Blue Ridge Naturalist: “Invasive” Plants Invaluable to Degraded Environment

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© Marlene A. Condon

A large stand of Garlic Mustard (Alliaria petiolata), which is considered an invasive plant species, grows underneath a native Eastern Redcedar (Juniperous virginiana). Both kinds of plants, located along a gas pipeline, tell the informed observer that the soil in this location is nutrient-poor and compacted. (Photo credit: Marlene A. Condon)
A large stand of Garlic Mustard (Alliaria petiolata), which is considered an invasive plant species, grows underneath a native Eastern Redcedar (Juniperous virginiana). Both kinds of plants, located along a gas pipeline, tell the informed observer that the soil in this location is nutrient-poor and compacted. (Photo credit: Marlene A. Condon)

As April transitioned into May, I was surprised to see a fair number of daffodils still blooming along the roadway where I walk. It was a sign of how chilly the spring had been.

Another sign I picked up on that morning was the “invasiveness” of daffodils.  There were many, many daffodil clumps spanning the miles of my exercise route.  They exemplified the ability of some plants brought to this country to reproduce successfully enough to move well beyond the garden gate and out into the larger world.

Such so-called invasive plants have constituted an issue for some time now, although I don’t recall ever hearing anyone complain about the invasive nature of daffodils.  Perhaps if a plant is lovely, people can forgive its tendency to reproduce and spread.

But when you are talking about the health of our environment, you can’t entertain such biases. If a plant meets the criteria for being considered “bad,” then it shouldn’t be granted a special exemption.

This situation begs the question, “Should nonnative plants be considered pestiferous when they spread?” I say absolutely not in most cases, especially in back yards, along hiking trails, in meadows and fields, and by roadsides. These plants are providing an invaluable service to a degraded environment.

Usually nonnative plants fill an area only after it had been left barren because of an altered soil profile brought about by man, severe storms, or both. Very few native plant species can grow in poor-quality soil.

By moving into these damaged areas, alien plants do what humans can’t easily do: they rehabilitate the soil. In other words, they are creating a rich soil so that—once they’ve done their job—native plants may again be able to grow there.

Nonnative species are able to obtain nutrients from nutrient-poor soil and transform them into plant tissue. When that plant tissue is returned to the soil (such as when leaves detach to be replaced by new ones or when the plant itself dies), it becomes humus—organic material that enriches the clay soil because its nutrients are in a form that’s usable by many more kinds of plants.

But enriching the soil is not the only thing invasive plants are doing for the environment. They are also supporting our wildlife, all of which require plants for food, shelter, and nesting sites. Every plant on invasive-species lists provides one or more of these basic necessities to our critters.

Although “invasive” plants are often referred to as noxious (deadly, harmful, dangerous), they are simply doing what they are meant to do—reproduce and multiply if there is room for them and the growing conditions are right.  It’s what “happy” plants do.

Consider Japanese Knotweed (Fallopia japonica), a large herbaceous perennial plant that was brought from Asia to this country in the late 1800s.  Its flowers feed abundant numbers of insects, especially bees of many kinds.

Yet according to the National Invasive Species Information Center, this plant is problematic because “it crowds out native species.” Well, yes, Japanese Knotweed eventually gets large enough and spreads enough to take up space so nothing else can share the space, but in all likelihood, this plant is not crowding out native species, but rather, other nonnative plants like itself!

One of the reasons this plant was originally brought to this country was erosion control after the ground had been denuded by man’s activities, such as road building.  The only reason to bring in a foreign plant to prevent soil from washing away in these areas during rain storms is because no native plant could possibly handle the job.

During construction, heavy equipment clears away topsoil that native plants have evolved to grow in. The subsoil that remains is hard, and made harder still by the heavy equipment driven over it. It takes a tough plant to grow in heavy, hard-as-rock dirt!

In Charlottesville, the City Council recently voted to continue to use pesticides for controlling unwanted plant growth, such as Japanese Knotweed growing along the Rivanna River.  People believe the plant “will take over next to streams so nothing else can grow there,” creating “a monoculture.”

However, it could well be that nothing else can grow there. The Rivanna runs red every time there’s a heavy rain. That color signifies sub-soil erosion, the result of development upstream and properties on which land has been cleared right to the edges of streams (it’s allowed on “pasture” in Albemarle County).

Although that soil is traveling towards the Chesapeake Bay and is a major contributor to its impaired state, some of it gets deposited along the edges of the waterways.  This red clay is not typically conducive to native-plant growth, which is why nonnative plants were able to start growing in the first place and to subsequently “take over.”

Although one might think the land along the river is in a pristine state, it’s easy to discern the truth of the matter by simply examining what plants are growing with the Japanese Knotweed. If you see many so-called invasive species, such as Japanese Honeysuckle (Lonicera japonica), Garlic Mustard (Alliaria petiolata), Japanese Stiltgrass (Microstegium vimineum), and Autumn Olive (Eleagnus umbellata), that’s an undeniable sign of disturbance.

Killing and then replacing the Japanese Knotweed plants along the Rivanna River will simply re-disturb the soil, setting back the clock for its rehabilitation. If people truly want to help the environment, they need to take the long view.

Over time, the Japanese Knotweed will ultimately be shaded out by trees because Mother Nature’s goal is to create forest. No environment is static; it’s constantly in a state of flux.

People can spend time, effort, and money to remove nonnative species that are able to grow vigorously in disturbed areas of our making, but it’s virtually impossible to do so without re-creating the conditions that brought about the problem originally.

In the majority of situations, it’s difficult to make right what man has done wrong.  Better to take the passive approach and let Mother Nature perform the renovations.

In fact, the whole invasive-plant issue has been a huge disaster for our environment.  As a result of the rush to judgment that says all of these plants are “bad,” no matter what, herbicide usage has increased tremendously. Even most environmentalists now consider the employment of pesticides acceptable.

It’s as if poisoning the Earth is far better than allowing plants to exist in areas where they are not native. Rachel Carson’s ashes must be whirling in her grave.

This scientist, by recognizing the dangers of pesticides, brought about the environmental movement in which people began to recognize the effects of their actions upon the planet.

Yet now these poisons (substances that are capable of causing illness or the death of a living organism when introduced or absorbed into its system) are seen as either totally innocuous or a choice that is preferable to the alternative.

What is the alternative? The alternative is that a nonnative plant should occupy a spot of ground that in most cases is degraded and incapable of supporting a native plant anyway.

Herbicides sicken and kill many kinds of organisms, either directly or indirectly.  Alien plants, on the other hand, often do far more good than harm to the environment. Can there really be any doubt about which choice is the better one to make?

19 COMMENTS

  1. Ms. Condon should do some homework. Many native plants can grow in disturbed soil given the opportunity without the invasive plants aggressive colonization. As for the value of native plants over non-native, please read Doug Tallamy on the subject. This article is not well researched and damaging.

    • Hi Carol,

      My next two articles in The Gazette will make clear that I have indeed done my research. Everything I write is based upon a lifetime of personal observations and note-taking. I do hope you will stay tuned!

      As for Doug Tallamy, I was given a copy of his book to review about the time it was coming out. I felt obliged to inform Timber Press that they might prefer that I didn’t write a review because there were too many errors, many of which I detailed in a two-page (if I recall correctly) letter. It’s possible that’s why a revised edition was issued in such short order after publication of the original version.

      That’s not to say that it isn’t important for people to grow native plants; it certainly is. However, thinking that everyone needs to get rid of so-called invasive plants, even in their yards, is not quite correct. And if you are employing pesticides to do so, it’s anything but environmentally friendly.

      Sincerely,
      Marlene

      • Marlene,

        Two questions.

        1. In your article, you say “This situation begs the question, “Should nonnative plants be considered pestiferous when they spread?” I say absolutely not in most cases, especially in back yards, along hiking trails, in meadows and fields, and by roadsides.” I see the “in most cases” qualification. Does that mean you think some nonnative plants are pests that need to be dealt with? If so, do you have some examples?

        2. How you feel about other classes of nonnatives, such as insects, plant diseases, aquatic plants, fish, reptiles, mammals, …

        Thanks,

        Rod

        • Hi Rod,

          Thank you for your thoughtful questions. Due to space limitations, it can be difficult to cover all aspects of a complicated subject in an article.

          When I said, “in most cases”, I was referring to situations in which the soil situation has been altered. The examples I gave were those in which people or their farm animals have compacted the soil or heavy equipment has totally altered the soil profile.

          As for whether some nonnative plants are pests that need to be dealt with, I believe that the word “pest” is subjectively used, just as “weed” is. It all depends on what the property is being managed for.

          However, if someone wants to get rid of particular plants, I would prefer to see him or her do that by way of physical labor as I do on my property. I’ll never believe that poisoning the Earth is environmentally friendly.

          The story is totally different for nonnative animals that can severely impact native animals by using up the food or space they need. The reason I see nonnative plants differently is because they are a source of food, shelter, and nesting sites where there would otherwise be only bare dirt, in most cases.

          I hope this answers your questions. If not, feel free to contact me again, although you might want to wait for my next article.

          Sincerely,
          Marlene

  2. This article is cribbed with errors. To start with, the author doesn’t seem to know the meaning of invasive species. Please, read this: http://www.invasivespeciesinfo.gov/docs/council/isacdef.pdf. Daffodil doesn’t fit the definition of invasive. Being lovely or not has nothing to do with it.

    “Very few native plant species can grow in poor-quality soil.” “Nonnative species are able to obtain nutrients from nutrient-poor soil and transform them into plant tissue.” Are you saying that poor soils have remained absent of native life for millions of years? Evolution fills in every available niche. Rest assured that there are many native species eking out a living from the poorest of soils.

    Non-native plants (and the insects or other organisms they bring along) can invade healthy communities, not just degraded ones. Vivid examples are the insects or other pests brought along with Chinese chestnut trees, hemlocks and Asiatic viburnums. They destroyed the American chestnuts throughout the continent, and they are devastating hemlocks and viburnums in healthy ecosystems.

    Japanese knotweed’s value as an erosion control is not entirely proven. As for its use by insects, practically no larvae feed on it (no insects-no bird food), not much wildlife value there. Their flowers attract pollinators, but, so what? There are plenty of native plants that do that. Ordinarily pollen from native plants is better co-adapted with the native pollinators and a better food for them.

    And so on and on. In addition to the article mentioned above, there are many scientifically supported pieces about invasive species. I strongly recommend you read some of them before writing more on the topic.

    • Dear Beatriz,

      I can only briefly address your comments, but I should be able to clarify the points you question.

      (1) The white paper you reference defines an invasive species as being non-native and capable of causing environmental harm. I would say that the usual argument against invasives–that they take space from native plants without offering equally valuable benefits–could most certainly be applied to daffodils. Not many critters make use of them and, over time–as is quite obvious along my exercise route–they can occupy quite a bit of ground. I’ve watched them spread for the past 30 years so I would say that they could qualify as being “invasive”.

      (2) “Are you saying that poor soils have remained absent of native life for millions of years? Evolution fills in every available niche. Rest assured that there are many native species eking out a living from the poorest of soils.”

      Poor soils don’t remain poor for millions of years. In central Virginia, evolution filled in the niche with VA Redcedar and Broomsedge. You may also see Black Locust, but that is not actually native to this particular area. Truth be told, there are not many native species eking out a living on the poorest of soils. If you think there are, I would appreciate some specific examples, please.

      (3) “Vivid examples are the insects or other pests brought along with Chinese chestnut trees, hemlocks and Asiatic viburnums. They destroyed the American chestnuts throughout the continent, and they are devastating hemlocks and viburnums in healthy ecosystems.”

      My article wasn’t about bringing in new plants. My article was about the non-native plants that are already here and that would be extremely difficult, if not impossible, to completely remove from the environment.

      (4) “As for its [Japanese Knotweed] use by insects, practically no larvae feed on it (no insects-no bird food), not much wildlife value there. Their flowers attract pollinators, but, so what? There are plenty of native plants that do that. Ordinarily pollen from native plants is better co-adapted with the native pollinators and a better food for them.

      Leaf-eating insects are not the only kinds of wildlife that people should concern themselves with. And birds eat many kinds of insects, not just those feeding on leaves. I’m afraid I can’t believe the statement about native pollen being a better food source for pollinators. My yard is home to an incredible diversity of pollinators, including honeybees, and it’s been that way for close to 30 years in this location. You can’t argue with decades of data.

      Sincerely,
      Marlene

      • Please, read the arguments presented more carefully before responding. Some of your answers are not relevant.

        (1) I told you I was showing you a practical definition of invasives used for purposes of policy making. The scientific definition is somewhat different. As Daniel Simberloff says in his book, “Invasive Species: What Everyone Needs to Know:” “Biologists have generally restricted the term invasive to cases in which the species is found well beyond the arrival area. By contrast with biologists’ usage, policymakers sometimes use invasive species to describe only introduced species with negative impacts.” I hope this clarifies your ideas about invasive species.

        (2) What makes you think that there aren’t poor soils anywhere? In fact some native plants thrive in poor soils and lose ground to invasives when fertilizers are introduced.

        (3) My comment wasn’t about newly introduced plants. I don’t know what made you think so.

        (4) I wasn’t talking about leaf-eating insects either. The entire plant, Japanese knotweed, provides practically no food for insects. This, in turn, affects the entire food chain and all the wildlife that relies on insects. Let me say it again, insects are near the base of the food chain; many species depend on them. Most introduced plants provide little food for insects and this is why they are detrimental to wildlife in general.

        Fortunately, Alonso already explained that experiential knowledge is not enough. You shouldn’t discard the accumulated knowledge of countless researchers. You need to read books and peer reviewed articles. The literature on invasive species is quite extensive. Also, as Alonso says, it is important to have a clear idea about the difference between introduced and invasive species.

  3. I also think that some points need to be corrected and clarified. Please note that no one considers all nonnative plants to be invasive, that is not the definition of an invasive plant. No one suggests we get rid of all non natives or that we shouldn’t have any nonnative plants around. Rather that we manage the invasives and where possible eliminate them because they do outcompete (partially because they do not support the same diversity of native wildlife and partially because some invasives are allelopathic and alter the chemistry to allow them to survive and reduce competition with natives) many native plants. Everything said that follows is about Invasive plants, not just any non native.

    That native plants cannot make use of disturbed soil conditions is also false, they certainly can and would do so better in absence of invasive competition. Plants have evolved in Virginia to make use of just about every niche, that is why we are blessed with such a great diversity in the Commomwealth.

    Since some invasive plants such as garlic mustard are allelopathic and alter soil conditions, the idea that leaving invasives because they improve the soil for natives later is not likely to happen. Rather more invasives will fill that new soil type since the invasives will alter the soil as they decompose and release chemicals to resemble their country of origin rather than native soils full of mycorrhizal fungi and other soil components symbiotic with our native plants (the vast majority of our natives have evolved not just with certain insect species dependent on them, but also fungi, something that invasives do not promote and some actually inhibit). As you observe in your article, that is another reason you see so many inavaisves growing among the invasives and “competing” with them. This is not soil rehabilitation that will help native plants as you suggest.

    Native plants evolved with native insects and fungi and so are codependent. Many of our insects need them as host plants, unable to feed anywhere near to the same extent as on invasives. These are not only caterpillars and other leaf feeders, but also about a third of our native bees that need the particular pollen of host flowers in order to reproduce (they are oligolectic). Invasives almost never provide the required chemicals or pollen types to serve as hosts for these native species and so are detrimental to the habitat and wildlife diversity in that manner as well. Not only do the vast majority of birds then feed on these insects sometime during their lives, but all 17 of our bat species do as well. So the effects of invasives are widespreading throughout the environment.

    You mention Japanes Knotweed as an example. I’ll use it as well then. It does Not serve as a host plant or bee specific pollen source for very many species (any?). In fact, studies have shown that amphibian species such as green frogs decline where it is dominant, many believe because it does not support sufficient insect life for them. You also forget to mention that Japanes Knotweed is one of the allelopathic plants. It exudes chemicals that impeded and help it compete with native plants. Some believe this same chemical warfare results in deleterious affects to developing tadpoles by the way as well.

    It is factors such as allelopathy, rapid growth, lack of natural insect predators, and out competing of natives that make invasives such an issue. This also does allow them to invade pristine habitats and take over at the expense of natives and all the life that depends on them. This is why control and not planting of invasives (not all nonnatives) is vital. That it takes the judicious application of herbicide to sometimes do so outweighs any negative effects in many situations. Just as not all uses of nonnative plants results in harm, so also not all use of herbicide results in harm, well, except to the invasive of course. I have made this much too long a response already, but I hope you see that there are many points that are in contention at least and some clarifications that also should be made. I will not go on, though there are many other points that can be made. Thank you.

    • Hi Alonso,

      I appreciate your concerns, but let me provide some clarifications, please.

      “That native plants cannot make use of disturbed soil conditions is also false, they certainly can and would do so better in absence of invasive competition. Plants have evolved in Virginia to make use of just about every niche, that is why we are blessed with such a great diversity in the Commonwealth.”

      (1) Please note that I am not talking about “every niche”. I’m specifically addressing the movement to get rid of non-native plants–usually via pesticides–in people’s yards and in parks where those plants are far more capable of growing and providing for wildlife than our native plants are. I’ve been observing the natural world all of my life–I know for a fact that there are very few native plants that move into areas of disturbed soil conditions. If you know of specific native plants that will grow in compacted clay, please let me know what they are specifically.

      “Since some invasive plants such as garlic mustard are allelopathic and alter soil conditions, the idea that leaving invasives because they improve the soil for natives later is not likely to happen.”

      (2) I realize that the idea of allelopathy is commonly mentioned for some kinds of plants, but I’ve yet to see the proof of it. Everyone’s heard of the allelopathic qualities of Black Walnut, but I can show you Black Walnut trees with a large variety of native and non-native plants growing right around the base of the tree. Additionally, I’ve done my own studies in my yard with Garlic Mustard and Japanese Knotweed. As far as I can tell, allelopathy is a myth. For example, my Japanese Knotweed is growing underneath Virginia Fringetree and right next to Mountain Laurel. Been there for years–never has been a problem. Years ago, a birding magazine even tried to say sunflower seed shells were allelopathic because they killed the grass! The truth is that they simply smother it. Sometimes people are too quick to overlook the truth, instead trying to make things “bad” or “evil”. I believe that’s what’s happened to a large extent with “invasive” plants.

      And yes, so-called invasive plants do indeed improve the soil. My yard is the living proof of that.

      Please note that all of my writing is based upon first-hand observation and knowledge. It doesn’t come from books or any source other than what I’ve seen and experienced over the course of decades. That’s why I’m able to write without any doubts about this issue. This is experiential learning.

      Sincerely,
      Marlene

      • Thank you for your response, you still seem to insist on using the terms nonnative and invasive interchangeably when more than one person has tried to explain that this not what is meant. No one urges getting rid of every nonnative plant, indeed they are fine in many applications including our gardens and crops. What people are trying to manage and discourage are Invasives, Not all nonnative plants.

        I appreciate your experiential learning, but that you somehow use it while ignoring the experiences and research of others, without any doubts about this issue, I find difficult to comprehend. You seem to take your limited experiences and try to apply to everyone else, ignoring others lifelong observations, experiences and research, and instead without a doubt apply them as an expert. Perhaps you should try to do some research as to why Japanese Knotweed is listed around the world as one of the top 100 invasives in the world. Please do an internet search into this, looking at peered reviewed (so it’s not just one person’s experience) research papers for example. This will provide a wide variety of research and experiences, from a wide variety of disciplines.

        Doing so (and understanding that allelopathic properties do not affect every species or in the same manner) you will find out that other researchers have found that Japanese Knotweed has been found to affect the growth of native plants and amphibians. You will find that these results have been replicated and accepted all around the world. That you believe that allelopathy is a myth when so many other scientists and researchers have done replicable and peer reviewed experiments to the contrary is a bit hard to believe.

        Please also note that when you notice the “improvement” of the soil in your soils, that does not necessarily (and likely does not) mean that it is improved for native plants or the animals that depend on them. As I mentioned in my first response, they often alter it to make it more suitable for other nonnative and especially invasive plants. This results in less diversity of native plants and the wildlife who need them as host plants and oligolectic pollen sources. I am unaware of any native bee, caterpillar, or indeed any native organism that has to have Japanese Knotweed for its existence. Native alternatives such as Lizardstail, Pickerelweed, Pennsyvania Knotweed, Cattails, Buttonbush, and so many others depending on the exact moisture and soils conditions support much more wildlife. When a monoculture of Japanese Knotweed grows, it out competes native flora, alters the soils, is allelopathic, affects the amphibians, and simply occupies the location where these natives with more habitat benefits can grow. You may not believe it, but it is the experience and what has been researched by many other knowledgeable people, many of which have also been observing, experiencing and studying the natural world their whole lives as well. They do not believe, as you state, that invasives can provide for wildlife better than our native plants can, indeed they recognize invasives (not all nonnatives, please let’s use the same terms) as a threat and providing less habitat. Please try to see that you may be falling into your own concern that you mention, being too quick to overlook the truth, and ignoring the observations, experiences, and research of others. Experiential learning is great, but it needs to be tempered with that of others and their research, experiments, and using/accepting standard definitions such as invasive and allelopathic. Please try and look up some of the research on Japanese Knotweed for example and why it is not only nonnative, but more importantly invasive and allelopathic. Thank you for your time and consideration.

      • Thank you for defending blameless non-native plants against the mistaken beliefs of nativists. Here are a few studies to assist you in this effort.

        Here are too critiques of a misleading article which attempts to make the case that non-native plants are harmful to birds: http://milliontrees.me/2014/03/18/are-non-native-plants-ecological-traps-for-birds/ and http://milliontrees.me/2014/03/25/are-non-native-plants-ecological-traps-for-birds-part-ii/

        Since those critiques were written, the author of some of those studies has published a follow-up study in which she compares nesting success in non-native honeysuckle with areas in which the honeysuckle has been eradicated. She reports that, “the lowest overall nest survival rates” of birds were in the plots where honeysuckle had been removed. “Does removal of invasives restore ecological networks? An experimental approach,” Amanda Rodewald, et. al., Biological Invasions, March 2015.

        Also, here is a typical ecological study which set out to prove that non-native plants are harmful to birds. They were unable to prove what they believed. They found that the birds preferred to nest in non-native plants and their reproductive success was not reduced by their choice. The birds are smarter than we are. Who is surprised? http://www.sciencedaily.com/releases/2015/06/150610161742.htm?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+sciencedaily%2Ftop_news%2Ftop_environment+%28ScienceDaily%3A+Top+Environment+News%29

        There are many similar studies about the choices made by pollinators. Here is a brief description of some of those studies: http://milliontrees.me/2013/09/03/niche-theory-is-there-room-for-everyone/

        Nativism is an ideology, not a science. When science tests the hypotheses of nativism, they do not find evidence to support the gloomy predictions of nativism. The fact is, nature is resilient and while humans may be attached to historical landscapes, nature is not. Nature can’t afford romantic attachments to the past. Fortunately, it is entirely focused on survival.

        • Dear Beatriz and Alonso,

          I can tell that both of you care deeply about our natural world and I’m grateful for that. Far too many folks couldn’t care less about it. I care deeply too–nature has been my life for literally as long as I can remember. So I hope you can understand that I, of all people, would not write something unless I sincerely believed it needed to be said.

          The point of my article concerned the usage of pesticides, which has vastly increased. According to a paper published by the National Center for Biotechnology Information, “Over 1 billion pounds of pesticides are used in the United State (US) each year.” According to the EPA, “Herbicides were also the most widely used type of pesticide in the home and garden and industrial, commercial, and governmental market sectors.” I don’t find this information comforting. I’ll never agree that there is such a thing as a “judicious use of pesticides.” I feel that if you don’t want a plant somewhere, use your own physical labor or that of a machine to get rid of it. That’s my informed opinion on the use of poisons to get rid of so-called invasive species. You are certainly free to disagree.

          But as regards all of your other talking points, I’m afraid I can’t continue to respond to the same issue again and again because you bring a new parameter to the conversation. I responded specifically to the white paper referenced by Beatriz only to have a new paper referenced. I responded specifically to Alonso regarding the allelopathic properties of Japanese Knotweed, only to then to be given yet more arguments against it.

          The fact is that I am a voracious reader of scientific papers and therefore know of the flaws in many of them. One of my articles that is coming up will deal with the topic of scientific “truths” that are actually myths because the science was not done properly. I see this again and again in papers having to do with biological phenomena. I hope you’ll keep reading The Crozet Gazette as I’m sure you will find the article of interest.

          Sincerely,
          Marlene

          • Thanks once again for taking the time to read my comments. I won’t dwell on things too much since we seem to not agree on either definitions or the truth-fullness of so many studies and other people’s longterm experiences. I certainly do not think that herbicide use is the answer to all invasive plant issues, certainly not. However, there are certain applications and situations where that is the only practical option. I’ll give you one example and then will try to not bother you any more. Lesser Celandine is an invasive plant that can cover whole areas and out compete native spring ephemerals (such as spring beauties) in particular. You cannot pull it since any piece that is left will grow a new plant (one reason why it spreads so badly). So efforts to remove it mechanically only make the situation worse and actually benefits the invasive while harming the native vegetation. This where judicious use of an herbicide, spot spraying just before the plant goes to bloom, at proper concentration and under proper weather conditions, is the only practical method. Left alone, Lesser Celandine has been proven to out compete and replace native ephemeral plants and form a massive groundcover to the exclusion of native ephemerals. Again, this is the experience and what studies have proven to be true. There are so many other examples, but hopefully this example will suffice to make that point.

        • Dear Million Trees,

          Thank you SO MUCH for sending along these links, some of which may already be in my 2000-plus scientific papers e-mail notifications I’m trying to get caught up on!!!!!! I’ll definitely take a look at them.

          I truly appreciate your support of my efforts.

          Ever so gratefully,
          Marlene

          • Hi Alonso,
            Several years ago, I dug up some Lesser Celandine and planted it in a bare spot in my garden. As with many other kinds of so-called invasive plants that I’ve brought home, it has had great difficulty spreading. I’ve gone from 2 original groups to 4. Thus I can tell you from my own experience that these plants need open space (bare spots) to start growing and to spread.
            Since you think my personal experience doesn’t count for much, I just looked up this plant. The information said that ” It prefers bare, damp ground”. However, the same article goes on to say that the plant can be invasive. This is contradictory. What people are missing is that the area must have been barren for the plant to fill it in. No one’s looking at PRIOR HISTORY. Just because you see an area filled today with Lesser Celandine does not mean it pushed out native plants–it means they weren’t there to begin with, for whatever reason.
            As further proof of what I’m saying, this plant is in the Buttercup Family and is known as a plant that typically grows in disturbed (poor) soil. There is a disconnect between what people think has happened and what did actually happen. I don’t believe this plant out-competes native plants, but rather that people just don’t understand that today’s area filled with Lesser Celandine (or most any other “invasive”) was yesterday’s barren ground.
            I don’t want to get into a discussion about the use of pesticides, but I’ve managed my property for 30 years without poisons so again, I know it can be done if you truly care about the environment . If Lesser Celandine (LC) is the only thing keeping native plants from coming up in an area, then physically removing the LC each year will make room for spring ephemerals to come up, reducing the bare space for LC to move into. Physically removing plants does reduce their numbers over time. The area didn’t fill in with LC overnight; why does it suddenly need to be removed overnight?
            I can’t continue this discussion, but I would hope you can recognize that my experience ties right in with what you’ll find are the preferred growing conditions for Lesser Celandine, while comments about “invasiveness” are contradictory with the growth preferences of this plant.
            Sincerely,
            Marlene

  4. I would like to respond to the perception of native plant advocates that pesticides are “judiciously” used in their “restoration” projects. The California Invasive Plant Council conducted a survey of 100 land managers about what methods they use to eradicate plants they consider “invasive.” Ninety-four percent of land managers report using pesticides. Sixty-four percent use them “frequently” and 10% used them “always.” Only 6% say they don’t use pesticides. Here’s the full report: http://milliontrees.me/2014/02/09/methods-used-by-land-managers-to-control-invasive-plants/

    They were also asked what pesticides they use. Virtually all of them report using glyphosate (AKA Roundup). As you probably know, glyphosate was recently classified as a “probable human carcinogen” by the World Health Organization. The second most popular pesticide used by land managers in California to eradicate plants they consider “invasive” is Garlon with the active ingredient triclopyr. Triclopyr is considered more toxic than glyphosate by the Material Safety Data Sheets mandated by the EPA. It is acutely toxic to aquatic life and moderately toxic to bees and nesting birds. The risk assessment done for the California Invasive Plant Council said it poses “reproductive and developmental risks to female applicators.” Yet it is widely used by land managers in public parks and open spaces. Here is an article about its use in the public parks of San Francisco: http://milliontrees.me/2015/05/15/five-reasons-its-okay-to-love-oxalis-and-stop-poisoning-it/

    Here in the San Francisco Bay Area we are presently trying to prevent the destruction of over 400,000 trees because they are non-native. Native plant advocates have successfully created a cover story for this project, claiming that these trees are more flammable than the native vegetation they are trying to “restore.” In fact, even a rudimentary knowledge of our natural history would inform you that the vegetation (predominantly grassland and chaparral) in our Mediterranean climate is adapted to and dependent upon fire. In other words, it is more flammable than any tree, regardless of its nativity. One of the reasons why we are trying to prevent this project from being implemented is that herbicides must be sprayed on the stumps of the trees after they are cut down to prevent them from resprouting, usually repeatedly. Supporters of this project claim that only minimal amounts of herbicides will be needed for this purpose. In fact, the public record proves they are wrong. After the University of California, Berkeley destroyed 18,000 trees, they sprayed 141 gallons of Garlon and Roundup on the stumps to prevent them from resprouting.

    Either native plant advocates are unaware of how much pesticide is used in the projects for which they advocate or they are not telling us the truth about their projects. Please keep telling it like it is. The public is largely unaware of how their public lands are being poisoned by nativism.

    • Dear Million Trees,

      I deeply appreciate receiving this additional information about what is going on in California. To read that people want to remove over 400,000 non-native trees, in all likelihood with the assistance of pesticides, brings to mind one word: fanaticism.

      While I understand people’s desire to bring back native plants, the reality is that these plants thrived in areas that had not been dramatically altered by humans. In today’s world, very few areas have escaped the results of our presence, which means bringing back native plants is not as simple as simply removing alien plants that at some point in time were, and may still be, better suited to a site’s environmental conditions.

      As for the “judicious” use of pesticides, I doubt there’s a person out there who doesn’t believe his personal use of these poisons is judicious–but that’s why we have over a billion pounds of pesticides going into our environment in the United States alone, most of which is for the removal of plants that could be gotten rid of in better ways, such as by pulling or smothering.

      Thank you ever so much for your input.

      Sincerely,
      Marlene

      • I can’t resist the temptation to add to your perception that fanaticism is a factor in this controversy. One of the species of tree which nativists demand be eradicated in the Bay Area is Monterey pine. The modern native range of Monterey pine is less than 150 miles away from the Bay Area and there is fossil evidence that it lived in the Bay Area several times in the distant past. That finding was published in the journal of the California Native Plant Society and she concluded her study by recommending that we quit trying to eradicate Monterey pines where we know it lived in the past, partly because it is threatened in its native range. Sounds reasonable, doesn’t it? No dice!! Nativists demand that they all be destroyed in the Bay Area.

        Here’s another clue about the extremism at play in this debate: no one who is opposed to the destruction of our urban forest has anything against native plants. In fact, many of us prefer native oaks to our non-native tree species. We urge everyone to plant whatever they want. We ask only that they quit destroying everything else. Seems reasonable, doesn’t it?

        I think you would enjoy reading the latest book published in defense of non-native plants. “Beyond the War on Invasive Species” by Tao Orion starts from the premise that the herbicides being used for native plant “restorations” are doing far more harm than any perceived harm from the non-native plants. But then it goes on to tell us very specifically why the non-natives are here and how just eradicating them does nothing to change the underlying reason why they are here. So, we kill them, but we have little if any success bringing back their predecessors because they are not adapted to current environmental conditions.

        Your perspective is different from mine because it is informed by your experience and direct observation. It is a powerful perspective and one that is valuable. Thank you for publishing your opinions of this issue. It can result in some rather unpleasant encounters with “fanatics” and so many like-minded people are unwilling to express their opinion on the subject.

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