Tag: California Invasive Plant Council

Talking back to nativism

Dana Milbank is a political columnist for the Washington Post. He broke out of his political mold on April 7, 2023 to write an article about gardening published by the Post, which repeats every myth of the nativist ideology. 

A team of dismayed critics of invasion biology has responded to excerpts of Milbank’s column:

  • Marlene A. Condon is a garden writer based in Virginia and the author of The Nature Friendly Garden. She has a degree in physics. Her entire critique of Milbank’s column is available on her website.  Her comments address the reader.
  • Carol Reese is a retired Extension Horticulture Specialist who conducted her 27 year career from the University of Tennessee’s West Tennessee AgResearch and Education Center in Jackson, where a large and diverse display garden gave her the opportunity to observe biodiversity in action on an enormous range of plant species from other parts of the world. She describes herself as a farm raised country girl tomboy who has looked at the natural world in hundreds of settings and landscapes, natural and manmade, and read countless books and articles. She has written for several magazines, newspapers, articles for Garden Rant as well as university publications.  Her speaking engagements around the country have allowed her to engage with many other green industry professionals. Dana Milbank’s column prompted her to email him directly with her concerns, directly addressing some of his assertions. I publish some excerpts here from her emails sent directly to Milbank.
  • Conservation Sense and Nonsense is the webmaster of this website.  I have studied invasion biology and the native plant movement it spawned for over 25 years. I’ve watched forests of healthy, non-native trees in California be destroyed and replaced by weedy grassland.  I have used what I have learned to advocate for a less destructive approach to restoration, a word I am reluctant to use to describe projects that use herbicides to eradicate harmless plants and trees. My comments are addressed to the reader.

What follows are excerpts from Dana Milbank’s column with responses from Marlene Condon, Carol Reese, and Conservation Sense and Nonsense, just three of many skeptics of invasion biology.  To summarize the point of our criticism:

  • Insects are not dependent on native plants.  They are just as likely to use related non-native plants in the same genus or even plant family with similar chemical properties and nutritional value. 
  • While some non-native plants have potential to be harmful, many are beneficial. There are pros and cons to both native and non-native plants and that judgment varies from one animal species to another, including humans. For example, we don’t like mosquitoes, but they are important food for bats and birds.  
  • All plants, whether native or non-native convert carbon dioxide to oxygen and store carbon. Destroying them contributes to greenhouse gases causing climate change.
  • When the climate changes, vegetation must also change.  Many non-native plants are better adapted to current climate and environmental conditions in disturbed ecosystems.

Conservation Sense and Nonsense

“I’m no genius about genuses, but your garden is killing the Earth”
By Dana Milbank
Washington Post, April 7, 2023

Milbank:  I did almost everything wrong.

Reese:  I’m so sorry you thought this!

Milbank:  For 20 years, I found the latest, greatest horticultural marvels at garden centers and planted them in my yard: sunny knock-out roses, encore azaleas, merlot redbud, summer snowflake viburnum, genie magnolia, firepower nandina

In between them flowed my lush, deep-green lawn. I hauled sod directly from the farm and rolled it out in neat rows. I core-aerated, I conditioned, I thatched, I overseeded, I fertilized. I weeded by hand, protecting each prized blade of tall fescue from crabgrass and clover.

In this season, a symphony of color performs in my yard. The fading daffodils, cherry blossoms, saucer magnolias, hyacinths and camellias meet the arriving tulips, lilacs, creeping phlox and azaleas, with the promise of rhododendrons, peonies, hydrangeas, day lilies and roses to debut in the coming weeks.

But this year, the bloom is off the rose. And the hydrangea. And the rhododendron. And all the rest. It turns out I’ve been filling my yard with a mix of ecological junk food and horticultural terrorists.

Condon:  When Mr. Milbank posits that he’s “been filling his yard with a mix of ecological junk food and horticultural terrorists,” he’s channeling the kind of words Bringing Nature Home author Doug Tallamy loves to employ:  Biased expressions that implant negative images in the reader’s mind so he will become yet another minion of this scientist.  Nowadays you can’t read a garden or environmental column without being accosted with the same words or variations thereof, as if everyone has become a mouthpiece for Doug Tallamy, which I’ve never seen done more obviously than in this column by Dana Milbank. 

Conservation Sense and Nonsense:  Milbank’s lengthy list of “bad” plants in his garden paints with too broad a brush.  For example, instead of identifying a particular species of hydrangea and rhododendron, Milbank condemns an entire genus.  Both hydrangea and rhododendron genera have several native species within the genus.  Most (all?) species of phlox are also native to North America. 

Milbank:  When it comes to the world’s biodiversity crisis — as many as 1 million plant and animal species face near-term extinction because of habitat loss ― I am part of the problem. I’m sorry to say that if you have a typical urban or suburban landscape, your lawn and garden are also dooming the Earth.

Reese:  YIKES! This is pretty extreme, and dare I say inaccurate? No, home gardeners are part of the solution, no matter the plants in their garden. Doom will come from lack of diverse green space. Doom will come from climate warming as a result, as well as from pollution, tillage, factory farming and development.

Milbank:  I came to understand the magnitude of my offenses after enlisting in nature boot camp this spring. I’m in “basic training” with the state-sponsored Virginia Master Naturalist program. While others sleep in on rainy weekend mornings, my unit, the Arlington Regional Master Naturalists, has us plebes out in the wetlands distinguishing a yellow-bellied sap sucker from a pileated woodpecker.

I’m no genius with genuses, but I know a quercus from a kalmia, and because of my gardening experience, I began the program with confidence. Instead, I’ve discovered that all the backbreaking work I’ve done in my yard over the years has produced virtually nothing of ecological value — and some things that do actual harm.

A few of the shrubs I planted were invasive and known to escape into the wild. They crowd out native plants and threaten the entire ecosystem. Our local insects, which evolved to eat native plants, starve because they can’t eat the invasive plants or don’t recognize the invaders as food.

Anise swallowtail on non-native fennel. Courtesy urbanwildness.org “Papilio zelicaon, the anise swallowtail, typically has one to two generations in the mountains and foothills of California where it feeds on native apiaceous hosts. However, along the coast, in the San Francisco Bay Area and the urbanized south coastal plains and in the Central Valley, P. zelicaon feeds on introduced sweet fennel, Foeniculum vulgare, and produces four to six or more generations each year… the use of exotics has greatly extended the range of P. zelicaon in lowland California.” SD Graves and A Shapiro, “Exotics as host plants of the California butterfly fauna,” Biological Conservation, 2003.

Reese:  It sounds so logical, but is sooo inaccurate. Ask any entomologist that has spent their careers “fighting pests” on valued crop or ornamental plants. Remember Pangea [when all continents were fused into one]? More recently, have you thought about the exchange of plants and animals across Berengia when we were still connected to Asia? We can trace those relationships/kinships of our plants to Asian/Eurasian plants now through DNA. They eventually differentiated into species (a continuum of change caused by climate and geologic pressures until we [Man] declare it as a different species, though biologically it is still basically the same nutritional makeup)

Condon also dissects Milbank’s statement: 

  • “They crowd out native plants and threaten the entire ecosystem.”  Read virtually any description of where you find so-called invasive plant species and you will find the word “disturbed.”  This tells you the soil profile has been negatively impacted by people, animals, or weather, and usually means the topsoil is gone.  Only very tough plants—known as colonizers—can grow in disturbed areas because the soil is nutrient-poor and is typically compacted.  Consequently, these areas may fill with a mix of native and nonnative plants, or mainly one or the other—but every single plant is a colonizer that is working to rehabilitate the land for the benefit of the native plants that require topsoil in which to grow.  “Invasiveness” is nothing more than a derogatory word used by people with contempt for alien-plant colonization.  Conclusions:  Alien plants can’t “crowd out” native plants because once the soil is disturbed and thus degraded, most of our native plants can’t grow there and thus are not there to be crowded out.  As for “threatening the entire ecosystem,” to the contrary, alien colonizers are helping to restore it.
  • “Our local insects, which evolved to eat native plants, starve because they can’t eat the invasive plants or don’t recognize the invaders as food.”  This oft-repeated distorted premise comes straight out of Bringing Nature Home, in which Doug Tallamy deceptively writes about “an excellent demonstration of how restricted a specialist’s [an insect with particular food preference] diet is.” Tallamy tells the story of Eastern Tent caterpillars on a cherry tree denuded of its own leaves but hosting a Japanese Honeysuckle vine.  He writes that the caterpillars didn’t recognize the honeysuckle as food (sound familiar?)  But, of course, they didn’t because this species of insect can only eat plants in the Rose Family, which does not include honeysuckle.  What Doug Tallamy doesn’t tell the reader is that the tent caterpillars could certainly have eaten the so-called invasive Multiflora Rose, which I’ve documented in the photo below.  Conclusion:  Native insects did not evolve to eat only local (native) plants, but rather can typically feed upon dozens, if not hundreds or thousands, of plants related to each other by family classification, even though they grow in other countries.
Tent caterpillar on multiflora rose.  Photo by Marlene Condon.

Milbank:  This in turn threatens our birds, amphibians, reptiles, rodents and others all the way up the food chain. Incredibly, nurseries still sell these nasties — without so much as a warning label.

Reese:  As I read, I also watch the many birds on my lawn, the fence lizards on my decks, the insects humming among the flowers in my diverse collection of native cultivars and introduced plants. 

Hummingbird in eucalyptus flower. Eucalyptus blooms from November to May. It is one of the few sources of nectar and pollen for birds and bees during the winter months when little else is blooming. Courtesy Melanie Hoffman
Eucalyptus leaf litter makes excellent camouflage for this garter snake. Courtesy Urban Wildness

Milbank:  Most of my other plants, including my beloved lawn, are ecological junk food.

Reese:  Now, now! Many (most) natives do not supply useful forage either. All plants supply some benefit. They provide shelter, create, improve and anchor soil, cleanse air and water, make oxygen and cool the planet. The plant must be judged on benefits versus detriments in each situation. If a nonnative plant is the only thing that will flourish in bombed out rubble, or contaminated soil, if it is providing many benefits, shall we rip it out because caterpillars won’t eat it? If we let it get established, will it ready the site for other species with more benefits to become established? Shall we get out of the way and let nature do what she does, which is heal herself?

Milbank:  The trees, shrubs and perennials are mostly “naturalized” plants from Asia or Europe or “cultivars,” human-made varieties of native plants bred to be extra showy or disease resistant but lacking genetic diversity or value to animals. I, like other gardeners I know, planted them after mistaking them for their native cousins. They’re not doing harm, but neither are they doing anything to arrest the spiral toward mass extinction.

Reese:  Please know that the most influential native plant botanical garden in the country (Mt. Cuba Center)  has trialed the cultivars of native plants for their ecological benefits and found as should be expected, that each cultivar must be judged on its own merits. Some are better than the straight native as in the coneflowers where ‘Fragrant Angel’ scored tops for pollinators and many others were very close to being as good as straight species. These cultivars were even better than the other species of Echinacea tested. BTW, I grow E. purpurea, pallida, paradoxa, tennesseensis and laevigata as well as many cultivars. Remember that cultivars should also be judged on not just nutritional value, but other factors that increase benefits, such as length of bloom period, numbers of blooms, drought resistance, heat tolerance, hardiness, ease of production (cost) and durability. Please ask to speak to Sam Hoadley there as he leads the research on beneficial cultivars and has completed and undertaken several studies of different native species. Great guy and great speaker. 

Please be aware that many cultivars originated as naturally occurring deviations in seedling populations, and as we know this actually diversifies the genetic pool, allowing Mother Nature to select the better form. We sometimes agree with her, and other times we may move along that diversifying form by crossing it with others that are demonstrating genetic variance. Logically, this actually furthers the cause of a broader genetic pool that can help in today’s crisis in showing which can cope and flourish.

Milbank:  To get a sense of my missteps, I asked Matt Bright, who runs the nonprofit Earth Sangha, a native-plant nursery in Fairfax County (and a lecturer on botany for my nature boot camp) to walk through my yard with me.

He took aim at my day lilies: “I would remove them all. Those have also become badly invasive.”

He spied my creeping jenny on a slope: “Another nasty invasive.”

He condemned to death my rose of Sharon shrubs (natural areas “have really been torn up by these guys”) and my innocuously named summer snowflake viburnum.

Worst was my row of nandinas — “heavenly bamboo” — along the foundation. “You definitely want to remove it,” he advised. Its cyanide-laced berries poison birds.

Condon:  This tactic is typical of the followers of Tallamy who want folks to perceive supposedly invasive plants as “bad” even though no evidence exists to support their accusations, especially in this instance.  Mr. Milbank and Mr. Bright, who obviously supplied this information, have misspoken here.  A study out of the University of North Carolina, Chapel Hill, published in 2022, explains that Cedar Waxwings are the only birds that might be poisoned, and that’s only going to happen if someone grows so many nandinas that these birds consume large numbers of fruits in a single feeding bout.  If you grow just one or even a few plants, you are not going to poison waxwings.

Conservation Sense and Nonsense:  Here in California, most berry-producing, non-native plants are considered “invasive” based on the assumption that birds eat the berries and spread the plants.  Nandina was briefly on the list of invasive plants in California until knowledgeable people informed the California Invasive Plant Council that birds don’t eat the toxic berries.  Nandina was removed from the invasive plant inventory long ago.

Bumblebee on Cotoneaster, Albany, CA. Cotoneaster is one of many berry-producing non-native plants on the list of invasive plants in California. Himalayan blackberries are another target for eradication in California. They are frequently sprayed with herbicide in public parks where children and other park visitors eat the blackberries.

I also have personal experience with nandina and cedar waxwings.  Flocks of waxwings visited my holly trees in San Francisco every year.  They did not touch my three nandina plants.

California buckeye (Aesculus californica) is an example of a native tree that is toxic.  Its flowers are toxic to honeybees and its big brown seeds for which it is named were used by Indigenous people to stun fish to make them easier to catch.  The bark, leaves, and fruits contain neurotoxic glycoside aesculin.  Every negative characteristic attributed to some non-native plant species is equally true of some native plant species.  No one mentions buckeye’s toxic characteristics because it’s a beautiful native tree.  Photo Sacramento Tree Foundation

Condon:   I’ve had a Rose of Sharon (Hibiscus syriacus) growing in my yard since I moved to my home in Virginia almost 40 years ago. In all this time, only one seedling from the plant I brought here has ever “volunteered” to become a second yard denizen.  During the past 37 years, pollinators have fed at the original plant and then also at its offspring. What I’ve found by experience in my yard is that few plants can successfully move into a space that’s already filled with other plants. (Proving what physics tells us–that no two physical objects can occupy the same space).  I’ve brought home numerous so-called invasive plants, only to have them disappear or simply stay put where I planted them. That’s because hundreds, if not thousands, of plants fill my yard. 

Conservation Sense and Nonsense:  Virginia is one of only four states in which rose of Sharon is considered invasive.  Condon’s experience with rose of Sharon in Virginia suggests that lists of “invasive plants” are either inaccurate or are serving another purpose (perhaps both).  The longer the list of “invasive plants” the more work is created for the “restoration” (AKA eradication) industry.

Rose of Sharon is not considered invasive in California. This is a reminder that the behavior of plants varies because of the wide range of climate and environmental conditions.  Nearly one third of the plants on California’s list of invasive plants are not considered invasive in California.  They are on the list because they are considered invasive in Hawaii, a state with a warmer, wetter climate than California.  In naming rose of Sharon as a dangerous invasive, a media resource with a national readership has made a generalization that red-lines more plants than necessary.  They become targets for eradication with herbicide and they deprive us of the biodiversity that is particularly important in a changing climate in which biodiversity ensures resiliency.

Milbank:  Bright did praise two “good” species I have that contribute to biodiversity: a sycamore and a catalpa as well as a “great” American elm and a “phenomenal” dogwood. (I couldn’t take much pride in them, though, because all four were here long before I arrived.) And Bright assured me I wasn’t a particularly egregious offender; my one-sixth acre lot in town is typical of the urban/suburban landscape.

●  ●  ●

Lawns, and those useless, ubiquitous cultivars of trees, shrubs and perennials sold by the major garden centers, are squelching the genetic variety nature needs to adapt to climate change.

Reese:  It’s actually the opposite. We need more plants in the mix. We need “the tumult of nature” to decide. We aren’t the jury, and we continue to interfere with our well-intended assumptions that we know best.

Lawns are full of wildlife when management is minimal. Mow. That’s all. Mow judiciously when “lawn weeds” are blooming. Watch birds feed on the many insects in the lawn including lepidopteran larvae. Realize that many moths pupate underground. Think of your lawn as haven for them and for the grubs birds relish as millions of acres across our country are being tilled for factory farms. Remember that the best habitat is mixed. Open areas bordered by wooded areas and most species love the borders. Our suburban landscapes are ideal if we just stop killing things.

This is a lawn that serves pollinators. Homestead Stencil Company

Milbank:  The resulting loss of native plants in our fragmented urban and suburban landscapes deprives both plants and wildlife of the contiguous habitats they need to breed and, over time, to migrate in response to climate change.

The deck is stacked against nature in this fight.

●  ●  ●

If possible, you should remove the nastiest of the invasive plants if you have them: burning bush, Japanese barberry, Asian bush honeysuckle, English ivy, callery (Bradford) pear and a few others.

But leave the rest of your plants alone, for now. Tallamy ultimately wants to cut lawn acreage in half, but “there is room for compromise,” he said. Think of your noninvasive plants and cultivars as “decorations.”

Janet Davis, who runs Hill House Farm & Nursery in Castleton, Va., has a similar message for the purists who make you feel bad about your blue hydrangea. “Don’t give me crap about something that’s not native but not invasive,” she said. “I’m never going to tell you you can’t have your grandmother’s peony.”

Thus absolved, I shed my guilt about my yard full of ecological empty calories. I kept my hydrangeas, azaleas and roses but pulled out the truly bad stuff. I dug up the nandinas and replaced them with native winterberry holly, red chokeberry and maple-leaf viburnum. I removed the rose of Sharon and substituted American hazelnut and witch hazel. I uprooted the invasive viburnum and planted a native arrowwood viburnum in its place.

I also took a small step in the painful task of killing my beloved lawn. I used landscape fabric to smother about 400 square feet of turf. In its place, I planted a smattering of canopy trees (two white and two northern red oaks), understory trees (ironwood, eastern redbud), shrubs (wild hydrangea, black haw viburnum) and various perennials and grasses (Virginia wild rye, blue-stemmed goldenrod, American alumroot, woodrush, spreading sedge).

My 38 plants cost $439 at Earth Sangha. But these natives, adapted to our soil and conditions, don’t require fertilizer, soil amendments or, eventually, much watering. Over time, I’ll save money on mulch and mowing.

Reese:  This one is so oft repeated and so very wrong. It depends on the plant, and it depends on the site. Plants in the wild require no input to succeed whether native or not because we have not messed up the soil and we have let the natural cycles of plant debris/decay improve the soil as it was meant to, creating a live, moist, interaction of microorganisms that work symbiotically to support the plant, which, btw has also been selected by nature for that site. It has absolutely nothing to do with origins. In fact, why would nonnative plants become “invasive” if they did not adapt as well or better than the native plants? I want to snort with laughter!

Milbank:  Right now, my seedlings look pretty sad. Where once there were healthy lawn and vibrant shrubs, there is now mud and scrawny sprigs poking from the ground every few feet. I put up chicken wire to keep the kids (and me) from trampling them. The carcasses of my invasive plants lie in a heap on the gravel.

Condon:  This statement supports my contention that ridding your yard (and, in the case of government, natural areas and parks) of “invasive” plants destroys habitat, leaving our wildlife high and dry.  Follow the advice of Doug Tallamy, via Dana Milbank (and many others) and you make the environment far less hospitable to our wildlife by removing plants that supplied habitat NOW when our critters need it to survive.

Conservation Sense and Nonsense:  This description of Milbank’s ravaged garden is consistent with my 25 years of observing native plant “restorations” on public land.  They all begin with destruction, usually accomplished with herbicides.  The first stage of these projects is often described as “scorched earth.”  Years later, there is rarely habitat comparable to what was destroyed.  Colored flags usually outnumber plants. 

This is what a native plant garden on Sunset Blvd in San Francisco looked like after two years of effort: more colored flags than plants. The sign claims it is “pollinator habitat.” Since when do pollinators eat flags?

Milbank:  But in a couple of seasons, if all goes well, my yard will be full of pollinators, birds and other visitors in need of an urban oasis. Years from now, those tender oak seedlings, now 6-inch twigs, will stretch as high as 100 feet, feeding and sheltering generations of wild animals struggling to survive climate change and habitat loss.

Conservation Sense and Nonsense:  Destroying harmless vegetation contributes to climate change by releasing carbon stored in the living vegetation and reducing the capacity to sequester more carbon.  Above-ground carbon storage is proportional to the biomass of the living vegetation.  Destroying large, mature plants and trees releases more greenhouse gases in the atmosphere than the young plants and trees can sequester.  Meanwhile, the climate continues to change and the native plants that Milbank prefers are less and less likely to be adapted to conditions.  Native plant ideology is a form of climate-change denial. 

A small forest of non-native trees was destroyed in a San Francisco park to create a native plant garden. Nine months later, this is what the project looked like: a tree graveyard.

Milbank:  I won’t be alive to see it. Yet even now, my infant oaks give me something the most stunning cherry blossom never could: a sense of hope.

Conservation Sense and Nonsense:  I feel bad for Dana Milbank.  He has been successfully guilt-tripped into believing he has damaged the environment.  He hasn’t, but destroying his harmless garden WILL damage the environment. 

We hope he will find his way back to a less gloomy outlook on nature, which will outlast us all in the end.  Altered perhaps, but always knowing best what it takes to survive.  The way back from the cliff he is standing on is through a study of evolutionary change through deep time to appreciate the dynamic resilience of nature, which may or may not include humans in the distant future.  Our message is “Embrace the change because change will enable survival.”

Suggested reading for those standing on the steep cliff created by nativism in the natural world:

Revelations of the 2022 California Invasive Plant Council Symposium

I have attended the annual symposiums of the California Invasive Plant Council (Cal-IPC) for 5 years.  I have always learned something new and the most recent symposium in November 2022 was no exception.  This year there was a lot of important information about herbicides that are widely used to eradicate non-native plants. 

Several presentations reviewed the California laws that regulate pesticide use in California. (Slides for one of those presentations are available HERE.) The laws are designed to reduce risks of exposure to both applicators and the public. 

The presentations emphasized the importance of legally mandated personal protective equipment (PPE) for applicators.  The minimum PPE required by California law is protective eyewear and chemically resistant gloves:

Source: 2022 Cal-IPC Symposium

The toxicity of pesticides is rated by federal law as “Caution,” “Warning,” or “Danger,” with “Danger” indicating the most toxic and “Caution” the least toxic.  These ratings are defined as signal words.  Signal words of “Warning” or “Danger” require the applicator to also wear protective coveralls, in addition to protective eyewear and gloves. 

Other types of PPE may be required by the product label, shown in this picture:

Source: 2022 Cal-IPC Symposium

Comparing the toxicity of organic and synthetic herbicides

Signal words can be used to compare the acute toxicity of different products.  For example, the signal word on glyphosate products is “Caution,” indicating that it is considered less acutely toxic than other herbicides with higher toxicity ratings of “Warning” or “Danger.” Signal words are not a measure of long-term health damage of pesticides, such as cancer or kidney damage. Epidemiological studies of long-term health effects of pesticides are hotly disputed and are usually dismissed by the manufacturers of pesticides.

When glyphosate products were rated as a “probable human carcinogen” by the World Health Organization and tens of thousands of product liability lawsuits were filed by users of glyphosate products with cancer, there was a public backlash against the use of glyphosate partly because it is the most widely used herbicide on the market.  Glyphosate is found in most of our food and in the urine of most people. The health damage done by glyphosate is the result of 40 years of widespread use by agriculture. Glyphosate’s “Caution” signal word does not reflect the long-term effects of its use.

Consequently, glyphosate has been banned in many places all over the world. Los Angeles County has banned glyphosate. Locally, it is no longer used by East Bay Regional Park District (EBRPD) in developed park areas such as picnic areas, parking lots, and playgrounds.  Although EBRPD made an exception for “invasive” plants outside developed areas, they have significantly reduced their use of products containing glyphosate.  They are using more “organic” herbicides.  Marin County banned the use of glyphosate.  They are using exclusively organic herbicides.

What is the difference between synthetic and organic pesticides?  In general, organic products are derived strictly from sources in nature with little or no chemical alteration. Synthetic pesticides are products that are produced from chemical alteration. 

Are organic pesticides less toxic than synthetic pesticides?  The general public tends to assume that organic pesticides are less toxic than synthetic pesticides, such as glyphosate.  Based on the signal words the EPA assigns to pesticides to evaluate toxicity, organic pesticides are not necessarily less toxic than some synthetic pesticides.  Remember the signal words are “Danger” (the most toxic), “Warning,” and “Caution” (the least toxic.) 

Several presentations at the Cal-IPC conference compared the toxicity of organic and synthetic pesticides, using signal words as a proxy for toxicity.  This is a slide from one of the presentations:

I also compared the signal words of the organic products used by Marin County and East Bay Regional Park District.  Although they are using some organic products not evaluated by the presentation at the Cal-IPC Symposium, many of the organic products they are using have a “Warning” signal word, which means the EPA considers them more toxic than glyphosate. 

Clearly organic herbicides are not necessarily less toxic than synthetic herbicides and many organic herbicides are more toxic than glyphosate.

Comparing the efficacy of organic and synthetic herbicides

Are organic herbicides as effective as synthetic herbicides?  One of the presentations made at the Cal-IPC Symposium reported the results of a field study comparing the effectiveness of three organic herbicides with three synthetic herbicides, all with “Caution” signal words: 

Here’s a description of the field trial:

Here are the results of the field trial (one organic herbicide was removed from the field trial when glyphosate was reported as an undisclosed ingredient in the product):

WeedZap and Fireworxx are the organic herbicides used in the field trial.  The organic herbicides used in the field trial were found to be less effective than synthetic herbicides considered equally toxic.

This finding was corroborated by a publication of the UC Nursery and Floriculture Alliance, entitled “Organic Herbicides –Do they Work?”  The short answer to that question is, not very well:

  • “Organic herbicides kill weeds that have emerged but have no residual activity on those emerging subsequently. Further, while these herbicides can burn back the tops of perennial weeds, perennial weeds recover quickly.”
  • “These organic products are effective in controlling weeds when the weeds are small but are less effective on older plants.” The organic herbicides were significantly less effective when weeds were more than 12 days old.
  • “…broadleaf weeds were easier to control [with organic herbicides] than grassy weeds.”

Comparing the cost of organic and synthetic herbicides

The field study comparing organic and synthetic herbicides also compared the costs of these different product types:

In other words, organic herbicides are considerably more expensive than synthetic herbicides. 

The publication of the UC Nursery and Floriculture Alliance agrees:  organic herbicides “are expensive and may not be affordable…Moreover, because these materials lack residual activity, repeat applications will be needed to control perennial weeds or new flushes of weed seedlings.” 

Clearly, organic herbicides are not a substitute for synthetic herbicides because they are not less toxic, not as effective, and are very expensive.  Cal-IPC considers that assessment of organic herbicides a justification for continued use of synthetic herbicides.  I consider it an argument for declaring a truce in the war on “invasive” species.  We have waged that war for over 30 years.  We have not won that war.  In fact, we lose ground every year.  We have done more damage to the environment with our chemicals than the “invasive” species did.  We have reached a dead end.

Herbicides and Climate Change

The most valuable lesson I learned at the Cal-IPC Symposium was that climate change is making herbicides less effective.  Higher temperatures and higher levels of CO₂ are reducing the effectiveness of herbicides. This revelation was mentioned only briefly in a presentation by Regional Invasive Species and Climate Change (RISCC) Management Networks.  A search of the scientific literature substantiated that revelation:

These studies are just a small selection of the studies that respond to a search for “impact of heat and CO₂ levels on herbicide efficacy.”  They all point to yet another reason why the chemical crusade on introduced plants is a dead end. 

Climate change is a reality and it is here to stay.  Climate change has changed the ranges of where native plants can survive and it has made it impossible to destroy the non-native plants that are capable of surviving in the changed climate.  Switching from one poison to another will not overcome the forces of evolution, which dictate that vegetation changes when the climate changes. 

Spartina eradication is now a zombie project

Over 20 years ago the governors of California, Oregon, and Washington made a commitment to eradicate non-native spartina marsh grass on the entire West Coast of the country.  Intensive aerial spraying of herbicide killed over 95% of non-native spartina about 10 years ago, but the project continues in the San Francisco Bay.  The goal is now the eradication of hybrid spartina that grows at the same marsh elevations as native spartina and is so visually similar that it requires 500 genetic tests every year to determine that it is a hybrid before it is sprayed with herbicide (1). This article will explain why the Invasive Spartina Project in the San Francisco Bay Estuary is now a zombie project, a project that is dead, but is not being allowed to rest in peace.

Click on the picture to see the presentation of the Invasive Spartina Project to the California Invasive Plant Council on June 11, 2021. This is the source of some of the information in this article. Answers to questions at the end of the presentation are particularly important.

Hybridization is the boogey man of plant nativism

Hybrid spartina is being hunted because it outcompetes native spartina.  Nativists fear the loss of native spartina as a distinct species.  Rather than seeing the potential for a new, improved species of spartina, they see it as a loss of biodiversity, rather than an increase in biodiversity. 

Non-native spartina is also accused of “invading” mudflats where some animal species require that type of environment. However, that accusation is contradicted by these photos where native spartina has been planted on mudflats at Eden Landing. The source of these photos is the June 2021 presentation of the Invasive Spartina Project.

Hybridization is an important evolutionary tool that frequently increases biodiversity by creating new species on the margins of ranges where closely related species encounter one another.  For example, hybridization is credited with creating over 500 species of oaks all over the world that are well-adapted to their respective microclimates.  The rapidly changing climate and the globalization of trade have created more opportunities for hybridization and resulting speciation. 

Advances in molecular analysis has informed us of the frequency of hybridization and its benefits to biodiversity:

“With the growing availability of genomic tools and advancements in genomic analyses, it is becoming increasingly clear that gene flow between divergent taxa can generate new phenotypic diversity, allow for adaptation to novel environments, and contribute to speciation. Hybridization can have immediate phenotypic consequences through the expression of hybrid vigor. On longer evolutionary time scales, hybridization can lead to local adaption through the introgression of novel alleles and transgressive segregation and, in some cases, result in the formation of new hybrid species.” 

Restoration and expansion of wetlands is extremely important as we prepare for anticipated rising sea levels.  If hardier, denser, stronger hybrid species of marsh grass are available why would we reject that opportunity?  Nativist ideology should not deprive us of this opportunity. 

Native species are not inherently superior to species that are better adapted to present environmental conditions.  The rapidly changing climate requires corresponding changes in vegetation to adapt to present conditions.  Extreme weather events are natural selection events that kill species that are no longer adapted to the climate.  We cannot stop evolutionary change, nor should we try.

Why does this matter?

If herbicides were not required to eradicate hybrid spartina perhaps I could shrug and move on.  Hundreds of gallons of imazapyr herbicide were used by East Bay Regional Park District to aerial spray non-native spartina for the first few years of the eradication project.  In 2020, EBRPD used 43 gallons of imazapyr for “ecological function,” a nebulous category that includes spartina eradication. 

When the Invasive Spartina Project (ISP) made a presentation to the California Invasive Plant Council in June 2021, the public asked several questions about the toxicity of the herbicide (imazapyr) that is used to eradicate spartina (1). The ISP mistakenly claimed that imazapyr is not harmful to humans and wildlife because it uses a different metabolic pathway to kill plants that does not exist in animals.  They probably believe that claim, but they are wrong.

 A similar claim was made for glyphosate for 40 years.  We now know that the claim about a “unique pathway” for glyphosate existing only in plants is not true.  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.”

I asked Beyond Pesticides for help to determine if the exclusive pathway claim was true of imazapyr.  Beyond Pesticides informs me that both imazapyr and glyphosate use metabolic pathways that exist in animals. I summarize their response:  “You asked about the ALS pathway that is the target of imazapyr—is there a comparison to glyphosate?  [According to] the research I found, I think the comparison is valid.  This early paper appears to clearly state that ALS is a pathway found in yeast and bacteria as well as plants (2). Another early paper which identified ALS as coming from bacteria, fungi, and plants (3).”  These pathways exist in bacteria that reside in our bodies and perform important functions, particularly in our digestive and immune systems.  When we damage those bacteria, we are damaging our health.

Please note that both of these studies of imazapyr are nearly 40 years old.  If pesticides were being evaluated and regulated, the public and the users of imazapyr might know that it is harmful to animals.  I provided this information to the Invasive Spartina Project.  They responded that their use of imazapyr is legal.  Unfortunately, they are right.  Because there is no regulation of pesticide use in the United States, the Invasive Spartina Project has the legal right to use it.  But is it ethical?  I asked the Invasive Spartina Project to quit making the inaccurate claim that imazapyr kills plants, but cannot harm animals.  They did not respond to that request.

Unfortunately the judicial system is our only recourse to take dangerous chemicals off the market.  For example, chlorpyrifos that is known to damage children’s brains was finally banned as the result of a court order.  The EPA refused to ban chlorpyrifos, but a lawsuit finally resulted in a judge requiring that the EPA either provide studies proving its safety or ban its sale.  The EPA could not prove its safety, so it had no choice but to finally ban it. 

What about the animals?

Ridgway rail. Source: Cornell Ornithology Laboratory

The only issue that temporarily brought the spartina eradication project to a halt was the impact it has had on endangered Ridgway rail. Ridgway rail is a close relative to the Clapper rail on the East and Gulf coasts where the spartina species considered non-native here (S. alterniflora) is native.  Clapper rails are abundant where S. alterniflora resides.

“Fig. 2.  In marshes where invasive Spartina was present in large densities, populations declined rapidly commensurate with the amount of Spartina removed [from 2005 to 2011].” (4)

The eradication of Ridgway rail breeding habitat in the San Francisco Bay reduced the rail population significantly by 2011, according to the US Geological Service and the US Fish and Wildlife Service (4). The loss of rails was greatest where the most non-native spartina was killed with herbicide.  In response, USFWS mandated a moratorium on eradication in areas where rails were nesting (5). According to the ISP 2020 survey of rails in the project areas, the rail population rebounded where eradication was stopped.  When treatment resumed in 2018, the number of Ridgway rails in the previously restricted areas declined by 9% in the following year.  That outcome was predicted by the USFWS Biological Opinion: “In the 2018 Biological Opinion, the Service estimated that rails inhabiting the nine previously-restricted sub-areas may be lost due to mortality or exhibit decreased reproductive success due to loss of hybrid Spartina cover when treatment of these sub-areas resumed.”

Clearly, the endangered Ridgway rail has been harmed by spartina eradication, as USGS and USFWS concluded in their analysis that was published in 2016 (4):

“California [now known as Ridgway rail] rail survival was higher prior to invasive Spartina eradication than after eradication or compared to survival in a native marsh. The combined indication of these studies is that tall vegetation structure provides California rails with both higher quality nesting substrate and refuge cover from predation, particularly during high tides. Thus, habitat structure provided by invasive Spartina in heavily infested marshes may facilitate California rail survival, and continued efforts to remove invasive Spartina from tidal salt marshes could lead to further California rail population declines….” (4)

Given that Ridgway rail is protected by the Endangered Species Act, it is difficult to understand why this project is allowed to continue.  Much like the unregulated use of pesticides, it will probably take a lawsuit to enforce the Endangered Species Act on behalf of endangered Ridgway rail. When government is not functional, the judicial system can sometimes compensate.

Let’s bury this zombie project

The US Geological Service and the US Fish and Wildlife Service have put their finger on the failure of the Invasive Spartina Project.  The same could be said of many other pointless eradication projects:

“Removing the source of that novel habitat without addressing pre-existing native habitat quality limitations threatens to re-create an ailing landscape for California rails by dogmatically adhering to specific management approaches. In essence, the conservation community is choosing the winners and losers in this ecosystem by failing to solve the underlying problems that will support a healthy species community with all constituent members.” (4)

The spartina eradication project serves no useful purpose.  In fact, it damages the environment and the animals that live in it.  We cannot stop evolution, nor should we try.  Let natural selection determine the plant species that are best adapted to our environment and the animals that live in it.  Not only would we benefit from better protection for our coastline from rising sea levels, we could reduce our exposure to dangerous pesticides that are harmful to our health, as well as improve habitat for wildlife.  This project is doing more harm than good. 

  1. Presentation of Invasive Spartina Project to California Invasive Plant Council, June 2021 
  2. Falco, S.C., Dumas, K.S. and Livak, K.J., 1985. Nucleotide sequence of the yeast ILV2 gene which encodes acetolactate synthase
  3. LaRossa, R.A. and Smulski, D.R., 1984. ilvB-encoded acetolactate synthase is resistant to the herbicide sulfometuron methyl. Journal of bacteriology, 160(1), pp.391-394.
  4. M.L. Casazza, et.al., “Endangered species management and ecosystem restoration: finding the common ground,” Ecology and Society, 2016, 21(1):19. http://dx.doi.org/10.5751/ES-08134-210119
  5. Adam Lambert et.al., “Optimal approaches for balancing invasive species eradication and endangered species management,” Science, May 30, 2014, vol. 344 Issue 6187

Looking for Godot: Finding achievable restoration goals

There are chemical and non-chemical approaches to native plant restoration. Neither succeeds.  Non-chemical methods are labor-intensive, which makes them prohibitively expensive.  Chemicals are cheaper and they kill non-native plants, but they don’t restore native plants because they kill them and damage the soil. Either strategy must be repeated continuously to be maintained. This article is the 25-year story of reaching the conclusion that neither chemical nor non-chemical approaches are capable of restoring native plants on a landscape scale.  Where do we go from here?

In 2014, the California Invasive Plant Council (Cal-IPC) conducted a survey of land managers to learn what methods they were using to control plants they considered “invasive.”  The Cal-IPC survey reported that herbicides are used by 94% of land managers and 62% use them frequently.  Glyphosate was the most frequently used herbicide by far. In 2014, no other eradication method was used more frequently than herbicides.

Frequency of herbicide use by land managers in California to kill “invasive” plants. Source California Invasive Plant Council, 2014

We have learned a great deal about the dangers of herbicides since 2014. 

  • The World Health Organization has categorized the most frequently used herbicide—glyphosate—as a probable carcinogen.
  • The manufacturer of glyphosate, Monsanto-Bayer, was successfully sued by terminally ill users of glyphosate.  These product liability lawsuits resulted in multi-million dollar awards for damages. The awards were reduced on appeal but ultimately upheld.  Monsanto has agreed to pay more than $10 billion to settle close to 100,000 product liability claims. 
  • The US Environmental Protection Agency has finally published its Biological Evaluation (BE) of the impact of glyphosate products (all registered formulations of glyphosate products were studied) on endangered animals (mammals, birds, amphibians, reptiles, fish, invertebrates) and plants. The BE reports that 1,676 endangered species are “likely adversely affected” by glyphosate products. That is93% of the total of 1,795 endangered species evaluated by the study. Both agricultural and non-agricultural uses of glyphosate products were evaluated by the BE. Although only endangered plants and animals were evaluated by the BE, we should assume that all other plants and animals are likewise harmed by glyphosate because the botanical and physiological functions of plants and animals are the same, whether or not they are endangered. 

How have land managers responded to the dangers of herbicides?

San Francisco’s Recreation and Park Department has increased the use of herbicides in public parks every year since 2016.  In 2020, herbicide use increased significantly from 243 applications in 2019 to 295 applications in 2020.  SF RPD has been spraying herbicides on non-native plants for over 20 years.  They have been using hazardous herbicides on some 50 target plant species year after year. The longer they use them, the more resistance to the herbicides the plant develops.

Herbicides used by Natural Resource Division of San Francisco Recreation and Parks Department. Source San Francisco Forest Alliance based on public records of pesticide use

Chris Geiger, director of the integrated pest management program at the San Francisco Department of the Environment, told San Francisco Public Press that although the city has reduced its use of glyphosate outside parks, it won’t ban glyphosate because it hasn’t found a more efficient or safer alternative for controlling some weeds. He said, “In habitat management, there are certain plants you cannot remove from a natural area by hand.”

San Francisco’s IPM program recently published  “Pest Prevention by Design Guide” that illustrates the bind they are in with respect to promoting native plants while trying to reduce pesticide use.  On the one hand, the Guide promotes the use of native plants in landscape design plans by making the usual claim that “Native species are generally best suited to supporting local insect populations and ecosystems.”  On the other hand, the Guide recommends the use of “pest resistant” species that are not eaten by insects and grazing animals and are capable of outcompeting weeds.  Can’t have it both ways, folks!!  

East Bay Regional Park District has made a commitment to phase out the use of glyphosate in developed areas such as parking lots, playgrounds and picnic areas.  However, EBRPD remains committed to using glyphosate and other herbicides to eradicate non-native plants on undeveloped park land. In 2020, no glyphosate was used in developed areas, but about 23 gallons of glyphosate were used to eradicate non-native plants on undeveloped park land. Twenty-one gallons of triclopyr were also used to eradicate non-native shrubs and to prevent non-native trees from resprouting after they were cut down. They continued the 15-year effort to eradicate spartina marsh grass with imazapyr. A few other selective herbicides were used on other eradication projects. (2)

In the San Francisco Bay Area, most land managers are still committed to using herbicides, particularly in so-called “natural areas,” regardless of the damage herbicides do to human health, wildlife, and native plants.  In fact, the City of Oakland is planning to begin using herbicides on 2,000 acres of public parks and open spaces for the first time to implement its vegetation management plan.  The vegetation management plan is both a fuels reduction program and a “resource protection” program, which is a euphemism for native plant “restoration.”

Given what we now know about the dangers of herbicides, why are public land managers still committed to using herbicides?  The City of Oakland explains in the EIR for its vegetation management plan why it is proposing the use of herbicides where they were prohibited in the past:

“It is estimated that if the City were to rely on hand removal and mechanical treatments in place of herbicide, it would cost the City up to 40 times more to treat these areas than under the VMP. The cost for herbicide treatments, not including any associated physical treatments, is approximately $250-$500 per acre. This reflects a range of potential vegetation conditions, vegetation types, and densities. The cost for hand removal and mechanical treatments is estimated at approximately $1,000-$4,000 per acre, using the same range of site-specific conditions.” (page 5-9)

In other words, herbicides are the preferred method of killing non-native plants because it is the cheapest method.  However, there is another reason why herbicides are preferred to non-chemical methods.  There isn’t a non-chemical method that is more effective than using herbicides.

Looking for an alternative to herbicides

As we should expect, new information about glyphosate has increased the public’s awareness of the dangers of pesticides.  California Invasive Plant Council has responded to the public’s growing awareness and concern about the herbicides to which they are exposed in our public parks and open spaces.  They recently published a comprehensive 300-page brochure entitled “Best Management Practices for Non-Chemical Weed Control.”  (1) Many highly qualified land managers participated in the preparation of this credible publication.  The Cal-IPC brochure is credible because it frankly admits that no method of eradication is without problems.  Irrigation and intensive planting are required for good results, but without continuing regular maintenance the results are only temporary.  Few land managers have the resources needed for success.

If you wonder why herbicides are the preferred method of eradicating non-native plants, reading Cal-IPC’s brochure about non-chemical methods will tell you why.  There is no non-chemical method that achieves better results than using herbicide. 

Herbicides are not a magic bullet

Herbicides are the most frequently used method of killing non-native plants, but using herbicides does NOT result in a native landscape.  “Lessons learned from invasive plant control experiments:  a systematic review and meta-analysis,” analyzed 355 studies published from 1960 to 2009 to determine which control efforts were most effective at eradicating the target plants and which method was most successful in restoring native plants. The analysis found that “More than 55% of the studies applied herbicide for invasive plant control.” Herbicides were most effective at reducing invasive plant cover, “but this was not accompanied by a substantial increase in native species,” because, “Impacts to native species can be greatest when programs involve herbicide application.”  It’s not possible to kill non-native plants without simultaneously killing native plants and damaging the soil.

Reaching a dead—and deadly—end

Public land managers in the San Francisco Bay Area have been trying to restore native landscapes for over 25 years.  Every project begins by eradicating non-native plants, usually with herbicides.  Our public parks have been poisoned repeatedly, but native landscapes have not replaced the plants that were killed.  Meanwhile, we have learned that herbicides are dangerous to our health and animals who live in our parks. 

Oyster Bay is a park in San Leandro that was built on a former garbage dump on landfill in the San Francisco Bay.  The garbage was capped with barren soil and many acres were planted with native bunch grass, as shown in these photos.  This “restoration” method is called competitive planting. The bunch grasses did not survive and the ground was quickly colonized by weeds that were then sprayed with herbicides. 

The only viable alternative to using herbicides to “restore” native plants is to change the goals for native plant restorations such that herbicides won’t be required: 

  • An exclusively native landscape cannot be achieved where native plants have never existed, such as the many parks along the bay waterfront that were built on landfill.  It is an unrealistic goal.
  • Given that no effective method of achieving this unrealistic goal has been found after 25 years and the most popular method is poisoning our environment, it is time to stop trying.
  • Smaller, achievable goals must be set.  Landscape scale projects should be abandoned and replaced with small scale projects where native plants already exist. 
  • Smaller areas can be managed without using herbicides because they will be affordable to manage with labor-intensive methods that are more expensive.
  • If smaller projects are more successful, they will be less controversial.  The projects are unpopular partly because they aren’t successful. 

The native plant movement in the San Francisco Bay Area has bitten off more than it can chew.  Native plant advocates need to back out of their dead end and regroup with plans that are less destructive and more realistic.  As the Economist magazine said in 2015, “you can garden in a garden, but you can’t garden nature.”

(1) California Invasive Plant Council is offering free video training for non-chemical methods of killing “invasive” plants on May 4, 2021, 1-5 pm.  Sign up HERE. 

(2) 2020 IPM Report, East Bay Regional Park District available HERE.   

Invasion Biology vs. The “Restoration” Industry

Daniel Simberloff gave the keynote address to the symposium of the California Invasive Plant Council (Cal-IPC), entitled “Invasive Species Denialism and the Future of Invasion Management.”  Simberloff is the most vocal academic defender of invasion biology.  His presentation to Cal-IPC contains interesting clues about more effective strategies for the critics of invasion biology, of which I am one.  In a nutshell, Simberloff dismisses critics easily with a few waves of his hand, but he stumbles when faced with the economic and ecological costs of the methods used to eradicate so-called “invasive species.”  He can defend the theoretical hypotheses of invasion biology, but he finds it difficult to defend the “restoration” industry that invasion biology spawned, specifically the use of pesticides.

Simberloff opened his presentation with this rogue’s gallery of the critics of invasion biology.  Some readers will recognize some of these “deniers.”  If not, you might recognize some of the many books the “deniers” have published.

Simberloff categorized the criticisms of invasion biology then flipped them off, one by one.  Keep in mind as you read Simberloff’s summary that it does not do justice to the actual criticisms of invasion biology.

  • Critics say that most non-native species aren’t harmful.
    • Simberloff says we don’t know how harmful non-native species are because few are studied, their impacts are often subtle, and there is often a time lag before they become harmful. He believes that all non-native plants are potentially harmful to ecosystems.
  • Critics say that some non-native species are beneficial.
    • Simberloff says that critics only report the benefits, while ignoring the negative impacts of non-native species.  (Actually, most critics are proposing a cost/benefit analysis that acknowledges both positive and negative impacts.)
  • Critics say that invasion biology is xenophobic.
    • Simberloff says that if you’re looking for xenophobia, you often see it. He calls this the “law of instrument” or if your instrument is a hammer, everything looks like a nail.  (Frankly, I didn’t understand the point he was trying to make, but I have tried to describe it accurately based on what he said.)
  • Critics say that trying to eradicate non-native species is futile.
    • Simberloff says this argument ignores the progress that has been made in the technology of eradication methods. He used the “early detection and rapid response” strategy as an example of progress in eradicating non-native plants.  That strategy focuses on small populations of non-native plants, basically acknowledging the futility of trying to eradicate large areas of well-established non-native plants.
    • Much of Simberloff’s presentation was devoted to describing many developments in genetic engineering, such as CRISPR to drive species to extinction and gene silencing. All of the examples of such developments were aimed at killing insects (such as mosquitoes) and animals (such as rats and mice), with one exception. He was particularly enthusiastic about island eradications of which there are hundreds, and hundreds more on the drawing boards.  Only one gene-editing project on plants is trying to develop a genetic method to eradicate phragmites.

Things finally became interesting, when Simberloff took questions:  “Dan, you mention the “futility” argument, but what about the notion that the cost in environmental damage (e.g, pesticide use and nontarget impacts) is too high for some well-established invaders?”  Simberloff’s answer to this question was surprising and encouraging to critics of pesticide use to kill non-native species:

“Absolutely, it’s a huge problem, not only on non-target species, but also the fact that evolution of resistance leads to greater use of pesticides before they are useful and leads to greater impact on non-target species.  I didn’t talk about this, but yes, of course the cost both economically and ecologically might be too great even if management eradication is feasible.  But that’s not what denialism is about.  Denialism willfully denies that there are impacts or they confound arguments about values as if it is an argument about science.”

The Executive Director of Cal-IPC recognized the dangers of Simberloff’s answer because pesticides are the primary tool used by the “restoration” industry and much of the conference was devoted to telling over 650 employees of the “restoration” industry about new developments in pesticide use.  Those new developments are not good news to those who are concerned about the dangers of pesticides.  For example, a new “drizzle” technique increases the concentration of the active ingredient and lowers the volume of the application, increasing toxicity of the application.  Another alarming presentation described the use of drones to spray herbicides on hundreds of acres of phragmites in the Suisun Marsh.

The absence of good alternatives to pesticide use in eradication projects is another source of pressure on the “restoration” industry and therefore on Cal-IPC:

  • Jon Keeley’s presentation about the interaction of fire, fire prevention, and plant invasions included the observation that using prescribed burns to eradicate non-native plants results in more non-native plants, not more native plants.
  • A land manager in Southern California acknowledged that pressures to reduce pesticide use threaten the future of his project: “Natural herbicides result in more time intensive and costly weed control, with less confidence of success. Where herbicide application is completely restricted, other weed control methods like hand weeding or mowing can be implemented successfully, but they often fall short of herbicide in effectiveness. This resulting reduction in effective weed control must be taken into account in future plans for habitat restoration and management, and our existing programs will have to reevaluate the proposed efforts, cost of those efforts, and expectations for success, both short and long term.” (Scott McMillan, abstract)
  • Finally, with the exception of a few timid questions from participants, no mention was made about the threat of climate change on the future of native ecosystems. Simberloff likened critics of invasion biology to “climate change deniers.”  In fact, it’s fair to say that those who demand that we replicate native ranges existing 250-500 years ago are more accurately called climate change deniers.

The Executive Director of Cal-IPC tried to save the day by portraying those who oppose pesticides as extremists, based on what he considers “unscientific” studies.  But Simberloff wouldn’t take the bait.  He wasn’t willing to dismiss the concerns about pesticides.  Instead, Simberloff passed the buck:

“I’ll beg off on answering that question on grounds that I’m not a social scientist or psychologist.  This is not my area of expertise.  There is some reason for the extremists because Monsanto has sometimes lied to us and there have been problems associated with pesticides.  I leave this question to policy scientists.”

Simberloff reveals the flaw in the “restoration” industry

As a critic of invasion biology and the use of pesticides, I have always been frustrated that critics of invasion biology do not use the damage done by eradications as a reason for their criticism.  With the exception of Tao Orion’s Beyond the War on Invasive Species, none of the books written by critics have used this argument.  It is a missed opportunity and Simberloff’s presentation to Cal-IPC is an indication that it is the strongest argument against eradication projects that are inspired by invasion biology.

Invasion biology is a theoretical construct.  It does no harm to ecosystems until it justifies the use of harmful methods to eradicate non-native species.  I humbly ask that critics of invasion biology wake up to this opportunity.  Pesticides are a winning argument against “restoration” projects that eradicate non-native plants.  Any cost/benefit analysis of new eradication projects should include the ecological and economic costs of pesticides in the equation.

Beyond Pesticides points the way forward

I try not to leave the field without offering a compromise because opposition without solutions is not constructive.  I offer this sage advice from Beyond Pesticides about case-by-case evaluations of weed invasions that will reduce damage to ecosystems.  Beyond Pesticides responded to this question:  “I’m working on a pesticide policy in my community and am interested in how you might suggest we deal with “invasive” species. Can you point us in the right direction? Martin, Boston, MA.”  This is BP’s thoughtful answer:

“It’s Beyond Pesticides position that invasives, or opportunistic species, should be dealt with on a case-by-case basis, with established priorities and a plan. With any unwanted species, there needs to be an understanding of the ecological context. We need to be asking the right questions: What role is the plant currently playing in a landscape—what niche is it currently filling? If we remove this plant, what will fill that niche? Will we be replanting the right native species to fill that niche? What are the detrimental impacts of letting it spread? Is there a way we can isolate it to stop its spread? Can we ever remove this plant altogether, or will we be working at control indefinitely? These are important questions that we need to be asking before we even consider management methods. Regarding policy, requiring an individualized invasive species management plan seems to be the right answer, though unfortunately many pesticide reform policies sidestep the issue and simply exempt invasives to avoid opposition. Just like all organic approaches, we’ll want to place a focus on prevention and working with ecological systems, rather than against them, making even least-toxic pesticide use a last resort. There is a strong potential to undermine the stability of an ecosystem if we simply go in and immediately break out the strongest tools in the toolbox without a plant replacement strategy. On a turf system with common weeds a simple answer is grass plants. But, in forested areas already subject to intrusion (from construction/logging, etc.), rights-of-way, and urban areas, the focus is on alternative vegetation or ground cover. Sometimes, little should be done except simple mechanical cutting to keep these species in balance. This is an interesting and, at times, contentious issue that environmentalists grapple with, so there is certainly room for fresh ideas on how to approach opportunistic species without the use of toxic pesticides. For more information, we encourage you to watch the talk given at Beyond Pesticides 37th National Pesticide Forum in New York City by Peter Del Tredici, PhD, senior research scientist at Harvard’s Arnold Arboretum (www.bp-dc.org/ invasives).”

 

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 Species.  Tao 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 specific firebrand found in the 1991 Oakland Hills fire was found approximately 1 km (.6 mile) west from the perimeter of the fire, “though it may have travelled several  kilometres [1.86 mile].” 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