacturer claims that the product dries within 24 hours, which exempts most of the herbicides used by land managers, including glyphosate (Roundup) and triclopyr (Garlon).

Pesticide use by land managers in California. Source California Invasive Plant Council

I didn’t know how extensive herbicide use is on our public lands until the California Invasive Plant Council conducted a survey in 2014 of 100 land managers about the methods they were using to kill “invasive” plants. Here’s what we learned from that survey:

  • Ninety-four percent of land managers are using herbicides to control plants they consider “invasive.”  Sixty-two percent are using herbicides frequently.
  • Ninety-nine percent of the land managers who use herbicides, use glyphosate products. Seventy-four percent use Garlon, which is one of the most hazardous herbicides available on the market.  The Pesticide Research Institute says that Garlon “poses reproductive and developmental risks to female applicators.”
  • Foliar spray is the method used most frequently by land managers to apply herbicides.  This method of application has the potential to drift into non-target areas and kill non-target plants.

Chapter Two:  World Health Organization takes a position

In 2015, one year after the Cal-IPC survey was done, the World Health Organization’s International Agency for Research on Cancer (IARC) classified glyphosate as a “probable human carcinogen.”  That decision suddenly and radically altered the playing field for the use of glyphosate, which is the most heavily used of all herbicides.

Since that decision was made, 25 countries have issued outright bans on glyphosate, imposed restrictions or have issued statements of intention to ban or restrict glyphosate-based herbicides, including Roundup.  Countless US states and cities have also adopted such restrictions. Locally, the Marin Municipal Water District made a commitment to not using pesticides—including glyphosate—in 2015.  MMWD had stopped using pesticides in 2005 in response to the public’s objections, but engaged in a long process of evaluating the risk of continuing use that resulted in a permanent ban in 2015.

Chapter Three:  Nativists dig in

The reaction of native plant advocates to this bad news of the dangers of glyphosate has been to dig in and aggressively defend their use of herbicides.

One of the first indications of this reaction was an article about the IARC decision in the Fall 2015 newsletter of the California Invasive Plant Council (Cal-IPC) that concludes:  “In the final analysis, this means that there’s no good reason to stop using glyphosate whether it’s a carcinogen or not.”  If the IARC decision isn’t a good reason, what is?  If the prospect of cancer isn’t a legitimate reason not to use glyphosate, what is?

In its Fall 2016 newsletter, Cal-IPC stepped up the volume.  The Executive Director’s introductory letter stated the highest priorities for Cal-IPC, including, “the increased need for Cal-IPC to publicly support the appropriate use of herbicides.”

That edition of the Cal-IPC newsletter also includes a review of Tao Orion’s book, Beyond the War on Invasive SpeciesTao Orion is a practicing permaculturalist who shares many of the objectives of native plant advocates. Permaculture is committed to conservation, preservation, and restoration, but practitioners achieve those objectives without using pesticides.  They focus on restoring ecological functions by identifying and correcting the underlying causes of change, such as loss of water resources.

Given Cal-IPC’s commitment to herbicide use, it was unable to find value in Orion’s book.  Much of their criticism seemed unfair.  They said that Orion’s recommendations for using restoration methods such as burning or grazing that don’t require the use of pesticides are preaching to the choir.  They claim that native plant restoration projects are, in fact, doing the same thing.  Yet, the survey Cal-IPC conducted in 2014 says otherwise.  Forty-seven percent of land managers said they “never” use grazing to control “invasive” plants, compared to 94% who said they use pesticides.  Burning was not mentioned by any land manager as a method they use.

The survey and accompanying risk assessment of the herbicides used by those who took the survey was presented at the annual Cal-IPC conference in fall 2014.  It was available on the Cal-IPC website until very recently, when it was scrubbed.  The risk assessment is still available on the website of the Pesticide Research Institute, which conducted that evaluation.

In October 2017, Cal-IPC published a position statement regarding glyphosate, “The Use of Glyphosate for Invasive Plant Management.”  Cal-IPC’s “position on the issue” is:  “Cal-IPC supports the use of glyphosate in invasive plant management as part of an Integrated Pest Management (IPM) approach. When using glyphosate according to the label, with appropriate personal protective equipment and best practices, glyphosate is low-risk for wildlife, applicators and the public.”  Their position is primarily based on their belief that doses of glyphosate used in wildland weed management are too low to be a health hazard.

Several new studies, published after the IARC decision, strengthen the case against glyphosate.  New research suggests that glyphosate is a health hazard at low doses considered “safe” by the EPA.  The Global Glyphosate Study is being conducted by six scientific institutions all over the world. This international consortium of scientific institutions recently published preliminary results of their study: “The results of the short-term pilot study showed that glyphosate-based herbicides (GBHs) were able to alter certain important biological parameters in rats, mainly relating to sexual development, genotoxicity and the alteration of the intestinal microbiome, at the ‘safe’ level of 1.75 mg/kg/day set by the U.S. Environmental Protection Agency (EPA).”  In other words, at doses deemed safe by the US EPA, significant negative health effects were found in animals used in testing.

Another recent study of glyphosate found that the formulated product is considerably more toxic than the active ingredient alone.  US National Toxicology Program recently conducted tests on formulated glyphosate products for the first time. In the past, tests were conducted only on the active ingredient…that is glyphosate alone. The formulated products that are actually applied as weed killers contain many other chemicals, some of which are not even known. The head of the National Toxicology Program Laboratory, told The Guardian newspaper the agency’s work is ongoing but its early findings are clear on one key point. “We see the formulations are much more toxic. The formulations were killing the cells. The glyphosate really didn’t do it,” DeVito said. A summary of the NTP analysis said that “glyphosate formulations decreased human cell ‘viability’, disrupting cell membranes. Cell viability was ‘significantly altered’ by the formulations, it stated.”

Two empirical studies found that low levels of exposure to the weed killer Roundup (glyphosate) over a long period of time can cause liver disease.

Is Cal-IPC aware of these recent studies?  Are the people who apply glyphosate aware of these studies?  Are the employers of these applicators aware of these studies?  Are these applicators the plaintiffs of future product liability lawsuits against Monsanto?

Chapter Four:  California Native Plant Society defends herbicides with fantasies

If you read the publications of the California Native Plant Society (CNPS) or attend their conferences, you know that little mention is made of herbicides by their followers and those who engage in “restoration” projects.  In the past, the best defense was to turn a blind eye to herbicide use.

More recently, the intense opposition to the use of herbicides on public lands seems to have forced CNPS to become actively engaged in the defense of herbicides.  The most recent edition of the Journal of the California Native Plant Society, Fremontia (Vol. 46 No. 1) is a “Special Issue on Urban Wildlands.” The introductory article is illustrated with a photo of Oyster Bay.  I nearly choked on this statement in that article:  “In order to control invasive plants, agencies and volunteers have sometimes resorted to using herbicides as a step in integrated pest control.  While use of herbicides is contentious, the use for spot treatments has enabled small groups of volunteers to successfully eliminate invasive weeds in some areas where future herbicide use will not be needed.” Oyster Bay is being doused with herbicides as we reported in a recent article that is available HERE.

Oyster Bay herbicide applications, May 2018

That same edition of Fremontia also includes several articles in which specific native plant “restorations” are described in detail.  All of the projects use herbicides, often repeatedly and often without successfully establishing native plants:

  • “Bull Creek Ecosystem Restoration Project: Not Quite a Success Story”:  This project began in 2008, after over 10 years of planning.  Bull Creek was reconfigured with bull dozers, eliminating the existing landscape.  Although natives were planted, weeds quickly took over the site.  It was weeded by hand initially and considered a success until the creek bank eroded significantly and the artificial oxbow filled with silt.  But “weeds continued to thrive” because the native plants were irrigated and they resorted to herbicide applications in 2010.  Subsequent failures of native plants were blamed on unauthorized public access and the state-wide drought.  Volunteer weeding has been abandoned.  The future of this project is very much in doubt.
  • “Weed Control Efforts in the Sepulveda Basin”: “Based on more than 20 years of experience with attempting to control various weeds in the Sepulveda Basin, and given the lack of support from the city due to budgetary priorities, it is apparent that without herbicide it will be impossible to control non-native weeds that threaten regional biodiversity.”
  • “Nature in the City: Restored Native Habitat Along the LA River…”:  The site was sprayed with Roundup (glyphosate) several times to remove as much of the non-native seed bank as possible.  Weeding continued throughout the habitat restoration and construction period.”

Did CNPS notice the contradiction between their first article and subsequent articles in the same publication?  Their introductory article claims they rarely use herbicides and when they do it is only temporary.  But subsequent articles about specific projects make it clear that herbicides are routinely and repeatedly used and even then, weeds persist.

Pesticides used in San Francisco’s “natural areas.” Courtesy San Francisco Forest Alliance

In the Bay Area, one of the oldest native plant “restorations” is in San Francisco, where the so-called Natural Areas Program (now called Natural Resources Division) started in 1998.  They have used pesticides consistently since the program began.  The San Francisco Forest Alliance began tracking their use of pesticides in 2008.  In their most recent report, the Forest Alliance informs us that pesticide use in the so-called “natural areas” has increased significantly in the first half of 2018.  This increase was anticipated because the program plan and its Environmental Impact Report were finally approved in spring 2017, after 20 years of being hotly contested.  The approval of the program enabled them to increase the staff of pesticide applicators from one to five.  Most of the increase in pesticide use in 2018 is of Garlon, one of the most toxic pesticides available on the market.  San Francisco’s native plant restorations are a specific example of the long term use of large quantities of herbicide.  You can visit those areas to see for yourself that 20 years of effort and herbicides have not successfully established native plant gardens.

Good luck to DeWayne Johnson

It is difficult to understand how nativists can continue to advocate for the use of herbicides.  It is even more difficult to understand how land managers can continue to use public money to spray herbicides on our public parks and open spaces.  Since they are apparently impervious to scientific assessment of the health hazards of herbicides and blind to the failures of their projects, we can only hope that DeWayne Johnson will prevail in his lawsuit against Monsanto.  We would like to see justice for Mr. Johnson and his family and the bonus will be the legal liabilities and associated economic costs of continuing to use a dangerous herbicide that damages the environment and everyone who lives in it.

Tamarisk beetle: A case study in the dangers of biological controls to eradicate non-native species

Our readers were introduced to Matt Chew in his guest post about the economic interests of ecological “restorations.”  Dr. Chew is a faculty member of Arizona State University’s Center for Biology and Society and an instructor in the ASU School of Life Sciences. 

The most recent newsletter (see page 8) of the California Invasive Plant Council (Cal-IPC) informed us that the beetle that was introduced in Arizona to eradicate tamarisk has spread to California, where it was not introduced.  When the beetle was originally introduced, its spread beyond where it was introduced was not predicted, based on climatic restrictions on its life cycle.  As usual, evolution overturns the best laid plans.  According to Cal-IPC, Rapid evolution in this developmental trait, however, allowed beetles to stay active later in the season and thus facilitated their expansion southward…”   

Tamarisk defoliated by tamarisk leaf beetle along Colorado River, near Needles, California

The rapid defoliation of tamarisk throughout the southwest, including California, is an immediate threat to the endangered Southwestern willow flycatcher, which long ago adapted to tamarisk in the absence of its native host, willow.  The native willow requires a great deal more water than tamarisk. Therefore, willow died off when water throughout the southwest was diverted out of riparian corridors for human consumption and agricultural production.

Dr. Chew is an expert on tamarisk and the role it plays in the ecosystems of the southwest and so we asked him to write another guest post for us on this topic.  He has generously obliged with this detailed history of biocontrols and their use to eradicate non-native species. 

Biocontrols are also topical because a new biocontrol was recently approved by the USDA to eradicate cape ivy.  This biocontrol was eagerly anticipated by native plant advocates and is likely to be widely used by land managers in California.  Therefore, this is a timely opportunity to learn about the pros and cons of biocontrols.  How long will it take the introduced insect to start feeding on the many other species of ivy that are not considered “invasive?”

Evolution and natural selection are wild cards in attempts to eradicate non-native plants and animals.  Although there are many dangerous consequences of using pesticides, the role that evolution plays in rendering pesticides useless is less understood and taken into consideration.  Much like the hungry beetle that now is running rampant in the southwest, the weeds that are continuously sprayed with herbicide are also adapting and evolving defenses against the chemicals being used to eradicate them.  There are now millions of acres of agricultural crop land infested by weeds that are immune to the pesticides that were sprayed on them for decades.  Our pesticides are now useless on these “superweeds.” Instead of getting off the pesticide treadmill, we are developing stronger—and therefore more toxic—herbicides.

There are many reasons why we object to the eradication of non-native plants and animals.  The tamarisk beetle is an example that illustrates a few of our objections:

  • Many of the plants being eradicated are providing food and habitat for animals. The animals that depend upon them are being harmed by their elimination.
  • The methods used to eradicate non-native species often have unintended, negative consequences, such as breeding “superweeds” that cannot be eradicated.
  • The puny tools of humans are often powerless against the much stronger forces of nature, such as natural selection and evolution. These forces of nature should be treated with greater respect, particularly by people who call themselves “scientists.”

Million Trees


Southwestern willow flycatcher

From California to Texas and occasionally beyond, tamarisks are among the most talked-about introduced plants in the US. Most of that discussion consists of familiar anti-alien dogma, augmented by the long-obsolete assertion that tamarisks are profligate water-guzzlers. Suffice for now to say that anti-tamarisk sentiment led to state and federal suppression policies beginning around 1940, and eventually to legislation at both levels. Little more than accumulated bad reputation of tamarisk and its presence in the region of interest led the US Fish and Wildlife Service to include tamarisks among the supposed threats to the persistence of the Southwestern Willow Flycatcher (Empidonax traillii extimus) when that subspecies was formally listed “endangered” in 1993. All of that meant both political will and appropriations were applied to the US Department of Agriculture’s search for biological control agents to deploy as “counter-pests” against tamarisks. By 1998 they had their critter, an Asian leaf-eating beetle that putatively specialized on tamarisks and would rather die than eat anything else.

By that time, though, circumspection had set in, because especially in southern Arizona the endangered birds had taken to nesting in tamarisk stands. USDA promised USFWS that their armored foreign legion would not jeopardize flycatcher populations. USDA argued that the beetles they were about to propagate and release by the multi-millions were genetically incapable of surviving below 38° North latitude. In addition to famously dividing North from South Korea, that frontier runs from near the tip of Point Reyes through Stockton and Mono Lake; just south of Tonopah, Nevada; south of Canyonlands Nation Park; through Moffat and Swink, Colorado; on through the Garden City Kansas and increasingly irrelevant points east. Southern Arizona would surely never see a tamarisk leaf beetle. “Because SCIENCE!” Hold that thought.

In 1952 the otherwise obscure and perhaps pseudonymous writer Rose Bonne copyrighted a succinct cautionary account of biological pest control. Perhaps it was read or sung or shown to you as a child: I know an Old Lady [who swallowed a fly].  Ms. Bonne denied knowing how or why the old lady swallowed the fly, but considered it portentous: “Perhaps she’ll die!” Subsequent actions had definite (if sometimes puzzling) rationales. The next four animals consumed represented a hopeful trophic cascade: the Old Lady swallowed a spider to catch the fly, then a bird to catch the spider, a cat to catch the bird and a dog to catch the cat. At that point, distended and incoherent, she panicked, swallowing a goat to catch the dog, a cow to catch the goat, then finally, fatally, a horse. (Revisionists inserted a pig between the goat and the cow. If you doubt me, Google it.)

The history of biocontrols

We can barely pause to consider the long and checkered history of biological control. Its inception required a few conditions, which may have arisen in different orders in different places.  A sense of ownership, territorial claims or resource collection rights seems necessary, as does dissatisfaction with the dictates of fate. Why attempt to affect an outcome without expecting to benefit from the effort? A bit of empirical, practical natural history knowledge is also indispensable. Together they add up to the possibility of acting on the basis that “the enemy of my enemy is my friend,” to garner a greater share of whatever natural product seems desirable. Dogs to guard flocks and cats to discourage rodents are biological controls. The more organized and concentrated agriculture became, the greater the need for knowledge of “natural enemies” to enlist as economic allies. Even after revolutions in industrial chemistry offered alternatives, better living was still sometimes available through biology.

With private property rights come boundary disputes, complaints about trespass and spillover effects of management decisions. Public property, especially where subject to intensive multiple use mandates, adds complexity and diversity (if not novelty) to the mix. Rights collide with powers and authorities. Politically compromised jurisdictions—like U.S. state authority over wildlife except where superseded by federal laws and treaties or licensed to private parties—are endless fodder for litigation and finger pointing. All the while, science reconstructs what is known or considered knowable, changing expectations, affecting policies and destabilizing political balances.

Modern civilizations depend upon the plants they have introduced

Modern agricultural, horticultural and forestry practices are all legacies of the Renaissance, Reformation and Enlightenment motivations underpinning European colonialism. Empires were assembled and contested primarily for their economic advantages. During the past half-millennium they generated new wealth and new social classes that developed new governments. Among the array of actions those governments continue to undertake is facilitating the redistribution of valuable plants and animals. A visit to any retail food market reveals our near-total embrace of that redistribution. Almost every staple ingredient in every foodstuff is raised or grown far from its “wild” point of origin. Even insistent locavores prefer locally raised food, not locally evolved food. A negligible fraction of us recognize never-transported, never-domesticated edible organisms. Fewer still could survive on them as hunter-gatherers. Such are among the generally intended, hoped-for, positive outcomes of imperial colonialism. Famine is unnecessary, though it is a political tool, deployable as a weapon.

Fish, meat and leather, plant and animal fibers, timber, pulp and derived products can still be wild harvested, but are mostly and increasingly farmed. Anything worth gathering is worth cultivating, from redwood trees to bison to sugarcane to minks to soybeans to insects, yeasts, and bacteria. Even aspirational exceptions like native plant gardening are actually impossible to accomplish: seed intentionally transported from one location to another has been biogeographically rerouted; plants sold by native plant nurseries are raised in multi-source, formulated soils in plastic pots. Even simply deciding to leave a plant where it was found can render it an artifact, and there may no longer be any wilderness so remote that the configuration of its biota remains uninfluenced by human agency.

Benefits of introduced species often outweigh harm

We are told that some of the consequences of all this redistributed and reconfigured biota are marginally negligible. Others are cutting into the profits. Some organisms are moved around unintentionally and unknowingly (zebra mussels, various “blight” fungi) often because unaware transportation technology designers and operators never prevented their distribution. Many intentionally abducted and marooned populations are behaving in unexpected ways, thriving without always accomplishing their intended purposes (alligator apples and cane toads in Australia; house sparrows and wild carrots in North America) or even significantly over-achieving (“Asian” carps and kudzu in North America; rhododendrons and grey squirrels in Britain). Even where post-colonial inclinations to recover and reinstate pre-colonial values are tolerated, they hardly withstand translation into economic choices.  We are adeptly, fundamentally invested in moving things around. We are likewise invested in competition, and building coalitions and alliances to help us win competitions. Especially competitions we thoughtlessly or accidentally set in motion.

Tamarisk on the Colorado River

The Old Lady who swallowed the fly would probably have been fine had she not overthought the problem. The fly was doubtless well on its way to being digested by the time she found a spider, which was likewise moribund before a bird came to hand. Maybe should could have swallowed a willow flycatcher (already protected by the Migratory Bird Treaty Act) and skipped the spider? Had the US Army Corps of Engineers, the USDA and others not overthought the problem in the late 19th and early 20th centuries, they might have come up with suitable alternatives to planting tamarisks to stabilize Texas barrier islands, deepening Four Corners arroyos and fly-away Dust Bowl topsoils. Yes, tamarisks, too, were brought to us to biologically control problems of our own making and conception. Then we needed a beetle…

As things turned out, USDA scientists were either mistaken or disingenuous regarding the latitudinal limits of their tamarisk leaf beetles. Likewise, even about the identity of the beetles, which is why I haven’t inflicted their Latin epithets on you yet. By 2010, sniping between USFWS and USDA, abetted by various conflicting conservation NGOs, led to a new “Biological Assessment” for the federally imposed tamarisk leaf beetle invasion. (I usually avoid using “invasion” in such circumstances, because invading exceeds many capacities of so-called “invasive species.” This was a real invasion, though, planned and carried out by people, not beetles. Beetles merely bred and spread.) One species of beetle became five, four which had been introduced: Diorhabda carinulata; D. elongata; D. sublineata; and D. carinata. Some were quite well-adapted to life in southern Arizona (31-32° N) and beyond. Furthermore, the endangered birds were also nesting in tamarisks in southern Utah, c. 37° N. USDA washed its hands of the federal program and revoked federal permits to release beetles; but that had no effect on the State of Colorado, which was heavily invested in producing them and continues to do so.

Distribution of tamarisk leaf beetle. Tamarisk Coalition

Tamarisk leaf beetle

Fast-forward to 2017. Tamarisk leaf beetles have been spreading along Arizona waterways at rates up to ten times faster than their most ardent cheerleaders imagined they could, and from multiple directions. They will arrive in almost every known Southwestern Willow Flycatcher nesting area sometime this year. By next spring those riparian thickets will be defoliated just at the point when the nestlings most require thermal cover (i.e., shade). Thanks to Reclamation-Era water diversion projects, attempts to re-vegetate those areas with willows will require constant gardening. Reclamation replaced willow habitat with tamarisk habitat. Nevertheless, the birds persisted. Beetle releases suppressed the tamarisks, but will almost certainly fail to eliminate them entirely. Beetles are just another evolutionary pressure on a tamarisk population that is already unlike any other in the world due to unforeseen hybridizing among several species. New tamarisks and new beetles are evolving. Maybe the beetles will try a bite of something else. They’re in California now; could they find something there? Maybe the birds will evolve to eat the beetles, although that hasn’t happened yet. Perhaps the day will come when the Southwestern Willow Flycatcher gives way to the Tamarisk Beetlebird. It might not even take very long. But don’t bet on it. And don’t bet on biologists, bureaucrats or any other ambitious adults to re-learn the lesson of unintended consequences they laughed at as children, then (like so many other lessons) forgot.

Matt Chew

Embers start spot fires: The real and the imagined stories

Bay Nature recently published an article about the 1991 fire in the East Bay Hills and the closely related belief that such a fire can be prevented in the future by destroying all non-native trees.  To Bay Nature’s credit, it was a more balanced article than most.  Although the article was heavily weighted in favor of those who want to destroy all non-native trees in the hills, several defenders of our urban forest were also interviewed.

However, the article contains a fantasy about future fires that feeds into the fear of fire that has been fostered by those who advocate for removing all non-native trees:

“A strong wind begins blowing over the hills from the east. And then somehow—maybe a spark from a car, maybe a tossed cigarette—the whole dry, airy mess catches fire.  Now the flames on the ground are 30 feet high and even higher off the boughs, roaring like a jet engine. At the fire’s edges, trees appear to explode as the volatile oils in their leaves reach their boiling point and vaporize. The heat of the fire forms a convection column, with 60-mile-per-hour winds that rip burning strips of bark from the trees and toss them upward. This is another of blue gums’ talents—its bark makes ideal braziers. Tucked away inside a rolled-up strip of bark, a fire might live for close to an hour and fly 20 miles.” (1)

Although we have read many times in the plans to destroy trees that eucalyptus casts embers starting spot fires, we have never seen such an extreme description of how far embers could travel while still on fire and capable of starting a spot fire.  So, we tracked down the source of this theoretical scenario with the help of the author who cited this as the source of the theoretical scenario:  “The potential for an internally convoluted cylinder of bark to be transported tens of kilometres in a continuously flaming state is indicated by the sample that maintained flaming combustion for the entire experiment…This would correspond to a flameout time of almost 2000 s for a sample 2700 mm long, a lofted height of 9600 m and a spotting distance of ~37 km.” (2)

First let’s translate that quote into measurements we commonly use to appreciate how extreme this particular test was:  “This would correspond to a flameout time of almost 33 minutes for a sample 9 feet long, a lofted height of 6 miles and a spotting distance of 23 miles, traveling at 41 miles per hour.”  That is a very long ember, lofted a great distance at a great speed (but NOT 60 mph), staying lit for a long time (but NOT “close to an hour”).  

Theory vs. Reality

The study that was the source of the extreme prediction in Bay Nature about the distance that burning embers can travel was conducted on samples of Eucalyptus viminalis bark (NOT Blue Gum Eucalyptus, E. globulus) “tethered in a vertical wind tunnel.”  These are not real-world conditions.  So, how does this theoretical study compare to real-world conditions?

The FEMA Technical Report about the 1991 fire in the East Bay Hills contains a map of the full extent of the 1991 fire.  As you can see on this map, the maximum distance from the northern-most edge of the fire to the southern edge of the fire is less than 3 miles…not remotely close to 20 miles.  In other words, embers could not have started fires 20 miles away because the fire wasn’t even close to 20 miles long.

1991-fire-map-2

The FEMA Technical Report doesn’t tell us what the wind speeds were during the 1991 fire, although they describe the wind as being strong at several times during the fire.  If there is any evidence that winds were as much as 60 miles per hour, it’s not evidence we have been able to find.  We found a source of wind speeds measured on the Bay Bridge, including historical records.  This website says the strongest wind measured since 2010 was 31 miles per hour in April 2013.  That suggests that 60 mph winds are probably unusual in the San Francisco Bay Area.

The FEMA Technical Report doesn’t report any observations of firebrands or burning embers from eucalyptus.  The report mentions embers twelve times, but identifies the source of those embers only once.  In that one case, the source of embers was “a growth of brush”….not a eucalyptus tree or any tree, for that matter.  There are anecdotal reports of finding debris from the fire as  far as San Francisco, but no reports that the debris was still on fire or that it started another fire.

US Forest Service study of embers in actual fires

US Forest Service participated in a comprehensive study of “spotting ignition by lofted firebrands” based on actual wildfires all over the world, including the 1991 fire in the East Bay Hills. (3)  There is nothing in that study that corroborates the claim that eucalyptus bark embers are capable of travelling 20 miles while remaining lit and therefore capable of starting spot fires:

  • “In the wildland-urban interface fires in California—Berkeley in 1923, Bel-Air in 1961, Oakland 1991—wooden shingles which were popular in California as roof material, assisted fire spread. Wooden shingles increase fire hazard owing to both ease of ignition and subsequent firebrand production.
  • “Unlike the flying brush brands which are often consumed before rising to great heights, the flat wood roofing materials soared to higher altitudes carried by strong vertical drafts…”
  • The only firebrand found in the 1991 Oakland Hills fire was found approximately 1 km (.6 mile) west from the perimeter of the fire. It was a cedar shingle.  Here is a photograph of that shingle:  ember-1991-fire-2
  • Cylinder shaped embers do not travel as far as flat particles. Firebrands in the shape of cylinders were found to have a maximum spotting distance of 2050 meters, because “cylinders always fall tumbling.”
  • “The increased burning time inherent in larger firebrands was cancelled out by an increased time of flight because larger firebrands move more slowly.”
  • In a study of 245 extinguished fires, experiments and simulations, and observing 48 wildfires, “The longest spotting distance was observed as 2.4 km.”

This comprehensive study of actual wildfires all over the world finds no evidence of embers capable of travelling 20 miles while still burning and starting spot fires.  It reports that wooden shingles were the only observed burning embers in the 1991 fire and that wooden shingles are particularly vulnerable to being lofted as embers in a wildfire.  There are countless houses in the East Bay Hills covered in wooden shingles, yet instead of addressing that obvious source of embers, we are destroying blameless trees.

Developing the Cover Story

Claims about the extreme flammability of eucalyptus have escalated in the past 15 years as opposition to destroying trees and associated pesticide use has escalated.  Nativists have become increasingly dependent on flogging the fear factor as their other storylines have been dismantled by empirical studies and reality:

  • Monarch butterflies roosting in eucalyptus tree.
    Monarch butterflies roosting in eucalyptus tree.

    The “invasiveness” of eucalyptus has been downgraded by the California Invasive Plant Council from “moderate” to “limited,” their lowest rating. There is little evidence that eucalyptus is invasive unless planted along streams and swales that carry their seeds.

  • There are many empirical studies that find that all forms of wildlife—such as insects and birds—are served equally well by both native and non-native plants. Some iconic species—such as Monarch butterflies, bees, hummingbirds, hawks, owls—are dependent upon eucalyptus for winter nectar and safe nesting habitat.
  • Huge global studies of biodiversity report that the introduction of non-native species has resulted in no net loss of biodiversity. This is particularly true of introduced plants.  There is not a single instance of extinction caused by a non-native plant in the continental United States.
  • Climate change is making nativism increasingly irrelevant. California’s native conifers, oaks, and redwoods are dying by the millions.  Unless we want a treeless landscape, we must plant tree species that are capable of tolerating changed climate conditions.

    Owl nesting in eucalyptus, courtesy urbanwildness.com
    Owl nesting in eucalyptus, courtesy urbanwildness.com

These studies have left nativists with few tools to justify the eradication of non-native plants.  We can see the development of the FIRE!! cover story in the archives of the conferences of the California Invasive Plant Council.  In 2004 Cal-IPC held a workshop regarding exotic trees and shrubs.  Over 30 representatives of major managers of public lands attended, such as National Park Service, San Francisco’s Natural Areas Program, Marin County Open Space, etc.  The record of this meeting reflects the dependence upon fire to justify the eradication of non-native shrubs and trees:  “Golden Gate National Recreation Area:  ‘inform public ahead of time; use threat of fire danger to help build support for invasive plant removal projects.’”  The Golden Gate National Recreation Area—a National Park–advises other land managers to frighten the public into accepting the loss of their trees. 

Subterfuge is also recommended to land managers to hide the eradication of shrubs and trees from the public:  “To avoid public upset, drilling around into tree buttress roots and injecting 25% glyphosate…Trees die slow and branches fall slowly, so won’t pose an immediate hazard.”  In other words, land managers were advised to kill trees using a method that won’t be visible to the public. 

Perhaps most disturbing of all is that those who attended this workshop admit that they don’t really know if eucalyptus trees are more flammable than native vegetation and some doubt that they are:  “People are afraid of fire.  Help them understand Eucalyptus trees and other invasive plants are very fire hazardous.  Is there any solid research about Eucalyptus and fire?  Are Eucalyptus and brooms any greater fire danger than native chaparral?”  In other words, even those who wish to destroy non-native shrubs and trees seem to understand that fire is a cover story for which no supporting evidence exists. The evidence has been fabricated to support the cover story.

We now seem to live in a fact-free world in which various interests can make things up and distribute them on the internet with impunity.  The mainstream press is dying and is being replaced by fact-free social media.  If we are to protect ourselves from such manipulation, we must drill down into these storylines.  In the case of eucalyptus, we have debunked the myth that it is more dangerous than the replacement landscape.  Now it’s up to us to disseminate that information far and wide as an antidote to fear-driven nativism. 


  1. Zach St George, “Burning Question in the East Bay Hills: Eucalyptus is flammable compared to what? Bay Nature, October-December 2016
  2. James Hall, et. al., “Long-distance spotting potential of bark strips of a ribbon gum (Eucalyptus viminalis), International Journal of Wildland Fire, 2015, 24, 1109-1117
  3. Eunmo Koo, et. al., “Firebrands and spotting ignition in large-scale fires,” International Journal of Wildland Fire, 2010, 19, 818-843

Island eradications in the Bay Area rear their ugly head again

The Farallon Islands are a National Wildlife Sanctuary just 27 miles off the coast of San Francisco, where millions of birds and marine animals are legally protected.  Plans of the US Fish and Wildlife Service (USFWS) to aerial bomb 1.3 metric tons of rodenticide to kill mice on the Farallon Islands originated over 5 years ago.

Farallon Islands, NOAA
Farallon Islands, NOAA

The stated purpose of this project was to protect the ashy storm petrel, a legally protected species of concern.  The mice are not a direct threat to the petrel.  Rather, USFWS claims that another legally protected species of concern, the burrowing owl, eats the chicks of the petrel when the population of mice dwindles.  Because the average population of burrowing owls on the Farallons is said to be only 6 burrowing owls, the scale of their predation of petrel chicks seems minimal given that their preferred prey is mice.  USFWS theorizes that if the mice are killed, the burrowing owls will leave the Farallons.  This rather fanciful scenario is less credible than the more likely outcome that the burrowing owls will either be killed by the poison or eat yet more petrel chicks if their mice diet is eliminated.

Aside from the convoluted and questionable rationale for this project, the main concern is the anticipated collateral damage caused by aerial bombing huge quantities of rodenticide (brodifacoum).  The planned rodenticide is an anti-coagulant that is highly persistent and causes all vertebrate animals (mammals, reptiles, birds, fish, etc.) to bleed to death.  Death is not quick; the poisoned animals stumble around before dying and are easy prey for other animals that are then killed by the poison.  Dead, poisoned mice are equally attractive food for some birds.  The poison pellets are also as appealing to other animals as to mice.  Even the supporters of this project readily admit that many animals other than mice are likely to be killed directly by the rodenticide or as secondary victims.  “Stuff happens,” they say with a shrug.

The author of the Environmental Impact Statement is the same organization—Island Conservation—that will implement the project, if and when it is approved.  This conflict of interest seems one of many unwise decisions made by US Fish and Wildlife Service.

The opposition to this project has been loud and clear.  Maggie Sergio, who reported this project on Huffington Post, published a petition in opposition to the project that was signed by over 32,000 people.  And many prestigious organizations including the EPA, American Bird Conservancy, City of San Francisco, The Ocean Foundation, and several retired USFWS scientists, have also criticized the project.  Yet, five years later approval of the Revised Draft Environmental Impact Statement is still pending. Theoretically this project is still alive.

Farallons project comes to life again

The Farallons project has always seemed to us so ill-advised and misconceived that we could not believe it would materialize.  We have therefore not covered it since 2014 when we republished Maggie Sergio’s Huffington Post article and asked people to sign her petition.

Unfortunately, we were under-estimating the power and influence of the supporters of this project.  Bay Nature, a local nature magazine, recently published an article about the Farallons project and island eradications in general.  That article seems to assume there is consensus that mice must be eradicated on the Farallons and that the only question is the method that will be used (more about Bay Nature’s proposed method later).  And the California Invasive Plant Council (Cal-IPC) has published an endorsement of island eradications—including the Farallons—in its most recent newsletter (available here: Cal-IPCNews_Summer2016).  Cal-IPC’s preferred strategy for eradications is aerial application of rodenticide.  Therefore, our concern about the proposed Farallons project has once again been elevated to crisis levels.  When two local organizations, which claim to advocate for conservation endorse the Farallons project, we must take it seriously.

History of island eradications

Since learning about plans to eradicate mice using rodenticides, we have learned that the practice originated in New Zealand, where poison applications began over 60 years ago to kill a wide range of non-native animals.  Bill Benfield tells the entire story of eradications in New Zealand in his book, At War With Nature.  (1) We have relied on that valuable resource for this article.  That history is relevant to us because there are some striking similarities between the North American and New Zealand versions of invasion biology, the ideology that drives eradication attempts in North America and New Zealand.

The moa was a huge flightless bird that was hunted to extinction by Polynesians when they occupied New Zealand.
The moa was a huge flightless bird that was hunted to extinction by Polynesians when they occupied New Zealand.

Humans occupied New Zealand more recently than their arrival in North America.  Prior to their arrival, New Zealand was inhabited by many flightless birds that were successful because they had no predators.  The moa was the largest of those birds.  Although it has been extinct for hundreds of years, palaeontologists tell us the moa was about 12 feet tall and weighed about 500 pounds.  It was easy prey for the first humans who arrived in New Zealand about 800 hundred years ago from Polynesian islands.  As most sea-faring humans do, they unintentionally brought with them a species of rat, the kiore.

The climate of New Zealand is much colder than the Polynesian home of the first humans and their agriculture was not well suited to the climate of their new home.  The moa quickly became the main source of food for the humans. The moa were rapidly driven to extinction by hunting, which forced the humans to retreat to the northern end of New Zealand where the climate is milder and their agriculture was more successful.

Although there is some debate about the size and range of the moa population, Dr. Graeme Caughley reported that the moa population was very large and widely spread, based on a calculation of the available sustainable bio-mass.  He believes moa populations existed in all vegetation types, including forests where they would have browsed the forests.  Intense browsing of the forests would have encouraged the growth of the slower growing and unpalatable browse-resistant trees that became the forest giants. The faster growing species of trees were the palatable browse- tolerant species that were held back by browse, allowing the growth of slower growing trees that would in time become the forest giants.  The moa also would have spread the seeds of the trees they ate and inhibited the growth of an understory.  In other words, the forest that humans found when they arrived in New Zealand around 1200 AD was adapted to the big population of moa.

In the absence of moa the composition of the forest quickly responded to the absence of browsing.  Fast growing trees that were formerly held back by browse were no longer at a disadvantage compared to slow growing and unpalatable browse-resistant trees; the forest under-story became denser.  The composition of the forest that was found by Europeans when they arrived in New Zealand several hundred years later was in transition. 

Forest in New Zealand
Forest in New Zealand

The first humans on New Zealand did not have a written language.  The landscape they found when they arrived is not recorded in history and is only known to the extent that archaeological and paleontological evidence is accurately used to reconstruct it.  As all human science does, these disciplines are continually evolving and therefore did not inform the earliest versions of ecology that spawned the eradication movement on New Zealand.  In other words, the forest found by Europeans when they arrived in New Zealand is still considered the pristine ideal that ecologists wish to replicate.  In fact, that landscape was just as modified by human habitation as any modern, “novel” ecosystem.

This fantasy of a pristine, pre-human landscape is similar to the fantasy in North America that the landscape found by Europeans when they arrived on the East Coast in the 16th century and the West Coast in the 18th Century was the “natural” landscape, unaltered by humans.  They are just as mistaken in that assumption as they are in New Zealand. Native Americans actively managed the landscape to serve their horticultural and cultural needs.  The consequences of that fantasy have been just as deadly and destructive in New Zealand as they have been here in California.

The deadly crusade in New Zealand

Europeans brought many animals with them to New Zealand, just as they did to North America.  They brought both domesticated animals such as sheep and wild animals such as deer that they could hunt.  The deer browse the forest, just as they do here, and the impact they have on the forest is similar to the impact moa had on the forest. The deer and other browsers are the functional substitute for the extinct moa. Fast growing palatable species of trees are disadvantaged by browsing and these are the trees that early ecologists considered the “natural” forests of New Zealand because they were the trees that were found when Europeans arrived. 

1080 Poison Warning in New Zealand
1080 Poison Warning in New Zealand

Deer poisoned by 1080. Graff Brothers, New Zealand
Graf Brothers, New Zealand

Hence, aerial poisoning of the land began over 60 years ago to kill all browsing animals in New Zealand except domesticated animals kept behind fences.  Smaller non-native animals such as possum are also targets for eradication because they are assumed to be predators of the few flightless birds that remain in New Zealand.  This accusation is refuted by Bill Benfield who tells us that possum are primarily vegetarians and that a study of the contents of possum stomachs found no evidence of bird predation.  Possum are also accused of being carriers of bovine TB, a disease that infects domesticated animals.  However, recent laboratory tests find no evidence that possum are infected with bovine TB, beyond minute levels.  In any case, the possum population is small because it is a species that rears only one pup per year, so its population would grow only slowly if they weren’t being exterminated in New Zealand.

The killing fields

A different poison is used in New Zealand–called Compound 1080–that operates in a different way than anti-coagulant rodenticide.  It kills indiscriminately any life form that requires oxygen.  It was developed as an insecticide in Europe, and was initially used in the US where it was briefly used to kill coyotes and other wildlife considered inconvenient predators until its use was severely restricted because of its extreme toxicity.  It is entirely banned in California, which is why our local version of island eradications use anti-coagulant rodenticide instead of 1080.

Graff Brothers DVD available on Amazon
Graf Brothers DVD available on Amazon

1080 is a slow, grisly killer of EVERYTHING: insects, fish, mammals, birds, amphibians, etc.  It is just as likely to kill native animals as non-native animals and it does.  This indiscriminate killing of every living thing in New Zealand was described in chilling detail by Elizabeth Kolbert in the New Yorker.  It is also visible in the videos of the Graf brothers for those with a strong stomach.  HERE is one of many of their videos.

Exporting death

We could turn a blind eye to what is happening in New Zealand if this strategy were not being exported all over the “civilized” world.  Amazingly, such island eradications have happened in many places and are being proposed in many places where local resistance is trying to prevent them from being implemented.  What have we learned from the projects that have been done?  The record is sketchy because very little after-the-fact monitoring of completed projects has been done.  What we DO know, suggests that it is not in the interests of the promoters of these projects to monitor the outcome of their projects because the results are consistently deadly and unsuccessful.

Killing one species of plant or animal does not restore an ecosystem

Readers of Million Trees will not be surprised to learn that killing one species does not magically “restore” an ecosystem to some historic ideal because ecosystems are very complex and their occupants live in communities with many, complex interactions that are not perfectly understood by humans, even humans calling themselves invasion biologists.

One study of islands off the coast of New Zealand compared the vegetation structure and ecosystems of three island systems: islands that never had rats, islands with rats, and islands on which rats had been “controlled.” They concluded that, “The extent to which structure and function of islands where rats have been eradicated will converge on uninvaded islands remains unclear…Since most impacts of rats were mediated through seabird density, the removal of rats without seabird recolonization is unlikely to result in a reversal of these processes. Even if seabirds return, a novel plant community may emerge.” (2)

There are many other factors that prevent the re-creation of historical landscapes, such as climate change.  There are undoubtedly many factors that are not known to us, which prevents us from “fixing” something we do not understand.  In any case, many of us don’t consider it necessary to “fix” something that we don’t consider broken.

Collateral damage and incompetent execution

In those few cases when after-the-fact monitoring was done, there is considerable evidence that many non-target animals were killed and the water was polluted.

In the case of Rat Island, off the coast of Alaska, no monitoring was planned after the aerial bombing of 46 metric tons of anti-coagulant rodenticide to kill rats.  However, neighbors of Rat Island demanded an investigation when they saw dead birds and animals floating in the vicinity of the island after the project was done.  That investigation (available HERE) was done by USFWS Law Enforcement.  The investigation found that the manufacturer’s recommendations regarding dosage were exceeded, that instructions to collect dead rats so they would not be eaten by birds were not followed, and that hundreds of birds died, including many legally protected bald eagles.  The investigation was not done until 7 months after the project was completed.  We should assume that the number of dead animals found would have been greater if the investigation had been done promptly after the project was completed.

Palmyra Atoll. USFWS
Palmyra Atoll. USFWS

In the case of Palmyra Island, off the coast of Hawaii, the scientific study conducted after the aerial bombing of rodenticides reported, “We documented brodifacoum [rodenticide] residues in soil, water, and biota, and documented mortality of non-target organisms. Some bait (14–19% of the target application rate) entered the marine environment to distances 7 m from the shore. After the application commenced, carcasses of 84 animals representing 15 species of birds, fish, reptiles and invertebrates were collected opportunistically as potential non-target mortalities. In addition, fish, reptiles, and invertebrates were systematically collected for residue analysis. Brodifacoum residues were detected in most (84.3%) of the animal samples analyzed. Although detection of residues in samples was anticipated, the extent and concentrations in many parts of the food web were greater than expected.” (3)

The rats return

The most damning evidence of all is that after killing untold numbers of animals, including those not meant to be killed, and poisoning the environment with a deadly toxin that bioaccumulates and persists in our bodies, the rat population often returns to pre-project levels within a few years. 

Henderson atoll in the Pacific is an example of such a failure.  Eighty tons of rodenticide pellets were aerial bombed on Henderson in 2011.  Apparently, at least two rats survived, one presumably male and one presumably female.  Within a few years the rat population had returned to pre-projects levels of 50,000 to 100,000 rats.

The rats were said to have been introduced to Henderson over 800 years ago.  Surely they had reached some balance between population size and available food sources.  Rats are an ancient species that would not be here if they completely wiped out their food sources.  Rat population growth is modulated by available food sources.  Hence, when almost completely eradicated, the rats rapidly reproduced back to equilibrium with food sources.

Claims that the Henderson project was urgently needed to prevent the extinction of a bird species with which rats had co-existed for over 800 years were bogus.  If rats had not exterminated the birds within 800 years, they weren’t likely to do so before this pointless project killed tens of thousands of animals, probably including many birds.

Like most “restoration” projects, claims are made about a conservation crisis that is often just an emotional appeal without any scientific basis.  Money is raised and spent in response to these fabricated crises and many “non-profit,” untaxed organizations subsist on these campaigns.  In the case of New Zealand, the poison they are using is manufactured by the government, creating an unholy financial incentive for these eradication projects. 

The failure of the extermination attempt on Henderson is not an isolated incident.  Lehua is one of the Hawaiian islands on which extermination was attempted and failed.  An evaluation of that attempt was published in 2011 to determine the cause of the failure so that a subsequent attempt would be more successful.  That evaluation included this report on the success of similar attempts all over the world:  “An analysis of 206 previous eradication attempts against five species of rodents on islands using brodifacoum or diphacinone is presented in an appendix to this report. For all methods, 19.6% of 184 attempts using brodifacoum failed, while 31.8% of 22 attempts using diphacinone failed.”  Brodifacoum and diphacinone are both anti-coagulant rodenticides.  Diphacinone is considered less toxic and less persistent than brodifacoum.

The silver bullet?

The “restoration” industry is meeting with a great deal of public opposition.  Because some of the opposition is based on concerns about polluting the environment with pesticides–such as herbicides used to kill plants and rodenticides used to kill animals–the “restoration” industry is looking for a less controversial method of accomplishing their deadly goals.

This brings us back to the recently published article in Bay Nature about island eradications.  The article informs us that a genetic modification of mice is now being developed, which would drive that species to extinction by ensuring that all off-spring would be males, thereby ending reproduction of the species. This method has a seductive appeal because it would not poison the environment.  However, it is an insidious proposal and we will let some of the commenters on the Bay Nature article tell us why, because some of them sound like knowledgeable scientists with ethical concerns:

  • Has the conservation movement lost its mind? Gene drive is unsafe, unproven and unethical. It is the most insane idea I have heard of in my 20 years reporting on genetic engineering. And it is presented here with no critical analysis, scientific, ethical, or environmental. I have spent my life in conservation and want to do all I can for to stop extinction but using extinction to stop extinction? Gene Drive is a technology that says one species (us) gets to decide which other species live or die. This is not populations that will be eradicated, it is aimed at an entire species. Who likes pests like rats or mosquitoes? But think. What’s next? Could this be a cynical ploy to use conservation to test this dangerous technology? Because once accepted it can then be used for many far less “acceptable purposes – such as a bioweapon.” – Claire Cummings
  • “The Alison Hawkes article reminds me (as a Kiwi i.e. New Zealander) of the mad and dangerously flawed science that is rampant in New Zealand. And just because it’s labelled science, don’t unquestioningly believe in it. Scientists here have to operate under a commissioned, paid science regime. The science becomes warped and inaccurate. Too often pseudo science (e.g. New Zealand’s destructive 1080 programme) intrudes and disrupts the natural ecosystem with disastrous consequences.  In NZ, objectives are often founded on unrealistic goals, i.e. turning NZ ‘s ecological clock back to 500AD. That’s impossible while humans and mad science remain.” – Tony Orman
  • It is extremely disappointing to see Bay Nature carry an article on such a controversial and risky plan with such lack of balance or even basic journalistic diligence. Contrary to the impression presented here CRISPR CAS9 gene drives are highly immature – it being barely 15 months since the first proof of principle of the ‘mutagenic chain reaction’s shown and they already have generated enormous controversy including a 200 page National Academy of Sciences Study that warned against open release and growing discussions at the Convention on Biological Diversity where there have been strong calls for a moratorium on this risky new technology.” – Jim Thomas

It seems that destructive “restoration” techniques are developing faster than human common sense can keep up with.  What can we do to slow it down?  What can we do to prevent the pointless poisoning of our environment and the needless killing of defenseless animals and harmless plants?  I don’t know the answer, but I will keep asking the questions and I hope my readers will as well. 

Update:  The Final Environmental Impact Statement for the mouse eradication project on the Farallon Islands was published on March 15, 2019.  The Final Environmental Impact Statement recommends the original plan as the “preferred alternative.”  In other words, despite intense opposition to this plan, its implementation is now eminent. 

No public comments are allowed on a Final Environmental Impact Statement, so there’s nothing further we can say about what seems to be an unnatural disaster in the making.  At this stage of a project, lawsuits are the only way to stop it.  I don’t know if anyone is willing and able to sue. 


  1. William F Benfield, At War With Nature: Corporate Conservation and the Industry of Extinction, 2015, available on Amazon.com in digital format
  2. Christa Mulder et.al., “Direct and indirect effects of rats: does rat eradication restore ecosystem functioning of New Zealand seabird islands?” Biological Invasions, August 2009, 1671-1688
  3. William Pitt, et. al., “Non-target species mortality and the measurement of brodifacoum rodenticide residues after a rat (Rattus rattus) eradication on Palmyra Atoll, tropical Pacific,” Biological Conservation, May 2015, 36-46

Beyond the War on Invasive Species

Tao Orion is the author of Beyond the War on Invasive Species:  A Permaculture Approach to Ecosystem Restoration, the latest in the rapidly growing literature about the futile and destructive attempts to eradicate non-native species.  Ms. Orion will give a workshop at a PLACE for Sustainable Living on Thursday, September 17, 2015:

“Rethinking Invasive Species from a Permaculture Perspective”

Thursday, September 17, 2015, 6-8 pm

PLACE for Sustainable Living

1121 64th St, Oakland, CA 94608

Donations $12-$25 requested

Update:  This is the answer PLACE for Sustainable Living gave to a question about wheelchair accessibility:  “It is not wheel chair accessible yet – we have carried wheelchair persons up the steps with their wheelchairs – we can arrange for that. And the yard is filled with chipwood, wheel chairs have rolled over fine, but not sure if everyone in them can push through. Our friend, male, can push through fine.”  Please contact PLACE for Sustainable Living directly if you have specific questions about accessibility.  (addendum dated 9/10/15)

Update #2:  Ms. Orion’s presentation has been cancelled because the venue is not wheelchair accessible.  CUIDO (an organization which represents disabled people) asked that it be moved to a facility with wheelchair accessibility or cancelled.  Such a facility could not be found, so it has been cancelled.  

Update #3:  Some adjustments have been made in plans for Ms. Orion’s presentation which are apparently acceptable to at least some members of the disabled community.  Ms. Orion has therefore decided against cancelling it.  Sorry for the confusion.

Ms. Orion is visiting the Bay Area from the Willamette Valley in Oregon, where she has a small farm in the country.  She has a degree in agroecology and sustainable agriculture from UC Santa Cruz and she has studied at the Columbines School of Botanical Studies in Eugene, Oregon.  She teaches permaculture design at Oregon State University and a non-profit sustainable-living educational organization.  She has also worked as a permaculture designer for ecological restorations.

Beyond the War on Invasive Species

Beyond the War on Invasive SpeciesThe first chapter of Ms. Orion’s book is a breakthrough because it is an explicit indictment of pesticides used by so-called “restoration” projects.  Although previously published books were critical of invasion biology and the ecological industry it spawned, pesticides were barely mentioned in them.  In contrast, it is primarily the use of pesticides in ecological “restorations” that convinced Ms. Orion that the war on invasive species is doing more harm than good.

Concern about unwanted plants – AKA weeds – is as old as human engagement in agriculture, that is, thousands of years old. And most of the plant and animal species now considered “invasive” were introduced by humans to serve a variety of purposes, including aesthetics, such as mute swans and multiflora roses.  Some of these introduced plants and animals had unintended consequences such as competing with native plants and animals for available resources.  Concern – even regret – about these introductions has increased greatly in the past 25 years.  Attempts to manage these introductions has escalated from import limitations to fines and penalties and finally to attempts to eradicate plants and animals with pesticides.

The role of the pesticide industry in the escalating war on “invasive” species

Ms. Orion turns to the public record to make the case that the current focus on eradicating introduced species using pesticides was influenced by business interests.  She points out that the federal Invasive Species Advisory Committee is a consortium of academic, professional, and business interests, including at least two people who are employed by manufacturers of pesticides.  They make invasive species management policy recommendations to the National Invasive Species Council (NISC), created by Executive Order in 1999.  The federal government is spending over $1 billion annually on research and control of “invasive” species, including pesticide applications.

National Invasive Species Council

The NISC is modeled after the California Exotic Pest Plant Council, created in 1992.  That Council is now known as the California Invasive Plant Council (Cal-IPC).  Cal-IPC brought together representatives from government agencies and non-profit environmental organizations, as well as manufacturers of pesticides and spray equipment:  “Monsanto has sponsored Cal-IPC since its inception and both DuPont and Dow AgroSciences have also supported the group.”  (1)

The first annual conference of Cal-IPC in 1993 featured an employee of Monsanto, Dr. Nelroy Jackson.  Jackson’s presentation to Cal-IPC stated that “chemical weed control is the optimal method for control and removal of exotic plant species during…most native habitat restoration projects.” 

Jackson’s involvement in escalating attempts to eradicate introduced species is troubling, but is not the only example of such collaboration between the “restoration” industry and the manufacturers of pesticides.  The Weed Science Society, which advocates for “research, education, and awareness of weeds in managed and natural ecosystems,” has employees of Dow Agrosciences, Syngenta, and Dow Chemical on its board of directors.  Those manufacturers of pesticides, as well as Monsanto, Bayer Crop Science, Dupont, and BASF Corp are also donors to the weed society, at the highest levels of donations.

The manufacturers of pesticides also influence the “restoration” industry by investing and participating in the consulting firms that write environmental impact reports for ecological “restoration” projects, such as Tetra Tech (which wrote the draft Environmental Impact Report for San Francisco’s so-called Natural Areas Program).

The manufacturers of pesticides influence public policy regarding ecological “restoration” by making large tax-deductible contributions to many land-grant universities that conduct research on agriculture:  “A 2012 Report from Food and Water Watch found that nearly 25% of funding for agricultural research at public universities comes from private companies.”  (1) This is one of many reasons why there is so little research done on non-chemical approaches to ecological restoration.

As disturbing as this collaboration between the government and the pesticide industry is, the evidence of the relationships between trusted non-profit environmental organizations and corporate interests is even more so.  Nature Conservancy, National Audubon Society, and Ducks Unlimited all have close relationships with the manufacturers of pesticides and receive funding from them.

Ms. Orion then describes the use of pesticides by the “restoration” industry.  She also describes some of the damage pesticides are known to do, such as killing microbes in the soil and binding minerals in the soil.  She describes the persistence and mobility of pesticides in the environment.  She describes the inadequacy of testing and regulation of pesticides in the United States.  These issues are well known to the readers of Million Trees, so we won’t repeat them here, but new readers can click on the blue links to visit posts about those issues.

All introduced species are presumed to be harmful

Ms. Orion’s next chapters are more similar to the books that precede hers.  There are several examples of specific “invasions” that illustrate the point that “invasive” species are usually symptoms of changes in the environment, rather than causes of those changes.  Attempting to eradicate them does not reverse the changes in the environment and often causes more environmental damage.  “Invasive” species are often performing valuable ecological functions that are not understood until they are eradicated.  We have reported many examples of these issues and won’t repeat them here.  However, Ms. Orion’s telling of the history of Asian Carp in the Mississippi River and the Great Lakes was new to us and is well worth a retelling.

Song dynasty painting attributed to Liu Cai (c.1080–1120). Contains various types of fish and other marine animals, such as goldfish, perch, catfish, carp, minnows, bass, and shrimp.
Song dynasty painting attributed to Liu Cai (c.1080–1120). Contains various types of fish and other marine animals, such as goldfish, perch, catfish, carp, minnows, bass, and shrimp.

Asian carp has been a mainstay in the diet of the Chinese for several thousand years, according to their historical literature.  Asian carp are well adapted to aquaculture techniques, so they have the potential to replace or supplement other sources of protein.  They were introduced to the Midwest in the early 1800s and they spread throughout the Mississippi River many decades ago.  Although they are prevalent in the Mississippi River, they have not driven any native fish to extinction.  Yet, despite their usefulness and the lack of evidence that they have caused any harm, they suddenly became the latest invasion crisis when it was feared they would soon enter the Great Lakes.  A government fisheries biologist put that fear into perspective:

“We are trying to keep invasive Chinese carps out of the Great Lakes, to protect an invasive (yet purposefully stocked) Pacific salmon fishery, which was stocked as a management tool to control hyper-abundant alewifes, another invasive fish species, because the native piscivore, the Lake Trout, was nearly wiped out by another invasive species, the sea lamprey, because people built the Welland Canal around Niagara Falls to promote intercontinental shipping deep into the Great Lakes basin.” (1)

It makes the head spin to follow the “logic” of this sequence of events, which we paraphrase, “we solved one problem by creating another, then we solved that problem by creating another…ad infinitum.“  This is an ecosystem that has been radically altered by man, including reversing the flow of the Chicago River which connects the Mississippi River to the Great Lakes to solve Chicago’s sewage problems.   The water is warmer, polluted with agricultural runoff, and there is no longer a seasonal, cleansing water surge.  These changes in the environment set the stage for the arrival of Asian Carp in the Great Lakes.  The habitat for native fish has been radically altered such that removal of Asian carp from the river is an irrelevant, inconsequential improvement of habitat needed by native fish.

Despite what would seem overwhelming evidence that Asian carp could be a valuable food source and that being rid of them is unlikely to benefit anyone, here is a brief list of what has been done so far to try to prevent them from entering the Great Lakes:

Fish kill using rotenone. http://www.encyclopedia.com/doc/1E1-X-rotenone.html
Fish kill using rotenone. http://www.encyclopedia.com/doc/1E1-X-rotenone.html

  • US Army Corps of Engineers constructed a submerged electric fence to shock and kill the fish as they enter the Great Lakes. The fence cost millions of dollars but is largely ineffective.
  • The Illinois Department of Natural Resources dumped 2,200 gallons of rotenone into sanitary and ship canals feeding into the Great Lakes. This poison kills all gilled animals. The result:  “Among the tens of thousands of dead fish, researchers found one Asian carp.” (1) This fiasco cost $3 million.
  • Other researchers have suggested a system of strobe lights and bubble and sound barriers to stop the northward migration of Asian carp.

Permaculture philosophy

Ms. Orion’s closing chapters reflect her training in permaculture design.  She considers the tending of the wild by Native Americans a model for ideal stewardship of the land.  And she advocates for land management strategies that reflect the realities of our changed environment and are sustainable into the future.  We will let her speak for herself:

“Holistic restoration planning requires an honest accounting of what has come to pass as well as a comprehensive view of what we can do about it.  The problems are complex, and the solutions are likely to be more so…Navigating from a paradigm that views invasive species as scourges to one that looks at them as opportunities for deeper ecological and economic engagement will take time and commitment, especially because the old paradigm is so entrenched politically, economically, and academically.  The tide is shifting though, as more and more of us are coming to realize that the herbicide-based eradication approach to restoration is outmoded—a futile attempt to regain an imagined past—and we need to be focusing our time, resources, and energy on adapting to the future.” (1)

Please show your support for Tao Orion and her book by attending her workshop on Thursday, September 17th.


 

(1) Tao Orion, Beyond the War on Invasive Species:  A Permaculture Approach to Ecosystem Restoration, Chelsea Green Publishing, 2015 

Science in the National Parks

We were so encouraged by our reader’s report about the conference of the California Native Plant Society (CNPS) that we decided to attend the conference of the National Park Service (NPS), “Science for Parks, Parks for Science” at UC Berkeley, March 26-27, 2015.  As we have reported many times, the National Park Service is heavily engaged in native plant “restorations.”  Their projects are some of the most aggressive in the Bay Area and some of the most successful, because they seem to have greater resources than other local managers of public land.  Therefore, we were curious about their assessment of those efforts.  Are they starting to have doubts, as expressed by some of the presentations at the CNPS conference?  This is a brief summary of what we learned.

The angry old guard

The keynote speaker was E.O. Wilson, the granddaddy of “biodiversity.”  He spoke of his desire to safeguard biodiversity by preserving one-half of the Earth as “protected areas” and the closely related goal to connect all protected areas. This lofty goal should be compared to the current figure of 13% of the earth which is presently protected and the internationally agreed-upon goal of 17%, according to the second speaker, Ernesto Enkerlin, Chair of the IUCN World Commission on Protected Areas.

The moderator, Steven Beissinger, Professor of Conservation Biology at UC Berkeley, asked Professor Wilson a few pointed questions:

  • “Can working landscapes play a role in conservation?” Professor Wilson said. “That is a stupid, dangerous way of looking at conservation.  Parks cannot be evaluated in terms of their value to humanity.  The natural world is valuable in its own right.  Emma Marris and Peter Kareiva of the Nature Conservancy are pushing this; they have the least experience with studying the natural world.  This dangerous thinking must be countered immediately.”  Granted, Emma Marris is a science journalist, but Peter Kareiva was an academic scientist at University of Washington for decades before becoming Chief Scientist at the Nature Conservancy.
  • “Must protected areas be devoid of people?” Professor Wilson said “Of course not.  Indigenous people might be included.”  In fact, indigenous people have been evicted from many protected areas around the globe.  Furthermore, virtually the entire population of the US is not indigenous.  Where does that leave us?
  • “Given the challenges faced by conservation, is triage necessary to prioritize projects to focus on the most important and threatened species?” Professor Wilson said with some feeling, “That’s ridiculous!  We CAN bring them all back, we must SAVE THEM ALL!”

Professor Daniel Simberloff, the well-known invasion biologist, was another speaker who believes it is necessary and possible to eradicate all non-native plants and animals in our public lands.  He also called out by name Marris, Kareiva and others for their criticism of invasion biology.  Frankly, we think these personal attacks are unseemly in the context of what should be considered a scientific debate about the most effective methods of conservation.  The moderator, Professor Holly Doremus (UC Berkeley, Boalt Hall), asked Professor Simberloff a few tough questions as well:

Most other speakers at the conference had a less sanguine view of our ability to “save every species” and “eradicate every non-native species.”  The need for “triage” was repeated in many presentations and descriptions of past and present projects were often pessimistic about the prospects of success.  Climate change and its impact on the environment was the dominant theme of the conference.

All loss, no gain

Mission Blue butterfly.  Wikimedia Commons
Mission Blue butterfly. Wikimedia Commons

The endangered Mission Blue butterfly exists only in a few locations in the San Francisco Bay Area:  Twin Peaks, San Bruno Mountain, Milagro Ridge in San Mateo County, and the headlands of Marin County.  We recently reported that the 32-year effort to restore butterfly habitat on San Bruno Mountain has been plagued by natural succession to native coyote brush that competes with the butterfly’s host plant, 3 species of lupine.  The status of the butterfly population on San Bruno Mountain is unknown because of inadequate monitoring.  Save Mount Sutro Forest has reported that the butterfly population on Twin Peaks remains very small despite repeated attempts to move butterflies from San Bruno Mountain.  We learned at the NPS science conference that the effort to restore butterfly habitat in the Marin Headlands in order to increase the butterfly population there has experienced its own difficulties.

The restoration of butterfly habitat to the Marin Headlands was controversial because about 500 Monterey pines were destroyed to make way for the lupine scrub required by the butterflies.  The pines had been planted by the military over 100 years ago.  They were heavily used by raptors during their annual fall migration through the Bay Area.  The Marin chapter of the Audubon Society was therefore opposed to their destruction.  As usual, this opposition was ignored by the National Park Service, which manages that property, and the trees were destroyed in about 2009.

NPS has been engaged in the effort to restore the habitat needed by the Mission Blue since the trees were removed.  Those engaged in that effort presented a poster at the NPS science conference which reported:

  • In 2010, NPS and its collaborators attempted to promote the growth of the 3 species of lupine required by the Mission Blue by removing all vegetation mechanically and with prescribed burns, then seeding with lupine.
  • Neither burn nor mechanical treatments resulted in increased lupine species cover after one or three years. In fact, both mechanical and burn treatment resulted in increased cover of non-native forbs and grasses after three years.

In other words, 500 trees were destroyed, which were heavily used by migrating raptors, but Mission Blue butterflies did not benefit from the destruction of these trees because efforts to restore the habitat they require have been completely unsuccessful.  This is a familiar scenario:  all loss and no gain.

Karner blue butterfly - USFWS
Karner blue butterfly – USFWS

We also heard a presentation about a 20-year effort to “restore” the habitat required by an endangered butterfly (Karner blue) at Indiana Dunes National Lakeshore.  The complete failure of that effort is attributed to changes in the climate, considered “abnormal:”

Despite advances in our understanding of habitat needs of the Karner blue, and extensive management to meet those needs, Karner numbers at Indiana Dunes have fallen more than 99% over the past fifteen years, with precipitous declines associated with historically abnormal weather in 2012. We have documented a role phenological [seasonal] mismatching between the butterfly and its host plant plays in this population decline and the sensitivity of this species to habitat fragmentation.”

One wonders what “abnormal” weather means during a time of extreme changes in the climate, which are not expected to return to “normal.”  The speaker predicted that the likely outcome for the Karner blue at Indiana Dunes is its complete disappearance and probable replacement with a different butterfly species which is better adapted to the new climate.

Reality Check

Doug Johnson, Executive Director of the California Invasive Plant Council, made a presentation about new digital tools to identify populations of plants considered “invasive:”  CalWeedMapper and WHIPPET.  These tools will enable land managers to set priorities for attempts to eradicate these plants.  Using  a thistle species as an example, he showed a map that indicated this “invasive” plant is present everywhere in northern California, but there are isolated pockets of it south of there.  These small, isolated populations represent potential opportunities to prevent its spread before it is so widespread that eradication is impossible.  This is an example of triage, which was the dominant theme of the conference. 

Oxalis in Glen Canyon Park, San Francisco
Oxalis in Glen Canyon Park, San Francisco

Mr. Johnson was recently interviewed by Bay Nature about a non-native species of oxalis, which San Francisco’s so-called Natural Areas Program has been attempting to eradicate for many years by spraying it with Garlon.  Garlon is the most hazardous pesticide used by the Natural Areas Program.  Mr. Johnson expressed his opinion to Bay Nature that it is futile to attempt to eradicate oxalis: “‘It’s not a target for landscape-level eradication because it’s way too widespread.’”

On March 13, 2015, the California Invasive Plant Council published its final reassessment of Blue Gum Eucalyptus (available HERE).  Cal-IPC has downgraded its rating of invasiveness and ecological impact from “moderate” to “limited.”  Although the detailed assessment is less than perfect, the overall rating itself is an improvement.  We are grateful to our readers who sent comments to Cal-IPC on its deeply flawed first draft of the reassessment.

In other words, the California Invasive Plant Council seems to have entered a new era of realistic expectations.  This looks like a BIG step forward to us, because if that viewpoint is adopted by land managers it should mean less destruction and less use of pesticides.

The Take Away

The old guard is unprepared to compromise their firm belief that it is possible to save every species of native plant and animal and that every non-native plant and animal must be killed to achieve that lofty goal. They defend their indefensible opinion by attacking those who are looking for a more realistic approach to conservation. However, climate change is bringing more and more converts to this viewpoint, which was best expressed by one of the plenary speakers, Hugh Possingham, Professor of Mathematics and Ecology, University of Queensland in Australia.  He was asked how his model of “ecological parks” fits with the mission of the National Park Service to preserve the parks “unimpaired.”  We paraphrase Professor Possingham’s answer:

“The Australian conservation ethic is similar to the United States’.  We yearn for pre-invasion days.  When I grew up in Adelaide we had 7.5 hectares of pristine vegetation for the entire city, which had 750 species at one time and now there are 500 species left.  It’s a museum.  It isn’t a functioning ecosystem.  So, we have got to embrace the creation of ecosystems that are not particularly natural.  However, I’ve learned that the birds don’t care where the plants come from.  Where weeds have been ripped out, bird diversity has plummeted.  I have been converted to the European viewpoint of disturbed landscapes: that is, these new plants have value.  Australia is completely over-run with non-native plants and animals.  Australians would be willing to shoot all the feral cats, but the fact is it’s not possible because we don’t have the resources to attempt it, let alone succeed at it.”

Thank you, Professor Possingham, for your frank acknowledgement of the value of new species to wildlife and your acceptance of more realistic goals for conservation in the 21st Century.


Videos of the plenary speakers are available on the conference website, as well as abstracts of posters and presentations.

Birds and butterflies in the eucalyptus forest

The deadline for sending comments to the California Invasive Plant Council (Cal-IPC) about their draft reassessment of blue gum eucalyptus is Thursday, July 31, 2014 (send to info@cal-ipc.org).  We are hoping to inspire you to write your own comment by sharing our personal favorites of some of the goofy statements Cal-IPC uses to justify its classification of blue gum as “moderately invasive.”

Eucalyptus trees do NOT kill birds!

Our regular readers have heard the absurd claim that eucalyptus trees kill birds by “gumming” up their noses or beaks with the nectar of the eucalyptus flowers.  We have published detailed critiques of this claim, so we won’t repeat them because you can visit those posts by clicking HERE and HERE.

Of course, all of this detailed information was provided to Cal-IPC when the original request to reconsider their classification of blue gum was submitted in December 2013.  In their draft reassessment, Cal-IPC now sinks to a new low by claiming Ted Williams as the source of the claim that eucalypts kill birds.  Mr. Williams writes an opinion column published by Audubon magazine, which is appropriately entitled “Incite.”  In 2002, Audubon magazine published Mr. Williams’s opinion of eucalyptus, which he called “America’s Largest Weed.” 

Ted Williams is not a scientist or a journalist.  He is a commentator. His column in Audubon magazine is not entitled “Insight,” because it is intentionally inflammatory.  It engages in rhetoric and hyperbole in support of Mr. Williams’s opinion.  In an article in High Country News, Mr. Williams describes “Incite” as a “muckraking column” and he calls himself an “environmental extremist.”  Citing Mr. Williams as a source of information undermines the credibility of Cal-IPC’s draft reassessment.  Quoting Mr. Williams on the subject of eucalyptus is a bit like quoting Rush Limbaugh on the subject of immigration.

But let’s be more specific with examples of the absurd statements Mr. Williams makes and the evidence that these statements are not factually correct.

The truth about Anna’s hummingbirds

Hummingbird in eucalyptus flower.  Courtesy Melanie Hofmann
Hummingbird in eucalyptus flower. Courtesy Melanie Hofmann

Cal-IPC’s draft reassessments says, “Williams reported that PRBO found that 50% of the Anna’s hummingbird nests [in eucalyptus] are shaken out by the wind, while only 10% of nests are destroyed by wind in native vegetation.”

Cal-IPC’s quotes from Williams are not found in any publication of the Point Reyes Bird Observatory (PRBO), which Williams claims as the source of the information.  Statements about the nests of Anna’s hummingbird are explicitly contradicted by Cornell Ornithology Laboratory, America’s preeminent research institution of bird biology and behavior:

  • “In the first half of the 20th century, the Anna’s Hummingbird bred only in northern Baja California and southern California.  The planting of exotic flowering trees provided nectar and nesting sites, and allowed the hummingbird to greatly expand its breeding range.”
  • “Anna’s Hummingbird populations increased by almost 2% per year between 1966 and 2010, according to the North American Breeding Bird Survey…The Anna’s Hummingbird is the most common hummingbird on the West Coast, and it has thrived alongside human habitation.  Its range has increased dramatically since the 1930s, when it was found only in California and Baja California.  Thanks to widespread backyard feeders and introduced trees such as eucalyptus, it now occurs in healthy numbers all the way to Vancouver, Canada.”
  • “Females choose the nest site, usually a horizontal branch of trees or shrubs 5-20 feet off the ground (occasionally higher) near a source of nectar.  They often build nests in oak, sycamore, or eucalyptus trees…”
  • “They [Anna’s Hummingbirds] are notably common around eucalyptus trees, even though eucalyptus was only introduced to the West Coast in the mid-nineteenth century.”

In other words, the nation’s most prestigious ornithological research institution tells us that Anna’s Hummingbirds have benefited greatly from eucalyptus trees, which provide both winter sources of nectar not otherwise available in California as well as safe, secure nesting habitat.  Since Anna’s Hummingbirds nest preferentially in eucalyptus, their populations would not be increasing if 50% of their nests were destroyed, as Mr. Williams claims.

Red-tailed hawk nesting in eucalyptus.  Courtesy urbanwildness.org
Red-tailed hawk nesting in eucalyptus. Courtesy urbanwildness.org

Furthermore, the implication that eucalypts provide a less stable nest site than native trees is also explicitly contradicted by a study that Cal-IPC cites elsewhere in its draft reassessment.  Stephen Rottenborn studied the nesting choices and reproductive success of red-shouldered hawks in Santa Clara County.  He found that the hawks prefer eucalypts to native trees and that their nests were more successful when they made that choice.  He attributes that greater success rate to the fact that eucalypts are “large, sturdy trees” that provide “greater stability and protective cover.”

“Fourteen of 27 nests in 1994 and 38 of 58 nests in 1995 were in exotic trees, predominantly eucalyptus.  Nesting and fledging success were higher in exotic trees than in native trees in both years, owing in part to greater stability and protective cover.  Most nest trees in upland areas were exotics, and even in riparian habitats, where tall native cottonwoods and sycamores were available, Red-shouldered Hawks selected eucalyptus more often than expected based on their availability.  Of the habitat and nest-tree variables measured at each nest, only nest-tree height and diameter were significantly associated with reproductive success, suggesting that large, sturdy trees provided the best nest sites.  Red-shouldered Hawk populations in the study area have likely benefited from the planting of exotic eucalyptus and fan palms.” (1)

 Magic!  Turning 2 dead birds into 300

Cal-IPC’s draft reassessment says, “Stallcup reported finding two dead warblers and ‘about 300 moribund warblers with eucalyptus glue all over their faces’ over the years, including ‘a large number of gummed-up Townsend’s warblers, yellow-rumped warblers, ruby-crowned kinglets, Anna’s and Allen’s hummingbirds, and a few Bullock’s orioles. Anyone who birds around eucalyptus trees sees it all the time’ (Williams 2002).”

This particular quote from Ted Williams is easily discredited because Rich Stallcup published his theory about birds being harmed by eucalyptus trees (available HERE).  In this publication, Mr. Stallcup reports seeing just two dead birds (one hummingbird and one ruby-crowned kinglet) in the eucalyptus forest during his long, illustrious career as an amateur birder.  He says nothing about seeing “300 moribund warblers” in his publication.  A small measure of common sense enables the reader to evaluate Mr. Williams’s claim:  If Mr. Stallcup had seen 300 dying birds, why would he say he had only seen 2 dead birds in his published article in which he is trying to make the case for removal of eucalyptus?

Overwintering monarch butterflies use predominantly eucalyptus

Monarch butterflies roosting in eucalypus tree.
Monarch butterflies roosting in eucalypus tree.

Cal-IPC’s draft reassessment says, “Natural experimental evidence from mixed stands (native trees mixed with eucalyptus) show that Monarchs do not consistently cluster preferentially on eucalyptus, and at times, appear to prefer native trees in some seasons and locations. (Griffiths & Villablanca 2013)”

This is a misleading statement because it implies that monarchs have the option of overwintering in native trees.  In fact, the reference cited by Cal-IPC is speaking specifically of three species of native trees with small native ranges:  Monterey pine, Monterey cypress, and redwoodsThe study is reporting observations of monarchs within the native ranges of these three tree species.  These tall trees provide a similar microclimate to overwintering monarchs.     However, the native ranges of these tree species are small.

Monterey pines are native in “three disjunct populations in San Mateo and Santa Cruz counties, Monterey County, and San Luis Obispo County.  The native population of Monterey cypress is significantly smaller:  “The native range of the species was confined to two small relict populations, at Cypress Point in Pebble Beach and at Point Lobos near Carmel, California.” Where Monterey pine and cypress have been planted outside their native range, they are being eradicated by the same public land managers who are eradicating eucalyptus.

For example, when UC Berkeley destroyed approximately 18,000 non-native trees over 10 years ago, many were Monterey pines.  Their plans to eradicate 80,000 more trees include all Monterey pines in the project area.  In San Francisco, the plans (SNRAMP) of the Natural Areas Program propose to destroy many Monterey cypresses on Mount Davidson.  The GGNRA has destroyed about 500 Monterey pines on Hawk Hill in Marin County and many Monterey cypresses throughout their properties.

Furthermore, both Monterey pine and Monterey cypress have much shorter lives than eucalyptus.  Monterey pine lives at most 150 years and Monterey cypress about 250 years, compared to E. globulus, which lives in its native range from 200-500 years.  Therefore, even where they are not being eradicated, they will die long before E. globulus and are unlikely to be replanted outside their small native range by public land managers who are committed to a “natives-only” policy.

We are unaware of any attempts to eradicate redwoods outside their native range, in the few locations where they still exist. They seem to have escaped the wrath of nativism. However, the range of redwoods is very narrow:  “The redwoods occupy a narrow strip of land approximately 450 miles (724 km) in length and 5 to 35 miles (8-56 km) in width.  The northern boundary of its range is marked by two groves…within 15 miles (25 km) of the California-Oregon border.  The southern boundary of redwood’s range is marked by a grove…Monterey County, California.”

Although native plant advocates may be willing to plant redwoods outside their native range, they do not have that option because of the horticultural requirements of redwoods.  Redwoods require more water than Monterey pine and cypress and they do not tolerate wind, which prevents them from being successful in many coastal locations, where monarchs overwinter.  Redwoods cannot be successfully grown south of Monterey County where the climate is warmer and drier than its native range.

In other words, monarchs do not have the option of roosting in native trees in most of the places in California where they overwinter.  This is a more accurate description of the behavior of overwintering monarchs and the alternatives that are available to them in about 300 locations along the entire coast of California, where they have overwintered in the past:

Three types of trees were used most frequently by roosting monarchs:  eucalyptus (75% of the habitats primarily Eucalyptus globulus), pine (20% of the habitats; primarily Pinus radiata), and cypress (16% of the Cupressus macrocarpa).  Twelve other tree species were identified…with a combined prevalence of only 10%…The negative sign for this indicator means that habitats had smaller populations when the roosting tree type was a species other than eucalyptus, pine, or cypress…our long-term analysis showed that abundance has historically been greater at habitats dominated by eucalyptus, pines, or cypress than at those with ‘other’ species.  Stands of these three signature taxa may be more likely to produce a community structure and associated microclimate that increases the residence time of monarchs.  Furthermore, these taxa may produce a more attractive landscape architecture in terms of sensory cues to migratory monarchs arriving in a certain region.” (2)

For the record, we will add that we would be happy to have more Monterey pines and cypress and if public land managers would quit destroying them, we would consider them attractive alternatives to eucalyptus.  However, for the moment, we must assume that the crusade against all non-native trees will continue unabated.

What is your personal favorite?

We have shared our personal favorites with you, but everyone comes to this issue from a different place.  We have been flabbergasted by the unfounded claims that the eucalyptus forest is devoid of life.  We wonder if the people who say that, really believe it.  Or is it just one of the many strategies used to justify their demands that our non-native landscape be destroyed?

Please choose your own personal favorite and write your own comment by Thursday, July 31, 2014.  Are you primarily concerned about the herbicides that are needed to prevent the trees from resprouting when they are destroyed?  Are you concerned about the loss of your protection from wind or noise?   Or do you value eucalyptus as a sight screen or for shade in an otherwise treeless environment?  Are you concerned about the carbon loss that will contribute to climate change?  Please help us to save our urban forest from being needlessly destroyed by telling Cal-IPC why they should take blue gum eucalyptus off their “hit list.”

Thank you for your help to save our urban forest.

Update:  On March 13, 2015, the California Invasive Plant Council published its final reassessment of Blue Gum Eucalyptus (available HERE).  Cal-IPC has downgraded its rating of invasiveness and ecological impact from “moderate” to “limited.”  Although the detailed assessment is less than perfect, the over all rating itself is an improvement.  Thanks to those who sent comments to Cal-IPC.


(1)    Stephen Rottenborn, “Nest-Site selection and reproductive success of urban red-shouldered hawks in Central California,” J. Raptor Research, 34(1):18-25

(2)    Dennis Frey and Andrew Schaffner, “Spatial and Temporal Pattern of Monarch Overwintering Abundance in Western North America,” in The Monarch Butterfly Biology and Conservation, Cornell University Press, 2004.

Tracking down the truth about blue gum eucalyptus

Last week, we told our readers about the California Invasive Plant Council’s (Cal-IPC) draft reassessment of blue gum eucalyptus, Eucalyptus globulus. (available HERE) Cal-IPC is accepting comments on its draft until July 31, 2014 (send to info@cal-ipc.org).  Although Cal-IPC now acknowledges that blue gum has “low invasive potential” and its population is stable in California, it proposes to maintain its over-all classification of “moderately invasive.”  You might wonder how Cal-IPC manages to accomplish this sleight of hand, so we will tell you how its scoring system enables it to maintain its overall rating of blue gum.

Cal-IPC has three main evaluation categories:  “Impact,” “Invasiveness,” and “Distribution,” which are combined to produce an over-all rating.  Cal-IPC’s draft lowers the rating of “invasiveness” to “limited,” but it has changed its rating of “impact” from “moderate” to “severe.”  These changes cancel one another, enabling them to reach the same over-all rating of “moderately invasive.”  In this post, we will focus your attention on Cal-IPC’s opinion of the “impact” of blue gum so that you can see how they arrived at their conclusion. 

Drought is on our minds

Epicormic sprouts on trees in Glen Canyon Park, June 2014
Epicormic sprouts on trees in Glen Canyon Park, June 2014

As we told our readers recently, the drought in California is making water use an important issue that is getting a lot of attention, as it should.  Native plant advocates have not hesitated to jump on that band wagon.  For example, they now claim that eucalypts in San Francisco are dying of drought.  With the help of a highly qualified arborist, we evaluated that claim in a recent post and reported that the trees are reacting to the loss of their understory and their neighboring trees, as well as the herbicides used to kill the understory and prevent their former neighboring trees from resprouting from their stumps.

Given this recent experience, we weren’t surprised to find that Cal-IPC has introduced accusations of extreme water use into their assessment of blue gum for the first time, and this new issue helps them to claim that blue gums have a “severe” impact on the environment.  Now let’s drill down into this claim, examine the source of the claim and tell you why we believe this is another bogus issue used to vilify eucalyptus.

Tracking down the truth about water use by blue gums was a bit like a game of gossip.  Starting with the final version of the rumor in Cal-IPC’s draft reassessment, we tracked that version back to its original source.  We found exaggeration at each iteration of the rumor, from its source to its landing in the Cal-IPC draft.  The final version bore little resemblance to the original version.  The original version is over 100 years old and therefore describes circumstances that have since changed substantially.

Exaggerated and outdated description of root structures

Cal-IPC’s draft assessment of “impact on hydrology” is: “Eucalyptus globulus is adept at tapping into deep groundwater, even under drought conditions (DiTomaso & Healy 2007), altering water availability to depths of 45 feet and distances of 100 feet from the trunk.”

The first distortion of evidence occurs with Cal-IPC’s exaggeration of its cited source.  Here’s what DiTomaso & Healy actually said about the roots of blue gum:   “In deep soils with high water tables or other deep soil water source, lateral roots grow toward the moisture source and can deeply penetrate soil to 14 m deep.”  In other words, DiTomaso and Healy say that such deep roots occur only in certain conditions of “deep soil,” “high water table,” or a “moisture source.”

The source of DiTomaso & Healy’s description of the roots of blue gum is a similar statement in Bean & Russo, who wrote an evaluation of blue gum for the Nature Conservancy in 1989:  “Large roots have been discovered at a depth of 45 feet below the surface, and surface roots frequently spread over 100 feet away from the trunk. (Sellers 1910)”

Bean & Russo provide a reference for their statement, which takes us to the original version of this rumor.  A book about eucalyptus in California by C.H. Sellers was published in 1910.  Here is what Sellers actually says about the roots of E. globulus, grown in the State of California

“The root system consists mostly of numerous strong laterals; the tap root rarely penetrates to a depth of more than 10 feet.  Abundant supply of moisture is demanded and as the roots grow quickly toward water Eucalyptus globulus should never be planted near wells, cisterns, water pipes, irrigating ditches or similar water impounding structures.  In loose, sandy or gravelly soils the large lateral roots penetrate to great depth, and extend almost incredible distances.  In digging wells large roots have been discovered at a depth of 45 feet below the surface and the surface roots of large trees frequently spread over 100 feet from the trunk of the tree.” (1)

In other words, the extreme root lengths reported by DiTomaso & Healy are an anomaly, only found in specific conditions and unusual cases.  The roots of E. globulus are “rarely” deeper than 10 feet, according to this original source of information regarding the roots of E. globulus

Contemporary sources which are not trying to make a case against E. globulus describe its roots in a less extreme manner: “Bluegum eucalyptus generally does not form a taproot.  It produces roots throughout the soil profile, rooting several feet deep in some soils.” (Esser 1993)  Also:  Bluegum eucalyptus generally does not form a taproot. It produces roots throughout the soil profile, rooting several feet deep on soils that permit it, or shallowly otherwise.” (Skolmen & Ledig 1990)  Esser and Skolmen wrote their evaluations of blue gum for the US Forest Service.

Bringing Sellers up to date

We will assume that Sellers’s observations are accurate, but we will now consider the possibility that an observation that is over 100 years old may not be relevant to present conditions. For a more contemporary perspective on blue gum, we turn to R.G. Florence, an Australian academic scientist who studies eucalyptus and was also a visiting professor at UC Berkeley.  R.G. Florence helps us to understand why the observations of Sellers may be very different from more recent observations:  “As a tree develops through the sapling and pole stages it will tend to form a main root which penetrates vertically downward, but this main root is rarely significant in a large tree.“ (2) Florence reports that E. globulus uses more water during early stages of growth, when it is growing quickly, than it does as a mature tree.  Sellers was reporting in 1910 at a time when most eucalypts in California were young.  Their roots may have been longer during these early stages of growth.  Since E. globulus has not been planted in California for decades and is no longer available for planting, its root structure at early stages of development is irrelevant to evaluating its behavior in California presently.

Is blue gum drought tolerant?

Cal-IPC denies that blue gum is drought tolerant:  “E. globulus is able to withstand prolonged dry summers by tapping into deep water reservoirs; they do not economize in the use of water but have far-reaching root systems and can extract water from the soil at even higher soil moisture tensions than most mesophytic plants (Pryor 1976, Florence 1996).”

Once again, Cal-IPC misquotes its cited sources.  R.G. Florence does not make the statement that Cal-IPC attributes to him.  Rather, this is how Florence describes the water needs of eucalypts:  “…the eucalypt might be generally characterized as being a drought-tolerant mesophyte, that is, it tends to maintain transpiration and cell metabolism under conditions of developing drought.”  (2)

Florence says drought tolerance and water use varies by species of eucalyptus.  He places E. globulus in this category of drought tolerance:  “coastal zone species with high rates of growth and water use, but with somewhat wider environmental [drought] tolerance.”  He makes these observations about water use by E. globulus:

  • Water use is greatest when the trees are young and generally tapers off as the tree grows, between 10-15 years of age.  As we have said, only mature E. globulus exists in California presently or will in the future.
  • E. globulus has been observed to regulate water use by opening and closing its stomata in response to temperature and moisture:  “Water use may be regulated in this way.” (2)

Pryor’s description of drought tolerance of eucalypts was published 20 years earlier than Florence at a time when variations in drought tolerance of different species of eucalyptus had not yet been studied.  He therefore, does not report on the ability of E. globulus to withstand drought, as Florence does in 1996.  He acknowledges some variability with respect to drought tolerance in genus Eucalyptus, which is consistent with Florence’s later report specifically about E. globulus, although Pryor says nothing specifically about E. globulus.

Self-watering blue gums

Sutro forest on a typical summer day.  Courtesy Save Sutro Forest.
Sutro forest on a typical summer day. Courtesy Save Sutro Forest.

E. globulus was planted most widely along the coast of California.  Most of the coast of California is foggy during summer months, when there is little if any rainfall.  Tall eucalypts are known to condense the moisture in the fog which has been measured to double annual rainfall. (3) In these regions, eucalyptus is essentially self-watering.  Ironically, Cal-IPC acknowledges this self-watering feature of eucalypts:  “The volume of water channeled down the stem is about eight times more than that of falling rain, so soil at the base of trunks receives relatively large quantities of water…” (May & Ash, see “allelopathy” section of Cal-IPC draft).

A recent study conducted in 24 parks in San Francisco measured moisture in the soil in the late summer months (August to September), when the soil would be driest in the absence of fog condensation.  That study reported that the greatest amount of moisture (15%) was found in the parks with eucalyptus forests.  Soil in parks vegetated with grassland or scrub contained significantly less moisture.  In other words, even late in the dry season mature eucalypts were not draining all available moisture from the soil.  Their water needs were met by the condensation of moisture from the fog during the dry summer season. (4)

Please come to the defense of our urban forest!

We hope that we have made the case that the draft reassessment is not a fair evaluation of the predominant tree in our urban forest, blue gum eucalyptus.  We ask that you write to Cal-IPC by July 31st about their biased reassessment.  Tell them why you think our urban forest is important to the environment and the people and animals living in it.  Ask them to remove blue gum eucalyptus from their “hit list” which is being used by managers of our public lands to justify the destruction of our urban forest. 

Eucalyptus forest, Lake Chabot
Eucalyptus forest, Lake Chabot

Thank you for your help to save our urban forest from being needlessly destroyed.

Update:  On March 13, 2015, the California Invasive Plant Council published its final reassessment of Blue Gum Eucalyptus (available HERE).  Cal-IPC has downgraded its rating of invasiveness and ecological impact from “moderate” to “limited.”  Although the detailed assessment is less than perfect, the over all rating itself is an improvement.  Thanks to those who sent comments to Cal-IPC.

 


 

 

(1)    C.H. Sellers, Eucalyptus:  Its history, growth and utilization, published by A.J. Johnston, Sacramento, CA, 1910

(2)    R.G. Florence, Ecology and Silviculture of Eucalypt Forests, CSIRO, 1996

(3)    Page 37, Weather of the San Francisco Bay Area, Harold Gilliam, 2002

(4)    Kevin M. Clarke, et.al., “The influence of urban park characteristics on ant communities,” Urban Ecosyst., 11:317-334, 2008