Author: Conservation Sense and Nonsense

Beyond the War on Invasive Species: Interview with Tao Orion

I am republishing with permission a portion of Kollibri terre Sonnenblume’s interview of Tao Orion.  Kollibri is a writer, photographer, tree hugger, animal lover, and cultural dissident. Kollibri was born and raised in Nebraska, earned a Bachelor of Arts in Writing at the St. Olaf Paracollege, and lived in the Twin Cities and Boston before moving to Portland in 2001. Since 2011, Kollibri has lived predominantly in rural areas in the Western US, working in agriculture and exploring wildtending. Kollibri has published several books, including The Troubles of ‘Invasive’ Plants (with Nicole Patrice Hill), originally a zine and soon to be published as a book.  Kollibri has also recorded interviews available as podcasts, “Voices for Nature & Peace,” which can be found at radiofreesunroot.com.

Conservation Sense and Nonsense

Tao Orion, author of “Beyond the War on Invasive Species”

Tao Orion is the author of “Beyond the War on Invasive Species: A Permaculture Approach to Ecosystem Restoration.” She is a permaculture designer, teacher, homesteader, and mother living in the southern Willamette Valley of Oregon. I interviewed her on May 18, 2020, for my podcast, “Voices for Nature & Peace.” What follows is a partial transcript of that conversation, edited for clarity. [Listen to the entire interview here]

Kollibri terre Sonnenblume, macska moksha press

K: A lot of people have heard the term, “invasive species” and most of them of course are assuming it’s something bad, but when it comes right down to it, it’s actually very difficult to define the term and we could even say that there isn’t one definition of that term.

T: Yes, that’s something that I found really interesting as I was researching my book, because I was really trying to find out if there was a clear, objective description of what an invasive species is, and I found that even the National Invasive Species Council—which in the US is the federal government level board that looks at invasive species issues—spent years on deliberating on the definition and even so, they weren’t able to come up with something that I felt was purely an objective description that could be [applied] in all contexts. It seemed to vary from place to place and time to time.

K: Monsanto was one of the companies involved in setting [that council] up.

T: That’s another disturbing element about how the big frenzy around invasive species and the purported damage that they do came to be so popular; a lot of that was informed and funded by pesticide interests to spur the sale of products, herbicides in particular, to deal with species invasions.

K: I think that most people are probably not aware of the fact that the use of pesticides and herbicides has been rising over the last 20 years, not falling. I think people hear about organic agriculture and they think we must be on the right path. But due in part to the war on invasives and also due to genetically modifying crops to be Round-up Ready so they can survive the use of pesticides—these two things seem to have driven an increase in the use of pesticides over the last 20 years.

T: Yes, it’s definitely alarming. My background is in organic agriculture. I was immersed in that world. Even before writing this book, I was under the impression that herbicides were somewhat less toxic in the realm of pesticide toxicity [as opposed to insecticides or fungicides, for example]. In researching herbicides more for invasive species management and agriculture in general, I learned a lot more about their toxicity and insidious toxicity to insects and mammals and other lifeforms that I don’t think gets talked about enough. People assume they’re more ecologically benign, but really they’re not, and that’s important to bring to the table.

K: One thing you mentioned in your book that I hadn’t thought about much before is that it’s not only the active ingredient in a pesticide, but also the adjuvants—the things that they add to the active ingredient to help it stick to plants or to help make it soluble in water, etc.

T: Yeah, that was a big realization for me too. We talk about these two different terms: “Round Up” is the trade name of the herbicide, of which “glyphosate” is considered the active ingredient. Glyphosate is the ingredient that’s tested for pesticide registration purposes, but that might be only ten percent of a mixture that’s sold in the bottle. The rest of that solution is made up of other ingredients that help the herbicide stay on the plant if it rains or if its windy, or help the herbicide active ingredient penetrate the cells of the plant. A lot of these are trade secrets so they’re not tested and the manufacturers don’t have to say what’s in there. But one compound that has been pulled out and studied by independent researchers is POEA [polyoxyethyleneamine], which has been shown to make glyphosate penetrate human placental cells. So even if you come into contact with glyphosate itself, that wouldn’t necessarily happen, but if you come into contact with Round Up, which contains this adjuvant, POEA, it can actually then allow the glyphosate to enter into the cell. Because that’s what it’s in there to do.

K: The reason we’ve been talking about pesticides because herbicides are such a big part of getting rid of “invasive” species… But your book tries to turn things on its head and to question the concept of whether we should be trying to eradicate them.

T: Yes. I was shocked when I started working in the field of ecological restoration, coming from a background in organic agriculture. I had heard of “invasive species” before but when I got into this context, I was around people who did this professionally, it was just assumed that I was going to use herbicides and I would be totally fine with that, because that’s just what everybody did. The whole context was, “we have to get rid of these plants at all costs, and if we do, everything will be okay.” [Laughs.] That’s the the framework in which we’re approaching ecosystem restoration, and to me, I was amazed because from a more holistic perspective, I could see right off the bat that in every case where invasive species were thriving, there were other things going on in the ecosystem that pesticides weren’t going to address.

It’s the same in conventional agriculture. If you’re having, quote, pest pressure issues, the issue isn’t the pest, the issue is the soil or the plant stress or drought stress. There’s all these different things playing into the manifestation of pest pressure in the ecosystem. So, taking that knowledge a few steps further to ecosystem restoration I think is really necessary. A lot of people involved in these contexts are really highly trained ecologists and it’s still hard for me to square that with the belief that herbicides, pesticides are the only solution. These are often people who are shopping at organic food markets, and only buy organic food, and believe really strongly in that framework for food production, and yet are making decisions about ecosystem restoration outside of agricultural contexts that rely on pesticides and I just think that really needs to be questioned.

I had some very interesting discussions over the years and maybe the needle is starting to shift a little bit, although as you mention, sometimes these discussions flare up online where people are really quite defensive about their position and belief around this.

K: The issue tends to infect any discussion around plants. I’ve been using a couple of plant ID groups on Facebook because I’m in a new area and I’m seeing things coming up and I’m like, “What is this?” Of course if you’re in a native plant group, that’s definitely going to be someplace where [the invasive framework] is strong. You know, a native-plants-equals-good, non-native-plants-equals-bad, black and white paradigm. Which brings us around to looking at the invasive plant not being a problem in and of itself but of being a symptom of something going on.

T: That’s a huge part of the conversation that a lot of folks really aren’t willing to easily engage in, but the design of our livelihood system has really degraded ecosystems to a place where native flora and fauna aren’t thriving. You know, to really sit with that, and acknowledge it, think about how we might approach things differently as a basis for our understanding is challenging. It’s a lot easier to blame the messenger. Also I think one of the things that’s really missing from the discussion of native plants is the fact that native ecosystems were or are managed by indigenous people. They don’t just exist in a vacuum, free from people’s influence and the whole idea of this “pristine” wilderness is very much a western, colonial thought pattern that definitely needs to be disrupted.

K: What you’re referring to in part is that when people are designating a plant as invasive or non-native, there’s a point in time they’re referring to, and that might be different from place to place, but it’s generally accepted in the United States that anything anything that showed up after 1492 is not native. There are people who are willing to describe most non-native plants as “invasive” or throw them in that bin as soon as possible, and then the poisons come out, so this is an important issue.

T: Yes, but we don’t really know the social, ecological, economic context that was going on at that point in time that led to a particular assemblage of plants. There’s no doubt that the floral and faunal assemblies were different, but we should think really hard about why they’ve changed. Draining the wetlands of the Sacramento and San Joaquin valleys in California has major ecological implications. Damming the Colorado River for hydro-power and irrigation capacity has major ecological implications. These bigger scale things that we do—that we support—are going to change the surrounding ecosystem. If we can acknowledge that and observe what’s happening because of those major shifts, I think we’ll be in a better position to understand so called “invasions” from a more holistic perspective.

K: Because the entry of an invasive plant or animal into a landscape is in virtually all cases preceded by a human-caused disturbance of some kind.

T: It’s interesting. When I was writing, [I wondered if I] should I put forward the idea of reclaiming a different name because “invasive species” has kind of this negative connotation, but the more I looked into evolutionary biology and some of the ways—in the deep time perspective—how systems have changed, “invasion” is one of these processes and it’s not unnatural. Taking that longer term perspective is important as well. That’s how plants came to be on land. There were marine beds of algae hanging out in the shallow seas a couple billion years ago and eventually, speciation happened because of changing conditions and the land was “invaded” by those plants. You just see that change over time leading to the type of biodiversity that we have now, punctuated by other kinds of events of course, but it’s not something that’s “outside the realm of nature,” which is how invasive species are situated in a lot of discussions.

Words Matter: “Die-Off” vs. “Die-Back”

California has been in severe drought conditions for over 10 years.  Climate change is the underlying reason for the extremity of the drought.  Maintaining our carbon sinks that sequester greenhouse gases causing climate change is one of our most important defenses against climate change and forests are one of our primary carbon sinks.  Unfortunately, California’s forests are dying of drought and associated insect infestations. You might think that given these conditions, we would try to preserve our forests. 

In fact, the drought has accelerated the war on our non-native urban forest in the San Francisco Bay Area.  All trees and plants have suffered during our prolonged drought.  Where trees are not irrigated in our parks and open spaces, signs of drought stress are visible.  Today, I am publishing my letter to the IPM Director and Fire Chief of East Bay Regional Park District about the need to make a distinction between dead trees and trees that are not dead, but showing symptoms of prolonged drought. My letter explains why we must distinguish between dead (described as “die-off”) and living trees (described as “die-back”) when making commitments to destroy trees that we desperately need during this climate crisis.

Links are provided to email addresses of recipients of my letter.  Please consider writing a letter of your own.

To:   Pam Beitz, Aileen Theile

CC:  Natural and Cultural Resources Committee, Matteo Garbelotto

As you know, the Park District hired the Garbelotto Lab at UC Berkeley to evaluate two species of trees in the parks, acacia and eucalyptus.  The reports of the Garbelotto Lab were recently published on the Lab’s website.  I am writing to ask that responsible staff read those reports and make adjustments in plans to remove trees as needed, based on those reports. 

Source: Report of Garbelotto Laboratory
Acacia die-off in Leona Canyon, East Bay Regional Park District. Source: US Forest Service

The diagnoses for acacia and eucalyptus are entirely different.  The pathogens are different in the two tree species.  The pathogens killing acacia are new and they are lethal.  The pathogens found in eucalyptus are not new.  They have been latent and asymptomatic in eucalyptus for decades and have only become symptomatic because of the stress of drought. The pathogens found in eucalyptus disfigure leaves and twigs, but are not fatal. 

Much like the microbes (bacteria, viruses, fungi, parasites) in our bodies that outnumber human cells, every tree is inhabited by microbes that are usually asymptomatic.  If similar tests were done on other tree species in the Bay Area, similar results would be found where trees are not irrigated.  The pathogens are always there.  Drought has made them visible.  If we were obligated to destroy every tree in the parks showing signs of drought stress, we would be required to remove most trees in the parks. 

There are significant disadvantages to destroying living trees:

  • A dead tree is not capable of resprouting, but a living tree is capable of resprouting unless it is a species that is not capable of resprouting. Eucalyptus, acacia, redwoods (not candidates for removal, but dying of drought nonetheless) and bay laurels are all vigorous resprouters.  The stumps of these living tree species will require herbicide applications to prevent them from resprouting. 
  • The herbicides used to prevent resprouting travel through the roots of the tree to kill the roots. Herbicides used to prevent resprouting damage the roots of neighboring plants and trees connected by their mycelium networks. 
  • The trees that are destroyed release their stored carbon into the atmosphere contributing to the greenhouse gasses causing climate change. In the absence of those trees, less carbon dioxide is removed from the atmosphere in the future.  Since the underlying cause of increased frequency and intensity of wildfires is the warmer/drier climate, removing living trees increases wildfire risks in the future.
  • As more trees die, wood debris has accumulated to the point that there isn’t sufficient disposal capacity. When roadsides in the Berkeley hills were clearcut over one year ago, it took 9 nine months to dispose of the wood debris.  Huge piles of wood debris were stacked on roadsides, creating a fire hazard.  The more trees that are destroyed, the more wood debris is created.
One of many piles of logs, Claremont Ave, November 2020. Photo by Doug Prose, courtesy Hills Conservation Network.

I am therefore concerned about the Park District’s plans to remove one million trees from parks in the East Bay, according to press coverage: “In consultation with academics and state experts, they’ve identified a mass die-off of trees in the parks as a result of stress from drought, climate change and a proliferation of non-native species. Now they estimate they need to remove more than 1 million trees on their land, at a cost of $20 million to $30 million in one park alone. One area of the die-off, located between Mt. Diablo and communities in Oakland and Berkeley, is particularly concerning to Fire Chief Aileen Theile.”  

In an earlier media interview Fire Chief Theile included eucalyptus in the list of dead trees: “The die-off, first noticed last October, has mostly hit eucalyptus, acacias, pines and bay laurels and has expanded this summer amid an exceptional drought.”  Oaks are strangely absent from that list of dead trees, although it is well known that there are thousands of dead oaks in the Park District that have not been removed.

In summary, I ask for your reconsideration of Park District plans and public communications regarding tree removals in the parks:

  • The Park District should confine plans for tree removals to dead trees. Dead trees are public safety risks that should be mitigated. Drought stressed trees that may be unsightly are not a priority for removal.  Given our heavy rains in December, it is still possible that many will recover.
  • Park District communications with the public should make a distinction between “die-off” and “die-back.” Acacias are accurately described as experiencing a die-off.  Eucalyptus are accurately described as experiencing a die-back.

Thank you for your consideration.

“When the Killing’s Done” Maybe never.

I have few opportunities to read fiction because most of my time is spent trying to keep up with rapidly evolving ecological science.  I was grateful for the chance to read the fictional account of island eradications on the Channel Islands because it closely relates to my interest in the planned eradication of mice on the Farallon Islands, which is still pending and as controversial as similar projects on the Channel Islands.  TC Boyle’s book foretells the Farallones project as he sends a member of the fictional project team to the Farallon Islands after completion of the project on the Channel Islands.

When the Killing’s Done by TC Boyle is not entirely fictional. (1)  It is impressively accurate in its description of the eradication projects themselves, but Boyle weaves a tight fictional plot around the key players who implemented the project and those who fought like hell to prevent it from happening.  Like other books by Boyle that I have read, When the Killing’s Done creates intense suspense that moves the reader along at top speed.  His characters are vivid and complex. 

Boyle lives in Montecito, near Santa Barbara, close to the Channel Islands.  No doubt he followed the projects closely as they were debated and resisted by opponents, who were primarily animal rights activists according to Boyle’s account.  In interviews after the publication of the book in 2011, Boyle claimed not to have a personal opinion of the projects:  “I’m not an activist in any way. With certain exceptions, I don’t think politics and art mix very well.”  He sees value in both sides of the debate and the characters in his story have much in common.  The antagonists are vegetarians who value nature and care deeply about the environment and the animals who live in it.  I believe this common ground is also true of the adversaries in the debate about the Farallones project and others like it.

However, the ending of the book suggests that Boyle doubts the ability of humans to control nature.  Although the projects on the Channel Islands were completed to the satisfaction of the land managers–National Park Service and The Nature Conservancy—the final image in Boyle’s story is of animals considered non-native on the Islands making their way to the shore of the Island.  The implication is that maybe the killing is never done and that is the crux of the problem with island eradications in general and the planned mice eradication on the Farallon Islands in particular.

Rat eradication on Anacapa Island

The aerial application of rodenticide to kill rats on Anacapa Island in 2001-2002 was the first of its kind in North America.  The project was also unique because it was complicated by the need to spare a population of endemic native mice on Anacapa.  Over 1,000 native mice were captured before the aerial application of rodenticide and released back on the island after the poison was no longer effective. 

Anacapa Island is the usual success story cited by supporters of the Farallones project where non-native mice are the target for eradication.  Native mice on Anacapa were not considered a threat to birds, but non-native mice on the Farallones are, although there is no evidence that mice actually harm birds on the Farallones either.  The operative word here is “native.”  The mice on the Farallones are targets only because they aren’t native.  The mice on Anacapa undoubtedly eat vegetation too, but that’s not considered a problem so long as they are native.   The mice on Anacapa are probably an important source of food for birds, just as they on the Farallones. 

If mice are not harmful to birds, there is no legitimate reason to poison them, along with untold numbers of non-target animals.  The mice on the Farallones are targets only because they aren’t native. 

Killing of non-target animals

Rodenticides are indiscriminate killers of warm blooded animals, including birds.  An animal who eats rodenticide slowly bleeds to death.  The grisly process of dying takes about 10-20 days.  If poisoned mice are eaten by other animals that animal is also poisoned.  It is therefore inevitable that non-target birds who are predators of mice will be killed by widespread dispersal of rodenticide pellets on the ground that can also be directly eaten by birds and other animals.  This deadly sequence of events has been demonstrated many times by island eradications using rodenticides all over the world and the project on Anacapa Island is no exception. 

Billboard sponsored by Raptors Are The Solution (RATS)

Raptors are the main predators of mice.  Therefore, 63% of raptors on Anacapa Island (37 of 59 individual birds) were captured and either relocated or kept in captivity until the project was done, according to the first study of the project published in 2005. According to that study, “The fate of the remaining birds of prey on the island is unclear. There is evidence that some birds survived the bait application… However, three barn owls, six burrowing owls and an American kestrel either died while in captivity or were found dead on the island. The American kestrel and a burrowing owl that were captured in 2001, after the bait application, likely died from brodifacoum poisoning.” The analysis of the project considers these deaths “negligible.”

A total of 94 seed-eating birds were also found dead after the poison drop.  Most were song birds, but an additional 6 birds were too decomposed to identify the species.  The study notes that these collateral kills were consistent with other similar projects.

Western Gull on Channel Islands. NPS photo

The study makes no mention of gulls that were undoubtedly killed by the project.  Gulls are omnivorous scavengers for whom dead and dying mice are ideal food, preferable to dive bombing for French fries on your picnic table.  According to the National Park Service, “Western gulls are the most abundant breeding seabird in the Channel Islands National Park, with a population estimated at more than 15,000.” Shortly after the poison drop, dead seabirds washed up on the shore near the Santa Barbara harbor.  UC Santa Barbara’s daily newspaper said, “…a strong correlation exists between the National Park Service’s most recent airdrop of pesticide on Anacapa Island and the dead birds.”

In other words, those who implemented the eradication project on Anacapa are probably not telling the full story about the death of non-target birds.  The death of hundreds of gulls is anticipated by the promoters of the project on the Farallones.  If the organization that implements the project is the same organization that monitors and reports on the project (as was the case for the projects on the Channel Islands), we may never know the actual impact on the birds living on the Farallones.

Those who promote these poisonous projects justify the death of non-target birds by saying they are “incidental” and have no lasting impact on the species population.  They will apply for and receive “incidental take permits” in advance of the Farallones project that will satisfy legal requirements of the Migratory Bird Treaty Act and the Endangered Species Act.  The lawsuit that was filed to prevent the Anacapa project was overturned on those grounds.

The killing is never done

Rat eradication on Anacapa and pig eradication on Santa Cruz (where over 5,000 pigs were shot by sharpshooters and 54 Golden Eagles were removed because they were predators of endemic foxes) are the focus of TC Boyle’s masterful book.  Both were implemented and considered successful by the organizations that implemented the projects.  Although land managers are no longer killing animals (to our knowledge) in the Channel Islands they are waging a continuous war on non-native plants by spraying them with herbicide.  When we visited Santa Cruz Island in 2010, we witnessed the application of Garlon on non-native fennel.

Roundup (glyphosate) has been used on the Farallon Islands every year since 1988.  Between 2001-2005, an average of 226 gallons of herbicide were used annually (5.4 gallons per acre per year), according to the annual report of the Farallon National Wildlife Refuge.  Given that these islands are not far from the California coast and are visited by thousands of migratory birds every year, we must expect that the arrival of new plants to the islands will be continuous: seeds are eaten and carried by birds; seeds are carried by birds in their feathers and feet; wind and storms carry seeds to the islands, etc.

The Environmental Protection Agency recently published a Biological Evaluation of glyphosate products.   EPA reports that glyphosate is “likely to adversely affect” 93% of legally protected endangered and threatened plants and animals. That finding applies equally to all plants and animals, whether they are legally protected or not because the physiological processes of species in the same order are similar.

The Environmental Impact Statement for the Farallones project accuses mice of eating vegetation, although far more vegetation is probably killed by herbicides.  Non-native vegetation arrives on the Farallones partly because birds eat it and carry it to the Farallones.  Animals do not care if edible vegetation is native.  Nativism is a human prejudice not shared by animals who seek food and shelter wherever they can find it.

The constant poisoning of plants is perhaps a trivial consideration in comparison to the futility of trying to eradicate mice.  Although rats have been successfully (leaving aside the death of non-target animals) eradicated by some projects, attempts to eradicate mice have been significantly less successful. 

A study of 139 attempted eradications on 107 Mediterranean islands in eight countries, with Greece, Italy, and Spain accounting for the highest number found that eradication projects targeted 13 mammal species. The black rat was the target of over 75% of the known attempted eradications in the Mediterranean Basin; other species targeted were feral goat, house mouse, European rabbit, and domestic cat. The most widely used technique was poisoning (77% of all eradications), followed by trapping (15%) and hunting (4%).  Techniques were largely target-specific.

The average failure rate of the projects was about 11%, but success was defined only as the death of animals living on the islands at the time of the project. However, this percentage varied according to species. The failure rate of house mouse eradication was 75%. Reinvasion occurred after 15% of eradications considered initially successful. 

Farallon Islands, NOAA

The proposed project on the Farallon Islands is a dead end in many ways.  It will kill many non-target animals. It will probably not be successful in the short run or the long run.  Every time it is repeated it will kill more animals. Furthermore, it is pointless because mice do not harm birds on the Farallon islands. 

  • T.C. Boyle, When the Killing’s Done, Viking, 2011.

Open Letter to California Native Plant Society

A diverse garden of native and non-native plants will be the most resilient to climate change. Photo credit Marianne Willburn, Garden Rant

In a recent edition of Nature News, Jake Sigg published an announcement of a new publication and a brief description of it that was apparently written by Susan Karasoff, Outreach Chair of the Yerba Buena Chapter of the California Native Plant Society:

San Francisco Estuary Institute (SFEI) developed Making Nature’s City: A Science-based Framework for Building Urban Biodiversity, which summarizes the key indicators supporting urban biodiversity. Local native vegetation is the base of the food web for our wildlife, including our local native pollinators, our native bees, butterflies and hummingbirds.

Biodiversity is biosecurity. Biodiversity only applies to locally native plants and wildlife. Introduced, invasive and non-local native plants contribute to landscape diversity, not to biodiversity. Our pollinators eat local native plants and pollen as caterpillar food. Introduced plant leaves feed few, if any, caterpillar species. Caterpillar species feed the rest of our local food web. Healthy urban ecosystems are measured by the health of contributors to their biodiverse food web and habitat.

Native plants planted in plant communities are resilient to climate change. Introduced and non-local native plants and trees are not resilient to climate change. San Francisco benefits from native plants planted in plant communities. San Francisco Estuary Institute (SFEI)’s Hidden Nature project, done in conjunction with the Exploratorium, maps the locations of plant communities in San Francisco prior to European arrival.

Jake Sigg’s Nature News, February 18, 2022

I compared the description to the SFEI document because the description contains several counterintuitive statements.  Although the SFEI document reflects a clear preference for native plants, it does not corroborate these specific statements:

  • “Biodiversity only applies to locally native plants and wildlife. Introduced, invasive and non-local native plants contribute to landscape diversity, not to biodiversity.”
  • “Introduced plant leaves feed few, if any, caterpillar species.”
  • “Native plants planted in plant communities are resilient to climate change. Introduced and non-local native plants and trees are not resilient to climate change.”

Here are a few studies, references, and public policies that explicitly contradict these counterfactual statements.

Biodiversity is not confined to native plants

“Biodiversity is the biological variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic, species, and ecosystem level.” (Wikipedia)  The Simpson index and the Shannon-Weaver index are the two most commonly used measures of biodiversity by ecological scientists.   Neither index makes a distinction between native and non-native species.  In fact, such a distinction is difficult to make and is often hotly debated. 

In San Francisco, home of the Yerba Buena Chapter of the California Native Plant Society, public policy explicitly acknowledges that non-native species contribute to local biodiversity:  “Parks and open spaces in San Francisco include both native and non-native species, both of which can contribute to local biodiversity.” (Policy 4.1, Recreation and Open Space of San Francisco General Plan)

 Non-native plants are host to many butterflies in the Bay Area

Butterflies lay their eggs on plants called their host plants. The eggs develop through several larvae stages into caterpillars that feed on the host plant that is often confined to a particular plant genus or family.  Few butterflies are confined to a single plant species. For example, plants in the milkweed genus are the host of monarch butterflies.  There are many species within the milkweed genus and many are not native to the San Francisco Bay Area.  An introduced milkweed species, tropical milkweed, is a particular favorite of monarchs and it has the advantage of being available throughout the year, unlike native milkweed species that are dormant during winter months. Some have attributed the recent comeback of the California monarch migration to the widespread planting of tropical milkweed in residential gardens.

This article from the UC Davis Bug Squad says they plant tropical milkweed and two species of native milkweed in their experimental garden. Monarchs show a strong preference for tropical milkweed in their experimental garden: “In July, we collected 11 caterpillars from the narrowleaf [native] milkweed; we rear them to adulthood and release them into the neighborhood. But in the numbers game, the tropical milkweed [A. curassavica] won. From July through today, we have collected a whopping 43 eggs or caterpillars from A. curassavica. How many from [native] A. speciosa? Sadly, none.”

Anise swallowtail butterfly is another common butterfly species in the Bay Area that is dependent upon a non-native host plant.  Before non-native fennel was introduced to California, anise swallowtail bred only once each year. Now it is able to breed year around on non-native fennel and is therefore more plentiful than it was in pre-settlement California.

These butterfly species in the San Francisco Bay Area are not unique with respect to their need for non-native plants:  “California butterflies, for better or worse are heavily invested in the anthropic landscape [altered by humans].  About a third of all California butterfly species have been recorded either ovipositing [laying eggs] or feeding on nonnative plants.  Roughly half of the Central Valley and inland Bay Area fauna is now using nonnative host plants heavily or even exclusively.  Our urban and suburban multivoltine [multiple generations in one year] butterfly fauna is basically dependent on ‘weeds.’  We have one species, the Gulf Fritillary that can exist here only on introduced hosts.  Perhaps the commonest urban butterfly in San Francisco and the East Bay, the Red Admiral is overwhelmingly dependent on an exotic host, pellitory.  And that’s the way it is.” (1)

During the butterfly phase of life, butterflies eat pollen and nectar of many different plants, not just its host plant.  When native plant advocates eradicate important sources of food for butterflies, they aren’t helping butterflies.  For example, butterfly bush (buddleia) is as popular with butterflies as they are unpopular with native plant advocates because they aren’t native.  Butterflies don’t care if they are native because they are an important source of food. 

Butterfly bush is the host plant of Variable checkerspot butterflies. It is also an important source of nectar for butterflies and bees. It is being eradicated on public land because it is not a native plant. butterflybush.com

Native plants are NOT more resilient to climate change

The most dangerous of the counter-factual statements by the spokesperson for the California Native Plant Society is the claim that native plants are resilient to climate change, but non-native plants are not.  That claim defies reality and it prevents us from responding effectively to climate change. 

Here are a few samples from scientific literature that contradict this inaccurate claim about native plants.  There are many others, just Google “Are native plants more resilient to climate change.” 

  • “As spring advances across the Midwest, a new study looking at blooming flowers suggests that non-native plants might outlast native plants in the region due to climate change.”
  • “Warming temperatures affect native and non-native flowering plants differently, which could change the look of local landscapes over time, according to new research.”
  • ”Whether in natural areas or in our gardens, climate change is affecting native plants. According to the Maryland Climate Summary, our temperatures are expected to increase 5⁰ F to 11⁰ F by 2100.
    1. “Higher temperatures cause native plants to experience more heat-related stress. Heat stress causes higher water demand, a situation made worse by longer droughts.
    2. “Higher atmospheric carbon dioxide (CO2) levels preferentially promote the growth of invasive plant species, decreasing the space needed to support natural areas.
    3. “Elongated growing seasons cause earlier leaf out and bloom times, which in turn affects the animal species synchronized to the life cycles of native plants, especially pollinators.”

An appeal to native plant advocates

I am publishing this article today as an open letter to the California Native Plant Society as an appeal to their leadership to make a new commitment to accuracy.  CNPS and native plant advocates enjoy a vast reservoir of positive public opinion.  However, they put their reputation in jeopardy by advocating for policies that are not consistent with reality, with science, or with public policy.  CNPS can’t distance itself from the Yerba Buena Chapter of CNPS because Susan Karasoff has made several presentations for CNPS that are available on its website.  Native plant advocates can best promote their agenda by providing accurate information.

Where do squirrels live? Wherever they can.

We have always had a big population of squirrels in our neighborhood, probably because we have many big trees, including our coast live oak.  Oaks in California had a big mast year in 2021, which means they produced many more acorns than usual.  The population of squirrels increased significantly, which is typical of mast years.

Some of the big trees in our neighborhood before they were pruned or removed. Google Earth

In the fall of 2021, several of our neighbors radically pruned their trees, presumably because they wanted more light in their yards and their homes. They also cut down several trees including a big, old tree behind us and several fruit-bearing trees down the street from us.   

Same trees after pruning.

We didn’t give it a lot of thought when that happened.  We respect the rights of our neighbors to do what they think is best on their property. I remember thinking it wasn’t nesting season for the birds, but I also should have given some thought to the squirrels. (California Department of Fish and Wildlife biologists have defined the nesting season as February 1st through August 15th.) Even if I had, I doubt that I would have objected because it wouldn’t have been neighborly.  I have always confined my activism on behalf of trees and wildlife to public land that belongs to everyone (although I have also tried to help property owners to save their trees at their request).  

Fox squirrel in our Coast Live Oak, one of many that live in our yard.

 We didn’t realize that our neighbors’ trees were the homes of many of the squirrels who are now searching for new homes.  Squirrels have gnawed holes into the eaves of our roof and the wood shingled siding of our home.  They are living in the walls of our home.  If we can’t move them on to new homes, they will soon have their babies inside our home. 

We have found a service that uses humane methods to coax the squirrels out of one-way doors and seal their holes behind them. If you have a similar problem, I recommend the Wildlife Detectives in San Rafael. 

I had not predicted the impact of tree pruning and removal in my neighborhood.  As we try to deny squirrels access inside our home, it only recently occurred to me why the squirrels are seeking refuge inside our home and our neighbor’s home after 15 years of living in peace with them. 

This has been a humbling experience because I considered myself fairly knowledgeable about both trees and wildlife.  Apparently I’m not.  Humans aren’t very good at anticipating the consequences of the choices we make in nature and our choices rarely take wildlife into consideration because our understanding of their needs is limited.  That’s one reason why I often advocate for the “leave it alone” approach to land management.

The Big Picture

The squirrels looking for new homes in our neighborhood are a reminder to keep wildlife in mind when making changes in our gardens and homes.  Our gardens are food and habitat for wildlife. 

But protecting wildlife goes far beyond our own homes because the activities of humans have an impact on wildlife on a population level.  Here are a few examples of projects that have kept wildlife in mind…or NOT!

  • The federal infrastructure bill includes $350 million to construct wildlife road crossings.  Such road crossings help to prevent serious accidents caused by cars hitting animals and save animal’s lives.  California is building a wildlife bridge over the 101 freeway to connect split portions of the Santa Monica Mountain National Recreation Area.  A vegetation bridge is also being built over the Ventura freeway in California.  These wildlife corridors benefit wildlife populations by preventing genetic isolation that can weaken the species. The California Governor’s budget for 2022-2023 includes funding to build more wildlife corridors. 
  • Scientists have learned it is possible to relocate burrowing owls before their underground burrows are destroyed to build new developments.  The owls are enticed into their new homes by surrounding them with the poop of other burrowing owls.  The owls are more willing to stay in their new homes if they believe other owls are living there.  Just like people, they want to live among friends.
  • We must convince native plant advocates to quit destroying important food and habitat for wildlife.  The birds don’t care if Himalayan blackberries are not native.  It is a primary food source that is more productive than its native relative.  When Himalayan blackberries are sprayed with herbicides—as they are regularly in San Francisco—the birds are being poisoned as well.   

There are many more opportunities to take wildlife into consideration in everything we do.  Please write a comment to add more examples. 

The Global War on Non-Native Trees

“In some cases, removal of urban trees because they are non-native may represent an ‘over-shoot’ where the removal of non-natives becomes an end unto itself… the non-native trees being removed are not necessarily highly invasive, and removal is more driven by a desire for native species rather than any real or perceived problems caused by the non-native species.”

An international team of academic scientists studied the many conflicts around the world between those who find value in introduced trees and those who demand their destruction. (1) Team members were from Australia, France, New Zealand, and South Africa.  Professor Marcel Rejmanek at UC Davis was the only American on the team.

Professor Rejmanek is well known to us as the author of the chapter about eucalyptus in Daniel Simberloff’s encyclopedic tome about biological “invasions.”  Rejmanek said, “…eucalypts are markedly less invasive than many other widely cultivated trees and shrubs…they have been orders of magnitude less successful as invaders than pines and several other widely planted trees…Where eucalypts have invaded, they have very seldom spread considerable distances from planting sites, and their regeneration is frequently sporadic.”  He noted that eucalyptus is useful to bees and hummingbirds and I add here that it blooms throughout winter months when little else is blooming in California.  He said,  “Conclusions about positive or negative environmental and economic impacts of eucalypts are often anecdotal, highly controversial and context dependent.”    Professor Rejmanek’s assessment was instrumental in my effort to convince the California Invasive Plant Council to remove blue gum eucalyptus from its list of invasive species.  Cal-IPC downgraded its assessment of invasiveness of blue gum eucalyptus from “medium” to “limited” in response to my request. 

Professor Rejmanek is also the author of the most recent report on plant extinctions in California, published in 2017.  At that time there were 13 plant species and 17 sub-species native to California known to be globally extinct and another 30 species and sub-species extirpated in California but still found in other states.  Over half the globally extinct taxa were reported as extinct over 100 years ago.  Although grassland in California had been converted to Mediterranean annual grasses by grazing domesticated animals nearly 100 years before then, most of the plants now designated as “invasive” in California were not widespread over 100 years ago.  Only one extinction mentions “invasive species” as one of the factors in its disappearance.  Rejmanek speculates that livestock grazing is the probable cause.  He said, “Indeed, one needs quite a bit of imagination to predict that any native plant species may be driven to extinction by invasive plants per se.”

This recap of Rejmanek’s expertise about so-called “invasive” trees and plants establishes his credentials as a reliable witness as the co-author of “Conflicting values:  ecosystem services and invasive tree management,” which I will summarize for readers today.

Setting the stage for conflict

As Europeans colonized the new world in the 18th and 19th centuries, they often brought trees from home with them, motivated primarily by an aesthetic preference. When the colonial era came to an end, nationalism during the 19th century encouraged a new appreciation of indigenous flora.  When planting their own gardens and farms, America’s founding fathers had a strong preference for planting native trees.  While fighting the Revolutionary War, George Washington wrote to the caretakers of his farm at Mount Vernon instructing them to plant NO English trees, but rather to transplant trees from the surrounding forests.

Sources of conflict

By mid-20th century, this preference for indigenous trees escalated to the current belief that non-native trees are threatening indigenous ecosystems.  Conflict arises when there is a “failure to account for, assess, and balance trade-offs between the eco-system services or, at times, a failure to agree on the relative value of particular services.” (1) The study identifies the tree species that are the focus of such conflicts around the world and the ecosystem services those species provide:

Conservation Sense and Nonsense has reported on many of these conflicts around the world:

  • The stated purpose of the destruction of forests in Chicago was the “restoration” of grassland that existed prior to the arrival of Europeans.  Conservation Sense and Nonsense described the conflict regarding that destruction in one of my first articles in 2011 because the issues were similar to those in the San Francisco Bay Area. The debate raged in Chicago for over 15 years, but the destruction of the forest was finally accomplished, despite opposition.  Likewise, in San Francisco after 20 years of conflict, the eradication of eucalyptus forests is being achieved.
  • In 2012, we republished an article by Christian Kull about the practical value of acacia trees to Vietnamese farmers and their opposition to the attempt to destroy them.
  •  We republished an article in 2014 about opposition to the destruction of willow trees in Australia that were planted to control erosion.  Willows are one of many examples of a tree that is considered valuable in North America where it is native and hated in Australia where it is not. The authors of the article described the arguments used to justify the project, ‘Sure, it makes a big mess and causes erosion, and nutrient release, and carbon emissions, and local temperature increases, and loss of habitat, but it’s necessary because we’re going to make Australia a place for natives-only again.’
  • Conservation Sense and Nonsense published a guest post by Matt Chew in 2017 about the eradication of tamarisk trees that were introduced for erosion control in southwestern US.  In that case, the survival of an endangered bird is threatened by this misguided attempt to eradicate tamarisk by introducing a non-native insect.
  • Conservation Sense and Nonsense published a guest post in 2015 by a South African who objected to the destruction of jacaranda trees.  In that case, the beauty of these iconic trees was the primary objection to their destruction.
Jacaranda trees in Pretoria, South Africa

Many similar conflicts around the world are described by the study, which categorizes the conflicts as focused in three areas:  urban and near-urban trees; trees that provide direct economic benefits; and invasive trees that are used by native species for habitat or food.  I will focus on conflicts in urban and suburban areas because they are close to home.

Where is conflict greatest?

The study searched for examples of such conflicts around the world and found that most were in developed countries where ecological knowledge has suggested that eradication is necessary and democracy is strong enough to enable dissent.  Such conflicts are well documented in urban areas where many non-native trees have been introduced. Based on my experience with many of these urban conflicts, I can agree with the authors of the study that they are “frequently vitriolic, as seen in letters to editors, public protests, websites, and blogs.” (1)

How NOT to reduce conflict

The authors of this study dismiss suggestions that “educating” those who object to eradication projects can reduce conflict.  Their assessment of why that approach intensifies conflict is consistent with my own reaction to being lectured about the claimed benefits of eradication projects:

“However, the concept of ‘education’ implies that opponents of tree removal are inherently ignorant or unaware and discounts the importance of their views and values.  Sceptics of environmental issues are frequently highly educated and scientifically literate, with conflict driven by fundamental values, not lack of knowledge.  Further, what one party in a conflict views as education can be viewed as propaganda by those with opposing priorities.” (1)

The authors suggest that the planning process for such projects must be a two-way dialogue that recognizes shared values, such as a strong commitment to conservation of the environment.  The authors describe some of my own reservations about eradication projects:

“In some cases, removal of urban trees because they are non-native may represent an ‘over-shoot’ where the removal of non-natives becomes an end unto itself…Objective evaluation of the ecological services affected may not result in the removal of non-native trees being justified.  Indeed, in some cases the non-native trees being removed are not necessarily highly invasive, and removal is more driven by a desire for native species rather than any real or perceived problems caused by the non-native species.” (1)

There is no doubt that the demand to destroy eucalyptus in California is a case in which removal has become an end in itself that is not justified.  These are some of the accusations used to justify the destruction of eucalyptus that have been disproven by academic scientists without getting eucalyptus off nativists’ hit list.

Source: Conference of California Native Plant Society, 2018

Pessimistic conclusion

The study concludes that we should expect plant invasions around the world to increase and that increased wealth and democracy will make conflicts about tree eradications more widespread.  The authors “suggest that conflict should be seen as a normal occurrence in invasive species removal…Avoiding conflict entirely may be impossible…”

I can’t disagree with the authors of this study about the poor prospects of resolving conflict regarding the destruction of non-native trees that are the heart of our urban forest in California.  However, I am grateful to the authors for their understanding of the issues and their respect for introduced trees as well as those who advocate for their preservation. They understand that lectures by those who demand that trees be destroyed despite the functions they perform are condescending and exacerbate conflict rather than resolving it. 

A Postscript

Jake Sigg has been the leader of the crusade to destroy eucalyptus forests in the San Francisco Bay Area for over 30 years.  He and I have debated this issue many times, without resolution.  In his newsletter of January 20th, Jake seems to acknowledge the futility of our debate as well as his motivation to create a native landscape. It seems he has reached the same conclusion as the authors of the international study of the inevitability of conflict about the destruction of non-native trees, although he concedes that he won’t quit trying…and neither will I. 

“For years I’ve been fighting tree huggers, who understandably don’t want to cut healthy trees down.  The blue gums are handsome brutes.  In my eye I see the rich diverse native biological communities that they displaced; those I fight with don’t see that and don’t value that.  So you can see the communication problem at the beginning.  The same consideration plagues many contentious issues in the world.

“How do you explain this to them?  Mostly, you can’t; you do what you are able to do.  This is not an age for listening to fellow beings.  I find it hard to do.  David Brooks, a favorite, wrote a fraught opinion piece in today’s NYT.  He has just about thrown up his hands, as have I—except that I can’t—and neither can Brooks.”

Eucalyptus canopy on east side of Glen Canyon Park, taken from Turquoise Way December 2012, before tree destruction escalated beyond riparian areas. Glen Cayon Park is one of 33 parks in San Francisco where most eucalyptus trees are being destroyed because they are not native. Courtesy San Francisco Forest Alliance
  1. Ian Dickie, et. al., “Conflicting values:  ecosystem services and invasive tree management,” Biological Invasions, 2014.

California Natural Resources Agency writes a BIG blank check to the “restoration” industry

California Natural Resources Agency has published the draft of “Pathways to 30X30 California” and has invited the public to comment on the draft by February 15, 2022.  “Pathways to 30X30” is the last in a series of documents that defines the program before implementation in February 2022, when distribution will begin of $15 Billion dollars to public and non-governmental agencies to fund specific projects. 

To recap the process that began in October 2020 with the passage of an Executive Order:

  • In October 2020, Governor Newsom signed Executive Order N-82-20 “enlisting California’s vast network of natural and working lands – forests, rangelands, farms, wetlands, coast, deserts and urban greenspaces – in the fight against climate change. A core pillar of Governor Newsom’s climate agenda, these novel approaches will help clean the air and water for communities throughout the state and support California’s unique biodiversity.” The program and its implications are described by Conservation Sense and Nonsense HERE.
  • California Natural Resources Agency held a series of public workshops in summer 2021 that were theoretically an opportunity for the public to participate in the process of defining the program.  Conservation Sense and Nonsense identified potential opportunities as well as pitfalls of the program HERE.
  • California Natural Resources Agency published the first draft of implementation plans in fall 2021.  Conservation Sense and Nonsense published its favorable opinion of the first draft that is available HERE.

The draft of the final implementation document is disappointing.  My public comment on the draft of “Pathways to 30X30” is below.  To preview it briefly here, this is its concluding paragraph:  “California’s 30X30 initiative had great potential to improve the environment rather than damaging it further.  Instead, draft “Pathways to 30X30” suggests that opportunity may be squandered.  Of course, the proof will be in the projects, but for the moment it looks as though the lengthy public process may have been a charade intended to benefit the “restoration” industry, not the environment or the public.”

Please consider writing your own public comment by February 15, 2022.

  • Email: CaliforniaNature@Resources.ca.gov;
  • Letter via postal mail: California Natural Resources Agency, 715 P Street, 20th Floor, Sacramento, CA 95814;
  • Voice message: 1 (800) 417-0668.
  • There will be a virtual meeting on Tuesday, February 1, 2022, 3-6 pm in which the public will be invited to make 2 minute comments.  Register HERE.

TO:        California Natural Resources Agency

RE:         Public comment on draft “Pathways to 30X30”

I have attended the public workshops regarding the 30X30 initiative and sent written feedback when given the opportunity.  I am therefore in a position to tell you that the “Draft Pathways to 30X30” is a significant retreat from principles defined by previous drafts because it is so vague that it is meaningless. Any project could be approved within its limitless boundaries. The document puts CNRA in the position to do whatever it wishes, including violate principles defined in previous draft documents.

My public comment is a reminder of commitments made in previous drafts and a request that they be reinstated in the final version of the Draft “Pathways to 30X30” document:

  • “Pathways to 30X30” must confirm its commitment to reducing the use of pesticides on public lands.  The draft mentions the need to “avoid toxic chemicals” only in the context of working lands.  That commitment must also be made for public parks and open spaces because widespread pesticide use is exposing the public and wildlife to dangerous pesticides and killing harmless plants while damaging the soil.
  • Unlike the previous draft, “Climate Smart Strategy,” “Pathways to 30X30” requires the exclusive use of native plants, which contradicts the commitment to “promote climate-smart management actions.”  The ranges of native plants have changed and must continue to change because native plants are no longer adapted to the climate.  We cannot reduce greenhouse gas emissions causing climate change if we cannot plant tree species that are capable of surviving in our changed climate, as acknowledged by previous draft documents. As Steve Gaines said in the January 12th public meeting regarding “Pathways to 30X30,” “We must help species move [because the changing climate requires that they do].”

There are significant omissions in “Pathways to 30X30” that epitomize my disappointment in this draft:

  • The draft kicks the can down the road with respect to integrating climate change into consideration of projects funded by the initiative:  “Designations have not yet been established that emphasize climate benefits such as carbon sequestration or buffering climate impacts. While the definition of conserved lands for 30×30 builds upon existing designations, it will be important to integrate climate…” (pg 26)  Climate change is the underlying cause of most problems in the environment, yet “Pathways to 30X30” dodges the issue by declining to take the issue into consideration as it distributes millions of grant dollars to projects that are toxic band aides on the symptoms of climate change.
  • The 30X30 initiative made a commitment to protecting 30% of California’s land and coastal waters.  At 24%, we are close to that goal for land, but at only 16% we are far from the goal for coastal waters.  Yet, the draft declines to protect more marine waters:  “MPA [Marine Protected Areas] Network expansion will not be a component of meeting the State’s 30×30 marine conservation goals.” (pg 29, deeply embedded in fine print) The excuse for this omission is that the decadal review of existing MPAs won’t be completed for another year.  That is not a legitimate reason for refusing to designate new MPAs.  The evaluation of existing MPAs can and should be completed and inform the management of new MPAs going forward. 

The lack of guidance in “Pathways to 30X30” is particularly dangerous because California law has recently been revised to exempt projects considered “restorations” from CEQA requirements for Environmental Impact Reports for three years, ending January 1, 2025. An Environmental Impact Report is the public’s only opportunity to preview planned projects and challenge them within the confines of CEQA law.  The public is effectively shut out from the process of distributing millions of grant dollars of the public’s tax money by this blanket exemption on CEQA requirements for an EIR. 

The Draft of “Pathways to 30X30” writes a big blank check for projects that will potentially increase the use of pesticides on our public lands and increase greenhouse gas emissions by destroying plants and trees that sequester carbon and are capable of surviving our current and anticipated climate. 

California’s 30X30 initiative had great potential to improve the environment rather than damaging it further.  Instead, draft “Pathways to 30X30” suggests that opportunity may be squandered.  Of course, the proof will be in the projects, but for the moment it looks as though the lengthy public process may have been a charade intended to benefit the “restoration” industry, not the environment or the public. 

The need for diverse urban forest and the obstacles to achieve that goal

Matt Ritter is a professor of biology at Cal Poly San Luis Obispo and Director of Cal Poly Plant Conservatory.  He is the author of several books about California’s unique flora, including A Californian’s Guide to the Trees Among Us.  He is considered an expert on the horticulture, ecology and taxonomy of the Eucalyptus genus.

Click on picture to view Professor Ritter’s presentation

In October 2021, Professor Ritter gave a presentation to the California Urban Forests Council, entitled “Underutilized Species for the Future of Urban Wood and Urban Forestry.”   He began by explaining why it is important to identify new tree species for our urban forest.

  • “Baja is moving to Oregon,” said Ritter to set the stage.  Within 50-80 years trees living in California now will no longer be adapted to the anticipated warmer, drier climate.  Trees killed by wildfire in California are not returning.  Forests are quickly converting to grassland and shrub.  As of 2018, California had lost 180 million trees to drought, disease, bark beetles, heat, and wildfire, which is nearly 5% of the total tree population in California.  Adding subsequent years to date, we have probably lost 7% of all of our trees.
  • Trees in urban areas will help Californians cope with warmer conditions because they cool our cities and reduce energy consumption.  Fewer trees will mean a lower quality of life, for us and for birds.  The loss of our trees reduces carbon storage, which contributes to more climate change. 

Ritter then explained why we must diversify tree species in our urban forests.

  • There are over 60,000 tree species in the world and only 7% of tree species are found in urban areas around the world.  In California our urban forests are even less diverse.  There are only 234 tree species on average in California’s urban forests.  The average number of approved tree species for planting in California’s municipalities is only 49 and few species on those approved lists are native to California.
  • Diversity of tree species ensures greater resiliency that enables our urban forests to survive changing conditions.
  • Only 9% of tree species in California’s urban forests are native. 
The native ranges of tree species in California’s urban forest.

An inventory of Oakland’s urban forest (street trees, medians, and landscaped parks only) was recently completed.  With 535 tree species, the diversity of Oakland’s urban forest is greater than average for California.  With 14% native trees, Oakland’s urban forest is more native than average. There are 59 species on Oakland’s list of approved trees, of which only 4 are native to Oakland.  The most significant finding of Oakland’s tree inventory is that our urban forest is only 64% “stocked,” meaning that of existing tree wells, only 64% are currently planted with trees.  When trees die in Oakland, they aren’t being replaced.  I don’t doubt there is a will to plant trees in Oakland.  I assume it is a question of means in a city with more pressing needs than resources.

Ritter and his colleagues at Cal Poly have created a website called SelecTree to help Californians choose the right tree for the right site and conditions.  There are 1,500 tree species described on SelecTree, using 60 characteristics, such as drought tolerance.  SelecTree rates blue gum eucalyptus “medium” for drought tolerance, the same rating as native coast live oak and bay laurel.  Ritter clarified that drought tolerance on SelecTree is a measure of how much water the tree species uses.  Claims that eucalyptus uses more water than native trees is bogus, like most bad raps about eucalyptus.  

Ritter recommended specific tree species, based on their drought and heat tolerance.  He said that when diversifying our urban forests “we have to think about Australia” because it is the hottest, driest, flattest, and oldest place on the planet, which is another way of saying that tree species in Australia have survived terrible conditions that are comparable to the challenging conditions in urban environments.

Ritter recommended oak species that are native to Texas; eucalyptus and closely related tree species; and several tree species in the legume family, especially acacia.  In each case he mentioned the suitability of tree species based partly on the quality of its wood.  Apparently, I’m not the only person in California who is disturbed by huge piles of wood chips wherever trees have been destroyed.  Ritter also thinks we should be thinking about how we can use wood when trees are destroyed, rather than building potential bonfires.  

Obstacles to diverse urban forests in California

When Professor Ritter took questions from the audience, we learned that the main obstacle to a diverse urban forest in California, adapted to our climate conditions, is the myopic focus of native plant advocates:

Question:  “Are we introducing new pathogens to our natives by importing new species?”

Answer:  There are many laws and rules that restrict the importation of plants to prevent that from happening.  We also import only the seeds of plants, not grown plants.  The seeds are sterilized and they don’t carry the pathogens that may exist on grown plants in their native ranges.

Question:  “Do we know how quickly birds and insects adapt to new species?”

Answer:  “No we don’t, but who cares?  We are facing a climate emergency.   We have 50 years before life in our cities becomes hell.  We have a responsibility to protect the quality of life in our cities.  We should stop developing the wild, but cities are different.” 

Ritter anticipated a question that is often a concern of native plant advocates by saying we should not be concerned about “weediness,” AKA “invasiveness.”  He said, “That should be far down on our list of priorities of what to worry about.  We need to be primarily concerned about what tree species will grow in our changed climate.”

Rhetorical Question:  “But insects need native plants!”

Answer:  Ritter instantly recognized the mantra of Doug Tallamy.  He replied that it is not well established that there are more insects living on native plants than on introduced plants.  He mentioned a single study that inventoried plant and animal species in eucalyptus compared to oak forests, presumably Dov Sax’s study which concluded:  “Species richness was nearly identical for understory plants, leaf-litter invertebrates, amphibians and birds; only rodents had significantly fewer species in eucalypt sites.  Species diversity patterns…were qualitatively identical to those for species richness, except for leaf-litter invertebrates, which were significantly more diverse in eucalypt sites during the spring.” 

Rhetorical Question:  “We are still dealing with a legacy of blue gum eucalyptus in the Bay Area.  Why should we repeat that mistake?”

Answer:  Ritter agreed that blue gum eucalyptus is “inappropriate” in many places where it was planted in the Bay Area, but we’re not planting blue gums.  There are 800 eucalyptus species and many are ideal for our conditions.  He said, “Why not plant eucalyptus?  It would be dumb not to plant suitable eucalyptus species just because it shares a name.”

Ritter added that, “Planting only natives just doesn’t work in San Francisco.  There would be no trees in Southern California because we don’t have very many native trees in California.”  The pre-settlement coast of California was virtually treeless in most places and that’s a fact. For example, a study of historic vegetation in Oakland, California reported that only 2% of pre-settlement Oakland was forested with trees. “Vegetation before urbanization in Oakland was dominated by grass, shrub, and marshlands that occupied approximately 98% of the area.” (1)

San Francisco in 1806 as depicted by artist with von Langsdoff expedition. Bancroft Library

Oakland as a case in point

The San Francisco Chronicle recently published an article about a guerilla tree-planter in Oakland who is planting native oak trees on public land, wherever he wants.  Oakland’s Director of Tree Services, David Moore, gently suggests that many of these tree plantings are ill-advised:  “‘There is a part of all of us that loves with our hearts the coast live oak tree because of its heritage, the symbolism of our city, and just the legacy that they have,’ Moore said. ‘But we have to diversify, and we are diversifying to other ones that are recommended to be more adaptable to climate change…The reality is that we have created a world that is not the native conditions of these plants,’ Moore said. ‘If we want trees to survive in these non-native conditions, we have to pick trees from around the world that can survive these conditions.’…Moore said oaks, while beautiful, are not the ideal tree for today’s hot, dry and cramped urban landscape. Without careful and costly maintenance, he said, oaks could destroy sidewalks, block light from street lamps and grow their branches into streets and walkways, creating hazards for motorists and pedestrians. The city still plants oaks, but mainly in parks rather than streets because that’s where they do better, Moore said…”

Stalemate

So, here we are.  We have a pressing need for a more diverse urban forest that is adapted to present and anticipated conditions, but we are paralyzed by the ideological commitment of native plant advocates who are demanding that we destroy our urban forest because it is predominantly non-native.  In a recent edition of Nature News, Jake Sigg said, “Hysterical tree planting is worse than a waste of time and resources…”

I am grateful to Professor Ritter for being bluntly frank with members of the arborist community who should know better.  Dare we hope they learned something from that presentation? 

I wish you Happy New Year.  Please join me in my hope for a more peaceful year.  Thank you for your readership.

(1) Nowak, David, “Historical vegetation change in Oakland and its implications for urban forest management,” Journal of Arboriculture, 19(5): September 1993

When ideas remain unexamined and unchallenged, they intimidate ©

My last article of the year is a guest post by Marlene A. Condon, the author/photographer of The Nature-friendly Garden:  Creating a Backyard Haven for Plants, Wildlife, and People (Stackpole Books; information available HERE.)   You can read her blog In Defense of Nature.

Merry Christmas !

Million Trees

A birds-eye view of the University of Virginia (UHall seen in first photo) in Charlottesville, Virginia, makes clear that there are plenty of native trees to be found in developed areas.

The novelist E. L. Doctorow, in a 1989 conversation with PBS journalist Bill Moyers, said, “When ideas go unexamined and unchallenged for a long enough time, they become mythological and very, very powerful. They create conformity. They intimidate.”

He could have been speaking about the current environmental narrative regarding so-called invasive plants. Anyone who speaks out feels the wrath of the folks pushing their fictional environmental manifesto; I’ve lost jobs because of these people.

Most neo-scientists and -environmentalists, having arrived late to the party, have no clue as to why some alien plants exist in profusion along roadways, in former farm fields, and along trails in forests. The popular notion that native plants would otherwise be filling those areas is easily accepted by people who don’t possess knowledge of soil science, or who lack experience with gardening and/or closely observing the natural progression of plants in unmanaged, disturbed areas.

Knowing the prior history of the land is essential to understanding why particular nonnative plants fill some areas. Road building discomposes soil. Trail development/use and cows/farming-equipment moving over the land compact soil. Only “colonizer plants”—those capable of thriving under the altered and nutrient-poor conditions of these sites—can grow there.

Usually such areas, after many years, support a mix of native and nonnative pioneers, but sometimes alien plants outnumber the natives because they are best suited to the constraints imposed by the physical attributes of the site. Anyone (no Ph.D. required) can verify this statement by taking the time to observe the progression of plants in an area not revegetated by people. Doing so would make clear that alien plants do not “push out” native plants by “invading” and “taking over”, but rather, they fill disrupted areas where few native plants can successfully grow.

Yet, the desire by scientists and environmentalists is so great to get folks to remove supposedly invasive plants from the environment that we now have tall tales being spread. Herewith a sampling of some of the most egregiously untrue declarations regarding alien plants.

Johnny Randall, Director of Conservation Programs at the North Carolina Botanical Garden (University of North Carolina at Chapel Hill) wrote a New Hope [North Carolina] Audubon blog post called “Invasive Plants Are NOT for the Birds.”

  • He writes that, “The scientific literature on invasive plants and bird-dispersal is moderate but growing, and almost all of the research warns that this is a serious and multi-layered phenomenon. First off – birds either do not discriminate between native and invasive plants or often prefer invasives over natives. One reason for this is that a large proportion of invasives are high in carbohydrates, whereas the natives are often higher in protein and lipids/fats. Birds are consequently (pardon the analogy) choosing candy bars over cheeseburgers, which could affect bird nutrition, particularly during fall migration”.

The suggestion that birds are choosing “autumn olive berries [that] are sugary sweet treats, the junk food of the bird diet” is echoed by many people. This quote, from a letter to the editor of The Crozet Gazette by Susan A. Roth, William Hamersky, and Manuel T. Lerdau, Ph.D., is supposedly based upon a study published by the Wilson Journal of Ornithology in March, 2007, entitled “Fruit Quality and Consumption by Songbirds during Autumn Migration”.

Yet this study states that “Most common fruits on Block Island [where the study took place in Rhode Island] contained primarily carbohydrates…and little protein…and fat.” As the research paper’s authors were mainly speaking of native plants, this statement directly contradicts that of Mr. Randall that natives are often higher in proteins and fats than so-called invasives.

Additionally, the research paper’s authors state that “fruit selection by birds on Block Island was not simply related to differences in macronutrient composition between fruits…studies of wild and captive songbirds have shown that some species preferentially select high-fat fruits…or high-sugar fruits…”, which hardly implies that Autumn Olive fruits are a necessarily inferior food choice, as declared by Roth, et al.

A variety of foods exists to serve a variety of purposes. Turning sugar into something “bad” for birds comes as a result, perhaps, of this same application to human nutrition. But sugar is not in and of itself, “bad”. A runner in need of glucose who eats some jelly beans gets a quick burst of energy to continue exercising. There’s absolutely nothing wrong with that.

Sugar is only a problem if it’s eaten in excess, as might be done by children. But birds are not children; if they feel the need for protein and fat, they will search for insects and fruits that offer what they need.

  • Furthermore, Director Randall wrote that “Researchers have also shown that many invasive plants have fruits that persist longer than do native plant fruits into the fall and winter. The invasives are therefore available when our natives are not.”

In a world of disappearing habitat for wildlife because of human development, the fact that fruits on invasive plants are available when native-plant fruits are depleted should be seen as a positive rather than a negative.

Charlottesville, Virginia, residential area, has so many trees that you can’t see the roadways interspersed among them. In other words, insects and birds aren’t disappearing because alien plants have replaced native trees.

“Recent research published by Narango et al., in the October 22, 2018, issue of the Proceedings of the National Academy of Science demonstrates that native plants are best for birds. The research showed that yards landscaped with the usual garden center plants, which are mostly nonnative ornamentals, could not support a stable population of chickadees. Yards where native plants composed at least 70 percent of the plantings were able to do so. This is because native plants host more insects than non-natives and therefore provide the necessary high-protein food that birds need to feed their chicks.” [from a letter to the editor of The Crozet Gazette by Susan A. Roth, William Hamersky, and Manuel T. Lerdau, Ph.D.]

Narango’s study cannot be generalized to all birds, although many people have made the mistake of claiming it can. This study applies only to chickadees and certain other birds that inhabit forest because such species are dependent upon the native plants (trees) that comprise our forestland. In other words, if you want forest birds to reproduce in your yard, your yard must be forest. For a fuller explanation, please read “Chickadee Chicanery” at In Defense of Nature.

“These invasive species not only impact our forests, wetlands and streams, but also our economy, health and safety. They kill the trees that shade our homes and that our kids play hide-and-seek around. They increase the presence of other disease-spreading species like ticks. They diminish visibility along trails where safety is important”. [quote from an article from the Central Ohio Partnership for Regional Invasive Species Management at a Nature Conservancy-sponsored website]

The only “forests” where you will see alien-plant species are those that are either managed improperly (overly thinned and thus allowing too much sunlight to reach the ground under the trees) or those that are actually “woods” in the process of succession (transforming from a field to a forest that has not yet reached maturity). “Invasive” plant species are sun-loving and therefore do not inhabit shady mature forests.

As for killing trees, if “they” refers to vines (a common complaint in the eastern U.S.) one must ask, why was the homeowner unable (or unwilling) to keep a vine from killing a tree in his yard that his “kids play hide-and-seek around”? However, if “they” refers to nonnative animals and/or diseases killing trees, that is a different situation altogether, which is not the point of this article. It’s unfortunate the writer did not make clear what “they” referred to. As far as I can tell, there’s no proof that “invasive” plants, in general—as stated above—increase the presence of organisms such as ticks. A study published in Environmental Entomology

purportedly shows that barberry-infested plots support more mice and thus ticks than plots in wooded areas with no barberry.

However, the “no barberry” plots were severely browsed by deer and thus “little understory vegetation was present.” In other words, these scientists compared two completely different habitats, which explains the greater number of ticks in the shrubby (Japanese Barberry) area that provided “questing habitat [for] blacklegged ticks [whereas] little other suitable vegetation exist[ed] in [the] severely browsed forests.”

“Questing habitat” refers to plants upon which ticks can wait at the appropriate height to grab onto an animal that comes by. Obviously, ticks are not going to be found in an area with little understory vegetation as they have nowhere to sit and wait for their quarry.

And we’re to believe “invasive” plants diminish visibility along trails, and native plants don’t? It sounds more like the folks who are supposed to be maintaining the trails have been derelict in their duties!

It’s clear that scientists and journalists are doing everything they can to assure that government and the general public view so-called invasive plants in a negative light. Yet, to my knowledge, no study condemning “invasive plants” exists that has the least bit of merit.

Marlene A. Condon

Addendum by Million Trees

FUZZ: Fatal encounters of animals with humans

In Fuzz, Mary Roach treats a serious subject with a light touch, intended to entertain.  Whether you are amused or horrified, Fuzz will inform you of the fatal consequences of animals threatening or inconveniencing humans.  In every case, choices made by humans are the cause of these interactions.  In most cases, animals pay for these encounters with their lives.  When animals are spared, adjustments in human behavior are needed.

Hungry Bears

Bears became a problem for us when we occupied their territory and intercepted their travel corridors with our own corridors.  Our relationship with bears became lethal when they learned that we are an easy source of food.  We created that association partly by feeding them in our National Parks for 60 years by making huge, open garbage dumps available to them.  That policy was abruptly abandoned in the 1960s when NPS made a commitment to “restoring natural processes.”  NPS mistakenly assumed bears would disappear into the forest quietly and without incident. Predictably, the bears took to raiding campsites and vehicles.  There were many grisly deaths of hikers and campers before NPS realized they had created a situation requiring active management.  Bear proof containers and trash bins were developed and requirements to use them were rigorously enforced.

Bears being fed by visitors at Yellowstone National Park

Dangerous encounters with bears in wild places are still common.  Relocating problem bears to distant, uninhabited locations is rarely successful.  Many quickly find their way back.  Those that stay are likely to engage in the same behavior and the pressure on them to do so is greater because they are in unfamiliar territory.  Bears are reluctantly killed only after they hurt people. 

Mary Roach visited Aspen, Colorado, where there are many bears and wealthy animal lovers as well as unlimited resources to prevent fatal conflicts between them.  Home owners who experience bear break-ins are coached about how to harden their homes against entry.  They are also encouraged to reconsider their landscaping preferences to avoid favorite foods of bears, such as plants that produce berries, fruit, and acorns.  The poor sods tasked with keeping the citizens of Aspen safe from wild animals were horrified when the city planted crabapple trees downtown.  Patrolling restaurants late at night to enforce requirements that they secure their garbage is another of their thankless tasks.

When birds get in the way

Farmers have been at war with birds for as long as humans have engaged in agriculture, some 10,000 years.  Crows, grackles, blackbirds, and starlings are often targets of efforts to eliminate them in agricultural areas.  Between 1939 and 1945 about 3.8 million crows in Oklahoma were killed by dynamiting their roosts.  A study of that effort found no evidence that either the population of crows or crop production was affected by that campaign because nature adjusts:  “Destroy a chunk of a population, now there’s more food for the ones who remain.  Through a variety of physiological responses—shorter gestation periods, larger broods, delayed implantation—a well-fed individual produces more offspring than one that’s struggling or just getting by.”  This balancing act is known to be true of many other species, such as coyotes and rodents.

Dynamiting rookeries has been abandoned, but the National Wildlife Research Center continues to search for effective methods to deter birds.  Many methods of scaring birds have been tried and found to be only temporarily frightening.  “It is easy to scare birds away, but much tougher to keep them away.”  Scarecrows are the traditional method used by farmers.  Research suggests that scarecrows may actually attract birds, because birds associate them with food, like the golden arches on the highway is a signal to pull off for a burger.   

When the twin towers collapsed on 9/11, there was a real world test of our ability to haze birds.  About 2,000 human corpses were scattered among the debris of the towers.  Within 3 days, the gulls arrived to scavenge in the debris.  Harmless explosions were used to scare the gulls.  When the gulls became accustomed to the explosions, those guarding the human remains resorted to shooting and killing the gulls. Twenty-three gulls were shot and their remains were hung in effigy over the debris pile as a warning to their brethren.

 

Gullls scavenging a garbage dump. Attribution

These experiences with hazing birds should be a lesson to those who plan to dump 1.5 tons of rodenticide on the Farallon Islands to kill mice. There are about 250,000 gulls living on the Farallon Islands and they are expected to eat poisoned mice, but the perpetrators of this deadly project want us to believe they can scare the gulls away from the islands before two poison drops about 21 days apart.  Given that mice are expected to survive for 21 days after being poisoned, and the poison is expected to be effective for over 100 days, how can we believe that hazing will be effective long enough to save the gulls?  Must we shoot gulls to save other gulls?  Is this the Hobson’s choice “restorationists” ask us to make?

Human attitudes toward animals

Humans are ambivalent about wild animals.  We have an abstract sympathy for animals that can quickly dissolve when animals get in our way or we feel threatened by them.  Our sympathy is universal, but is often influenced by cultural attitudes.  India is a place where we can observe this conflict between our sympathies and our physical need for food and safety.

Hindu deity Krishna and his cow companion. Attribution

Hinduism is the predominate religion in India and respect for animals is a central theme in Hindu life.  Many of the gods in the Hindu pantheon are animals.  Ganesh, the elephant god, symbolizes wisdom, understanding, and an astute intellect.  Hanuman, the monkey god, is a central character in the Hindu epic Ramayana.  Cows are sacred in India and roam freely through suburban neighborhoods where poor people share the food they have with revered cows.  The line between humans and animals is obscured by the Hindu belief in reincarnation.  The cow wandering in the neighborhood could be your departed uncle returned to Earth in the exalted status of a sacred cow.  He must have had good karma!

As we should expect, many Indians make every effort to spare the lives of animals, even when they are destructive.  Elephants must travel long distances to find the great quantities of vegetation they eat and their corridors are often obstructed by human activities.  Elephants often resort to eating and trampling crop fields of poor farmers, who quite rightly are outraged by their loss.  Indian officials who are responsible for the lives of the elephants are deeply committed to protecting people and elephants. They try to create refuges for the elephants to minimize their raids on agricultural crops.  With a growing population and diminishing wild land, this is a challenging task. 

Monkeys are difficult to control partly because they are very intelligent.  In a national park with many naïve visitors, monkeys have learned to pilfer valuable objects from tourists, such as glasses and phones, and then barter with the tourists for food that is equally valuable to the monkey. 

Attempts to prevent deadly tiger attacks are particularly sad because they are often fatal for both humans and tigers.  Tigers are stealthy hunters at night and even in daylight.  School children walking to school are attractive prey for tigers as well as women who must walk into the forest alone at night to relieve themselves where there are no available latrines.  Animal rangers try to mitigate for these encounters by building latrines and urging children to walk to school in groups. 

When a tiger kills, human sympathy is stretched beyond its capacity to tolerate loss.  Angry mobs sometimes kill the first tiger they encounter after such incidents.  Rangers counsel patience while they hunt for the culprit and confirm its guilt with a DNA test.  Rangers are willing to kill a tiger that has been confirmed as a killer.

The need for tolerance

Mary Roach manages to give us a happy ending by visiting a feed lot where beef and dairy operations send their cattle to be raised.  The grain elevator where animal feed is stored is swarming with mice, but the fellow who runs the feed lot just shrugs them off:  “In the grand scheme of things, the wind probably blows away more than the mice eat.  You know, so I’m not sure that’s a huge problem.”  He has barn cats to keep mice out of his vehicles where they can chew up wiring. Other than that, he doesn’t see much point in pursuing the mice. 

Mary Roach sees hope in this encounter:  “To me, he represents a possible future where people may be frustrated by wild animals that get up in your business but they’re living with them.  In that possible future, people’s reaction to the damage brought about by wildlife is something akin to acceptance.” 

A timely reminder

I publish this article today as a reminder that on Thursday, December 16, 2021, the California Coastal Commission will consider the approval of the project on the Farallon Islands that will aerial dump 1.5 tons of rodenticide on the marine sanctuary to eradicate mice.  If you are ready to accept the existence of mice where they have lived in peace with hundreds of thousands of birds and marine mammals for nearly 200 years, please consider writing a public comment or making an oral comment at the hearing.  Here’s how to do it.

Send written comments to the Commission here:  EORFC@coastal.ca.gov. The deadline to send a written comment is 5 pm, Friday, December 10, 2021.  You can also submit a request to speak on agenda item 11b at the meeting HERE.   The deadline to request to speak is 5 pm, Wednesday, December 15, 2021. 

All quotes are from Fuzz by Mary Roach (W.W. Norton & Company, 2021)