Conservation Sense and Nonsense

The Illusive Definition of “Invasive” Plant

Kollibri Terre Sonnenblume and his writing partner, Nikki Hill, are co-authoring a book tentatively entitled “Don’t Blame the Messenger: A critique of the ‘invasive plant’ narrative.” Kollibri has published a draft chapter of their book on his Substack, “Speaking for the Trees, No Matter Where They’re From.” The chapter is foundational to their book and serves as a teaser for the rest of the book. More chapters of the book will be available to paid subscribers of Kollibri’s Substack, “Speaking for the Trees.”

Many thanks to Kollibri and Nikki for this important contribution to our understanding of invasion biology as an ideology based on many conundrums and contradictions.

Conservation Sense and Nonsense

St. Johnswort. Photo by Kollibri Terre Sonnenblume

What is an “invasive” plant?

What is an “invasive” plant? Colloquially, some gardeners call any plant that thrives and spreads with little or no care “invasive.” They cast the term on both “weeds” and on ornamental nursery plants that have the temerity to spread outside their apportioned area. Such gardeners are seeking to uphold a particular aesthetic and their impulse to design and direct can yield results ranging from elegant to cloying. If this were the only way that people used the word, “invasive,” it would be harmless, and there would be no need for this book. However, the label is applied far beyond this narrow context.

Going to the dictionary for the meaning of “invasive,” Merriam-Webster provides: “relating to, or characterized by military aggression.” The Cambridge Dictionary defines “invade” as: “to enter a country by force with large numbers of soldiers in order to take possession of it; to enter a place in large numbers, usually when unwanted and in order to take possession or do damage; to enter an area of activity in a forceful and noticeable way.” For “invasive” it says: “moving into all areas of something and difficult to stop.”

That’s clear enough. But what is the official definition of an “invasive species,” whether plant or otherwise?

The short answer is that there is none.

The longer answer is that there are many definitions crafted by various policy-makers, non-governmental organizations and advocacy groups. Here are a few:

US federal government: “an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.”ⁱ
The United Nations Environmental Program: “introduced species that become established in a new environment, then proliferate and spread in ways that are destructive to human interests and natural systems.”ⁱⁱ
The International Union for Conservation of Nature (IUCN): “animals, plants or other organisms that are introduced by humans, either intentionally or accidentally, into places outside of their natural range, negatively impacting native biodiversity, ecosystem services or human economy and well-being.”ⁱⁱⁱ
Convention on Biological Diversity: “species whose introduction and/or spread outside their natural past or present distribution threatens biological diversity.”^iv

These definitions might seems straightforward at first glance, but a lot of ambiguity emerges as we unpack them.

The key words—“harm,” “destructive,” “negatively impacting,” “threatens”—beg the question of what constitutes “harm.” As we shall explore in this book, that’s not at all simple to answer in terms of ecological interactions. It’s even more difficult to identify what is “likely to cause” harm, as the feds put it. As invasion biologists have discovered, attempts to predict the results of species introductions based on the attributes of the species, for example, don’t have a very successful track record.

Also, if “harm” is being alleged then the possibility of benefit must also be admitted, a point completely ignored not just in these definitions but in most discussions or media coverage about “invasives.”

Economic concerns or “human interests” are named first by the US and UN, which might surprise people who think of the issue of “invasive” species as solely environmental. But commercial interests have had a strong hand in drafting the official policies that guide the “management” of “invasive” species. As we discuss in a later chapter, Monsanto and other nasty entities played a central role in the shaping US federal policy around “invasive species” because they profit from the sale of toxic pesticides used in their control. As for measuring the bottom line, one might assume that economic harm is readily quantifiable, but that’s also quite tricky, as we explain in the chapter “Lies, Damned Lies, and Statistics.”

“Alien” and “introduced” are synonyms for “non-native” (as are “exotic” and “non-indigenous”). The very concept of a “native plant” is a recent invention, though, and is another subject of contested deliberation, which we detail in “A Brief History of Invasion Biology.”

What is a fairly straightforward question in the Western Hemisphere—was it here before 1492?—is less clear in other regions. In the UK, some point to the Roman invasion of two millennia ago as the cut-off date (perhaps in part because that’s when bed bugs were introduced). In the case of Pacific islands like Hawai’i, some scientists designate species brought by Polynesians before the age of settler-colonialism as “non-native” but others limit it to European-introduced species. British colonization of the Australian continent commenced in 1788 (though the 1606 landing of a Dutch East India Company ship is the first documented European arrival) but some scholars label the dingo, introduced by Aboriginal people 4000 years ago, as non-native.

Political boundaries with no ecological significance can be a basis for defining nativeness, which also highlights the fact that nativeness is a scale-dependent factor. Tropical Milkweed (Asclepias curassavica) is native to North America from Mexico southwards but is called “invasive” in the United States (even though its pre-Columbian native range may have included southern Florida). Yet it’s also accurate to describe the species as “native to North America.” If a climate-induced, natural range shift of a species crosses the border of a country or a province will it be counted as non-native, but not otherwise?

Finally, how far does a species have to travel to be “out of range”? The endangered Monterey Cypress (Cupressus macrocarpa) is, according to journalist Andrew Cockburn, “a frequent target for the chain saws of the San Francisco Recreation and Parks Department—even though two small stands in Monterey, just fifty miles south, are cherished and protected as natives.”^v Meanwhile, a 500 mile drive north of its relict range, a large specimen planted by European settlers near Brookings, Oregon, in the 1850’s is an officially designated “Heritage Tree,” which we personally hope grants it safety because we’ve seen it and it’s majestic.

“Introduced” is shorthand for “introduced by humans either intentionally or accidentally.” It doesn’t include the actions of animals, weather, or other more-than-human agents in transporting species. It also doesn’t usually include indigenous humans, not because their own actions in moving around species haven’t been significant or are considered qualitatively different than those of settler-colonialists, but simply because they are generally not considered at all. This narrative omission is meaningful because it narrows the realm of possibilities for both human activity and human nature, a point we will be returning to in depth in later chapters.

In some cases, the non-native requirement has been dropped entirely. The State of New York includes the native Cup Plant (Silphium perfoliatum), on their “Prohibited and Regulated Invasive Plants” list because they characterize its growth as “aggressive.”^vi

This cursory sweep of these definitions demonstrates that we only need to scratch the surface of what is presented as a black and white issue to reveal a lot of gray area.

As we relate in detail later, similar accusations of “encroachment” by native flora are currently playing out with horrific results in the western US, where healthy woodlands of Pinyon-Juniper—declared a “native invasive” by some^vii—are being razed to expand rangeland for cattle.^viii

Further muddying the picture, the term “noxious weeds” is often used interchangeably with “invasive species” by organizations and individuals alike. The USDA has a list of “Introduced, Invasive, and Noxious Plants.”^ix The designation of “noxious weeds” is typically decided by local government entities in support of conventional farming and ranching, so a particular plant—native or introduced—will be added because of its purportedly negative effect on domesticated crops or animals. Thus, St. Johnswort (Hypericum perforatum) is bad because it can cause phototoxicity in sheep, Chervil (Anthriscus sylvestris) because it might carry a rust fungus that can affect cultivated carrot seed crops, and Pigweed (Amaranthus palmeri) because it grows in cornfields. Note that in the first two cases the plant or animal species supposedly threatened are themselves not native, and are products of a system—industrial agriculture—that is severely detrimental to the environment wherever it is practiced. Though Corn (Zea mays) is native, the ultra-hybridized and genetically-modified varieties grown today are so far from what indigenous people tended in Three Sisters arrangements that one could question if it’s even the same plant anymore. All three of these “weeds” also happen to be edible or medicinal for humans, so it’s a matter of priorities rather than usefulness that they’re slapped with a negative label and their eradication actively pursued. The primary motivation of noxious weed management is economic, not ecological—despite recent glosses of “sustainability” or “conservation” applied by some of its adherents—and more often than not involves pesticides.

What about science? How does invasion biology itself define “invasive?”

Scientists are well-known for disagreeing about definitions, and “invasive” is no exception. One biologist summed up the discussion by stating that there is “no indication that the field [will] be able to achieve uniformity in language in the near future.”^x

These are some of the concepts that have been used or proposed for “invasive”:

a species that successfully establishes itself in a new place
- such a species that establishes and has impact
  - such a species whose impact is negative
a species that, regardless of impact, establishes and spreads rapidly
a species that does any of the above which is non-native and introduced by humans
a species that does any of the above which is non-native, regardless of how it was introduced
a species that does any of the above which is native

These can’t all be true at once, obviously. There are too many contradictions. The science also suffers for dearth of agreement. One researcher noted that the “lack of consensus regarding the definition of invasive alien species (IAS) and vagueness around the demonstration of their impacts limits knowledge and research in this field.”^xi

Whether or not to use the word “invasive” at all is an ongoing debate in invasion biology. Historically, some scientists used the word “invade” and “colonize” to merely describe the movement of a species into a new area, or just the establishment of a species in a recently opened area, like after a fire, flood or landslide. But many scientists now recognize that, these days, the word has indisputably negative connotations which have implications not just within the field but for social discourse. Writes biologist Mark Davis, in his book, Invasion Biology:

I have never liked the term ‘invasion’ and think the field would have been much better off had it never been adopted, along with its accompanying military metaphors. Although the usage of military language may help to attract a group of highly motivated supporters, this same language may help foment a strongly confrontational approach, making it much more difficult to negotiate and resolve conflicts.^xii

More on the discussions within the field of invasion biology about terminology follow later.

A “confrontational approach” has certainly been a feature of too many discussions about introduced plant species. We have both been saddened to watch as native plant forums online, once a place to good-naturedly share photos and get IDs, have become toxic places where the word “invasive” is wielded like a club. Hateful rhetoric is the hallmark of dogma, not reason or thoughtfulness, and unfortunately it has been metastasizing in too many circles. We wonder how different the attitudes would be if “invasive” had never been used and we’d only ever had something neutral like “introduced” or nostalgic like “pioneer.”

**What’s not defined as “invasive” is just as important as what is**

Excluded from virtually everyone’s definition are the hundreds of non-native domesticated plants important to agriculture. This is highly significant given that over one fifth of the land in the lower 48 states of the US is cropland. That’s nearly 400 million acres of what was originally habitat for many, many native plant species. The excuse of “We need to eat!” doesn’t fly here; only 20% of that cropland is devoted to growing food directly for people; the majority of the remainder is for ethanol production, export industries, and livestock feed.^xiii

These stats should put the “invasive” dialogue into perspective. Picture the Midwest’s horizon-to-horizon corn and soy crops, California’s vast rice fields and almond orchards, or Oregon’s expanses of grass seed. These monocrops of non-native plants displaced prairies, forests and wetlands brimming with native flora and fauna. They are maintained with toxic pesticides and fertilizers, unsustainable water use, heavy machinery, fossil fuels, and oppressive labor practices. They dominate more than just their local geographical footprint, sucking in resources from distant places. According to the “invasive plant” narrative, the only “invasives” in these abused landscapes are the weeds coming up in the ditches or between the rows, a perspective we find perverse.

Other exemptions apply to the “invasive” label. As the US Department of the Interior’s Invasive Species Advisory Committee points out: “Kentucky bluegrass would be considered an invasive species in Rocky Mountain National Park in Colorado, but considered non-invasive a mere 60 miles away at a golf course in Denver.”^xiv If anything is “invasive,” how is it not the golf course itself? In the arid Coachella Valley of southern California, over 140 irrigated golf courses represent the complete destruction of the desert habitats that they replaced, and are a significant draw on the region’s precious water.

The topic of golf courses leads us to another big omission: lawns, which in their emerald-green ideal are monocultures of non-native grass. If lawn grass were categorized as an irrigated crop in the US, it would be ranked number one in land area and water use.^xv Yet it is the Dandelion that sprouts up in the front yard that’s “invasive.”

The “invasive plant” narrative is not ultimately about logic or facts. It’s about beliefs and prejudices, so a more relevant question than, “What is the definition of an ‘invasive’ plant?” might be, “What is meant by ‘invasive’?” What does the word signify? From what cultural foundations does it spring and what narrative edifice does it help perpetuate? There’s the narrative—that some plants are bad because they’re foreign—and then there’s the why of the narrative, which we delve into in Part 3, “Culture.”

“Bad plant”

In sum, the term “invasive plant” is thrown around so carelessly these days that, in common usage, it doesn’t really mean anything beyond some vague notion of “bad plant.”

But there are no “bad plants.” There are just particular plants that particular people in particular places at particular times have considered undesirable for particular reasons. That’s a lot of particulars. Too many to brand a whole species of plant with a pejorative label like “invasive” or “noxious” as if that’s its entire, intrinsic nature. Does it make sense to weed a garden? Of course. But that’s no reason to elevate our subjective calls—useful as they might be in a particular place and particular time—to the level of a universal constant, and to manufacture an army of villains in doing so. That just encourages our own misguided tendencies and puts off the day when we resume healthy connection and relating with life on this planet.

A very real invasion commenced in 1492, and with it came what some Anishnaabe tradition-bearers call “invasive land-ethics,”^xvi a concept we explain in “Introduced Plants, Settler-Colonialism, Indigenous Perspectives and Decolonization.” These ethics drove the cutting of forests, draining of wetlands, mining of mountains, plowing of prairies, damming of rivers, and slaughter to near extinction of Buffalo, Prairie Dogs, Beavers, Bears, Cougars and Wolves. These misbegotten ethics are unequivocally real and are active threats to the planet’s environment. Without addressing them, the destruction will only worsen.

In the meantime, the “management” of “invasive plants” routinely has its own negative effects, which we detail in the next chapter.

Kollibri Terre Sonnenblume

Citations:

iExecutive Order 13112 – Section 1. Definitions, February 3, 1999. https://www.invasivespeciesinfo.gov/executive-order-13112-section-1-definitions

iiUnited Nations Environmental Programme. “Invasive Alien Species—A grwoing threat in regional seas” https://wedocs.unep.org/bitstream/handle/20.500.11822/13623/invasive_alien_brochure.pdf

iiiIUCN. “Invasive Alien Species” https://www.iucn.org/our-work/topic/invasive-alien-species

ivConvention on Biological Diversity. “What are Invasive Alien Species?” https://www.cbd.int/invasive/WhatareIAS.shtml

vCockburn, Andrew. “Weed Whackers: Monsanto, glyphosate, and the war on invasive species” Harpers (September 2015). https://harpers.org/archive/2015/09/weed-whackers/

viNew York State Department of Environmental Conservation. NYCRR part 575 Invasive Species Regulation. (September, 2014). https://www.dec.ny.gov/docs/lands_forests_pdf/isprohibitedplants2.pdf.

viiAnsley, R. “Managing Native Invasive Juniper Species Using Fire” Weed Technology 19 (Jul 2005):517-522 DO – 10.1614/WT-04-098R1.1 http://www.bioone.org/doi/abs/10.1614.

viiiFite, Katie. “The Terrible Destruction of Pinyon-Juniper Forests” Counterpunch (December 28, 2018). https://www.counterpunch.org/2018/12/28/the-terrible-destruction-of-pinyon-juniper-forests/.

ixUSDA https://plantsorig.sc.egov.usda.gov/java/noxious?rptType=Federal

xDavis, Mark. “Invasion Biology.” (New York: Oxford University Press, 2009), p. 3.

xiFachinello MC, Romero JHC, Chiba de Castro WA (2022) Defining invasive species and demonstrating impacts of biological invasions: a scientometric analysis of studies on invasive alien plants in Brazil over the past 20 years. In: Giannetto D, Piria M, Tarkan AS, Zięba G (Eds) Recent advancements in the risk screening of freshwater and terrestrial non-native species. NeoBiota 76: 13–24. https://doi.org/10.3897/neobiota.76.85881

xiiDavis, 2009.

xiiiMerrill, Dave and Leatherby, Lauren. “Here’s How America Uses Its Land” (Bloomberg, July 31, 2018). https://www.bloomberg.com/graphics/2018-us-land-use/.

xivUS Department of the Interior Invasive Species Advisory Committee. “Invasive Species Definition Clarification and Guidance” April 27, 2006, p. 3. https://www.doi.gov/sites/doi.gov/files/uploads/isac_definitions_white_paper_rev.pdf.

xvCristina, Milesi & Elvidge, Christopher & C, J. & D, B. & Nemani, Ramakrishna & E, S.. (2012). A strategy for Mapping and Modeling the Ecological Effects of US Lawns.

xviReo, Nicholas J., Ogden, Laura A. “Anishnaabe Aki: an indigenous perspective on the global threat of invasive species,” Sustainability Science (2018) 13: 1443-1452. https://doi.org/10.1007/s11625-018-0571-4.

Environmentalism in the Rear-View Mirror

One year ago, less than a month after Donald Trump was re-elected President, I announced on Conservation Sense and Nonsense my intention to “hunker down and watch the changes [in the federal government] play out.” Although I predicted major changes in federal public policies, I did not foresee the scale and speed of changes in environmental policies that we have witnessed in the past year. The uncomfortable reality is that some of what is being destroyed deserved to be destroyed, but at the expense of some valuable environmental protections.

In describing the changes we have witnessed, I will focus primarily on environmental issues in the following main categories. Please keep in mind that changes in environmental policies are but a small fraction of the changes that have occurred in all aspects of American life and global geopolitics, e.g., education, public health, arts and entertainment, architecture, science, economics, immigration, media sources, judicial system, disaster relief, social safety net, foreign aid, tariffs, etc.

Policy intended to protect endangered plants and animals, included “loss of habitat” as one of the harms that recovery plans must mitigate. “Harm” is now defined by the Endangered Species Act narrowly as only harm directly to the endangered plant or animal. The Trump administration has also proposed significant new limitations on the application of the Endangered Species Act that will remove obstacles to resource extraction that will have a negative impact on endangered wildlife.
Federal agencies that were responsible for protecting the environment in the past have been defunded and their staff drastically reduced. The President calls them “Democrat agencies.” National parks, wildlife refuges and marine sanctuaries have lost both their funding and much of their staff. Places that were protected from unfettered resource extraction, no longer are.
Manufacturers of pesticides are lobbying Congress to prevent product liability lawsuits filed by people who have been harmed by pesticides. Congress is trying to prevent states from regulating the use of pesticides. Supporters of Robert F. Kennedy, Jr. are disappointed that Health and Human Services will not attempt to limit the use of pesticides in the US.
Laws and agency regulations that enabled the protection of the environment, the proverbial teeth in environmental policies, are being repealed:
- USFWS is in the process or rescinding the Roadless Rule, which prohibited new road construction in 60 million acres of national forests since 2001, enabling the expansion of timber operations.
- Bureau of Land Management is rescinding a policy that included conservation as one of many official uses of BLM land.
- Policy intended to protect endangered plants and animals, included “loss of habitat” as one of the harms that recovery plans must mitigate. “Harm” is now defined by the Endangered Species Act narrowly as only harm directly to the endangered plant or animal. The Trump administration has also proposed significant new limitations on the application of the Endangered Species Act that will remove obstacles to resource extraction that will have a negative impact on endangered wildlife.
- The Trump administration has proposed a significant limit on the EPA’s authority to limit pollution in wetlands, rivers and other bodies of water across the country: “These changes could strip federal protections from up to 55 million acres of wetlands, or about 85 percent of all wetlands nationwide, according to the Natural Resources Defense Council…”
- All efforts to reduce greenhouse gas emissions causing climate change have been abandoned. The President made good on his campaign promise to “drill, baby drill.” New commitments have been made to increase oil and gas extraction, as well as coal mining, off-shore drilling, and seabed mining. Corresponding new policies have eliminated commitments to develop renewable energy sources, such as wind and solar. The Environmental Protection Agency is promising to erase the endangerment finding that underpins climate regulations nationwide. The endangerment finding established that greenhouse gases endanger public health and must therefore be regulated to protect the public.

The Trump administration has left the international Paris Agreement, the legally binding treaty adopted in 2015 to limit global warming to below 2 degrees Celsius. The US was not represented at the November 2025 meeting of the UN Conference of the Parties (COP30) to the agreement in Brazil, but the US actively campaigned against the new commitment on the agenda to limit pollution from cargo ships by using fines. According to the New York Times, “…the United States launched a pressure campaign that officials around the world have called extraordinary, even by the standards of the Trump administration’s combativeness, according to nine diplomats on its receiving end.” US diplomats and officials were successful in threatening countries with loss of US port access and other onerous penalties if they voted for the proposal. The Trump administration hasn’t just dropped out of the Paris Agreement. It is also actively engaged in preventing other countries from reducing greenhouse gas emissions that cause climate change. COP30 ended without any new commitments to reduce the sources of greenhouse gas emissions, or even explicit mention of fossil fuels as the primary greenhouse gas.

America Accommodates

Many of these changes have been delayed by legal challenges, but until appeals reach the Supreme Court, the final verdict on most issues is not known at this time. However, the Supreme Court has signaled their intentions with many emergency orders, also known as the shadow docket. These decisions have upheld most of the federal government’s actions, without providing any legal reasoning for doing so. These preliminary decisions foretell the ultimate victory of the actions of the Trump administration.

Other segments of American society are contributing to the control the President has over the implementation of his agenda. At his request, Congress has completely defunded National Public Radio and the Public Broadcasting Service. They are scrambling to find other sources of revenue, while cutting programs and staff as well as closing stations. Associated Press was banned from White House press briefings when they refused to call the Gulf of Mexico the Gulf of America, as renamed by President Trump. Legal challenges have not restored AP’s access to White House press briefings.

Mainstream media has paid multi-million dollar settlements to resolve defamation lawsuits (ABC and CBS) brought by President Trump over perceived slights. One major network (CBS) has changed ownership and is now owned by Trump supporters (Larry & David Ellison). The Department of Defense (now calling itself the Department of War) has restricted access of the press to department staff and now requires department approval of press releases prior to publication. Most members of the Pentagon press corps refused to agree to these restrictions and have left their offices in the Pentagon. Self-censorship is a more insidious threat because the public no longer knows when the media is pulling its punches to avoid retribution, which is the President’s modus operandi.

The legal profession has also been brought to its knees by the President’s threats of punishment if they participate in lawsuits that try to prevent the implementation of the administration’s policies. Many major law practices have been forced to provide pro bono legal services for President Trump after being threatened with access restrictions to the judicial system. Major law practices are refusing to represent plaintiffs who are trying to protect themselves from government prosecution, hoping to stay out of the line of fire.

California Responds

The same day that Americans re-elected Donald Trump in November 2024, California voters passed Proposition 4 , the $10 billion bond that funds climate change mitigation and ecological restoration in California. California’s bond funding will help to compensate for the loss of federal funding of ecological and climate mitigation projects in California. California Natural Resources Agency reported the cancellation of federal funding for these projects in California:

Source: California Natural Resources Agency, July 2025

Does California have enough money to compensate for the loss of federal funding of climate change mitigation and ecological restoration in California? I don’t know, but I do know that federal funding is also being lost for many other purposes that are important to Californians, such as subsidies for health insurance and food assistance needed by many Californians. Some municipalities are responding by raising sales and property taxes to backfill the loss of federal funding in many sectors of the economy. While federal taxes are being cut, California’s taxes may rise.

Meanwhile, California is challenged by related issues such as the need to build more housing in order to reduce the cost and house our growing homeless population. In July 2025, California responded to that issue by revising the California Environmental Quality Act (CEQA), which will remove many obstacles to building new housing and allow more aggressive fire hazard mitigation.

The cost of gas in California has been consistently higher than in most states because of voters’ desire for clean air. Regulations have made drilling for and refining oil in California costlier than in other states, which makes gas more expensive for consumers. Refineries have responded to California’s restrictive regulations by leaving the state, which reduces supply, raises prices further and is expected to restrict availability of fuel. California’s Senate Bill 237, signed into law in September 2025, addressed these concerns by streamlining approval of drilling permits, including idle pipelines, in an “environmentally responsible and safe manner.”

In other words, California has been forced to adapt to new economic and environmental realities. At the same time, California is aggressively fighting back. As of October 1^st, California has filed 46 lawsuits against the 2^nd Trump administration, “contesting the Trump administration’s executive orders, agency decisions and even recent laws that Trump himself signed.”

Americans Shrug

Composite opinion polls reported a persistent negative approval rating of 11% for the Trump presidency until the government shutdown in October, when the approval rating dropped to negative 15% before returning to negative 11% when the government re-opened. Over 40% of American voters still approve of the Trump presidency. Many voters have made up their mind and are not responsive to the daily onslaught of alarming information. I understand and am sympathetic to the public’s dilemma, summarized in a recent social media post: “My desire to be well informed is presently at odds with my desire to remain sane.”

For perspective, consider that President Biden’s composite approval poll on July 6, 2024 was negative 19.3%, just 15 days before Biden dropped out of the presidential race on July 21, 2024.

The demonstrations I have attended are another window into the mood of the American public. The NO Kings demonstration on June 14, 2025 is said to have drawn 5 million people. The second NO Kings demonstration on October 18^th claims to have drawn 7 million people. Although these seem impressive numbers, they don’t add up to a change-making revolt. The lack of young people participating in these demonstrations is dispiriting. The future is in their hands, yet their commitment to democracy is lukewarm compared to my generation, the boomer generation that still feels a strong commitment to the peace and prosperity that democracy has delivered to us.

On the other hand, Democrats aren’t dead yet. In November 2025, moderate Democrats won governorships in New Jersey and Virginia and a Democratic Socialist won the mayoral election in New York City. In response to Republican gerrymandering of congressional districts in Texas, 64% of Californians voted to gerrymander congressional districts in favor of Democratic candidates. A recent Marist poll indicated that registered voters in the US plan to vote for Democratic candidates for congressional seats in 2026 by a margin of 14%.

Changes in the elected leadership of the Bay Area chapters of the Sierra Club are an indication of a change in the public’s commitment to the environment. The San Francisco Bay Area Chapter is now led by activists who want more housing and more active recreational opportunities. The old guard, who were committed to restricting recreational access in favor of native plant restorations in public parks, has been replaced. The Lomo Prieta Chapter, which represents the South Bay, is now undergoing a similar transition to new leadership with new priorities.

Changes in the leadership of the San Francisco Bay Area chapters of the Sierra Club are symptomatic of the Club’s much broader decline on a national scale. According to the New York Times, the Club has lost 60% of the 4 million members it had in 2019. The Times attributes this loss of support to the change of the Club’s advocacy focus from environmental issues, most prominently climate change, to progressive social justice issues such as racial justice, gay rights, labor rights, and immigration rights. In 2019, one of the Board Directors objected to the proposed budget, but was voted down: “I said, ‘We have two F.T.E.s devoted to Trump’s war on the Arctic refuge, and we have 108 going to D.E.I., and I don’t think we have our priorities straight,’” Mr. Dougherty said.

Finally, wealthy American philanthropists are providing clues of a fundamental change in the political climate in America. Bill Gates, former owner of Microsoft and supporter of global health initiatives, recently announced that it is time for a “strategic pivot” in the global climate fight from focusing on limiting rising temperatures to fighting poverty and preventing disease. Gates still believes climate change is a serious problem, but it won’t be the end of civilization because he thinks scientific innovation will contain it. Unfortunately, federal support for finding such scientific innovations has been withdrawn. Gates’ message seems to be that we aren’t able to stop climate change, so we must cope with it. It’s another way of accommodating the environmental policies of the Trump administration.

Looking Ahead

I am deeply troubled by the many threats to America’s treasured democracy. However, many of the changes in environmental policies in the past year are aligned with the mission of Conservation Sense and Nonsense. Since its inception in 2010, the mission of Conservation Sense and Nonsense has been the preservation of our predominantly non-native urban forest, opposition to the use of pesticides on public lands and advocacy for mitigating the causes of climate change. Some of the changes in environmental policy in the past year are consistent with those goals:

Many projects that use pesticides and kill harmless animals and vegetation have been defunded by the federal government. The State of California is trying to compensate for the loss with state funding, but its ability to do so will be challenged by many other new demands on state resources, such as subsidies for health care and food.

When wildlife refuges and marine sanctuaries lost much of their funding and staff, many of their projects were abandoned. Many of those projects may have been beneficial, but the plans to aerially drop rodenticides on the Farallon Islands to kill harmless mice is an example of a project that is better off dead.

Prevailing public opinion that native plants and animals are superior and the corresponding belief that non-natives are a threat to them is unlikely to change in the near-term. I do not begrudge the horticultural preferences of home gardeners. However, native plant advocates will have limited ability to demand that public land managers eradicate non-native plants if there is no public money available to fund landscape-scale “restorations.”
As public money for ecological “restorations” on public land dries up, the “restoration” industry and the jobs it creates will probably dwindle over time. As economic interests in “restoration” evaporate, the advocacy that supports it is likely to as well. College students are likely to make other educational choices with more promising career prospects, which will further reduce the labor force engaged in “restorations.”
When forest “restoration” projects that involve clear-cutting or removing healthy trees are defunded, existing carbon storage is preserved. Every mature tree—native or non-native—sequesters carbon at a time when we need every available carbon sink to compensate for the loss of limits on greenhouse gas emissions causing climate change.
Climate change will accelerate as we abandon our efforts to reduce greenhouse gas emissions that cause climate change. The landscape that survives the changed climate will be best adapted to the changed environment. When the climate changes, vegetation changes or dies. No amount of human intervention can alter that ultimate reality because nature always bats last.

In 2026, Conservation Sense and Nonsense will continue to report major developments relevant to my mission. In other words, I will continue to “hunker down and watch it play out.” Guest posts consistent with my mission and civil comments, both pro and con, are always welcome here. Thank you for your readership.

Happy Holidays and best wishes for a more peaceful year in 2026.

“Instead of ‘controlling’ non-native plants, perhaps we should practice more ‘self-control’”

Julian Burgoff wrote a guest post for Conservation Sense and Nonsense about the undervalued functions of non-native aquatic plants in 2023. Necessary Nuisance explained that non-native aquatic plants perform valuable ecological functions. Attempts to eradicate aquatic plants deprive aquatic animals of valuable habitat. The herbicides used to kill aquatic plants also pollute the water, harming aquatic animals and killing non-target aquatic plants.

Julian Burgoff is an avid bass angler and aspiring fisheries ecologist from western Massachusetts. He recently received a master’s degree with the Massachusetts Cooperative Fish and Wildlife Research Unit at UMass- Amherst where he studied juvenile river herring growth, diets and habitat use in coastal Massachusetts lakes and estuaries. He is passionate about lake ecology and the management of aquatic vegetation in lakes and hopes to work in a field related to lake conservation and warmwater fisheries management in the future.

I am grateful to Julian for giving us another opportunity to publish an article about a specific project that is trying to kill valuable aquatic plants with herbicides. Thank you, Julian.

Conservation Sense and Nonsense

Hydrilla and the Connecticut River: Falling into the “Invasive” Trap

If you spend time on the tidal Connecticut River in summer, you will likely see thick green mats covering its shorelines, coves and backwaters. This is hydrilla — a non-native aquatic plant that’s long been demonized by state agencies and lake managers across the country.

One morning during a summer internship performing fisheries related fieldwork on the river, I saw a young doe on the bank nibbling on a clump of hydrilla exposed at low tide. I laughed to myself — I knew it was good fish habitat, but even deer like the stuff!

The “official” position was that it was choking the river, outcompeting native species, and impeding recreational use of the river. But as a passionate angler and ecologist who studies aquatic ecosystems, I’ve learned that what we (as western scientists) think about non-native species and their impacts — especially in the world of aquatic plants — often turns out to be driven more by ideology than by scientific evidence.

The War on Hydrilla

Hydrilla arrived in the Connecticut River around 2016 and has since spread through the lower mainstem and its tributaries. In response, the Connecticut Agricultural Experiment Station (CAES) and the U.S. Army Corps of Engineers (USACE) have launched an aggressive herbicide campaign that seeks to “restore” native aquatic plant communities and study the efficacy of using a cocktail of various herbicides to treat the areas of the river where the growth of hydrilla is most prolific. Over the past few summers and into next year, private contractors plan to treat hundreds of acres of river coves with a mix of chemicals, including diquat and florpyrauxifen-benzyl.

On paper, this might sound like responsible ecological stewardship — reducing non-native plant stands such that their native counterparts can flourish. But in my view, it’s another example of what resource managers in Minnesota have referred to as “the invasive trap”: the belief that any non-native species must be “harmful”, and that launching management campaigns to kill them must be ecologically and economically beneficial.

The problem is that this assumption is not based on data, but on the dogmatic assumptions of invasion biology that underpin the world view of many western scientists and management agencies.

Unexpected Ecosystem Services: What the Evidence Shows

Across the country, hydrilla has often played the opposite role of what managers might expect. In the Chesapeake Bay and its tributaries, researchers found that hydrilla helped stabilize sediments, clear up murky water, and create habitat for fish and invertebrates — even helping native aquatic plant stands return. In Florida lakes, scientists compared lakes with and without hydrilla and found no major differences in fish, bird, or aquatic plant diversity.

In other words, hydrilla didn’t destroy these ecosystems where it was introduced. It filled open niche space, performed valuable ecosystem services, and is now integrated into the food web, for better or for worse.

That’s not to say hydrilla should be introduced to new water bodies or can’t impact ecosystems in ways that are perceived as harmful. Like many aquatic plants (native and non-native), hydrilla can grow in thick stands that interfere with swimming or boating, alter water chemistry and change physical habitat suitability for aquatic organisms. But many of these impacts are human nuisances, not ecological disasters, and should be managed as such. In large, dynamic systems like the Connecticut River, hydrilla’s role is likely far more complex — and possibly beneficial — than its label as “one of the world’s most invasive aquatic plants” suggests.

The Risks of Herbicide Use to “Restore” Native Plant Communities

Despite the lack of evidence that hydrilla is causing ecological “harm” to the Connecticut River, the proposed management intervention — widespread herbicide use — carries significant ecological risk.

Diquat, one of the main herbicides being applied, is what’s called a contact herbicide: it kills whatever plant tissue it touches (including native plant taxa). Florpyrauxifen-benzyl is a systemic herbicide, meaning it’s absorbed into plants and disrupts their growth. When a large quantity of aquatic plants rapidly die, they decay and release nutrients into the water, which can fuel algal blooms that reduce water clarity. If water clarity is significantly reduced, the very native plants managers aim to “restore” can’t regrow.

Ironically, hydrilla often bounces back first because it’s more tolerant of poor water quality than many native species. This can lock managers into a costly, never-ending cycle: herbicide use → temporary die-off → algal bloom → hydrilla regrowth → more herbicides.

Similar outcomes have been observed in Florida, where researchers found a large-scale florpyrauxifen-benzyl treatment sharply reduced hydrilla abundance in a Florida lake, but the plant regained dominance within a year as reduced water clarity from the treatment hindered native plant recovery.

Cascading Food Web Effects

As primary producers, aquatic plants are essential to the foundation of food webs — sheltering young fish, providing surfaces for invertebrates to live, and supporting wildlife like waterfowl. When herbicides are used to kill aquatic plants, there are often complex indirect impacts to the integrity of aquatic food webs.

Diquat is known to be toxic to not just plants (native and non-native) but invertebrates (the tiny animals that feed fish), such as amphipods. Even at concentrations lower than what’s used in field applications, diquat has the potential to impact these organisms which in turn may reduce available habitat for organisms higher up the food web like fishes.

Diquat also contains bromide, a compound that researchers have linked to a neurological disease killing bald eagles in the southeastern U.S. The disease develops when a particular cyanobacteria grows on hydrilla plants and interacts with bromide — forming a toxin that bio-magnifies as it moves up the food web. Ducks eat the hydrilla, eagles eat the ducks, and the toxin accumulates, damaging the eagles’ brains.

While this phenomenon hasn’t yet been documented in the Connecticut River, applying bromide-based herbicides in a manner that is likely to contribute to algal blooms (including cyanobacteria blooms) is not an ecologically sound management practice.

What We Don’t Know

Despite the confidence behind these large-scale management interventions, there’s little data showing how hydrilla has actually affected biodiversity or water quality in the Connecticut River. To prove that hydrilla is causing ecological “harm”, we’d need long-term monitoring — decades of data on aquatic plants, fish, wildlife, and water quality — collected before and after hydrilla became established. These data likely don’t exist at the scale needed to make an informed, unbiased assessment. Yet herbicide applications in the name of ecological “restoration” are moving forward anyway. The “post-monitoring” required by the project plan mostly focuses on the “efficacy” of the treatment (e.g. how much hydrilla biomass is reduced) not on whether algae blooms occur or how invertebrate and fish communities are affected.

This is a common phenomenon with herbicide treatments: the indirect effects of the management intervention are simply too complex and too costly to quantify. Based on the current “post-monitoring” protocol, if it’s found that hydrilla biomass is reduced and that native aquatic plant communities continue to exist following treatment, the project will be considered a success.

Less is More: Observation Based Management

Sometimes, the most ecologically mindful (and most cost effective) management decision is to pause to let species interactions occur unmolested and find their own equilibrium rather than impose an imaginary concept of what a given ecological community “should” be.

Where hydrilla interferes directly with human activities — say, blocking a boat ramp or clogging a marina — mechanical removal or small, targeted herbicide treatments could be reasonable management interventions. But broad, river-wide herbicide use is neither justified by science nor a long-term sustainable solution to non-native aquatic plant management.

With non-native species introductions, the truth is that there is no going back. Climate change, nutrient loading, and decades of physical habitat alteration via damming etc. have already changed this river beyond what it was a few centuries ago. Plants and animals are constantly being introduced and adapting to a new reality — one where species origins and “native” vs. “non-native” status matter far less than their role in maintaining ecosystem functions.

Rather than pouring more chemicals into the water, perhaps we should pour our efforts into observing, monitoring, and trying to understand why certain plants succeed and how ecosystems adjust to change over time. Instead of “controlling” non-native plants, perhaps we should practice more “self-control” and let nature heal itself without the imposition of the human ego and its desire to constantly fight the expressions of the natural world in the Anthropocene.

Julian Burgoff
Amherst, MA
jburgoff@umass.edu

Luther Burbank: The Plant Inventor

Luther Burbank was born in Massachusetts in 1849, the 13^th of 15 children. As a child, he had an interest in nature. With an inheritance from his father, who died when Burbank was 18 years old, he purchased a 17-acre farm in Massachusetts.

Burbank bought his small farm intending to be a market farmer, selling seasonal fruits and vegetables. He was handicapped by challenging climate and growing conditions and competition from other market farmers with a head start. He could see that he would have to produce the best produce and offer it before his competitors could, which pushed him down the path of improving the plants he grew.

Burbank’s methods for improving plants

Burbank found his inspiration as a breeder of improved plants in his local library where he found the writings of Charles Darwin. He could see that the concept of natural selection described by Darwin, applied equally to breeding plants. He wrote, “It opened a new world to me. It told me, in plain simple sentences, as matter-of-fact as though its marvelous and startling truths were commonplace that variations seemed to be susceptible, through selection, of permanent fixture in the individual…I doubt if it is possible to make anyone realize what this book meant me.” (1)

Burbank quickly put his new understanding of selection to use as a means to improve the food crops he grew. He developed the Burbank potato that is known today as the Burbank russet potato. He found a seed ball on his potato plants containing 23 seeds. He grew the seeds, selecting the plants that produced the best potatoes in successive crops until he had a potato with smooth skin and few eyes that tasted good and stored well. It was also mildly resistant to the blight that caused the potato famine in Ireland, which killed one million people and caused a mass exodus from Ireland.

He understood that he had created a valuable commodity, but he couldn’t see how he could profit from it because he couldn’t produce it at scale on his small property and he didn’t have the commercial infrastructure to market it widely. At the time, it wasn’t possible to patent new plant varieties, so he sold his new variety to an established seed merchant for $150. It was a paltry sum, even at the time, but it was the beginning of a business model that financed most of Burbank’s career as a plant inventor.

Charles Darwin also introduced Burbank to another method of improving plants in his publication, “The Effects of Cross and Self-Fertilization in the Vegetable Kingdom.” Burbank described how Darwin led him to the realization that hybridization is another means of improving the quality and performance of plants: “One sentence in the very introductory chapter of that volume opened the door of my mind and took possession of my fancy. After discussing briefly the marvel of cross- and self-fertilization in plants, Darwin said: ‘As plants are adapted by such diversified and effective means for cross-fertilization, it might have inferred from this fact alone that they derive some great advantage from the process; and it is the object of the present work to show the nature and importance of the benefits thus derived [from hybridization].’” (1)

Darwin identified natural selection and hybridization as tools of evolution that produced plants and animals best adapted to current environmental conditions. When environmental conditions changed, as they have constantly over 4.6 billion years of the Earth’s existence, natural selection and hybridization enabled the survival of plants and animals best adapted to changed conditions. Using the same methods, but different criteria, Burbank bred the plants that conformed to the needs of humans: the most flavorful fruit, sturdy enough to be transported from fields to tables and the most beautiful flowers, in the opinion of humans. Burbank directed and accelerated evolution to serve humans, using the tools of natural evolution.

Grafting the branches of one type of fruit onto the root stock of another species of tree was the third method Burbank used to create new plants. Most orchard fruit is grown from grafting because growing fruit trees from seeds is unpredictable. The seeds of a flavorful apple, don’t necessarily grow into a tree that produces an equally flavorful apple. It takes years for some fruit trees to produce fruit, which can ultimately produce disappointing fruit. Grafting is a means of reducing risk and accelerating production.

California’s Bounty

After years of economic hardship, Burbank moved to California in 1875 at the age of 26 to join his brothers. Instantly, he was an enthusiastic promoter of the ideal climate and growing conditions of his new home in Santa Rosa. He bought 4 acres of land where he built a greenhouse, nursery, and experimental fields. Later, he bought an 18-acre plot of land in nearby Sebastopol he called the Gold Ridge Farm, where his experiments expanded.

Luther Burbank Home & Garden, Santa Rosa. Creative Commons Attribution-Share Alike 3.0 Unported license.

In California, Burbank had the climate and the acreage needed to run many experiments on fruit and nut trees as well as vegetables and flowers simultaneously. Each experiment required planting thousands of individual plants, grown through many generations. These experiments produced hundreds of varieties of many species of plants:

Fruits
113 plums and prunes
69 nuts
35 fruiting cactus
16 blackberries
13 raspberries
11 quinces
11 plumcots
10 cherries
10 strawberries
10 apples
8 peaches
6 chestnuts
5 nectarines
4 grapes
4 pears
3 walnuts
2 figs
1 almond
Grains, grasses, forage
9 types
Vegetables
26 types
Ornamentals
91 types
Source: Wikipedia

Finding His Tribe: Scientist or Businessman?

By the turn of the century, Burbank had made his reputation as the creator of new plant varieties. He captured the attention of scientists who wanted to adopt him into their community, learn his methods, and teach them to their students: “The San Francisco Chronicle advocates the seizing of Luther Burbank at his home in Santa Rosa and placing him in a chair at Stanford University….The main thing is to get the recluse away from his practical experiments long enough to tell people what he has done.” Los Angeles Times, June 7, 1901.

Burbank was invited to give a series of lectures at Stanford University at a time when botanical scientists were newly influenced by the discovery of the role of genetics in producing individual variations in plants and animals. Gregor Mendel’s studies of genetic variation done in the 1860s was buried in the archives of Mendel’s local botanical society until 1900, when they were rediscovered.

Burbank’s audience at Stanford was expecting his lecture to reflect the mechanistic determinism of Mendelian genetics. Instead, they got a dose of Burbank’s almost mystical view of the workings of nature “…as an intricate web of vibrations and magnetic forces where ‘all motion, all life, all force, all so-called matter are following the same law of heredity found in plants and animals, a forward movement toward attraction through lines of least resistance.’” (1)

Today, our understanding of genetics is more nuanced than it was over one hundred years ago and it is more consistent with Burbank’s observations. With the help of molecular analysis, we now know that there are hundreds of unexpressed genes that are latent unless triggered in response to specific growing conditions as well as random mutations. Burbank’s view of variation in nature was based on close, persistent observation and his own subjective intuition, based on decades of experience.

The Carnegie Institute of Technology tried to bridge this gap between science and Burbank’s art of creating new plant varieties by giving him a generous grant of $10,000 per year on the condition that a botanical scientist would trail Burbank in the field and turn his art into a data-driven algorithm capable of replicating Burbank’s accomplishments.

The scientist assigned to that task was immediately frustrated by the haphazard jumble of Burbank’s sketchy record-keeping. Watching Burbank in the field was equally frustrating. Burbank couldn’t translate the choices he made into words because his judgment was intuitive. Finally, The Carnegie Institute lost patience with the project and terminated the grant.

Henry Ford and Thomas Edison came to visit Luther Burbank in 1915 after their visit to the Panama-Pacific Exposition in San Francisco. It was a meeting of the minds and kindred spirits. They were businessmen whose commercial success was based on tireless effort, continuous incremental improvement, and practical invention. They were Burbank’s tribe, who became fast friends for the rest of their lives.

Thomas Edison, Luther Burbank, Henry Ford. Santa Rosa, 1915

Burbank Defends Evolution

It took Charles Darwin nearly 20 years to publish his treatise on evolution, On the Origin of Species, partly because he knew it challenged some of the basic premises of organized religion to which his family was committed. The evidence that life on Earth evolved over millions of years directly contradicted the religious belief that God created all life on Earth, as it presently exists, only 6,000 years ago. Evolution is also inconsistent with the religious belief that humans are chosen by God to rule the world and that all other creatures are subservient to our command.

In fact, pushback to the concept of evolution was minimal in the 19^th century after Origin of Species was published in 1859. Full-throated opposition to evolution emerged in the 20^th century and is epitomized by the Scopes trial that occurred in 1925, just one year before Burbank’s death.

The Scopes trial occurred because the state of Tennessee banned the teaching of evolution in public schools. The ACLU persuaded a high school teacher, John Scopes, to test the law. Two of the greatest orators of the time, stepped forward to try this important case. Clarence Darrow, defended Scopes for the ACLU. William Jennings Bryon was the prosecutor for the state of Tennessee.

Both Darrow and Bryon asked Luther Burbank to appear as a witness at the trial, which was an indication that the public was confused about Burbank’s close relationship with the natural world. Much to the disappointment of William Jennings Bryon, who considered himself a personal friend of Burbank’s, Burbank came down unequivocally in support of the teaching evolution.

In a letter submitted as evidence in the trial, Burbank said, “Those who would legislate against the teaching of evolution should also legislate against the teaching of gravity, electricity, and the unreasonable velocity of light, and also introduce a clause to prevent the use of the telescope, the microscope…or any other instrument of precision which in the future may be invented…for the discovery of truth.” (1)

Despite Burbank’s effort, Scopes was found guilty and the ban on teaching evolution in Tennessee remained in effect until 1967. In 2024, the Gallup Poll reported that only 24% of Americans believe in evolution unguided by God, a percentage that has increased steadily since 2000. The dominate view—at 37%–is that humans were created by God in their present form:

In a series of interviews with the news media, Burbank expressed his doubts about the afterlife and his admiration and kinship with Christ as a man rather than a deity: “[Christ] was an infidel of his day because he railed against the prevailing religions and his government. I am a lover of Christ as a man, and his work and all things that help humanity, but nevertheless just as he was an infidel then, I am an infidel today.” (1)

Burbank’s Last Success

By any measure, Burbank must be considered a success. Although he managed to make a living, he was not wealthy because his plant inventions could not be patented. Without patent protection, profits were realized by seed merchants, nurseries, and agricultural operations.

Burbank made many appeals to the US Patent Office for patent protection. His appeals sounded desperate and angry about the unfairness that often threatened him with economic ruin. His death in 1926 at the age of 77 sparked another campaign by other plant breeders to extend patent law to the development of new plant varieties.

The effort to extend patent law to plants was boosted by the Great Depression, which began in 1929. Farmers are always in debt as they must borrow money to plant their next crop. When commodity prices collapsed during the depression, many farmers lost their farms.

The proposal to extend patent law to plant “inventions” was perceived by many politicians as a way to help farmers, although the logic of that connection is questionable because patented seeds are likely to be more expensive. Despite that concern, the Plant Patent Act was passed with little opposition in 1930. There were many limitations on the first patent law, many of which have since been revised.

Sixteen of Burbank’s creations received patents, a small fraction of the plants being developed at the time of Burbank’s death.

We can still learn from Luther Burbank

I encourage readers to visit Luther Burbank’s home and garden in Santa Rosa, which is now a free public park, and the museum that is open during summer months. You will find many informational signs throughout the garden about Burbank’s inventions. You won’t find any hint of a nativist bias in the signs. This sign about creating a garden for butterflies makes it clear that these lovely creatures have no preference for native plants:

Luther Burbank Garden, Santa Rosa, CA. 2025

(1) The Garden of Invention: Luther Burbank and the Business of Breeding Plants, Jane S. Smith, Penguin Books, 2009

The Post-Native World

Today, I’m publishing an excerpt of “The Post-Native World,” which was originally published by Ground Up, the Landscape Architecture and Environmental Planning Journal of the University of California, Berkeley.

The author of the article, Mark Wessels, received his Master in Landscape Architecture at UC Berkeley. He is a licensed landscape architect and certified arborist. He is a Senior Associate with PGAdesign in Oakland, California.

Mark sent the following excerpt of his article in Ground Up to the members of the Oakland Urban Forest Forum, of which I am a member. Mark’s article reflects my own belief that resilience of urban landscapes in a changing climate requires diversity, redundancy, and flexibility that can only be achieved with both native and introduced plants.

Conservation Sense and Nonsense

Native ranges of trees in California’s urban forests. Source: Matt Ritter, Professor of Forestry, Cal Poly, SLO

CITIES AS HARBINGERS OF A POST-NATIVE WORLD
Native plant enthusiasts argue that native plants have evolved for thousands of years to be optimized for their environments. This is based on the assumption that environmental factors like soil type, climate, and ecological communities change very slowly, at the rate of geologic time. The fitness advantage of native plants depends on a relatively static, unchanging environment.

Yet cities are anything but static. Urban soils are altered by construction, compaction, and contamination. Impermeable surfaces and water infrastructure change urban hydrology. Urban heat island effect and microclimates affect soil and air temperatures. Cities are defined more by how urban they are than by where on the planet they are located. A tree adapted to urban environments, for example, is much more likely to flourish in San Francisco than one adapted to coastal dunes. In short, cities are post-native; they no longer reflect the environmental conditions for which native plants evolved. They are something new.

Cities are not the only places irreversibly altered by human activity. Human influence ripples out through resource extraction, food and energy production, and global climate change. Cities are already several degrees warmer than their historical temperatures, and many native plants cannot survive in this altered environment. Climate models predict several degrees of warming globally in the next 50 years. Native plants face challenges in urban settings today, and 50 years from now they will face challenges everywhere. As the effects of climate change spread beyond cities, landscape architects will need to move beyond geographic provenance to find plants adapted to a post-native world.

DIVERSITY OF APPROACHES VS. SINGLE STRATEGY
Globalization has irreversibly altered the planet, but it may also hold the key to surviving climate change. Designers today have unprecedented access to plants from around the world. For millennia, plants have been continuously evolving new, more efficient ways to survive in an astounding array of environmental conditions. In a post-native world, we will have to reconsider the idea that each plant is custom-evolved for a particular place on the earth, and instead think of global biodiversity as a library of adaptation. This library holds the key to successful planting in urban areas today, and hope for an uncertain future.

What I’m suggesting is that we embrace global biodiversity while we still have it; that our cities become hotbeds of plant species richness, hybridization, and cross-pollination; that we start a thousand divergent experiments, in small and controlled ways; and that we embrace this moment of globalization to produce an unprecedented explosion of diversity with which we can begin to replant and repopulate this irreversibly altered planet.

The resilience of natural systems lies in diversity, redundancy, and flexibility. Individual plants, and even individual species, die off frequently, but there is always another individual or another species to fill the void. Relying on a small set of native trees without embracing the redundancy and diversity of natural systems is a recipe for disaster.

Mark Wessels

A Walk in the Woods

We celebrated July 4^th with a walk in the woods. Huckleberry Botanic Regional Preserve in Oakland is a true remnant of native vegetation that is unique among the collection of 73 parks of the East Bay Regional Park District. The trail guide describes the conditions that created this ecosystem and enabled its survival while other native ecosystems have not survived:

Huckleberry is “a relic plant association found only in certain areas in California where ideal soil and climatic conditions exist. The vegetation association finds its roots in past climates and geologic history. The plants originated in the distant past along the southern coast of California when the climate was more moist and tempered by the cool coastal fog. Today, similar vegetation is found on the islands off the Santa Barbara coast and in isolated pockets on the mainland coast from Point Conception to Montara Mountain south of San Francisco.”

A view from Huckleberry Botanic Preserve of hills to the east. Source: East Bay Regional Park District

The preserve was created partly to protect an endangered species of manzanita, specifically pallid manzanita. There are 107 species and sub-species of manzanita, of which 95 are native to California. The ranges of most of these species are extremely small because manzanita hybridizes freely and therefore adaptive radiation has resulted in a multitude of species, sub-species, and varieties that are adapted to micro-climates. Many of these species are locally rare and 10 species of manzanita have been designated as endangered, two of which are limited to the San Francisco peninsula: Raven’s manzanita and Franciscan manzanita.

Manzanita is vulnerable to extinction partly because its ranges are small and partly because it is an “obligate seeder,” which means it can only be propagated in the wild from seed. The seed of manzanita is germinated by fire. However, the exact relationship between fire and germination is not known. Many complex experiments have been conducted on the few viable seeds produced by Raven’s manzanita, which was designated as endangered in 1979. Various combinations of fire, heat, cold, smoke, liquid smoke, etc., were tried and failed to determine exactly what triggers germination of manzanita seeds. The suppression of fire in the past 150 years has contributed to the decline of small manzanita populations in California.

Some endangered species of manzanita are available in commercial nurseries because they can be easily cloned, which means they are genetically identical. These commercially available manzanita species remain technically endangered because the criteria for endangered status requires that they be grown from seed in the wild to be eligible for removal of endangered status.

Pallid manzanita in the Huckleberry Botanic Reserve are not doing well:

And some pallid manzanita is dead:

The sign explains that as pallid manzanita dies, it creates space in the understory for chinquapin and it predicts that more competitive huckleberry will eventually “overgrow and kill” chinquapin. The sign describes this process as natural succession. It doesn’t accuse huckleberry of being invasive. If huckleberry were non-native, it probably would be considered “invasive.”

Chinquapin has a distinctive nut, which is encased in a bristly shell. My hiking companion said he and his brothers used to eat the tasty nut when camping in Mineral King in Sequoia National Park. The bristly shell doesn’t make it easy to access the nut, but birds and wildlife find a way:

Huckleberry is appropriately the namesake of this botanic reserve. In some portions of the narrow trail huckleberry creates tall, dense hedges on either side of the trail:

Because the Huckleberry Botanic Preserve is a relic of native vegetation that has been undisturbed by fire and development for hundreds of years, it is an excellent place to see huge native trees compared to much younger and therefore smaller native trees in other public parks in the San Francisco Bay Area.

Mature bay laurel trees in Huckleberry Preserve are an opportunity to witness the competitive strategy of this tree species. When it achieves some height as it grows, its branches fall over and often put down new roots that grow new vertical trunks. This prostrate posture of bay laurels gives them a competitive advantage over other plants in the understory. Mature bay laurels occupy huge expanses of space around them that create shade and make it difficult for other plants to become established in the shade. The prostrate posture of bay laurels also makes it more flammable because the fire ladder to its canopy extends to the ground. Crush a bay laurel leaf in your hands to smell its aromatic oils that also contribute to the flammability of bay laurels:

This madrone tree in Huckleberry Reserve is the biggest I’ve ever seen:

In early July some woody and herbaceous shrubs were still blooming. In this case, sticky monkey flower in the foreground and pink flowering current in the background:

Huckleberry Botanic Reserve is a unique gem in East Bay Regional Park District. I hope you will have an opportunity to see it and that you will appreciate it as much as I do.

Native Trees and Their Close Relatives

Over 10 years ago, Mark Speyer wrote one of the first guest articles for Conservation Sense and Nonsense about mulberry trees, one native to North America and the other introduced by American colonists because it is the host plant of silk worms. That article was a hit! It has been viewed by over 8,600 readers. It is still entirely relevant to the mission of Conservation Sense and Nonsense and I recommend it to you. You will find it HERE.

I am grateful to Mark for giving me this opportunity to publish his guest article about willows, some native to North America and one introduced. As in the case of introduced mulberry trees, some willow species are native to China.

Much of China and North America have been in the same latitude since the evolution of angiosperms. As a result of climate similarity and geographic proximity, many of our plant species considered native in Eastern North America are also native to 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.).

They are different species from their Chinese counterparts because they have been separated long enough to change as a result of genetic drift and in response to a new environment, but are in the same genus and plant lineage and therefore chemically similar. These plant species made their way from China to North America by natural means, such as being carried by birds, animals, wind and ocean currents.

In contrast, Chinese species of mulberries and willows were intentionally introduced to North America. Mulberries were brought with the hope of making silk and weeping willows were brought to grace our gardens with their beauty. Some say they don’t belong here because they were brought by humans. Others say that is a meaningless distinction. Whether brought by birds or brought by humans it is a distinction without a difference because humans are as much a part of nature as birds.

Mark Speyer is the Executive Director of the Stillman Nature Center in Barrington, Illinois. He can be reached at: stillmangho@gmail.com.

WILLOWS IN THE WIND ©

I’ve been writing nature columns for many years and I hope to write them for years to come but sometimes, the writing doesn’t come easy. The other evening, was one of those difficult times.

As I reached for a bottle of aspirin to alleviate a headache, it hit me– willows.

You see the scientific name for the willow genus is Salix and the main ingredient in the original 1899 aspirin was salicin, an extract from willows.

I’m not going to attempt to sort through the dozens of North American willows and their confusing hybrids. I don’t have enough aspirin for that. I’d like to concentrate on two of the willow trees, weeping and black, as well as a few of the willow shrubs.

Weeping Willow (Salix babylonica)

Unlike black willows, weeping willows aren’t native to this continent. The scientific name is somewhat misleading. This species originates from northern China, not the Middle East. Examples of Salix babylonica can be found growing along the famed Silk Road trade routes between China and Europe. The weeping willow arrived in Europe around 1730. It traveled to N. America courtesy of colonization. The weeping willow also landed on the W. Coast via Japan.

*Weeping willow along a highway in suburban Chicago.* Photo by Susan Allman

Its graceful, long, slender, drooping branches makes the weeping willow an easy tree to identify. This pendulous growth habit earned this willow its common name. Not surprisingly, the tree is a popular choice for landscapers and gardeners. It is also the choice of pollinators such as specialized bees and butterflies. If planted in full sun, this rapid grower can reach a height of sixty feet.

In addition, weeping willow tolerates soils that are somewhat acidic to alkaline. Finally, it thrives in low areas and wet spots where other trees might drown. Decades ago, my father and I planted two weeping willows in a sunny wet pocket on the property. They grew fast and sucked up the water, just as we had hoped. You see they are designed to do just that.

Like all willows, weeping willows are easily started from a sprig. Just stick it in some water and watch the rootlets sprout. When you think of where willows grow– along rivers, streams and other places prone to flooding– this asexual method of reproduction is a handy adaptation.

If a flood washes away a bank and the willow that grew on it, odds are one of its branches will end up on a spit of mud or in a shallow pool downstream. With the passage of time, that branch will take root and a new willow will be on its way.

In this country, most weeping willows are male clones and thus produce no fruit. Since reproduction for a willow is as easy as dropping a twig in running water, these clones can be found growing where no human planted them.

Black Willow (Salix nigra)

Rather plant a native species? Then, this next tree is for you. While some may appreciate the graceful form of a weeping willow, give me the craggy old coot of the willow family, the black willow. One of the world’s largest willows, it varies in appearance with where it is growing. Along an eastern seaboard stream, it is a tree reaching a height of forty to fifty feet. In the southern reaches of the Mississippi River’s floodplain, a black willow can reach a height of 100 feet in a mere forty years.

*Two black willows near the Fox River in northern Illinois.* Photo by Susan Allman.

Here at the Stillman Nature Center we had a couple of sprawling specimens of our own. They had large forks, beginning low down, each fork leaned outward giving the tree a “slouching picturesqueness” as Donald Culross Peattie wrote.

Black willow has many alternate names such as American, brittle, and, a favorite of mine, scythe-leaved willow. I like it because the botanical term for willows’ long narrow leaves is lanceolate or lance-shaped. Lances and scythes belong together, don’t you think?

Brittle is another appropriate name. Its slender reddish-brown twigs are flexible at first. As they age, the twigs become darker and brittle at the base. Anyone who has sat at a picnic table or parked a boat under a large black willow, will soon find these items decorated with fallen black willow twigs.

Unfortunately, willows are short-lived, rarely living past 85. But, as I’ve watched our willows here at Stillman, I have some questions about that figure.

For example, one of our largest black willows came down in a heap some years ago. After the chainsaws were done, all that was left was the short, thick trunk and a few feet of each main branch that the trunk divided into.

Was the tree dead? Not quite. As the years passed, flexible yellow branches grew from one of the large “dead” arms. Nutrients and water were obviously flowing from the roots and through the tissues of this “goner.”

So when is a tree dead? A newspaper story provided an answer that fits our willows. The article was about the fate of a sequoia. At the time, the tree was at least 2,500 years old, “We don’t know if it’s dying or not,” said an interpretive ranger at Sequoia National Park, “One branch with green leaves connected by live tissue to one root is all that’s needed for a tree to be considered alive.”

Of course, the Sequoia’s trunk remained standing unlike our willow’s old trunk that was down and decomposing.

Shrubby Willows

Most willows don’t have large trunks since they exist as shrubs. This is not the place to sort through them all. A partial list would include goat, Bebb, narrowleaf, sandbar, and, the florists’ favorite, pussy willow.

*Pussy willow in spring*. Photo by Lara Sviatko.

The native pussy willow (Salix discolor) is a boreal species that can occasionally be found growing in northeastern Illinois. As you might have guessed, it inhabits wet areas such as floodplain forests, marshes, and shrubby swamps.

Because willow thickets are within reach, deer, elk and domestic livestock will feed on willow leaves and twigs. This brings me back to where I started. Peoples from N. America to ancient Greece made teas and other medicines from willow bark to treat joint pain and other ailments. So, are animals eating willows just to fill their stomachs or to ease their aches and pains as well? The next time I run into a talkative deer, I’ll ask.

Mark Speyer, Summer 2025

Ideological vs. Scientific Definition of Biodiversity

Although there is broad agreement that maintaining biodiversity is necessary to achieve conservation goals, there is disagreement about the definition of biodiversity. Some native plant advocates believe biodiversity includes only native plants (example HERE). Most scientists include both native and non-native plants in measurements of biodiversity. I asked Claude.ai about this debate.

Data source: Living Planet Report (2022). World Wildlife Fund (WWF) and Zoological Society of London.

I publish Claude.ai’s answer to my question as a guest post today. Claude.ai now has immediate access to internet sources, which makes answers to such queries more current and comprehensive. Claude.ai has also provided links to the sources of the information provided.

Conservation Sense and Nonsense

The ongoing debate about measuring biodiversity

Claude.ai: Based on the available data, there’s a significant and ongoing scientific debate about whether biodiversity measurements should include non-native species. Here’s what the evidence shows:

Scientific Practice vs. Conservation Ideology

The Reality of Scientific Measurement:

In actual scientific practice, major biodiversity databases and assessment tools often do include non-native species. Research shows that “data used for biodiversity assessments and conservation planning should, initially, include all species” and that “including non-native species into the Biodiversity Intactness Index can lead to a 10% improvement in the index score” NihNCBI.

The Global Biodiversity Information Facility (GBIF), one of the world’s largest biodiversity databases, explicitly includes non-native species, stating that “information is the single most important variable necessary to support research, monitoring and management of alien and invasive species” GBIF.

Standard Biodiversity Definitions

Official Definitions Are Inclusive:

Scientific definitions of biodiversity do not exclude non-native species. As Britannica notes, biodiversity is defined as “the variety of life found in a place on Earth” and biologists most often define it as “the totality of genes, species and ecosystems of a region.” The most common measure is “species richness” – simply “the count of species in an area” BritannicaWikipedia.

The Convention on Biological Diversity (CBD) “emphasises the role of biodiversity in delivering benefits essential for all people and, as a result, seeks to safeguard all life-forms.” Research argues that “the absence of non-native species from biodiversity indices stands in contradiction to the CBD and Sustainable Development Goals {SDGs}” Do non-native species contribute to biodiversity? – PMC.

Scientific Consensus vs. Conservation Advocacy

The Evidence Shows Division:

A 2019 survey of 314 researchers found that “overall, a majority of respondents in our sample supported statements that the species-component of biodiversity should include all species (55%) or some types of non-native species” Diverse views among scientists on non-native species. This indicates significant scientific support for including non-native species in biodiversity measures.

However, there’s strong opposition from some conservation biologists. The IUCN argues it’s “misguided and potentially disastrous to consider native and non-native species as equal from the standpoint of both ecosystem services and conservation goals” Do non-native species count as biodiversity? – Crossroads blog | IUCN.

Practical Measurement Reality

How Biodiversity Is Actually Measured:

Standard biodiversity indices like Shannon diversity, Simpson diversity, and species richness simply count all species present. These indices “do not discriminate between species and communities with very different functionalities” and follow “a leading principle that ‘all species and individuals are considered equal'” 22.2: Diversity Indices – Biology LibreTexts +2.

Research shows that “the introduction of a non-native species increases the local species count (by one!)” and “because of the spread of non-natives, a general trend worldwide is that often local biodiversity (measured by a species count) is increasing even while overall global species numbers are in decline” Understanding and Defending the Preference for Native Species | SpringerLink.

Key Contextual Points

The Complexity of the Issue:

Scientists recognize this is “a broader social debate about what type of nature we need to ensure a good life for present and future generations.” The discussion involves “not only a scientific debate about the contributions of these species to society but also a broader social debate” Do non-native species contribute to biodiversity? – PMC.

Even in conservation contexts, scientists often use the term “alien species” rather than “invasive species” because “‘invasive’ suggests invasion potential and negative ecological effects, which is not necessarily the case for all alien species” Species data for understanding biodiversity dynamics: The what, where and when of species occurrence data collection – Petersen – 2021 – Ecological Solutions and Evidence – Wiley Online Library.

Conclusion

The available data clearly shows that:

Standard scientific practice: Most biodiversity measurements and major databases include all species regardless of origin
Official definitions: Neither CBD nor standard scientific definitions of biodiversity exclude non-native species
Research consensus: A majority of surveyed scientists support including non-native species in biodiversity measures
Conservation advocacy: Some conservation biologists argue for native-only measures, but this appears to be a minority position in the broader scientific community

The claim that “biodiversity only includes native plants” appears to be an ideological position held by some in the invasion biology community rather than the standard scientific practice for measuring biodiversity.

California’s Wildlife Conservation Board needs to hear from you!

Although I have stopped writing original articles for Conservation Sense and Nonsense, I am still actively engaged in local environmental issues. When there are opportunities to influence public policies that affect the environment, I often participate.

Today, I am sharing my public comment on the update of the strategic plan of California’s Wildlife Conservation Board (WCB) in the hope that it might inspire you to write your own comment on the draft plan, which is available HERE. The deadline for submitting comments is May 16, 2025. Comments may be sent to this email address: wcb@wildlife.ca.gov

The mission of the Wildlife Conservation Board is to “protect, restore and enhance California’s spectacular natural resources for wildlife and for the public’s use and enjoyment…” In service of that mission, WCB awards grants of millions of dollars every year for “restoration” projects. According to WCB’s annual report for 2024, WCB awarded $93.5 million for “habitat restoration and enhancement of 5,000 acres” of land in California in 2024.

Over the life of the updated strategic plan, from 2025 to 2030, the Wildlife Conservation Board will distribute grants of $1.02 billion ($204 million per year) from funding made available by Proposition 4, the $10 billion “California Climate Bond,” which was approved by voters in November 2024. Because most federal funding of climate and ecological restoration has been cancelled by the Trump administration (and being litigated, as we speak), the “California Climate Bond” will be one of the few sources of funding for these projects.

This is my public comment on the strategic plan update for California’s Wildlife Conservation Board:

WCB Strategic Plan Update

Thank you for this opportunity to comment on the draft of WCB’s update of its strategic plan (SP). I am writing to suggest that WCB consider the addition of a few over-arching principles that would apply to all of its programs. These principles would enhance the plan’s stated goals of climate resilience and biodiversity protection by ensuring projects are evaluated based on their actual ecological outcomes rather than adherence to historical conditions.

All projects funded by WCB should be more constructive than they are destructive. For example, a project that proposes to destroy more habitat than it creates should be less competitive than a project that will create more habitat than it destroys. A project that reduces carbon storage by destroying vegetation does not “reduce and remove carbon pollution,” as the SP proposes.
Projects that do not propose to use pesticides to destroy habitat should be more competitive than those that use pesticides because pesticides damage the soil and are harmful to wildlife and human life. The success of projects is jeopardized by pesticide use.
Projects that apply for additional funding for a continuing project must address the fundamental question of the viability of the project. In other words, if a project has been funded for 20 years, WCB should consider if the goals of the project are still realistic in a rapidly changing climate and environment (e.g., Invasive Spartina Project).
Projects should be consistent with the basic principles of science, such as:
- The scientific definition of biodiversity includes both native and non-native plants and animals.
- Hybridization is one of the tools of evolution that enables adaptation and speciation in response to changes in the climate and the environment.
- The flammability of vegetation varies, but the variation is unrelated to the nativity of the plant. Native plants are not inherently less flammable than non-native species.
- The native ranges of California’s native plants have changed in response to the changing climate and they must continue to change if they are to survive.
- Our changing environment dictates that historical landscapes cannot be replicated. Humans cannot stop evolution, nor should we try.

I recommend that the WCB consider incorporating these principles into its project evaluation criteria to ensure that funded projects align with current ecological knowledge and maximize benefits for California’s biodiversity in a changing climate. Incorporating these principles into the SP would strengthen the plan’s objectives related to climate resilience (C2.1, C2.2), biodiversity protection (B1.1, B2.1), and program evaluation (D2.1, D2.2).

In support of these principles, I offer the following scientific studies for your consideration:

On pesticides damaging soil and harming wildlife and human health

Wan et al. (2025): Pesticides affect a diverse range of non-target species and may be linked to global biodiversity loss. This study presents a synthesis of pesticide (insecticide, herbicide and fungicide) impacts on multiple non-target organisms across trophic levels based on 20,212 effect sizes from 1,705 studies. For non-target plants, animals (invertebrate and vertebrates) and microorganisms (bacteria and fungi), we show negative responses of the growth, reproduction, behavior and other physiological biomarkers within terrestrial and aquatic systems. Negative effects were more pronounced in temperate than tropical regions but were consistent between aquatic and terrestrial environments. Results question the sustainability of current pesticide use and support the need for enhanced risk assessments to reduce risks to biodiversity and ecosystems.
Klein et al. (2024): New Roundup formulations are 45 times more toxic to human health,on average, following long-term, chronic exposures. The study identified eight Roundup products in which Bayer has replaced glyphosate with combinations of four different chemicals: diquat dibromide, fluazifop-P-butyl, triclopyr, and imazapic. All four chemicals pose greater risk of long-term and/or reproductive health problems than glyphosate, based on the EPA’s evaluation of safety studies. Diquat dibromide and imazapic are banned in the EU. Diquat dibromide – present in all the new formulations – is 200 times more toxic than glyphosate in terms of chronic exposure and is classified as a highly hazardous pesticide. New Roundup formulations pose significantly more harm to the environment. The chemicals replacing glyphosate in Roundup are significantly more likely to harm bees, birds, fish, earthworms, and aquatic organisms, on average. They are also significantly more persistent in the environment and more likely to leach down into groundwater, increasing the risk of contaminating waterways and drinking water.

On biodiversity including non-native species:

Schlaepfer et al. (2011): This pivotal paper challenges the automatic negative classification of non-native species by documenting their potential conservation benefits. The authors present evidence that some non-native species provide ecosystem services, habitat, and resources for native species, particularly in human-modified landscapes where native species may struggle. They advocate for conservation approaches that evaluate species based on their ecological functions rather than origin alone.
Mascaro et al. (2012): This study examines novel forests in Puerto Rico dominated by the non-native Castilla elastica tree. The research demonstrates that these novel ecosystems maintain key ecological processes such as productivity, nutrient cycling, and carbon storage at levels comparable to native forests. The findings suggest that novel ecosystems composed of non-native species can maintain essential ecosystem functions even after native tree species decline.

On hybridization as an adaptive mechanism:

Hamilton & Miller (2016): This paper reframes hybridization as a potential adaptive resource rather than a conservation threat. The authors present evidence that hybridization can introduce genetic variation that helps species adapt to changing environmental conditions, particularly relevant in the context of climate change. They suggest that conservation strategies should sometimes protect hybrid zones as sources of evolutionary potential rather than trying to eliminate them.
Fitzpatrick et al. (2015): This study examines how hybridization challenges traditional conservation approaches based on species preservation. The authors argue that hybridization is a natural evolutionary process that can generate biodiversity and adaptive potential. They present a framework for evaluating conservation value that considers genetic, ecological, and evolutionary factors rather than focusing solely on taxonomic “purity.”

On flammability unrelated to nativity:

Zouhar et al. (2008): This comprehensive technical report examines relationships between non-native plants and fire regimes. While acknowledging that some non-native plants can alter fire behavior, the report emphasizes that flammability is determined by plant structure, chemistry, and arrangement rather than nativity status. It provides detailed case studies showing both native and non-native plants can increase or decrease fire risk depending on specific traits.
Pausas & Keeley (2014): This study documents abrupt changes in fire regimes that occur independently of climate changes. The authors demonstrate that shifts in vegetation structure and fuel characteristics—which can be caused by both native and non-native species—are often more important determinants of fire behavior than plant origin. The research challenges simplistic assumptions about the relationship between native plants and fire resilience.

On changing native ranges:

Pecl et al. (2017): This influential paper documents how species are naturally shifting their ranges in response to climate change. The authors present global evidence of species redistributions across latitudinal, longitudinal, and elevational gradients. The study emphasizes that these range shifts are necessary adaptations to changing conditions and argues that conservation strategies need to accommodate these natural movements rather than trying to maintain historical distributions.
Bonebrake et al. (2018): This paper synthesizes research on climate-driven species redistribution and its implications for conservation. The authors highlight how traditional conservation approaches focused on preserving species in their historical ranges are becoming increasingly unviable under climate change. They advocate for more dynamic approaches that facilitate range shifts and species movements as adaptive responses to changing conditions.

On novel ecosystems and historical conditions:

Hobbs et al. (2014): This seminal paper introduces a framework for categorizing landscapes as historical, hybrid, or novel ecosystems. The authors argue that many ecosystems have been irreversibly altered by human influences and climate change, making restoration to historical conditions impossible in many cases. They advocate for pragmatic management approaches that focus on ecosystem functions and services rather than historical composition.
Stralberg et al. (2020): This study examines climate refugia in North America’s boreal forests. The research demonstrates that even supposedly pristine ecosystems will undergo significant changes due to climate change, with some areas serving as temporary refugia. The authors emphasize that conservation strategies need to recognize the transient nature of these refugia and plan for ongoing ecological transitions rather than static preservation.

In Conclusion

As you know, the mission of the Wildlife Conservation Board is to “protect, restore and enhance California’s spectacular natural resources for wildlife and for the public’s use and enjoyment…” In addition, the Wildlife Conservation Board “envisions a future in which California’s wildlife, biodiversity and wild places are effectively conserved for the benefit of present and future generations.” My suggestions for improvements in the draft strategic plan are consistent with the mission of the WCB.

There was a time when academic scientists believed that the goal of conservation was to replicate historical landscapes by destroying plants and animals that were not here prior to European settlement. Although many of these plants and animals found their way to California by natural means, without human assistance, they were perceived as “alien invaders” that didn’t belong here. The assumption was that ecosystems can achieve an equilibrium state that represents an ideal that can be sustained by preventing change. Science has long ago abandoned that notion in favor of acknowledging that nature is constantly changing in response to constant change in the environment.

The belief that destroying such “alien invaders” would restore the landscape persisted for decades. In many cases, no replanting was done after introduced plants were destroyed. After poisoning our public land for decades, it has become clear to those who are not ideologically committed to historical landscapes that the original goal is not attainable because the plants and animals that survive are those that are best adapted to current environmental conditions, particularly the rapidly changing climate that is expected to continue to change. In most cases, the newcomers are performing the same ecological functions of their predecessors and the harm that was presumed is usually balanced by benefits of their existence.

Most academic scientists acknowledge this reality, but cultural lag has left the public behind as science has moved on. Non-profit organizations that survive by the grace of their donors, have contributed to the pressure on public land managers such as the Wildlife Conservation Board. Academic scientists are unwilling to participate in such grass-roots policy politics and their publications are often incomprehensible and inaccessible to the public and public land managers, leaving public land managers at the mercy of those with the least amount of information and the most amount of passionate belief.

The Wildlife Conservation Board has a responsibility to the public to inform itself of the consequences of conservation practices that are damaging the environment and are no longer realistic. I respectfully ask that the WCB read the scientific studies I have provided and take them into consideration as it distributes over a billion taxpayer dollars made available by the passage of Proposition 4.

Conservation Sense and Nonsense
May 1, 2025

References for cited studies

On pesticides harming soil and damaging wildlife and human health:

Wan, NF., Fu, L., Dainese, M. et al. Pesticides have negative effects on non-target organisms. Nat Commun 16, 1360 (2025). https://doi.org/10.1038/s41467-025-56732-xK
Klein, K, Starman, S, “New RoundUp, New Risks: Bayer’s new weedkiller more toxic than ever,” Friends of the Earth, October 2024 https://foe.org/wp-content/uploads/2024/10/Roundup_Report_2025_final.pdf

On biodiversity including non-native species:

Schlaepfer, M.A., Sax, D.F., & Olden, J.D. (2011). The potential conservation value of non-native species. Conservation Biology, 25(3), 428-437.
Mascaro, J., Hughes, R.F., & Schnitzer, S.A. (2012). Novel forests maintain ecosystem processes after the decline of native tree species. Ecological Monographs, 82(2), 221-228.

 On hybridization as an adaptive mechanism:

Hamilton, J.A., & Miller, J.M. (2016). Adaptive introgression as a resource for management and genetic conservation in a changing climate. Conservation Biology, 30(1), 33-41.
Fitzpatrick, B.M., Ryan, M.E., Johnson, J.R., Corush, J., & Carter, E.T. (2015). Hybridization and the species problem in conservation. Current Zoology, 61(1), 206-216.

 On flammability unrelated to nativity:

Zouhar, K., Smith, J.K., Sutherland, S., & Brooks, M.L. (2008). Wildland fire in ecosystems: fire and nonnative invasive plants. General Technical Report RMRS-GTR-42-vol. 6. USDA Forest Service.
Pausas, J.G., & Keeley, J.E. (2014). Abrupt climate-independent fire regime changes. Ecosystems, 17(6), 1109-1120.

 On changing native ranges:

Pecl, G.T., et al. (2017). Biodiversity redistribution under climate change: Impacts on ecosystems and human well-being. Science, 355(6332).
Bonebrake, T.C., et al. (2018). Managing consequences of climate-driven species redistribution requires integration of ecology, conservation and social science. Biological Reviews, 93(1), 284-305.

 On novel ecosystems and the impossibility of recreating historical conditions:

Hobbs, R.J., et al. (2014). Managing the whole landscape: historical, hybrid, and novel ecosystems. Frontiers in Ecology and the Environment, 12(10), 557-564.
Stralberg, D., et al. (2020). Climate-change refugia in boreal North America: what, where, and for how long? Frontiers in Ecology and the Environment, 18(5), 261-270.

Deforestation in San Francisco

I am publishing an article today that was published by the San Francisco Forest Alliance, with permission. Many thanks to SFFA for reporting about the continuing assault on San Francisco’s urban forest. You can express your opinion about these tree removals by calling 800-801-2661 Ext 4.

Conservation Sense and Nonsense

Deforestation on Clarendon Avenue

Posted on March 31, 2025 by SF Forest Alliance

There’s a lot of deforestation on both sides of Clarendon Avenue, above the Laguna Honda, and on the slope below Laguna Honda Hospital. This time it’s courtesy of SFPUC – San Francisco Public Utilities Commission (which our followers would recall is managed in the same way as SFRPD – San Francisco Recreation and Parks Department’s “Natural Resources Division.”)

Indeed, Lisa Wayne, who for many years spearheaded the SFRPD effort, moved to SFPUC in 2021.

Note: All pictures in this post copyright Anastasia Glikshtern

SAN FRANCISCO FOREST ALLIANCE WROTE TO SFPUC

San Francisco Forest Alliance is following up with SFPUC for evidence that the trees have indeed been evaluated as hazardous. We also pointed out that the bird nesting season has started on February 1 (it runs through August 31, 2025). It appears that the work continued through mid-February.

This forest added much to the beauty, privacy, and air quality of the neighborhoods around it. It’s historic: This charming article by Rex Bell described it in 2011 and compared it to the same places in 1896, where it was described as “A Genuine Old-Fashioned Country Road Within the Limits of the City of San Francisco.”

RISKS AND ISSUES

Quite aside from the historic beauty of this urban forest, and the many benefits of urban trees , there are issues of risk. One is slope stability – and we wonder if SFPUC actually assessed the risk of that steep slope above Clarendon Avenue being destabilized by this deforestation. The second is flammability. This is an area of the city that gets summer fog, and the fog moisture harvested by these trees kept the area below damp and cool. Now it will be dry and covered in fine fuels; we can only hope we do not face a hot dry summer any time soon.

Finally, since SFPUC uses herbicides as freely as does SFRPD’s Natural Resources Division, we can expect a lot more pesticides flowing into the groundwater.

San Francisco seems to have moved forward quickly with its war on trees. They have been felled everywhere where the urban forest exists in the city: Mount Sutro, McLaren Park, and now Clarendon Avenue. Ironically, they call it “Restoration.”