Below is my letter to California Assemblymember, Ash Kalra (District 25, San Jose), asking him to consider revising Assembly Bill 2509 so that it will reduce the use of pesticides in California to eradicate harmless and useful non-native plants. Please consider making this suggestion to your elected representatives in the California Legislature. AB2509 has the potential to reduce pesticide use in California if we make an effort to revise it as needed to accomplish that goal.
AB2509, your bill being considered by the California Legislature, will define “Integrated Pest Management” (IPM) and “invasive species.” The bill has the potential to reduce pesticide use in California’s parks and open spaces, but only if it is revised to accomplish that purpose. AB2509 is also an opportunity to improve the success of ecological restorations that begin by eradicating non-native plants considered “invasive,” by narrowing the target to those few species that are actually doing any harm.
In its present form (April 4, 2024), AB2509 defines invasive species, “to mean nonnative organisms that cause, or are likely to cause, economic or environmental harm, excluding humans, domestic livestock, specified domestic or domesticated species, and nonharmful nonnative organisms.”
That definition is based on Federal Executive Order 13112, which was passed 25 years ago, in 1999. We have learned a lot in the past 25 years about invasive species and the attempt to control them:
The climate has changed a great deal since 1999, and with it the environment, including the plants and animals that live in it. The native ranges of many plants and animals have changed and will continue to change.
We have learned that many introduced plants are often functional substitutes for native plants that are no longer adapted to the changed environment.
We have learned that insects are capable of rapidly adapting and evolving to make use of introduced plants.
We have learned, after trying to eradicate them for over 25 years, that most naturalized introduced plants cannot be eradicated.
We have learned that the herbicides being used to eradicate introduced plants are doing a great deal of harm to the environment and the animals who live in it. We now know that herbicides damage the soil, making it difficult for new plants to survive in sterilized soil, devoid of beneficial microbes and fungi.
We have learned that native plants don’t necessarily return after introduced plants have been eradicated. The damage done by eradication projects is often greater than the anticipated benefit.
Despite dire predictions to the contrary, there is no evidence that any introduced plant species has caused the extinction of a native plant species in California.
We need a new definition of invasive species that reflects these changes and accommodates the movement of plant and animal species needed for survival. We need a definition that does not attempt to stop adaptation and evolution. Like dynamic nature, our attempts to conserve nature must constantly evolve in response. We need a definition that distinguishes between actual harm and theoretical predictions of harm. We need a definition that does not require us to poison our public lands unnecessarily.
Please consider revising the definition of “invasive species” in AB2509 to reflect what we now know about introduced plants, such as:
“AB2509 defines invasive species to mean pathogens, diseases, and insects that are known to cause harm to plants and animals, including humans.”
In its present form, AB2509 also defines Integrated Pest Management as: “’Integrated pest management’ means an ecosystem-based strategy that focuses on long-term prevention of pests or their damage through a combination of techniques such as biological control, habitat manipulation, modification of cultural practices, and use of resistant varieties. Pesticides are used only after monitoring indicates they are needed according to established guidelines, and treatments are made with the goal of removing only the target organism. Pest control materials are selected and applied in a manner that minimizes risks to human health, beneficial and nontarget organisms, and the environment.”
Integrated Pest Management (IPM) is not a new concept. Most public land managers have had IPM programs for over 25 years. Some have resulted in reduced herbicide use in developed areas, without corresponding reductions in public open space and wildlands.
San Francisco’s IPM program has significantly reduced herbicide use on developed public land, but herbicide used to eradicate non-native plants in one-third of park acreage known as “natural areas” has changed little, as shown in this graph:
Source: San Francisco Integrated Pest Management Program
East Bay Regional Park District has also reduced its use of herbicides in developed areas of the park, such as parking lots, picnic areas, and playgrounds, without reducing their use in wildlands where non-native plants and trees are eradicated:
If we want Integrated Pesticide Management Programs to reduce the use of pesticides in our public lands, we must define IPM to achieve that purpose by:
Changing the definition of “invasive species” to focus only on those introduced species that are known to cause actual harm. The expectation of “likely” harm without evidence of actual harm should not be used to justify pesticide use.
Explicitly defining the “guidelines” that determine if pesticides are needed in order to prevent their use on harmless and beneficial plants.
Avoiding the use of vague terms that can be interpreted differently from different perspectives, such as “use of resistant species.” Resistant to what? In whose opinion?
By not making empty promises such as claiming that pesticides can be used on non-native plants without doing any damage to non-target species. Because of drift, persistence, and mobility of pesticides in the soil, it is not possible to make such assurances, which give the public the mistaken impression that herbicides can be used without unintended consequences
Please consider a revised definition of Integrated Pesticide Management that will reduce pesticide use and preserve the vegetation that is capable of growing in today’s environment, such as:
“’Integrated pest management’ means an ecosystem-based strategy that focuses on long-term prevention of pests or their damage through a combination of techniques such as biological control, habitat manipulation, and modification of cultural practices. Pesticides are used only after harm is documented, benefits of existing vegetation have been identified and weighed against harm, the health risks and environmental damage caused by herbicides is considered, and the outcome of eradication is determined to be positive, on balance.”
In conclusion, I will briefly describe my interest in invasion biology and the ecological restoration industry it spawned. My interest began over 25 years ago when my neighborhood park was designated a “natural area” by San Francisco’s Recreation and Park Department. When I moved to the East Bay, I learned that the native plant movement is equally committed to the eradication of introduced plants and the pesticides needed to accomplish that goal. I have visited many of these projects all over the Bay Area and elsewhere in California. I read the publications and attend the conferences of California Invasive Plant Council and California Native Plant Society so that I am as informed of their objectives and beliefs as I am of the academic criticism of invasion biology. I have had a website since 2010 that reports to the general public what I have learned about specific projects and the scientific evaluations of them. I invite you to visit my website to help you evaluate the advice I am sending to you today about AB2509. I can provide references for every statement I make in this letter, on request.
Thank you for your consideration and for your effort to reduce pesticide use in California.
Sincerely, Webmaster, Conservation Sense and Nonsense
CC: Patty Clary, Californians for Alternatives to Toxics Damon Connolly, Assembleymember, District 12 Jay Feldman, Beyond Pesticides Angel Garcia, Californians for Pesticide Reform Doug Johnson, California Invasive Plant Council Megan Kaun, Sonoma Safe, Ag Safe Schools Melinda MacNaughton, El Granada Advocates Margaret Reeves, Pesticide Action Network Jane Sellen, Californians for Pesticide Reform Nancy Skinner, Senator, District 9 Buffy Wicks, Assemblymember, District 15 Wildlife Conservation Board
Update, April 24, 2024:
The Assembly Agriculture Committee voted unanimously to pass AB2509 to the Appropriations Committee with no amendments.
Doug Johnson, Executive of Cal-IPC and Marc Landgraf, Santa Clara Valley Open Space Authority, spoke in favor of AB2509. Johnson claimed that only “small amounts of pesticide are used.” Landgraf said most plants are killed by grazing, mowing, and volunteers pulling my hand; herbicides are used only “when needed.”
Damon Connolly was the only committee member to speak. He expressed concern that AB2509 not conflict with his continuing support for AB99, which has the potential to reduce roadside spraying of herbicide by Cal Trans.
There were no speakers in opposition to AB2509. There was no acknowledgment of the public’s concern about AB2509 or of the public’s concern about herbicides being used on our public lands.
“What exists now can only ever come from what came before.” –Thomas Halliday, Otherlands
Otherlands, A Journey Through Earth’s Extinct Worlds was written by a paleontologist using the latest scientific techniques available. (1) Paleontology has advanced far beyond digging up fossils. Computer and DNA analysis enables paleontologists to reconstruct models of whole animals from bone fragments as well as describe the lifestyle of extinct animals such as what they ate and what ate them.
Geologic periods described by Otherlands. Source: Wikipedia
Thomas Halliday puts this knowledge of some of the 5 billion species that have gone extinct in the 4.6 billion years that Earth has existed into the context of geological and biological changes that caused their extinction. He describes vivid scenes of specific places at specific times, starting 500 million years ago (mya), a geological period when we can recognize most of the phyla (major groups of animals sharing characteristics) that exist today. These snapshots of deep time illustrate that “Environments shape their inhabitants as much as their inhabitants shape them.” (1)
In this article, we will visit a few of these scenes that demonstrate the biological innovations resulting from evolution and the associated geological and atmospheric events. And we will tell you about how modern conservation methods are often working at cross purposes against evolution and adaptation of life as it copes with catastrophic challenges.
Biological Innovation
Primitive life is said to have existed on Earth 3.7 billion years ago (bya). All life that presently exists on Earth is said to have evolved from the first life forms, although the common ancestor is yet to be identified. No life on Earth is truly alien.
The diversification of life on Earth began to accelerate when cyanobacteria developed the ability to photosynthesize about 3 bya. Photosynthesis converts sunlight to energy by consuming carbon dioxide, creating carbohydrates that feed plants and storing carbon in plants and the soil, while emitting oxygen into the atmosphere as a by-product.
This evolutionary innovation is responsible for the abundance and diversity of plants today. It is an important factor in the balance of carbon dioxide and oxygen in the atmosphere, which is one of the most important factors in the Earth’s climate. More plants also mean more food for animals that evolve alongside plants, often forming relationships with one another.
The first mass extinction, roughly 445 million years ago (mya), is the only mass extinction caused by a rapid change in the Earth’s climate from tropical to glacial, which is equivalent to saying the atmosphere changed from predominantly carbon dioxide to predominantly oxygen, the opposite of our currently changing atmosphere and climate.
Carbon dioxide levels are said to have dropped from 7,000 parts per million (ppm) to 4,400 ppm during the Ordovician extinction event that killed about 85% of plant and animal species. Currently our carbon dioxide level is about 420 ppm, just a fraction of what it was during the Ordovician period. In the context of the history of Earth, the climate we are experiencing is mild, a reminder of the potential for a much more extreme climate in the near future.
Comparing contemporary sea levels with those in deep time is another way to appreciate the potential for devastating changes in the future. 20,000 years ago, at the height of the last ice age, sea levels were 120 meters lower than they are now. Conversely, sea levels were highest during the mid-Silurian period, 430 mya, when sea levels were between 100-200 meters higher than they are now and atmospheric carbon dioxide concentrations were high.
Although the causes of the drastic change in the atmosphere and therefore the climate during the Ordovician period are still debated, the advent of photosynthesis is considered a factor. The development of fungi enabled plants to move from water to land by delivering moisture from soil to roots of plants, greatly increasing abundance and diversity of plants. About 80% of plants today receive much of their nutrients and moisture through mycorrhizal fungi.
The photosynthesizing capabilities of plants is one of the ways greenhouse gas emissions, currently causing global warming, can be reduced. Yet, we are using pesticides to kill plants that native plant advocates have arbitrarily decided “don’t belong.” Pesticides also kill fungi in the soil that enable plants to survive during drought conditions created by global warming. This is one of many examples of how management strategies used by humans are counteracting the accomplishments of evolution that occurred long before humans existed or began to think they were competent to “manage” nature.
Plant Evolution Timeline
To make a long, complicated story short, we’ll focus on the major plant groups we recognize today by starting with seedless land plants that reproduce by dispersing spores, such as mosses and ferns that evolved from algae about 460 mya.
Gymnosperms, which we recognize today as conifers, cycads, and Gingkos, are seed-producing plants that evolved about 300 mya. Early species of gymnosperms formed huge forests. The carbon they stored became the coal fields of today when they died during the Carboniferous period (360-300 mya). Today, we draw our fossil fuels from these coal and oil basins. They provide most of our energy, while releasing greenhouse gases causing climate change.
Continents were close together during the Cretaceous geologic period when angiosperms evolved. Source: Australian Museum
Angiosperms evolved from gymnosperms about 130 mya. They are flowering plants whose seeds are often encased in fruit. They are by far the most diverse group of land plants. The evolution of bees around the same time is an example of co-evolution: the flowers feed the bees and the bees pollinate the flowers, delivering pollen from the male anther to the female stigma. This sexual method of reproduction creates greater genetic diversity than self-pollination. Greater genetic diversity creates more opportunities for natural selection to operate on plant variations, which may result in species that are better adapted to existing conditions.
A recent study (2) found that the decline in the population of bees has increased the frequency of self-pollination of some plant species that are capable of both methods of pollination. This is an example of evolution at work today. Plants are responding to the existential need to reproduce in the absence of bees by self-pollinating.
What evolution has accomplished in the past can be undone. In this case, our indiscriminate use of pesticides such as neonicotinoids has decimated bee populations. Some plants will adapt to the loss of bees by self-pollinating, but not without some loss of genetic diversity provided by sexual reproduction and consequently the long term fitness of plants to face challenges in the future.
There’s another trade-off for both plants and bees. Producing nectar and attracting bees with colorful flowers is a big energy expense for plants. Plants therefore save energy by reducing flower size and color, when they can rely solely on self-pollination for reproduction. Obviously, self-pollination ultimately results in a loss of food for bees and may accelerate the decline in bee populations, a negative feed-back loop, if you will.
This example is a reminder that evolution is neither positive nor negative. It is simultaneously both positive and negative. It is what it is: an inexorable force for change.
Evolution of grasses
Grasses and grasslands are late comers to the Earth’s plant kingdom. Grasses evolved from angiosperms about 70 mya, during the Age of Dinosaurs that abruptly ended 66 mya when an enormous asteroid collided with Earth. Grasses are wind pollinated and their seeds are dispersed by the wind, which enables them to spread rapidly and widely.
Grasslands became dominant ecosystems about 30 mya, replacing many forest ecosystems. With the optimal combination of fuel, heat, and oxygen, wildfires were a factor in the transition from forests to grasslands in many places. Once again, wildfires in conifer forests are presently playing a role in converting forests to grasslands, suitable to a warmer and drier climate.
The development of enhanced photosynthesis by C4 grasses gave them a competitive advantage in hot, dry places where photosynthesis is suppressed. C4 grasses are more drought tolerant and they store more carbon than their predecessors, C3 grasses. There are only about 60 groups of C4 grasses, including several important food crops, such as maize, sugarcane, and sorghum. They are found in tropical and sub-tropical regions of Africa and South America and some deserts. California’s native grasses as well as introduced grasses considered “invasive” are not C4 grasses, according to a list of C4 grasses available on Wikipedia. (3)
Because of their potential to improve drought tolerance and increase productivity and carbon storage, there is great scientific interest in converting C3 grasses to C4 grasses. Despite decades of effort, agricultural science has not been able to duplicate what the natural forces of evolution have accomplished, reminding us that evolution is more powerful than we are.
The transition from forests to grasslands had a corresponding impact on the evolution of animals. Some browsers of woody plants learned to be grazers, if they could, while others went hungry, and the diversity and abundance of grazers increased.
Native plant advocates in California have selected grassland as their preferred ecosystem because it was the dominant ecosystem prior to the arrival of Europeans at the end of the 18th century. They have consistently failed to convert non-native grassland to native grassland in California. Nor is it clear that there would be any benefit to the environment or to its inhabitants to return to the treeless landscapes of California that existed prior to settlement in the late 18th century.
Where populations of native grazers of grassland were reduced by the activities of humans, many grasslands in California naturally succeeded to shrubs and trees. “Restoration” projects attempt to prevent succession of grasslands. Some of these projects destroy native trees and shrubs (e.g. Douglas fir, coyote brush, juniper, etc.) mechanically and with pesticides to maintain ecosystems as grassland.
Nativists also want to reintroduce the grazing animals of the pre-colonial period to replace domesticated animals humans introduced because nativists see them as competitors of native animals they consider superior. Where top predators have been killed, these herds of grazing animals outgrow available vegetation unless their numbers are controlled as domesticated animals are.
A recent meta-analysis of 221 studies of the impact of megafauna on plant abundance found, “no evidence that megafauna impacts were shaped by nativeness, “invasiveness,” “feralness,” coevolutionary history, or functional and phylogenetic novelty. Nor was there evidence that introduced megafauna facilitate introduced plants more than native megafauna. Instead, we found strong evidence that functional traits shaped megafauna impacts, with larger-bodied and bulk-feeding megafauna promoting plant diversity. Our work suggests that trait-based ecology provides better insight into interactions between megafauna and plants than do concepts of nativeness.” (4)
The author of Otherlands agrees that the concept of nativeness is not a useful way to understand the environment or conduct conservation because: “Where an animal or a plant from one part of the world appears in another, some might use the language of invasion, of a native ecosystem despoiled and rendered lesser by newcomers…In reality, species do move, and the notion of ‘native’ species is inevitably arbitrary, often tied to national identity…There is no such thing as a fixed ideal for an environment…To look into deep time is to see only an ever-changing list of inhabitants of one ecosystem or another…The concept of native that we so easily tie to a sense of place also applies to time…We must avoid putting our own ahistorical spin on what was, although certainly dangerous and unlikely, a journey guided entirely by chance.” (1)
Migration
The history of evolution is also a history of migration. The oscillation of the Earth’s climate between freezing cold and blistering heat created and destroyed land bridges that enabled or blocked migration as sea levels rose and fell. When North America and South America were connected by Central America as a result of lower sea levels and geological events about 3 mya, the plants and animals of those continents were mixed by migration. Likewise, aquatic life of the Pacific Ocean was separated from the Atlantic Ocean by the Central American land bridge until the Panama Canal was built in 1914.
Geological events also created or destroyed the same opportunities for migration. The opening and closing of the Strait of Gibraltar is a case in point. The Mediterranean Sea exists because the Strait of Gibraltar exists. When the narrow Strait is open, the Atlantic Ocean flows into the Mediterranean Basin, creating the Mediterranean Sea, which is an obstacle for migration of plants and animals between Europe and Africa.
About 6 mya the Strait of Gibraltar closed because the African tectonic plate moved north, colliding with the European tectonic plate. The Mediterranean Sea slowly evaporated, concentrating ocean salt from the Atlantic Ocean, laying down a sea bed of salt in the Mediterranean Basin and ultimately creating a migration corridor between Africa and Europe. There is every reason to believe that the Strait could close again. The Earth’s tectonic plates are in constant motion and there is no reason to believe they will stop moving.
The obsession with “where plants belong” seems to be based on ignorance of the history of dispersal and migration. Much of China and North America have been in the same latitude since the evolution of angiosperms. As a result, many of our plant species considered native in Eastern North America are also considered native in China. These paired species in the same genus are called disjuncts. There are many woody disjuncts in China and North America (magnolias, persimmons, hickory, catalpa, dogwood, sweetgum, tuliptree, tupelo, sassafras, Virginia creeper, etc) as well as many herbaceous disjuncts (ginseng, lopseed, mayapple, skunk cabbage, etc.). (5) They are different species because they have been separated long enough to change as a result of genetic drift, but are in the same plant lineage, therefore chemically similar and presumably used by the same insects. The study of these disjuncts says, “Most scientists do not consider long-distance dispersal to have played much of a role. The prevailing view is that most disjuncts are remnants of genera that were once widely distributed in the northern temperate zone during the Tertiary period [66 mya to 2.6 mya per Wikipedia]. These broad distributions in the northern hemisphere were made possible by recurring land bridges.” (5)
Lateral migration patterns of the past are changing in response to contemporary patterns of climate change. The temperatures at different latitudes are becoming more similar because Polar Regions are warming at a much faster pace than temperate and tropical latitudes. Plants and animals escaping extreme heat and associated changes in vegetation are moving to higher latitudes in the Northern Hemisphere and lower latitudes in the Southern Hemisphere. The increasing similarity of the Earth’s climate is changing wind and ocean currents and contributing to the extreme weather events of our changing climate. Although there are lessons in the events of deep time, we cannot assume that events in the past are entirely predictive of future events because of the complexity of natural processes and our limited understanding of them.
Of all the nonsensical conservation strategies humans are presently using, perhaps one of the most damaging is the futile attempt to stop migration. It is one of few survival strategies of plants and animals needed in a rapidly changing climate and it cannot be stopped.
The project that proposes to shoot barred owls in the Pacific Northwest is an example of a “conservation” project that does not deserve that honorific. Barred owls have migrated from the East to the West Coasts of North America via the boreal forests of Canada. This is another instance in which large contiguous stretches of land at the same latitude facilitate the migration of life because there is less variation in climate at the same latitude.
Source: USFWS
Specialists vs. Generalists
Barred owls are more adaptable than their closely related relative in the same genus, spotted owls. Barred owls have a more varied diet, they are willing to nest in less dense, second-growth forest, and they have greater reproductive success. They are therefore perceived as competitors of endangered spotted owls. Instead of letting natural selection identify the winner of that competition, the US Fish & Wildlife Service intends to shoot 500,000 barred owls in the next 30 years based on their belief that spotted owls will benefit. They do not expect to eradicate barred owls and they made a commitment to continue shooting barred owls in perpetuity. While we continue to log old-growth forests in which spotted owls live, we will kill barred owls with no expectation that they can be eradicated.
This project is typical of American “conservation” projects that attempt to save a specialist species by killing a generalist species. This strategy was enshrined in American law by the Endangered Species Act, which is now 50 years old. Like many 50-year-old public policies, we now know that this conservation strategy is not working because it is inconsistent with evolutionary principles. Change in nature is inexorable. Legal mandates are not capable of stopping evolution. If we had a functional political system, we could stop the greenhouse gas emissions causing climate change, but we don’t. Therefore, we must rely on evolution to cope with the changes in the environment that we have caused.
The most recent mass extinction occurred 66 mya when an asteroid hit the Earth, ending the Age of Dinosaurs. About 80% of all plant and animal species became extinct. The species that survived were the most versatile and the most mobile. Flying dinosaurs were the only dinosaurs that survived, as birds, perhaps because they were the most mobile. “Of the specialized insects, 85% were lost and it was the generalists that survived.” (1)
Mass extinctions have created many vacant ecological niches that are opportunities for experimentation, creating new species. Some were better adapted than others. Natural selection determined the winners of competition within ecological niches. The end of the Age of Dinosaurs created the opportunity for the Age of Mammals, as well as bony fish, marsupials, and lizards.
In other words, our outdated conservation strategy is wasting our limited resources to save specialized species that are probably doomed to extinction. And we are doing so at the expense of generalist species that might survive if we would quit killing them. Keep in mind that 99% of all life forms that have existed on Earth have gone extinct. At a time when the climate is changing rapidly, the goal of saving every endangered species seems both unrealistic and wasteful of limited conservation resources.
Hybridization
Hybridization is one of the tools of evolution. Closely related species, usually in the same genus and even family often mate and their offspring often survive to eventually give rise to new species. Successful hybridization is a means of increasing biodiversity. Hybridization is sometimes a means of improving adaptability and therefore survival.
Unfortunately, nativists see hybridization as a loss of biodiversity rather than an opportunity to improve adaptability and increase biodiversity. Their “conservation” projects often attempt to prevent hybridization by killing hybrids. For example, the plan to kill 500,000 barred owls includes all hybrids of barred and spotted owls. Because barred owls are more versatile, hybridization with spotted owls could even the playing field with barred owls by expanding food sources and nesting habitats of spotted owls.
The Spartina eradication project is another example of the pointless eradication of hybrids. In the case of Spartina, the non-native species grows more densely and it doesn’t die back in winter. Non-native Spartina provides better storm protection and better habitat for nesting birds. The Invasive Spartina Project has been spraying hybrid Spartina with herbicides for over 20 years, without total success. The hybrid looks so similar to native Spartina that hundreds of genetic tests are required to confirm their identification as hybrids before they are sprayed. The Invasive Spartina Project is a waste of limited conservation resources and it serves no useful purpose.
Evolution vs. Conservation
Otherlands should be required reading for those who are engaged in the “restoration” industry. Some of the methods and goals of conservation are at odds with the mechanisms of evolution that have ensured the survival of life on Earth for nearly 4 billion years.
The use of pesticides by “restoration” projects is antithetical to the goal of conservation because they do more harm than good.
Migration is a means of species survival. Natural migration of plants and animals cannot and should not be stopped.
Humans cannot duplicate the forces of evolution. Natural selection is the most powerful, efficient, and effective method of determining the winners of competition.
Hybridization has the potential to improve adaptability of closely related plants and animals. Hybridization cannot and should not be stopped.
Resources being wasted in the attempt to stop the natural forces of evolution should be redirected to reducing greenhouse gas emissions causing climate change. Such efforts are appropriately called “conservation.”
Thomas Halliday, Otherlands, A Journey Through Earth’s Extinct Worlds, Random House, 2023
Erik Lundgren et.al., “Functional traits—not nativeness-shape the effects of large mammalian herbivores on plant communities,” Science, February 2, 2024
David Yih, “Land Bridge Travels of the Tertiary: The Eastern Asian-Eastern North American Floristic Disjunction, Arnoldia, 2012
The Endangered Species Act requires that the Environmental Protection Agency (EPA) conduct biological evaluations (BE) of the impact of pesticides on threatened and endangered species protected by the ESA. For example, when the EPA published its final evaluation of glyphosate in 2021, it informed us that glyphosate is “likely to adversely affect” 93% of legally protected endangered and threatened plants and animals.
Source: EPA Biological Evaluation for Glyphosate
The EPA published a draftof a biologicalevaluation (BE) of 11 rodenticides in November 2023, which is a free gift to the island eradication industry. The deadline for making comment on this draft is February 13, 2024. Public comment can be made HERE.
The EPA’s biological evaluation for rodenticides reached the conclusion that rodenticides used in island eradications have “no effect” on any aquatic plant or animal, including birds in the aquatic food web and amphibians with a fully aquatic lifestyle. They made this “no effect” determination without evaluating any of those species, based on their claim that the Product Label for the rodenticide used in island eradications prohibits its use in water, which is not true. EPA also extended this “no effect” determination to all species under the jurisdiction of National Marine Fisheries Services. (1)
In fact, the standard Product Label for brodifacoum does not explicitly prohibit the use of the product in water. It merely warns of the deadly consequences for aquatic species if used in water: “This product is extremely toxic to birds, mammals, and aquatic organisms. Predatory and scavenging mammals and birds might be poisoned if they feed upon animals that have eaten bait. Runoff may be hazardous to aquatic organisms in water adjacent to treated areas. DO NOT contaminate water when disposing of equipment wash water or rinsafe.” The standard Product Label also explicitly allows aerial broadcast of rodenticides for island eradications.(2) In other words, it’s dangerous to apply rodenticides to water, but, in fact, it often happens during island eradications. The biological evaluation asks the public to believe the EPA’s claim that rodenticides are not used in water despite ample evidence that rodenticides land in water during aerial broadcasts on islands.
Although the standard Product Label acknowledges the potential that rodenticide runoff “may be hazardous to aquatic organisms in water adjacent to treated areas,” EPA’s biological evaluation dismisses that possibility by claiming that “use patterns preclude spray drift and runoff exposure.” EPA’s biological evaluation provides no evidence in support of that claim and that claim is explicitly contradicted by the EPA in its evaluation of the proposed island eradication on the Farallon Islands as well as the considerable record of contamination of the aquatic food web during completed island eradications, as explained below.
Supplemental Product Labels are required for island eradications because they require greater quantities of rodenticide bait than allowed by standard Product Labels and modifications in application methods. The Supplemental Product Label required for island eradications explicitly permits the use of brodifacoum on water (3):
Elevated and floating bait stations are allowed in intertidal zones above the mean low tide mark and below the mean high tide water mark.
Broadcast applications are allowed in coastal areas above the mean high tide water mark. Conversely broadcast applications are prohibited below the mean high tide water mark.
The cited Supplemental Product Label for Wake Island was recently published in preparation for a second attempt to eradicate rats on Wake and 2 adjacent islands. The first attempt in 2012 was a failure. Here is a photo of this complex of islands:
Wake Island. Source: NASA
As you can see, Wake Island is a narrow strip of land surrounding a lagoon that is open to the ocean. Two-thirds of the island is surrounded by sandy, tidal beaches. Scrub vegetation is in the intertidal zone. A portion of the island’s vegetation is wetland. It defies belief that it is possible to aerial broadcast rodenticide from helicopters (or float bait boxes in the intertidal zone) on Wake Island without getting rodenticide in the water.
The published study about the failure of the first attempt to eradicate rats on Wake Island was written by the organizations that conducted the project. It reports that rats were found on the island less than a year after the aerial broadcast and supplemental hand-applications were done. The study makes no mention of non-target deaths of any animals. The study speculates that the failure of the attempt was the result of not applying the rodenticide everywhere rats were living. They will soon try again, using the same methods. Rodenticide bait will surely end up in the water. More non-target animals will undoubtedly be killed. But the public will not learn about either of those issues, because the monitoring and reporting is entirely controlled by the perpetrators of these projects. (4)
Keep in mind that there are 239 taxa living in the intertidal zone around the Farallon Islands, according to Appendix J of the Final Draft of the Environmental Impact Statement for the proposed Farallon Islands. No Supplemental Product Label has been granted yet for the proposed island eradication on the Farallon Islands, but the Farallones are included on the list of 29 island eradications (below) in the EPA’s biological evaluation, which the BE says will be done within the next 5-7 years.
Source: EPA Biological Evaluation of Rodenticides
Contamination of the aquatic food web during island eradications is inevitable
EPA made a public record of its concerns about contaminating the aquatic food web during island eradications in its letter of December 9, 2013 regarding “EPA comments on the Revised Draft Environmental Impact Statement for the South Farallon Islands Invasive House Mouse Eradication Project.” (5) In response to the claims of the DEIS for the proposed island eradication that “the bait deflector will minimize, and in several places, prevent bait drift into the marine environment,” the EPA said, “The EIS should be clear that bait drift would occur.”
The EPA’s letter of December 9, 2013, goes on to report previous experience with aerial broadcast applications on Palmyra Island and states: “For future operations, the potential for bait to enter the marine environment must be a factor in the aquatic risk assessment and further methods to minimize the amount of bait entering the marine environment should be fully explored. The amount of bait that enters the aquatic environment from an aerial broadcast depends on shoreline configuration, island topography, overhanging vegetation, bird activity affecting flight lines, wind strength and direction, weather conditions, and pilot experience. On islands where these factors increase the potential for bait to enter marine environments, additional mitigation measures may be needed to protect sensitive marine environments.” (5)
Based on those concerns about contamination of the marine food web, the EPA’s letter of December 9, 2013 expresses these specific concerns about the proposed aerial broadcast application on the Farallon Islands: “Discuss and consider the factors that increase the potential for bait to enter marine environments that are identified above. Especially relevant are the irregular shoreline, the excessive bird activity from gulls, and the proposal to fly steep areas a second time (shorelines on the Farallones are steep) to increase the application rate in these areas.” (5)
Given the EPA’s explicit admission that aerial broadcast of rodenticides on islands have contaminated the marine food web in the past and are likely to do so in the future, the EPA is not in a position to now categorically deny that “use patterns preclude spray drift and runoff exposure,” as it attempts to do in the draft biological evaluation. Nor is the EPA in a position to categorically deny that aquatic species will be adversely affected by rodenticide bait that will inevitably land in the water surrounding the Farallon Islands, as it attempts to do in the draft biological evaluation.
Farallon Islands, NOAA
The deadly track record of island eradications
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 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. Clearly, mice aren’t considered a problem on islands, unless they have the bad luck of being non-native. Whether native or non-native, they are prey for many bird species.
Most of the raptors on Anacapa were removed before the rodenticide drop. Of those that were left behind, 3 barn owls, 6 burrowing owls, and a kestrel likely died from rodenticide bait or eating poisoned mice. 94 seed-eating birds were also found dead after the poison drop. The study says that these collateral kills were consistent with other similar projects.
Bird scavengers such as gulls, vultures, and condors are also vulnerable to secondary poisoning by poisoned rodents. Shortly after the Anacapa 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.” These deaths weren’t reported by the study of the success of the poison drop. As usual, the study was done by supporters of the project, with little interest in finding more collateral death from the drop. The public is not allowed to observe island eradications. Therefore, the public’s only source of information is those who are directly involved in the aerial application of rodenticides.
“In October 2008, two helicopters dropped approximately 46 metric tons of Brodifacoum 25-W bait on Rat Island’s 2800 hectares, supplemented by hand application of bait around the island’s freshwater lakes. This rodenticide is known to be highly toxic to birds. Some nontarget mortality was expected, but the actual mortality exceeded the predicted mortality. Forty six Bald Eagles died (exceeding the known population of 22 Bald Eagles on the island); toxicological analysis revealed lethal levels of brodifacoum in 12 of the sixteen carcasses tested. Of the 320 Glaucous winged Gull carcasses, toxicology tests implicated brodifacoum in 24 of the 34 tested. Carcasses of another 25 bird species were found; of these 54 individuals, three were determined by necropsy to have died of brodifacoum poisoning.” (6)
Palmyra Atoll was aerially broadcasted twice with brodifacoum rodenticide in 2011 as well as a follow-up hand broadcast application. The study of that project reported: “We documented brodifacoum residues in soil, water, and biota, and documented mortality of non-target organisms. Some bait (14–19% of the target application rate) entered the marine environment to distances 7 m from theshore. After the application commenced, carcasses of 84 animals representing 15 species of birds, fish, reptiles and invertebrates were collected opportunistically as potential non-target mortalities. In addition, fish, reptiles, and invertebrates were systematically collected for residue analysis. Brodifacoum residues were detected in most (84.3%) of the animal samples analyzed. Although detection of residues in samples was anticipated, the extent and concentrations in many parts of the food web were greater than expected.”
These published studies are helpful to understand the scale of water contamination and collateral deaths of non-target animals, including aquatic animals. However, they are just the tip of the toxic iceberg because little monitoring and testing is done on the many marine animals that have been killed in proximity of these projects. Robert Boesch is a retired pesticide regulator for the EPA and the Hawaii Department of Agriculture. Presently, he is Visiting Colleague at University of Hawaii at Manoa. He has written an unpublished discussion paper (7) that reports:
Strandings of whales, some hemorrhaging, occurred within 60 days following anticoagulant bombardment.
Unusual mass strandings of hemorrhaging dolphins occurred in San Diego and Hawaii years after anticoagulant bombardment.
There is very little known about the fate of anticoagulant residues in the oceans.
Source: Robert Boesch discussion paper available HERE .
The documented deaths of non-target animals caused by island eradications are direct poisonings by eating bait on the ground or by secondary poisoning by eating poisoned rodents. The EPA biological evaluation attempts to dismiss the potential for secondary poisonings by citing a study (Baldwin 2021) that claims most rodents die in their burrows after eating the poison, making them unavailable to be eaten by other animals. This study is not relevant to island eradications because it was conducted on ground squirrels (not rats or mice), it used a first generation rodenticide (diaphacinone) which is not used in island eradications, and most applications were burrow baits, rather than aerial broadcast.
What’s at stake?
About 1,200 island eradications have been done all over the world over the last 30 years, with mixed success. The EPA’s biological evaluation announces the intention to approve 29 new island eradications in US waters within the next 5-7 years, including the Farallones. In the case of Hawaii, the list says “all islands.” Many of the listed islands are actually a complex of islands, such as those in Boston Harbor. Many of the islands are residential communities, such as Nantucket and Martha’s Vineyard. As presently drafted, the biological evaluation will make it possible to approve those projects without addressing the considerable evidence that these projects are killing thousands of birds and animals and contaminating the ocean surrounding island eradications.
The Bottom Line
The draft biological evaluation is unacceptable because it gives the public the false impression that island eradications with rodenticides are harmless, when they clearly are not. It confers EPA’s blessing on island eradications by refusing to evaluate endangered species that may be harmed by island eradications. It ignores the evidence that rodenticide applications have killed many terrestrial and aquatic animals and contaminated the water.
The biological evaluation must be revised to correct these flaws in the present draft:
Exposure to rodenticides during island eradications must be based on Supplemental Product Labels for island eradications, not standard Product Labels that do not apply to island eradications.
The revised biological evaluation must evaluate all legally protected animals exposed to rodenticides during island eradications, including aquatic animals. Both bioconcentration and bioaccumulation must be considered in the determination of exposure to rodenticides. “No effect” cannot be assumed without such evaluation.
The revision must provide evidence in support of the claim that there is no drift or run-off of pesticide from aerial broadcasts done on islands or delete that claim, which is contradicted by actual experience with island eradications.
The revision must remove the claim that rodents die in their burrows after eating rodenticide bait (Baldwin 2021) because the study was done on a different animal, using a different rodenticide, and a different application method.
“The more we know about plans to eradicate harmless mice on the Farallon Islands with rodenticide, the less sense it makes.” – Conservation Sense and Nonsense
Plans to eradicate mice on the Farallon Islands with rodenticide were approved by the California Coastal Commission (CCC) two years ago, on December 16, 2021. Although CCC approval was contingent on a few conditions intended to reduce the inevitable death of non-target birds and marine animals, it is unclear if CCC will be able to enforce the conditions. Plans seem to be moving forward behind closed doors, so Conservation Sense and Nonsense continues to be concerned about this project.
First a brief reminder of the project and our objections to it. House mice were introduced to the Farallon Islands over 100 years ago by ships visiting the island. There is no evidence that mice harm birds on the Farallons. The mice are an integral part of the food web, eating primarily vegetation and supplementing that diet with insects during summer months when vegetation is sparse. The mice are also the prey of hundreds of thousands of birds that live on the islands as well as birds that stop over on their migratory routes. The mouse population varies throughout the year, dwindling during winter months and increasing in the fall. When the mouse population declines, food sources for their predators also decline. That’s when burrowing owls are said to prey on the nestlings of ashy storm petrels. Though the mice are blameless, the project proposes to kill them all based on the assumption that burrowing owls will not overstay their migratory stop over if food sources are significantly reduced. The project is expected to kill hundreds—perhaps thousands—of non-target birds who will eat poisoned pellets directly and/or poisoned mice.
The project has always seemed absurd and nothing we’ve learned about it in the past 2 years has made it seem otherwise. Our last article of 2023 will report new information learned since the project was approved.
Contamination of the food web
Robert Boesch is a retired Pesticide Regulator for the Environmental Protection Agency, region 9 and the Hawaii Department of Agriculture. Presently, he is Visiting Colleague at University of Hawaii at Manoa. Based on his research and experience, he has written a discussion paper about island eradications using rodenticides, which he has shared with the California Coastal Commission and many other agencies and organizations. This entire discussion document is available below as a footnote and this is his summary of “Eradication Programs Eliminating Invasives and their Predators and Scavengers!”
Eradication programs for mice and Polynesian Rats are planned for the Farallon Islands, Midway and Wake Island.
Brodifacoum, a potent, persistent and bioaccumulative anticoagulant poison is the toxicant. [This is the rodenticide that will be used on the Farallon Islands to kill mice. There are no rats on the Farallons.]
Brodifacoum residues have been detected in almost all fish that were collected following treatment of Palmyra, and trace levels were found in 10 percent of the fish after treatment of Wake.
Brodifacoum residues in fish caught at Wake increased from trace levels to detectable residues over 3 years.
Diphacinone is a greater threat of secondary poisoning to mammals than brodifacoum.
Strandings of whales, some hemorrhaging, occurred within 60 days following anticoagulant bombardment.
Unusual mass strandings of hemorrhaging dolphins occurred in San Diego and Hawaii years after anticoagulant bombardment.
There is very little known about the fate of anticoagulant residues in the oceans.
Our knowledge of contamination of the food web caused by rodenticide drops on islands is limited because monitoring is usually short-term and frequently done by the same contractors who implemented the project, with little motivation to report the extent or persistence of contamination. For the same reasons, we have limited knowledge of how successful the projects are.
Track record of island eradications
About 1,200 island eradications have been done all over the world over the last 30 years. Our evaluation of the proposed project on the Farallon Islands is based on the success or failure of those projects.
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 deer 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. Although post-project monitoring reported successful eradication of rats, they were not confident that all of the mice that were left on the island had been killed. (1)
Attempts to eradicate mice have been consistently less successful than attempts to eradicate rats. A study of 139 attempted eradications of animals on 107 Mediterranean islands in eight countries 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. 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 initially considered successful. (2)
Island eradications considered initially successful, are often failures in the long run. A recent visitor to Anacapa Island has reported seeing two dead rodents as her escorted group was leaving the island. One was identified as a deer mouse. The other rodent was not identified. Have rats returned to Anacapa? Are native deer mice still being killed by residues of rodenticide? (3)
The eradication of rats on Anacapa Island is relevant to the planned project on the Farallon Islands because rats were killed, but mice were saved. Although the Anacapa project considered rats a threat to birds, it did not consider mice a problem. Rats were killed, but mice were saved by trapping and removing them from the island before the rodenticide was dropped. Mice on the Farallon Islands are not a threat to birds. They will be killed only because they are non-native.
Mice are members of the food web
Mice on the Farallon Islands are as much a part of the food web as they are on Anacapa Island. They are prey of the birds and they are mainly predators of vegetation. On the Farallon Islands, mouse predation of vegetation is considered a problem, but on Anacapa Island it is not considered a problem. On the Farallon Islands, the study of the diet of mice reports that mice also eat insects when vegetation becomes scarce in the fall. (4)
The study of the mouse diet on the Farallons also reports that 63%-80% of the vegetation on the Farallons is non-native. That’s why 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. (5)
I took this photo on Santa Cruz Island in 2010, while visiting with an escorted group.
The Farallon Islands have never been inhabited and there has been no public access to the islands for over 100 years. Non-native plants were not brought to the Farallons by humans. Their seeds were brought by birds in their stomachs, in their feathers, on their feet and by wind and ocean currents. Non-native plants dominate vegetation on the Farallons partly because non-native plants are eaten by birds. The plants are members of the food web and their eradication is depriving birds and other animals in the ecosystem of food. If non-native plants were not being eradicated with herbicides, it probably would not be necessary for mice to eat insects, which are not their preferred food. We can safely assume that herbicides are harmful to the animals that consume plants that have been sprayed. (6)
Consequences of fiddling with the food web
There were also feral cats on the Farallons before they were killed. Predictably, the population of mice increased after the cats were killed. When 6,000 feral pigs were killed by sharp shooters on Santa Cruz Island, Golden Eagles substituted for that plentiful food source by preying on the rare, native Channel Island Fox. Golden Eagles were captured and relocated to the mainland. The fox population was restored to the island by a captive breeding problem. The same could be done on the Farallons to eliminate the only known threat to ashy storm petrels. The small population (approximately 6-10) of burrowing owls that are the only known predators of the petrels could be trapped and removed to the mainland as the Golden Eagles were on Santa Cruz Island.
Restoration plans for any ecosystem should begin with a thorough analysis of the food web. Plucking single species of plants and animals out of complex ecosystems without understanding their role in the food web results in unintended and harmful consequences.
The Farallons project is based on mistaken assumptions
The Farallons project is based on the mistaken assumptions of invasion biology. Most of the vegetation on the island is being killed with herbicide because it is non-native. The vegetation is clearly essential to all the animals living on the island, but invasion biology asks us to believe that it is not, solely because it is non-native. If the mice are killed on the island, it is only because they are non-native, not because they are harmful to birds. They are an important source of food for the birds, but invasion biology asks us to believe they are not, solely because they are not native. These assumptions are wrong, yet 50 years of nativist ideology still has a death grip on our public lands.
This deadly dogma is losing its grip, but apparently too slowly to prevent the destruction of the food web on the Farallon Islands. I always attend the conferences of the California Invasive Plant Council (Cal-IPC) and the California Native Plant Society (CNPS) to give native plant advocates every opportunity to convince me of their ideology. Consistently, I find more support for my contrarian viewpoint than I do for invasion biology. A presentation about the salt marsh harvest mouse at the Cal-IPC conference in October 2023, is an example.
California Department of Fish and Wildlife collaborated with UC Davis to study the food preferences of salt marsh harvest mouse (SMHM), an endangered native animal that lives in the wetlands of the San Francisco Bay. It has always been presumed to be entirely dependent on native pickleweed for food and habitat. The legally mandated recovery plan is based on that mistaken assumption.
Presentation to California Invasive Plant Council conference in October 2023
The study reported to Cal-IPC shows clearly that SMHM is NOT dependent on pickleweed for either food or habitat. SMHM is an extreme omnivore. SMHM ate 39 species of native and non-native plants as well as insects in empirical trials. In fact, it ate EVERY plant it was offered. A fecal study of SMHM living in the wild confirmed that finding. Fecal analysis found SMHM had eaten 48 native and non-native plant genera as well as some insects.
Presentation to California Invasive Plant Council conference in October 2023
SMHM have no preference for native plants for either food or nesting habitat. The most SMHM’s captured in the study were found where there was less than 10% pickleweed.
This was an absurdly simple experiment in which SMHM were captured and fed a variety of plants. It could have been done by anyone with little knowledge or fancy equipment. Why does this foolish mistake, caused by nativist bias, matter? Because “restoration” projects all around the San Francisco Bay have been eradicating non-native plants, claiming it would benefit the endangered SMHM.
Nativism in the natural world is not benefiting wildlife. Rather it seems to benefit only the army of “restorationists” who earn their living killing harmless plants and animals. As long as they continue to receive public funding for their projects, they have job security because they have spent over 20 years trying to do something that cannot be done. Evolution moves inexorably forward. The puny efforts of humans to regress landscapes to arbitrarily selected historical standards cannot change the forward trajectory.
There were two presentations about difficulties with native plant restorations on Anacapa and Santa Rosa Islands at the CNPS conference in October 2022. More than 20 years after non-native iceplant, rabbits, and rats were killed on Anacapa, native flora and fauna are still described as degraded, “Due to the cumulative and severe impacts to the soil and native seedbank, native vegetation communities have not recovered on their own…” On Santa Rosa Island the “restoration” community has installed artificial fog fences to replicate a historical cloud forest to improve survival of native chaparral plants. (7)
Alternatives to rodenticide drop on Farallon Islands
It is not necessary to kill mice on the Farallon Islands because they are not harmful to birds. If non-native vegetation weren’t killed with herbicides, there would probably be enough vegetation for omnivorous house mice as well as birds. Both mice and vegetation are being killed only because they are non-native. If the nativist ideology were removed from the agenda, dumping rodenticides on mice and herbicides on non-native vegetation would not be necessary.
If the protection of ashy storm petrels really were the goal of the proposed project on the Farallon Islands, the most obvious solution would be to remove the small population of burrowing owls that are the only known predators of the petrels. Keep in mind that ashy storm petrels are not considered threatened or endangered and that two applications for protected status have been denied. (8)
There is a non-lethal alternative to reducing populations of rodents using rodenticides that kill non-target birds and other animals. Academic scientists at Arizona State University have developed birth control for rodents that can be used on the Farallons to reduce the population of mice. (WISDOM Good Works)
In Summary
Killing house mice on the Farallon Islands with rodenticide is unnecessary and will be harmful to the ecosystem and its inhabitants because:
Aerial dropping 1.5 tons of rodenticide will poison the entire ecosystem, killing hundreds of non-target birds and marine animals.
House mice on the Farallon Islands do not need to be killed because they are food for birds and they are harmless.
If burrowing owls are killing nestlings of ashy storm petrels, they could be removed and relocated.
The nearly 40-year attempt to kill non-native vegetation with herbicide should be stopped because the vegetation is a vital element in the food web of the Farallon Islands.
“Urban Jungle is breathtaking in its scope, both geographic and temporal… I can say I probably learned more per page in Urban Jungle than in any other book I have read at all recently.” –Professor Art Shapiro
As climate change makes many places uninhabitable, there is a new urgency to restore natural habitats damaged by human activities.
After a lengthy and contentious battle, the European Union narrowly voted to make a commitment to restore 20% of nature areas on land and sea within their borders. Farmers were the primary opposition to making this commitment, claiming it would severely reduce their ability to produce sufficient food. 6,000 scientists from several countries disagreed: “They argued that in the long term, it was climate change and nature degradation that constituted the highest threat, and that the proposed policy would ensure sustainable food production.” (1)
The Biden administration has issued an executive order to conserve 30% of US lands and oceans by 2030. This 30X30 commitment has been funded by the State of Californiaand is in the early stages of implementation. In the US, the commitment to “restore” land is often interpreted as a commitment to destroy non-native species with pesticides with the goal of restoring native plants and animals.
“Restoration” could mean something entirely different and a recently published book, Urban Jungle: The History and Future of Nature in the City, invites us to redefine restoration in a very different way. In a nutshell, Urban Jungle proposes to let nature heal itself without a preconceived goal to replicate historical landscapes that aren’t adapted to the climate and the challenging conditions of the urban environment. Left to its own devices, nature creates novel ecosystems, plant communities that are biodiverse and self-sustaining.
World War II created a case study of novel ecosystems
When World War II ended in 1945, the Potsdam Agreement determined that Germany would be occupied by the allies that won the war: United States, United Kingdom, France, and Soviet Union. The map of post-war Germany (see below) shows the division of Germany among the allies. The white portion of the map was administered by the Western Allies and the gray portion of the map by the Soviet Union. Berlin (in red) was deep in Soviet controlled East Germany and was likewise divided into East and West Berlin. The Soviet Union did whatever it could to isolate West Berlin by restricting access routes to West Berlin and ultimately building a wall around it in 1961.
Berlin was heavily bombed during the war and was largely a pile of rubble at the end of the war. While other European cities were able to clear the rubble within a few years, West Berlin could not because the Soviets would not let them dispose of rubble outside city limits.
The physical isolation of West Berlin and the restricted access of the population to the countryside turned West Berlin into an ecological island. Scientists in West Berlin, with few other opportunities to pursue their interests in botany and ecology, studied and recorded the transition of many tons of building rubble into novel ecosystems populated by whatever plants could find their way there and survive the challenging conditions. West Berlin was physically isolated from 1945 until the reunification of West and East Germany in 1990, creating a unique opportunity to study natural succession in an urban setting when nature is left alone for nearly 50 years.
One of the first pioneer plants in West Berlin arrived with the Ukrainian army in the hay brought to feed their horses. Salsola collina, a tumbleweed, is native to southern Russia and central Asia. Its arrival was a preview of what was to come, a landscape that would be radically different from the pre-urban landscape. The plants best adapted to the harsh conditions of the ruined city were hardy non-native species.
Non-native plants that thrived in West Berlin were more tolerant of higher temperatures in an urban setting, where hard surfaces absorb more solar radiation, buildings block the wind, and greater pollution traps heat. This is known as the heat island effect. By the 1960s, the temperature in Berlin was on average over 4⁰F higher than the surrounding countryside.
Südgelände Nature Park in Berlin was a railway yard that was abandoned in 1952 as a result of the division of East and West Berlin. By 1984 there were 334 ferns and flowering plants and many animals, birds, and insects living in the park. It is a novel ecosystem that was shaped by human activities then left to natural processes. It remains as a nature park today because the people of Berlin fought against developing it into a train station again. They had come to love its wild beauty during their long confinement during the Cold War and they weren’t willing to give it up. Source: Südgelände Natur Park
The naturally evolving novel ecosystems in West Berlin were also surprisingly biodiverse. Where natural succession was allowed to occur over many years, 140 different plant species and 200 insect species were found in the 21st Century. In nearby Tiergarten Park, which is carefully maintained as a park, only one-quarter as many insects were found in an area of comparable size. By the end of the 20th century, 1,392 naturalized plant species were growing in Berlin, compared to 822 in the 18th century.
21st Century equivalent to World War II
Climate change is the 21st Century equivalent of World War II in its potential to cause death and destruction. Climate change will create similar requirements to restore environments that are destroyed. Urban settings will be particularly vulnerable to the consequences of climate change because they are population centers and they are already compromised by urbanization.
Tidal estuaries and wetlands are one of many ecosystems that are threatened by climate change, as sea-levels rise in a warming climate and intensity and frequency of storms increases flooding. These threats are greater in urbanized areas because most of our largest cities were built on coastlines and rivers at a time when transportation and shipping was easier by water than by land.
Historically, cities were protected from storms by surrounding marshlands that filtered and cleansed runoff from the land, polluted by human waste. But as cities grew, marshlands were often destroyed to create more land. In many cases, the landfill was composed of the garbage produced by city-dwellers.
The closure of urban garbage landfills and the restoration of wetlands to buffer the city from the rising sea and extreme weather events is another opportunity to redefine restoration as a natural process that uses the healing powers of nature. Urban Jungle uses Fresh Kills Landfill in New York City as an example of restoring nature by leaving it alone.
Fresh Kills was a tidal estuary and marshland on the west side of Staten Island in New York City. It was opened as a landfill to accept residential garbage in 1948. By 1986 it had reached peak volume, receiving 26,000 tons of residential garbage per day. When it was closed in March 2001, the garbage was from 90 to 225 feet tall, weighing 150 million short tons. It was reopened in September 2001 to accept about one-third of the rubble from the collapse of the World Trade Center on September 11, 2001. It was the largest garbage landfill in the world when it finally closed.
Fresh Kills Landfill is now in a 30-year process of being restored as a park, renamed Freshkills Park. The garbage was capped (see below) and methane produced by the decomposing garbage is being captured and used to heat about 22,000 homes on Staten Island.
The productive wetland ecosystem that was destroyed by the landfill cannot be restored. Instead, a new ecosystem will slowly emerge on top of the toxic garbage. The process began by seeding the slopes of garbage with fast-growing plants that were then plowed repeatedly back into the soil to add organic matter. Then tough native grassland species were planted to provide habitat for initial colonizers, such as insects, small mammals and birds. Now that basic conditions for life have been established, what happens next is in the hands of nature: “Freshkills Park will be reclaimed by whatever species are attracted to the foundation of grasses.Nature will do the bulk of the work, not human beings. Biodiversity will steadily build as winds and birds bring seeds to the site. This process of spontaneous successional growth is how nature rebounds from natural disasters such as forest fires, earthquakes, volcanic activity and climate upheaval. Only in the case of Freshkills Park, the disaster was humanmade.”(2)
View of Downtown Manhattan from Freshkills Park. Licensed by Creative Commons
Getting off the pesticide treadmill
Allowing nature to heal the places humans have damaged is also an opportunity to get off the pesticide treadmill. The natural process of succession does not require the use of herbicides to eradicate non-native plants that arrive naturally on the wind, in water currents, and in the stomachs of animals and birds. When all plants are welcome, there is no need for herbicides and there is more biodiversity that supports more animals and is more resilient as the climate changes in unpredictable ways.
In 2019, France banned the use of glyphosate-based herbicides for non-agricultural use. The French city of Blois imposed the ban before the national ban was adopted: “A study published in 2019 found more than 300 species of urban plants sprouting out of the pavements of the French city of Blois, which had recently phased out glyphosate weedkiller.” (2)
Allowing nature to “manage” our public parks, makes them safer for us and for wildlife as well as more biodiverse than human management that wages a never-ending war on so-called “invasive” plants. There are more bees and bee species in cities than in surrounding countryside because there is more available food in its diverse vegetation: “Analysis of honey from a bee in Boston, Massachusetts, found it had pollen taken from 411 different species of plants; nearby country honey contained traces from just eighty-two plants. Cities are islands of biodiversity compared to rural monocultures, with a bigger and more diverse source of nectar even than nature reserves and forests…” (2)
The takeaway message
Successful restoration of damaged land will take these facts into consideration:
Many hardy non-native plants are better adapted to challenging urban conditions than native plants: “If native plants can’t hack it in the metropolis, their place should be taken by specialist species drawn from around the world that find niches in the various microclimates of the concrete jungle.” (2)
A diverse landscape of native and non-native plants is more resilient in a changing, variable, and unpredictable climate.
Novel ecosystems created by natural succession are more biodiverse than their historical predecessors.
When pesticides are used to kill non-native plants, disturbed land is damaged further and is even less likely to support a native landscape. Killing non-native plants with herbicide also reduces biodiversity.
In June 2023, Washington Post published an opinion piece advocating for the use of herbicides to kill non-native plants, in which Doug Tallamy was quoted as saying that spraying herbicide on non-native plants is “chemotherapy,” equating non-native plants with cancer and pesticides with medical therapy. Tallamy. and more broadly his viewpoint, received some blowback from Conservation Sense and Nonsense and others.
Thomas Christopher and Doug Tallamy collaborate on their shared mission of promoting the use of native plants and the closely related goal of eradicating non-native plants they consider a threat to native plants and insects. In October 2023, Tom Christopher (TC) gave Doug Tallamy (DT) an opportunity to respond to criticism of native plant dogma on his Growing Greener podcast that is available HERE. Christopher also invited listeners to send him feedback on the podcast. Professor Art Shapiro, whose work was central to the interview, has responded separately and his response is available as a footnote. Conservation Sense and Nonsense (CSN) sent Christopher an email, which I hope he shared with Tallamy. The following is an excerpt from that email.
Hi Tom, Thanks for the air time for opposition to eradicating non-native plants in your interview with Doug Tallamy and for this opportunity to respond. I’m flattered that criticism of native plant dogma has attracted some attention on the East Coast. I’ve transcribed most of your interview with Doug Tallamy as best I can and provided some feedback to Tallamy’s viewpoint. I sent Art Shapiro the podcast and he has responded separately.
TC: Some people say that non-native plants are just as effective as natives in supporting food webs. For example, buddleia that is spreading throughout the East and West is used by butterflies.
CSN: Buddleia davidii is on California’s list of invasive plants, but it is not considered invasive in California. It was put on California’s list because it is considered invasive elsewhere, making the point that invasive plant behavior varies depending on local conditions, such as climate. Sweeping generalizations about invasiveness are rarely accurate. If gardeners are concerned about the potential for invasive behavior, they can plant a cultivar of buddleia that does not reproduce.
DT: We shouldn’t call all insects pollinators. Just because an insect visits a flower for nectar doesn’t mean it’s pollinating that flower. There are more visitors to flowers than there are pollinators. Butterflies visiting buddleia are just there to sip nectar.
Variable checkerspot. Photo by Roger Hall
CSN: Buddleia davidii is native to Central China. Non-native buddleia is used by a butterfly species that is native to California and other states in the Western US.
The first actual observation of checkerspot butterflies breeding spontaneously and successfully on buddleia was in Mariposa County, California in the Sierra Nevada foothills. Checkerspot bred there successfully on buddleia in 2005 and in subsequent years. This colony of checkerspot on buddleia was reported in 2009: “We conclude that buddleia davidii [and other species of buddleia] represents yet another exotic plant adopted as a larval host by a native California butterfly and that other members of the genus may also be used as the opportunity arises.” (1)
In 2017, a gardener in Mendocino County, California also reported the use of buddleia as the host plant of checkerspot: “By now I am questioning how it was that butterfly larvae were using my butterfly bush as a host plant, completely against everything I’d ever heard. How was this possible? I emailed Art Shapiro, a very well-known butterfly expert and author, sending him a pic. He wrote back to confirm they were butterfly larvae, but added, ‘These are not mourning cloak butterflies. They are checkerspots. And the only time I’m aware this has happened [like, ever, except one in a lab in 1940…] is in Mariposa County.’” (2)
Buddleia is available as the host plant of checkerspot butterflies with a native range from Alaska south along the Pacific Coast through California and Arizona to Baja California and Mexico; east to Montana, the Dakotas, Wyoming, Colorado, New Mexico. This is a clear case of a widespread native butterfly choosing a non-native plant as its host.
Arthur M. Shapiro and Katie Hertfelder, “Use of Buddleia as Host Plant by Euphydryas chalcedona in the Sierra Nevada foothills, California,” News of the Lepidopterists’ Society, Spring 2009
DT: Most bees that people see in their gardens are honeybees that are there to get pollen and sometimes nectar. These are generalist bees but specialist bees that require pollen from particular plants (always native plants) can’t be supported by those at all.
Squash bee. USDA public domain
CSN: Specialization of insects is exaggerated by Tallamy. For example, he would probably call a squash bee a specialist. As its name implies, its host plant is squash plants in the squash family, with 98 genera and 975 species. The squash bee is considered an excellent pollinator of zucchini and butternut squash, both native to Central and South America. However, they do not usually visit melon plants, according to Wikipedia. Again, we are reminded to avoid broad generalizations when describing the complex and diverse natural world.
Likewise, the native alkali bee is a particularly effective pollinator of alfalfa, which is native to the Mediterranean region. Alkali bees also pollinate members of the large legume family with over 16,000 species that are native all over the world. If you are interested in such associations, you can find an exhaustive list of native butterflies and their many non-native host plants in Art Shapiro’s butterfly guide for Central California and the Bay Area. It is not true that bees Tallamy considers “specialists” require pollen from only native plants.
DT: Sometimes butterflies adopt a new host plant as a caterpillar host. For example, black swallowtail butterflies caterpillars eat carrots or parsley or dill. What’s going on? There are two different kind of hosts: 1) The caterpillar has not adopted a new host at all because it was already adapted to that particular host. 2) Actual host switching from one plant to another is very rare. It happens on a time-scale of thousands of years. It requires a mutation or an adaptation to chemical defenses of new host plants.
CSN: Tallamy tries to make a distinction to avoid acknowledging that insects make use of introduced plants because they are chemically similar to the native plants they have used in the past, which in some cases are no longer available. The butterfly has, in fact, adopted a new host, a plant that wasn’t there before and is now hosting the caterpillar. There are many cases of rapid evolution that enable such transitions, but both cases are clearly transitions from native to non-native plants. If the original native host is still available, it isn’t necessarily abandoned in favor of a non-native. Such transitions are useful because they increase the population of available insect hosts and are essential if the original native host is no longer available.
TC: Pushback from California cites research of Professor Art Shapiro reporting that spontaneous spread of non-native plants has benefited native butterflies. He reports that 82 of 236 California native butterfly species (34%) are laying their eggs on introduced plant taxa, so caterpillars feed on them and many more butterflies use introduced plants as nectary sources.
DT: Great! These are host range expansions. Agriculture in California has eliminated the host plants of a lot of butterflies and it’s a good thing we had close relatives of natives so butterflies could expand their host range and use them. But if 34% of native butterflies are using introduced plants that means 66% are not. If all plants were introduced, we would lose 66% of butterflies in California. This is not the direction I want to go. I would choose 60% rather than 34%.
CSN: Christopher and Tallamy seem to have read one sentence in the abstract of Shapiro’s study without reading subsequent sentences: “Interactions with introduced plant taxa are not distributed evenly among butterfly species. Alpine and desert butterflies interact with relatively few introduced plants because few exotic plant species have reached and successfully colonized these habitats. Other California butterfly species are specialists on particular plant families or genera with no exotic representatives in California and have thus far failed to recognize any introduced plants as potential foodplants. Some California butterflies have expanded their geographic ranges and/or extended their flight seasons by feeding on exotic plants.” In other words, where there are more introduced plants and some are closely related to native plant hosts, more native butterflies use introduced plants.
TC: What do you say to the claims that introduced plants stay greener longer than native plants adapted to wet or dry seasons so that introduced plants give rise to extra generations of caterpillars?
DT: This is only true if caterpillars can use those plants and in host range expansions they can. Shapiro is also right about extending availability of nectar. For example, monarchs that migrate need forage along the way. The minus is that we’ve been so hard on native flora. These insects were doing just fine before we brought in non-native plants. It’s a Band-Aid we’re putting on an environment that has been ravaged by taking out native species that were here before. Let’s put native species back too.
CSN: The claim that non-native plants are driving native plants to extirpation or extinction goes to the heart of the controversy. Native plant advocates believe that accusation, although there is little evidence to support it. The greatest threat to native plants and insects is habitat loss, particularly converting wildlands to agricultural fields. The second greatest threat is the pesticides that are used by agriculture. Remember that Tallamy is an enthusiastic promoter of herbicides to eradicate non-native plants. He calls it “chemotherapy” in a recent opinion column in the Washington Post. Pesticides kill both plants and the animals that feed on them, they are anathema to biodiversity and the food web that Tallamy believes he is supporting.
Marcel Rejmanek (UC Davis) is 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 decades before then, most of the plants now designated as “invasive” in California were not widespread over 100 years ago.
Most of the globally extinct plant species had very small ranges and small populations. The smaller the population, the greater the chances of extinction. Most of the globally extinct plants were originally present in lowlands where most of the human population and habitat destruction are concentrated. Although there are many rare plants at higher altitudes, few are extinct. Plants limited to special habitats, like wetlands, seem to be more vulnerable to extinction. The primary drivers of plant extinction in California are agriculture, urbanization and development in general. Non-native plants are the innocent bystanders to disturbance.
“Invasive species” are mentioned only once in the inventory of extinct plants published by California Native Plant Society and only in combination with several other factors. However, the identity of this “invasive species” is not clear. Rejmanek suggests that the “invasive species” rating refers to animal “invasions” by predators and grazers. He says, “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.” (Marcel Rejmanek, “Vascular plant extinctions in California: A critical assessment,” Diversity and Distributions, Journal of Conservation Biogeography, 2017)
TC: 90% of all insect species are specialists that have evolved in concert with only one or a few plant lineages. How can they cope with the loss of native plants?
DT: Native plants are adapting in evolutionary time. Specialization is a continuum. Few insects are confined to a single plant species, some are confined to one or two genera, and others are confined to one or two families of plants. But if you are looking at the number of plants available to them, only about 7% of plants they are adapted to are available to them. 93% of available plants are not viable hosts for insects. Everything is a specialist on one level of another.
CSN: That sounds like an argument for a diverse garden, with many plant species that offer more food sources for insects. That doesn’t seem a sound argument for eradicating non-native plants.
TC: I understand that some native plants are more useful to insects than others?
DT: These are the keystone species. Many native plants don’t support insects because plants are well-defended against them. Keystone species are making most of the food for the food web. Just 14% of native plants across the country are making 90% of food that drive the food web. 86% of the native plants are not driving the food web. Insect food comes from the big producers, like oaks, black cherries, hickories, and birches.
CSN: That is a mind-boggling admission!! Earlier Tallamy complained that non-native plants are hosting only 34% of butterflies in California. Now he says that only 14% of native plants are useful to insects. He asks home gardeners to plant only native plants as well as limit our plantings to a small subset of native plants.
Tallamy’s ideology is antithetical to the goal of biodiversity, which could be the salvation of ecosystems in a changing climate. Since we can’t predict the climate of the future, biodiversity provides more evolutionary options, which increases the chances that some species will survive. Tallamy asks us to put a few eggs in the huge basket of our ecosystems, reducing their ability to survive the challenges of our changing climate.
For example, in Oakland, California, where I live, there were approximately 10 species of native trees prior to settlement. In 1993, there were 350 tree species in Oakland. (David Nowak, “Historical vegetation change in Oakland and its implications for urban forest management,” Journal of Arboriculture, September 1993) The recently published draft of Oakland’s Urban Forest Plan reports that there are now over 500 tree species in Oakland. I can’t fathom why Oakland would want to limit the planting of trees to only 10 native species.
I agree with Tallamy that many native plants are not useful to insects. I attend the annual conference of California Invasive Plant Council to give native plant advocates every opportunity to convince me of their viewpoint. At the most recent conference at the end of October, Corey Shake of Point Blue Conservation made a presentation about his project to “Evaluate native bee preference for common native and exotic plants.”
He designed 16 hedgerows around agricultural fields in Yolo County to determine if native bees have a preference for native plants or exotic plants, by controlling for availability of native plants compared to exotic plants. Here is his abstract:
“Farm edge restoration monitoring in Sacramento Valley highlights native bee use of some exotic plant floral resources. Corey Shake. Point Blue Conservation Science. cshake@pointblue.org
“Research of native bee preference for native versus exotic plant floral resources in California’s Sacramento Valley has shown mixed results. No studies have demonstrated a preference for exotic plants by native bees there, but some have highlighted the importance of exotic plant floral resources in plant-pollinator networks and expressed concern that rapid removal of exotic plants without restoring native plant populations could have negative impacts on native bees. We have been collecting native bee flower visitation, plant species, and floral abundance data on 16 farm edge restoration projects in Yolo County, California since 2019, which will allow us to assess bee preferences for some key native and exotic plants relative to their floral abundance. In our preliminary analysis, we see some important trends: (1) relative to their floral abundance in our plots, some native plant species are more frequently visited by native bees than other native plants that are infrequently or rarely visited, and (2) there is significant native bee visitation to some exotic plants relative to their floral abundance. We will further evaluate these data as well as our butterfly diversity and abundance data to provide plant-species specific insights to restoration practitioners and weed management specialists to help them reduce harmful impacts to native pollinators when executing restoration projects and managing weeds.”
In other words, not all species of native plants are useful to native bees and some species of non-native plant species are useful to native bees. Tallamy’s sweeping generalizations about the usefulness of native plants to insects are not supported by empirical or field studies. Although the characteristics of plants vary widely, the variation is unrelated to the national origins of plants.
From Micro to Macro Perspective
I recognize my voice in the questions Tom Christopher asked of Doug Tallamy, as well as Art Shapiro’s. Speaking for myself, not for Art, this interview misses the point of my criticism of native plant ideology. I like native plants as much as I like any plant and I encourage everyone to plant whatever they prefer. I only object to the pointless destruction of harmless non-native plants that thrive because they are best adapted to the conditions where they have naturalized. Non-native plants do particularly well in the wake of disturbance. Where they have replaced native plants, the natives were destroyed by disturbance, not by the hardy non-native plants that can tolerate disturbance. Non-native plants are a symptom of change, not the cause.
I object to destructive eradication projects because they poison the soil with herbicides, making it even less likely that non-native plants will be replaced by fragile native plants. I object to the loss of biodiversity which is a hedge against extinction in a rapidly changing climate. We don’t know which plants will be capable of surviving in the changed climate. We should not be taking cards out of the deck while we gamble with the future of the environment and everything that lives in it.
Unfortunately, native plant advocates take offense when anything positive is said about introduced plants. A positive statement about a non-native is routinely interpreted as a negative statement about native plants. It shouldn’t be. The emphasis on the negative assessment of introduced plants results in harmful land management decisions. The pros and cons of all plants should be considered before we condemn non-natives with a death sentence. Like our justice system for human society, all plants should be presumed innocent until proven guilty.
Thanks again for airing this debate on your podcast. I hope you will forward my email to Doug Tallamy
Juliet Stromberg is a plant ecologist who specialized in wetland and riparian ecosystems of the American Southwest. Her friends call her Julie and I will presume to do the same. She has retired from her position at Arizona State University, but her husband, Matt Chew, is still teaching ecology from a historical perspective at ASU. He is very much her partner in their 20-year project to restore 4-acres of dead citrus grove and an 80-year old Spanish colonial house, long abandoned and derelict. The property came with water rights, without which their project would not have been possible.
In her recently published book, Bringing Home the Wild: A Riparian Garden in a Southwest City, Julie tells us how she and her partner transformed—with the help of natural processes–this dead patch of land in South Phoenix, Arizona into the oasis that it is today. The first step was to restore the irrigation system, which immediately brought much of the dormant seed bank back to life.
Julie & Matt’s garden is in the center of this aerial view
Using the riparian vegetation of the Salt River—the source of their water—as her reference, she chose a half-dozen tree species as the foundation of their garden, such as Fremont cottonwood, Gooding’s willow, and velvet mesquite. Twenty years later, there are now 300 trees, sheltering a community of plants and animals. How did they get there?
The seeds of some trees such as blue elderberry and mulberry were brought from neighboring gardens by birds and small animals. Julie and Matt have seen 157 species of birds in their garden, so we can assume birds have done some of the planting. The seeds of some plants are aerodynamically shaped and were blown in by the wind, adding to the diversity of the garden.
Tropical milkweed seeds ready to be launched by the wind from a neighbor’s front yard. Conservation Sense and Nonsense, Oakland, CA, October 2023
Many of the trees are American in origin, but others are not. Regardless of the method of dispersal, most introductions are welcome in Julie’s garden. She spares her readers the tedious recitation of which plants are considered native and which are not. The Southwestern desert is not an ecosystem with which I am familiar. I was glad to have a tour of Julie’s garden without irrelevant information about the nationality of every plant. For the same reason, I like to travel in distant places where I can’t distinguish natives from non-natives. Everything looks great to me and nothing brings me down more than a guide who wants to inform us of what “belongs” and what doesn’t.
Julie and Matt also planted a fruit orchard and a vegetable garden that bring more birds, insects, and animals to the garden as well as providing food for their table. Eating the fruits of our labors in the garden deepens our respect for what plants do for us and establishes our working relationship with the land.
Managing a wild garden
In keeping with Julie’s opinion that ecological restoration is a form of “glorified gardening,” she actively manages her garden. A few plants that annoy members of her community of plants and animals—such as puncture vine and tumbleweed—are not welcome.
When the delicate balance between predator and prey becomes unbalanced, some protective measures are necessary. If coyotes and dogs can’t keep up with the rabbit population, it’s sometimes necessary to put vulnerable plants into cages to protect them. The root balls of some plants are covered in wire mesh to protect them from hungry gophers.
Plants also assist in their own defense. Where mesquite is grazed by cattle, the tree responds by growing longer thorns to repel the cattle. When plants are attacked by plant-eating insects, some emit a toxin to render themselves inedible. The scent of the chemical wafts to neighboring plants, alerting them to the arrival of predators. These natural defenses are an important line of scientific inquiry that has potential to substitute nature-based solutions for synthetic chemicals.
The population of roof rats in Julie’s home is kept in check with liquid birth control, lest they chew on electrical wires or build nests in car engines.
Gardening with the help of friends
Julie’s is not a manicured garden, but it requires constant pruning to keep trails clear and provide light and space for plants to thrive. The annual scouring of the flood plain by spring floods is one of the natural processes that Julie and Matt could not use to restore their land because irrigation water is channelized and confined by concrete. Julie has come to appreciate the flies and other insects who are the decomposing crew, helping to reduce the accumulation of debris in the absence of annual scouring floods. Sixty-six species of flies assist with decomposition as well as pollination in Julie’s garden.
Julie is happy to have coyotes in her garden, but her dogs disagree. Violent and fatal confrontations between these closely related species required building a wall that confines dogs close to the house at night, while coyotes safely roam most of the garden.
Dogs are an important part of Julie and Matt’s life. Early in the book’s introduction Julie warns readers that they should put her book down “NOW!” if they don’t want to hear dog stories. Julie has walked thousands of dogs in a nearby animal shelter. In addition to her own 4 dogs, there are also occasional foster dogs who need to recover from traumatic experiences to be adoptable. In Julie’s refuge, these traumatized dogs learn to trust again.
Peaceful co-existence
Julie is a recovering academic scientist. Before she retired, she felt that her focus on the accumulation of data needed for scientific analysis was causing her to lose track of the big picture. She needed to stop and smell the flowers, so to speak.
She received her graduate education during the heyday of invasion biology. Julie slowly shifted away from native purism based on her experiences in the field. She has rejected that doctrine, and regrets teaching her students to fear “those who came from somewhere else.”
Julie has a vivid memory of the first step she took on that journey to her gardening ethic of peaceful coexistence. She had been instructed to pull tree tobacco from land along the Salt River that was being restored. The nicotine in the plant was making her feel sick, which seemed to bring her to her senses. She began to wonder what she was doing, “following orders to kill creatures she barely knew.”
Fly on desert tobacco. Photo courtesy Juliet Stromberg
Part of Julie’s skepticism about such eradication projects is based on her understanding of how little we know. She realizes that the harm done by non-native species is exaggerated and their benefits are underestimated. Given the limits of our knowledge, we should be obligated to give introduced plants the benefit of the doubt before killing them. She now appreciates the beauty of tree tobacco, which also feeds birds, fixes carbon, and stabilizes the soil. Its seeds were naturally dispersed to Julie’s garden and tree tobacco is welcome there.
Imperatives imposed by climate change
Julie says, “The preoccupation with provenance diverts conservationists and gardeners from critical issues,” such as climate change, food security, and extinction (which, studies show, are not caused by introduced plants). Living in the Southwest, Julie has a front row seat on climate change. It’s always (within the context of our lifetime) been hot there, but now it is blisteringly hot during summer months. She watches hummingbirds in her garden seek shelter in the shade, close to the irrigation drip. She watches dogs panting, birds gasping for breath and plants wither and die in the heat. And she knows that both native and non-native plants store carbon that would otherwise contribute to greenhouse gases causing climate change. Carbon storage varies according to certain plant characteristics, but those characteristics are unrelated to the nationality of plants.
Those who insist on replicating the landscape that existed 200-400 years ago in America are depriving nature of the evolutionary opportunities that will enable survival. We don’t know what life will be capable of living in the climate of the near-future. Nature needs as many alternatives as possible to find the species that can survive. Plants and animals are blameless in this struggle of survival of the fittest. The least we can do is to get out of their way as natural selection finds the life that is adapted to the current and future climate.
Showing respect for nature
Julie does not use any pesticides in her garden….no herbicides, fungicide, or insecticide. She is concerned about the pesticides used by her neighbor across the road who grows cotton. She notices the blue cotton seeds scattered on the ground and surmises that they were coated in insecticide or herbicide that will infuse pesticide into the plant as it grows. The poisoned seed can kill seed-eating birds and other animals and the plant itself will be poisonous as it grows. The dust from the cotton field blows into her property when the field is plowed and after the cotton is harvested because no cover crops are grown to tamp down the dust and prevent the loss of carbon stored in the soil. Julie can see firsthand the damage caused by industrial agriculture and is confirmed in her commitment to avoid using pesticides.
Julie shows her respect for everything living in her garden by her choice of pronouns to describe them: “who” not “what,” “she/her” not “it.” She asks her readers to show the same respect for plants and animals, regardless of their nationality. Avoiding the use of pesticides in our gardens is another way to show our respect for the plants and animals on which we depend, with the added benefit of not poisoning ourselves.
Thank you, Juliet Stromberg, for telling us about your garden and congratulations for what you have accomplished and learned from the experience of nurturing it back to life with the help of nature.
On September 1st, I told readers that Oakland would soon publish a revised Vegetation Management Plan to reduce fire hazards in Oakland by managing vegetation on 2,000 acres of city-owned property and 300 miles of roadside. I also shared with readers my anxiety that the revised plan would be more destructive than the previous version of the plan in response to criticism of that version.
The 4th revision of Oakland’s Vegetation Management Plan and its revised Draft Environmental Impact Report was published on September 20th. These documents are available HERE. There will be a public hearing about the plan by Oakland’s Planning Commission on November 1st. The deadline for submitting written comments on the plan is November 4th. Comments can be submitted by email DEIR-comments@oaklandvegmanagement.org or by mail to Montrose Environmental, attention Ken Schwarz, 1 Kaiser Plaza, Suite 340, Oakland CA 94612.
Update: The deadline for commenting on the Vegetation Management Plan has been extended to Monday, November 6, 2023, at 5 PM.
The Oakland Planning Commission held a public hearing about the VMP on Wednesday, November 1, 2023. There was no expressed opposition to the VMP at the hearing. Representatives of Claremont Canyon Conservancy, North Hills Community Association, and Oakland Fire Safe Council spoke in support of the plan.
One speaker said that Oakland Fire Department and the consultant who wrote the plan successfully “threaded the needle” that made agreement possible. She also said that “of course, we wish all the eucalyptus were gone, but we understand that is expensive.”
All members of the Planning Commission expressed their admiration and support for the VMP.
Below is a map of the VMP project areas. Figure 2.2 in the revised plan also shows detailed maps of roads in VMP project areas, with property ownership adjacent to roads indicated, which require different vegetation management standards.
The authors of the plan have made it easy for you to read the revised version by underlining additions and striking out deletions. If you have read earlier versions of the plan, you won’t need to read it all again, because revisions are minimal. They are briefly summarized on page 1-2 of the plan:
“Expanded the Revised Draft VMP area to encompass the area from 30 feet to 100 feet of the edge of roadsides in the City’s VHFHSZ [Very High Fire Hazard Severity Zone] where dead and dying trees (as determined by a Certified Arborist, Licensed Forester, or Fire Safety Expert) are present on City owned property and could strike the road if they fell.
“Updated the vegetation management standards as follows:
Expanded the zone recommended for 3-inch maximum height of grasslands after treatment from 30 feet to 75 feet from habitable structures.
Clarified that, where feasible, horizontal crown spacing should adhere to the California Department of Forestry and Fire Protection’s (CAL FIRE’s) most recent defensible space standards (presently codified in Pub. Res. Code Section 4291).
“Updated treatment standards for eucalyptus stands to increase the trunk diameter of single-stem eucalyptus recommended for removal from 8 inches to 10 inches, and to recommend removal of trees that pose an unreasonable fire and/or life safety risk, based on the determination of a Certified Arborist, Licensed Forester, or Fire Safety Expert.
“Updated treatment standards for closed-cone pine-cypress stands to include removal of trees that pose an unreasonable fire and/or life safety risk, based on the determination of a Certified Arborist, Licensed Forester, or Fire Safety Expert.”
If you need a reminder of vegetation management standards in the previous version, you can find them on Table 2-4. Basically, the VMP will thin trees and vegetation and remove dead trees and fire ladders to canopies in management areas. The most significant revision of those vegetation management standards is the expansion of clearance of dead and dying trees from 30-100 feet from the edge of 300 miles of roadsides on city-owned property. The management standards defined by the previous version were acceptable to me and the proposed revision of those standards are also acceptable to me.
However, I am sorry to see that more eucalyptus will be removed because the diameter size standard for removal has been increased from 8 to 10 inches (circumference is greater than 31 inches). The flammability of eucalyptus has been exaggerated by native plant advocates who want all non-native trees to be destroyed. California’s native vegetation is fire adapted and fire dependent. Many of our most prominent native plants—such as ceanothus and manzanita–will not germinate in the absence of fire. The planned removal of isolated non-native trees within stands of native trees is unnecessary because it will not reduce fire hazards. The VMP should be a fire hazard reduction plan, NOT a native plant restoration.
Although I recognize that dead trees are important for the long-term health of forests because they provide food and habitat for insects and birds as well as recycle nutrients into the soil, we can’t indulge that preference in very high fire hazard zones in high-density population areas that are being treated by Oakland’s Vegetation Management Plan. As always, we must set priorities and the public’s safety must be a high priority.
Like most public policy, the revised Vegetation Management Plan is a compromise between two extremes. One extreme wanted all non-native trees to be destroyed in the management areas as well as within 100 feet from the edge of 300 miles of roadside. They also wanted Oakland to make a commitment to replace those trees with native vegetation. The opposite extreme wanted no trees to be destroyed and no herbicides to be used to control vegetation or prevent destroyed trees from resprouting.
The revised Vegetation Management Plan is the compromise I had hoped for. Specifically, I had hoped that fire hazards could be reduced in Oakland without destroying more trees than necessary to mitigate fire hazards. The thinning strategy that the VMP proposes has been used successfully by the East Bay Regional Park District for over 10 years. It leaves the canopy intact so the forest floor is shaded, which suppresses the growth of weeds and keeps the forest floor moist, which retards ignition.
I had hoped that herbicides would not be used in public parks, but did not achieve that goal. However, I am grateful that the revised plan makes many efforts to protect the public, their pets, wildlife and goats grazing in project areas from exposure to the herbicides that will be used. (Improvements in these protections are described on pages 2-81, 3.3-29, 3.3-32) There are also extensive new protections for monarch butterflies and a rare species of bee (see page 3.4-86).
If your interests in the Vegetation Management Plan are different from mine, I urge you to read the plan and form your own opinion. I hope you will be able to support the revision because it is going to be attacked by the same extreme interests that have prevented Oakland from adopting and implementing a fire hazard mitigation plan for over 7 years. Expressing our support might help to get the VMP over the finish line after years of delay caused by gridlock. I would welcome you to the middle ground that I occupy. It’s lonely here in the middle. We don’t have much of an audience above the noise made by the extremes, but we have the capacity to enable public policy to be made if we speak up in defense of compromise. If we want to reduce wildfire hazards in Oakland, we must compromise.
Oakland has been trying to adopt a vegetation management plan (VMP) to mitigate fire hazards since November 2016. The plan has been drafted three times in 2018, 2019, and 2020 and a draft Environmental Impact Report was also published in 2020. All three versions of the plan were acceptable to me and many others. Every version would have removed dead trees and thinned non-native trees on 2,000 acres of public land and 300 miles of roadsides in Oakland, leaving the tree canopy intact so that the forest floor would be shaded, suppressing the growth of weedy vegetation that ignites easily and keeping the forest floor moist, which retards fire ignition.
Unfortunately, none of the proposed vegetation management plans were acceptable to native plant advocates who want all non-native trees in project areas in Oakland to be destroyed and the land replanted with native plants and trees. The plan they are demanding is a native plant restoration, not a wildfire hazard mitigation plan. Since they have successfully prevented Oakland from addressing wildfire hazards for eight years, we might assume they aren’t concerned about wildfire.
A fourth version of the plan and a new Environmental Impact Report are expected to be published in September 2023 and there will be a new public comment period in October. Based on written and oral public comments at public hearings, we predict that the revised plan is likely to be far more destructive than previous drafts of the plan. Based on that prediction, I am alerting you to the need to read the revision and write a public comment. Please ask to be notified of the publication of the plan by sending an email to info@oaklandvegmanagement.org .
Update: The revised Oakland Vegetation Management Plan and revised Draft Environmental Impact Report were published on September 20, 2023. These documents are available HERE. There will be a public hearing by the Oakland Planning Commission on November 1, 2023. The deadline for public comment will be November 4, 2023. Comments can be submitted by email DEIR-comments@oaklandvegmanagement.org or by mail to Montrose Environmental, attention Ken Schwarz, 1 Kaiser Plaza, Suite 340, Oakland CA 94612.
When I have read the revised plan and its revised EIR, I will post a draft of my public comment on the draft by October 1st.
– Webmaster, Conservation Sense and Nonsense, September 20, 2023
What do opponents of previous plans want?
There is a wide range of opinions about a vegetation management plan for Oakland. I will use the public comment of the California Society of American Foresters (SAF) on the third version of the VMP as a representative opinion and the best available predictor of where the fourth revision is likely headed. The entire comment of the Society of American Foresters (SAF) is available HEREand here are some of the revisions SAF is asking for:
“Ecological restoration should be a goal of the VMP, including the establishment of native plant species where nonnative species dominate…Thinning of dense stands of nonnative tree species should only be done as part of an overall strategy of restoration, i.e., the goal of any tree removals should always be to eventually convert these stands to native tree or vegetation cover in order to build greater ecological resiliency.”
“In concert with the goal of ecological restoration, adaptive management in light of climate change should guide management practices and restoration plans. Adaptive management strategies that incorporate new information and changing conditions will be critical to ecosystem restoration. Annual grasslands may become more dominant, oak woodlands less so in the planning area in the future as climate changes. Management targets in many cases will have to be based on anticipated future conditions.”
“However, if thinning is kept as the desired practice, we ask that you design each entry to be sufficiently intensive to assure that tree crowns will not close before the next thinning entry (10 years from now?) and indeed is sufficiently thinned to allow work towards establishing native vegetation in these stands.”
“The use of prescribed fire as a vegetation maintenance tool should have been considered and included in the VMP especially on ridges where fire moving from adjacent jurisdictions might occur, or along power-line transmission corridors.”
“The vegetation management zones along roadsides, especially along routes of egress, should be modified to extend 100 feet from roadside edges and should include any trees with underlying structural or health conditions that are tall enough to fall onto streets and roads. This may in some cases require looking outside of the 100-foot roadside clearance.”
“It is important that the use of triclopyr herbicides is included to treat cut stumps in eucalyptus to prevent sprouting. Glyphosate herbicides will not be effective in treating eucalyptus stumps and will result in resprouts.”
“There should be an Ecological Restoration Guide added to the appendices…This new appendix would outline the City of Oakland’s current ecological restoration efforts, identify stakeholders (e.g., city departments, Oakland Wildlands Stewards, etc.) and their roles…”
Native plant restoration, NOT wildfire hazard mitigation
The Society of American Foresters (SAF) is asking the City of Oakland to make a commitment to eradicating all non-native trees in project areas and replacing them with native plants. Such a plan would not reduce wildfire hazards in Oakland because native vegetation is not inherently less flammable than non-native vegetation. Most wildfires in California occur in native chaparral and native conifer forests.
The plan proposed by the Society of American Foresters (SAF) is a native plant restoration plan, NOT a wildfire hazard mitigation plan. Their proposal would destroy much of Oakland’s urban forest, which would not be replaced by native trees:
Non-native trees were planted in Oakland in the 19th century because there were few native trees: “Vegetation before urbanization in Oakland was dominated by grass, shrub, and marshlands that occupied approximately 98% of the area.” (1) Non-native tree species in the East Bay are adapted to soil and microclimate conditions that are not suitable for native species.
Grassland was the dominant vegetation type of pre-settlement Oakland partly because of the land management practices of Native Americans and the stock grazing of early settlers: “Native Americans played a major role in creation of grasslands through repeated burning and these disturbance-dependent grasslands were maintained by early European settlers through overstocking of these range lands with cattle and sheep. Twentieth century reduction in grazing, coupled with a lack of natural fires and effective suppression of anthropogenic fires, have acted in concert to favor shrubland expansion.” (2)
Grassland in California is not native to California. Mediterranean annual grasses were brought to California in the early 19th century by the grazing herds of Spanish-Mexicans. California’s native bunch grasses are not adapted to heavy grazing by herds of domesticated animals. The grassland of California is about 99% non-native (Allan Schoenherr, A Natural History of California, UC Press, 1992). Attempts to convert annual grasslands to native bunch grass have not been successful. A team of scientists at UC Davis spent $450,000 and 8 years trying to convert 2 acres of grassland to native bunch grasses without success.Grassland that will replace our urban forest will not be native.
Grass is easily ignited and fires move quickly through grassland, particularly in a wind-driven fire. The deadly, destructive fires in Maui, Hawaii are a case in point. When agricultural fields of sugar cane, pineapple and other tropical fruit left Maui they were quickly succeeded by non-native grass that was considered a factor in the spread of fire. (3) Dormant, dry annual grassland in the East Bay Hills will be more flammable than the living vegetation that native plant advocates want to destroy.
A small redwood grove was the only pre-settlement exception to the otherwise treeless Oakland hills: “…for thousands of years [the Oakland hills] were treeless meadows, visited seasonally under Indigenous management…The one exception was the redwood groves of the southern Oakland Hills, a restricted forest that extended a few miles eastward from upper Dimond Canyon over the ridgetop to the outskirts of Moraga.” (4) Much of this grove still exists today because coastal redwoods are vigorous resprouters when they are burned or cut down.
SAF also predicts a vegetation type-conversion from forest to grassland: “Annual grasslands may become more dominant, oak woodlands less so in the planning area in the future as climate changes.” Grassland will naturally succeed to shrubland without regular burning, which SAF recommends to reduce fuel loads.
Prescribed burns in densely populated urban areas are rarely approved by Bay Area Air Quality Management District because they pollute the air and often cause uncontrolled wildfires. California law regarding liability for damage caused by prescribed burns was revised in 2022 to provide legal protections for those who manage prescribed burns. The revised law lowers the standard for liability to gross negligence from a previous standard of simple negligence. (5)
Consequences of landscape conversion to grass and shrubs
Destroying thousands of trees will increase air pollution and reduce air quality. Destroying thousands of trees will increase greenhouse gas emissions causing climatechange by releasing the carbon stored by the trees that are destroyed and reducing carbon sequestration going forward because the destroyed forest will not be replaced by a forest of native trees.
There was little biodiversity in Oakland’s pre-settlement forest: “Oakland’s original species composition has increased from approximately 10 tree species to more than 350…Today [1993], only 31% of existing trees are native to Oakland, the plurality of trees (38%) are native to Australia/New Zealand.” (1) Destroying thousands of non-native trees in Oakland will reduce the biodiversity of our forest. A more diverse forest is more resilient, particularly in a changing climate, with extreme and variable weather conditions.
Increasing 300 miles of roadside clearance from 30 feet (as proposed by the 3rd version of the VMP) to 100 feet (as proposed for the 4th version of the VMP) will produce wood debris on a scale that cannot be disposed of. We know what the outcome will be because of a similar project on Claremont Ave, where eucalyptus was clear cut 100 feet from the north side of 1.1 miles of the road in fall 2020. Below are pictures of the piles of wood chips and logs that remained along that stretch of road for about 9 months while project managers tried to figure out what to do with the wood debris, which was eventually dispersed throughout the hills. UC Berkeley implemented the project with funding from Cal-Fire.
The north side of Claremont Ave. was clear cut 100 feet from the road. The south side of the road was not cut because the trees are native. There is a creek flowing at the bottom of the canyon that creates the moist conditions needed for native trees, which will not grow where non-native trees now grow. Photo by Doug Prose, courtesy Hills Conservation Network.One of many piles of logs, Claremont Ave, November 2020. It took about 9 months for the logs to be dispersed along roads in the hills. Photo by Doug Prose, courtesy Hills Conservation Network.One of many piles of wood chips, Claremont Ave, November 2020
The roads in the East Bay hills are now lined with logs, preventing people from pulling off the road. No native plants or trees were planted after the trees were destroyed. Three years later, the clear cut roadside is vegetated with non-native annual grasses and coyote brush, a pioneer native shrub.
The project on the property of UC Berkeley was very small in comparison to the Oakland vegetation management plan that will clear cut 300 miles of roads, producing at least 300 times the amount of wood debris. What will Oakland do with the wood debris that is produced from the destructive VMP that native plant advocates demand? Tons of wood debris lying on the ground is far more flammable than living trees, which is another indication that the VMP that native plant advocates demand is not about mitigating fire hazards. It’s about their preference for a native landscape that is not less flammable than the landscape they demand be destroyed. Like all Mediterranean climates, our native vegetation is fire adapted and fire dependent. A significant number of our native species will not regenerate in the absence of fire. Most wildfires in California in the past 5-10 years have occurred in native chaparral and native conifer forests.
NY Times reported that 150 homes burned in this wind-driven fire in San Diego in 2003, but the eucalyptus surrounding the neighborhood did not burn. The flammability of eucalyptus trees is exaggerated to justify their destruction. NY Times photo
The more trees that are destroyed, the more herbicide will be required to prevent the trees from resprouting. SAF is correct in saying that tricopyr will be needed to kill the roots of the trees to prevent them from repsouting. Glyphosate will not accomplish that task. Triclopyr is more toxic than glyphosate. Triclopyr has a signal word of “warning” and glyphosate has a less toxic signal word of “caution.” Triclopyr kills the roots of woody plants by traveling from the cut stump to the roots of the plant in the soil. Triclopyr is known to kill mycorrhizal fungi in the soil, which are essential to the health of plants growing in the soil. The more herbicide that is used to kill the roots of destroyed trees, the less likely a newly planted native landscape is to survive. All the more reason to assume that the destroyed forest will not be replaced by a native landscape.
In Summary
The landscape that native plant advocates demand for Oakland will be predominantly non-native annual grasses.
Native trees will not replace the trees that are destroyed because they are not adapted to most places where non-native trees now live and because there is no available funding to purchase native plants, plant them on thousands of acres of public land, and irrigate them until they are established. Similar fuels management projects done by East Bay Regional Parks District, East Bay Municipal Utilities District, and UC Berkeley have not planted a native landscape to replace trees that have been destroyed.
Non-native annual grasses will naturally succeed to shrubs in the absence of frequent fire. Shrublands are more flammable than the existing urban forest because fire travels on the ground, unless wind-driven fire ignites tree canopies. In that case everything burns, both native and non-native trees. The wind-driven fire in Oakland in 1991 spared no trees in burned areas, whether native or non-native.
The project would produce many tons of flammable wood debris that has no commercial value and no place to be safely disposed of.
The loss of our urban forest will increase air pollution in Oakland, contribute to greenhouse gas emissions causing climate change, and raise temperatures in a city that is already a heat-island.
Herbicides needed to prevent the urban forest from resprouting will poison the soil and suppress the growth of a new landscape.
If you live in Oakland City Council District 4 or 6, you are likely to be directly affected by Oakland’s vegetation management plan. The most effective way to influence the VMP is to express your opinion to your representative on the City Council, as well as our at-large representative on the Council. Contact information for members of the Oakland City Council is available HERE.
I’m reading about the Great Lakes in preparation for a cruise on the Great Lakes from Chicago to Toronto. (1,2) It’s a story of continuous invasions of aquatic creatures, one after the other, with many more expected in the future. Every one of those invasions was caused by the removal of natural barriers from isolated bodies of water to accommodate human activities such as shipping of goods.
Connecting the Great Lakes to the Atlantic Ocean
The St. Lawrence River is the natural gateway into the Great Lakes from the Atlantic Ocean. The salty water of the ocean and the fresh water of the lakes was part of the natural barrier that protected the lakes from invasive species because, for the most part, the marine creatures that live in salty water are different from those that live in fresh water.
The St. Lawrence River was steep and narrow, creating white-water rapids that limited travel from the ocean to the lakes (or vice versa) in anything but a birch bark canoe that could be carried around the rapids. The natural barrier was penetrated by building the St. Lawrence Seaway in 1959 that widened the river and used locks to climb the steep incline of the river into Lake Ontario.
The St. Lawrence Seaway was instantly obsolete because of the unforeseen container revolution that transformed global shipping. The transition from traditional to container shipping was instantaneous because the advantages are so great. Container ships are huge in comparison to the small ships that had been loaded by hand for centuries. The St. Lawrence Seaway is too narrow to accommodate container ships. The loans given to the builders of the seaway by Canada and the US were eventually forgiven because the tolls on the seaway will never pay for the expense.
But the damage was done, although much of it could have been avoided. The ships that start their voyage in fresh water ports on rivers take on their ballast water when they start their voyage and with it freshwater aquatic creatures that don’t live in the Great Lakes. When they arrive in the Great Lakes they dump their ballast water to take on their cargo. The dumping of ballast water in the Great Lakes could have been regulated in 1959, but it wasn’t. Only very recently have ships from fresh water ports been asked to exchange their ballast water in the ocean, before entering the Great Lakes and those regulations weren’t mandatory until 2021. Such is the power of commercial interests that the consequences of introducing new species into the Great Lakes were not considered.
The second natural barrier that protected the Great Lakes was Niagara Falls in New York with a vertical drop of 160 feet. That steep cliff across the Niagara River prevented the movement of marine animals from the Atlantic Ocean, through Lake Ontario and into the other four lakes. It was one of the first barriers to be penetrated by the Erie Canal in 1825 and the Welland Canal in 1829. The Erie Canal connects the Hudson River that flows into the Atlantic Ocean to Lake Erie, bypassing Niagara Falls and creating a gateway from the Atlantic Ocean into the Great Lakes. The Welland Canal connects Lake Ontario to Lake Erie, which also bypassed Niagara Falls and created another gateway from the Atlantic Ocean to all of the Great Lakes.
Connecting the Great Lakes to the Mississippi River Basin
The St. Lawrence Seaway, Erie, and Welland canals opened the front door of the Great Lakes to salt water creatures in the Atlantic Ocean and the ships that brought foreign aquatic animals into the Great Lakes. The reversal of the Chicago River that connected Lake Michigan to the entire Mississippi River basin, opened the back door to the Great Lakes to all of the freshwater aquatic animals that live in the vast Mississippi River basin, east of the Continental Divide.
When Chicago was built, it dumped its sewage into Lake Michigan and it also took its drinking water from Lake Michigan. As the population of Chicago grew it became more vulnerable to typhoid epidemics caused by the polluted water Chicago was drinking. The Chicago River had sent a dribble of water into Lake Michigan from its headwaters not far west of Chicago before it was reengineered.
In 1900, Chicago built a huge sanitary canal that connected Lake Michigan to the Mississippi River. The sanitary canal carried Chicago’s sewage into the Mississippi River and created a shipping lane to the Mississippi River while giving Chicago a clean source of water from Lake Michigan. The sanitary canal reversed the flow of the Chicago River, which now flows out of Lake Michigan.
The Consequences
The first invasive predator of native fish arrived in the Great Lakes via the canals built early in the 19th century. The sea lamprey is a parasite that attaches itself to the bellies of fish and slowly sucks the blood out of it. Its suction-cup mouth is the stuff of nightmares.
Source: Great Lakes Fishery Commission
Lampreys, like salmon and sturgeon, are born in freshwater rivers and streams before living in the ocean and finally returning to their freshwater birth place to spawn and die. They are capable of living in both fresh and salty water. In the Great Lakes lampreys did not need to migrate to the ocean as their ancestors had because there was sufficient food in the lakes.
As late as the 1940s commercial fishermen in the Great Lakes were harvesting 100 million pounds of native fish, such as lake trout and whitefish, annually. Lampreys were first reported in Lake Michigan in 1936. By 1950, the commercial fishery had all but collapsed as the lamprey population reached its peak.
Lampreys met their match when a graduate student at University of Michigan wrote his Ph.D. thesis about the life cycle of lampreys. He spent several years stalking lampreys in Lake Michigan and its tributaries, finding out where and when they spawn and at what point in their life cycle they become parasites of fish.
The lamprey population had been so vast that it was impossible to target an attack on them. An understanding of their life cycle enabled the development of a strategy to eradicate them. More than 5 of their 7-year lifespan is spent burrowed in the gravel of small streams that feed into the lakes. At that stage they are not yet fish predators.
Armed with the knowledge of when and where lampreys were most vulnerable, the strategy was to build mesh barriers that prevented the lampreys from returning to the streams to spawn. There was some success with the barriers, but not sufficient to reduce the huge population.
The final solution to lamprey control was the use of a chemical that would poison lampreys without killing native fish. Finding the chemical that would do the job was a classic case of trial-and-error without regard for the consequences of using poisons in the environment. Chemicals were solicited from all over the country and the world for study as candidates. The tests, done in uncontrolled environments with no safety precautions for low-level workers, consisted of dumping hundreds of different chemicals into three jars, one containing a lamprey, another native lake trout, and a third native blue gill. After hundreds of trials, a chemical that killed only the lampreys was selected for the job of eradicating the lamprey population. No thought was given to the possible effect on all the other native fish in the lakes—such as whitefish and sturgeon—or humans, or plants. (3) The same chemical is still used today to control the lamprey population, which remains but is no longer considered a problem.
There are many invasions into the Great Lakes. The lampreys were followed by alewives, a species of small fish. The population of alewives boomed at first, then busted, resulting in massive rafts of millions of dead alewives. Finally, the population of alewives stabilized and now are considered the primary prey of salmon that were introduced in the 1960s to serve the sport fishermen who are the backbone of Michigan’s tourist industry.
Zebra and quagga mussels proved to be one of most damaging of the invaders in the Great Lakes, partly because of how widely they spread. They were brought to the lakes in the ballast water of ocean-going ships. The open back door of the Great Lakes into the vast Mississippi River basin enabled the inevitable spread of quagga mussels throughout the country, eventually crossing the Continental Divide into western states. Those who tried to prevent that spread, spent many years imposing strict regulations about decontaminating and moving boats into places where mussels weren’t yet found. Today, places like Lake Powell have given up enforcing the regulations.
The mussels are filter feeders of phytoplankton that is food for creatures at the bottom of the food chain, depriving them of food, as well as their predators higher in the food chain. The mussels have turned sandy beaches into foot-slicing no-go zones. They improve the water clarity of the lakes, but that’s a mixed blessing for other inhabitants of the lakes.
Quagga and zebra mussels are now part of the food web. Populations of diving ducks have increased where mussels are found. A species of non-native fish—the goby—thrives on quaggas. And native whitefish, yellow perch, and chub have slowly developed the ability to digest quaggas, a story not fit for the squeamish. Whitefish don’t have the jaws needed to crack the mussel open, so they swallow them whole and leave it to their digestive system to deal with it: “the typical whitefish has an anus about the size of a ‘swizzle stick.’ But the fish excrement, a paste of crushed mussel shell thick as unset concrete, stretched the whitefish’s underside orifice to the diameter of his pinky.” (1)
The latest arrival is Asian carp via the Chicago River and sanitary canal from the Mississippi River into Lake Michigan. Asian carp were introduced to the Mississippi River to eat sewage pollution drained into the river by many rural communities. The prediction is that Asian carp will decimate the commercial fishery of the Great Lakes, though it is still early in that story.
More man-made problems
Not all problems in the Great Lakes are caused by the arrival of foreign aquatic species, but other problems are also man-made. Lake Erie is the most polluted of the Great Lakes. In summer months, when temperatures are high, there are toxic algal blooms that kill fish and pollute drinking water. Although the sources of pollution are man-made, the shallow lake bottom contributes to the problem. Lake Erie is the shallowest of the Great Lakes.
The Great Black Swamp at the western edge of Lake Eric slowly drained the watershed into Lake Erie, filtering and cleansing the water as it flowed through the swamp. The swamp was drained and filled to create more land for agriculture and remove an obstacle to westward travel and migration. Now the rich agricultural land that surrounds Lake Erie drains run-off of chemical fertilizers into the lake, providing the nutrients that produce algal blooms.
Climate change has already created chaos in the Great Lakes and the damage is expected to accelerate in the future. While the climate has warmed on land, the temperature of the water in the Great Lakes has climbed even higher, promoting growth of toxic algae. Winter temperatures are no longer low enough to freeze the lakes during the winter because the dark water of the lakes in the winter absorbs more heat than reflective white snow and ice. The higher temperature of the water in the lakes also increases evaporation of the water, lowering water levels, causing erosion of the exposed shore, and destroying infrastructure on the shore.
Moral of the Story
Problems in the Great Lakes were caused by humans who were accommodating their own needs. The aquatic animals blamed for the problems were only symptoms of the changes made by humans. They were not the cause. Eradicating them will not prevent new invasions in the future, so long as the gateways to other bodies of water remain open. And over time, many of the species that cause problems at first will enter the food web and become contributing members of the ecosystem. We fear change, but in many cases that is because our time frame for evaluating change is too short.
We should assume that similar problems have occurred wherever isolated bodies of water have been connected to serve human activities. The Suez Canal connected the Mediterranean Sea to the Red Sea in 1869. The Panama Canal connected the Atlantic Ocean to the Pacific Ocean in 1914. I can only imagine the consequences of removing the impassable barriers between those vast bodies of water.
To be clear, I don’t regret the building of most of the canal passages, with the possible exception of the St. Lawrence Seaway. However, it is not realistic to expect that the environment will not be altered by removing impassable barriers on water or land and it is pointless to blame the plant and animal species that are merely responding to the changes we have made.
(1) Dan Egan, Death and Life of the Great Lakes, W.W. Norton & Co., 2017
(2) Jerry Dennis, The Living Great Lakes, St. Martin’s Press, 2003
(3) The pesticide 3-trifluoromethyl-4-nitrophenol (TFM) is used to control sea lamprey (Petromyzon marinus) populations in the Great Lakes through its application to nursery streams containing larval sea lampreys. TFM uncouples oxidative phosphorylation, impairing mitochondrial ATP production in sea lampreys and rainbow trout (Oncorhynchus mykiss). However, little else is known about its sub-lethal effects on non-target aquatic species. The present study tested the hypotheses that TFM exposure in hard water leads to (i) marked depletion of energy stores in metabolically active tissues (brain, muscle, kidney, liver) and (ii) disruption of active ion transport across the gill, adversely affecting electrolyte homeostasis in trout. Exposure of trout to 11.0 mg l− 1 TFM (12-h LC50) led to increases in muscle TFM and TFM-glucuronide concentrations, peaking at 9 h and 12 h, respectively. Muscle and brain glycogen was reduced by 50%, while kidney and muscle lactate increased with TFM exposure. Kidney ATP and phosphocreatine decreased by 50% and 70%, respectively. TFM exposure caused no changes in whole body ion (N a+, Cl−, Ca2 +, K+) concentrations, gill Na+/K+ ATPase activity, or unidirectional Na+ movements across the gills. We conclude that TFM causes a mismatch between ATP supply and demand in trout, leading to increased reliance on glycolysis, but it does not have physiologically relevant effects on ion balance in hard water.” (Oana Birceanu, et.al., “The effects of the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) on fuel stores and ion balance in a non-target fish, the rainbow trout,” Comparative Biochemistry and Physiology, March 2014)
Conservation Sense and Nonsense 