In our debates with native plant advocates, the scientist who is most often quoted to support their beliefs is Doug Tallamy who wrote an influential book, Bringing Nature Home: How Native Plants Sustain Wildlife in our Gardens. Professor Tallamy is an entomologist at the University of Delaware.
Professor Tallamy’s hypothesis is that native insects require native plants because they have evolved together “over thousands of generations.” Because insects are an essential ingredient in the food web, he speculates that the absence of native plants would ultimately result in “ecological collapse” as other animals in the food web are starved by the loss of insects. (1)
Professor Tallamy freely admits that his theory is based on his anecdotal observations in his own garden, not on scientific evidence: “How do we know the actual extent to which our native insect generalists are eating alien plants? We don’t until we go into the field and see exactly what is eating what. Unfortunately, this important but simple task has been all but ignored so far.” (1)
This research has now been done to Professor Tallamy’s satisfaction by a Master’s Degree student under his direction. The report of that study does not substantiate Professor Tallamy’s belief that insects eat only native plants. In his own words, Professor Tallamy now tells us:
“Erin [Reed] compared the amount of damage sucking and chewing insects made on the ornamental plants at six suburban properties landscaped primarily with species native to the area and six properties landscaped traditionally. After two years of measurements Erin found that only a tiny percentage of leaves were damaged on either set of properties at the end of the season….Erin’s most important result, however, was that there was no statistical difference in the amount of damage on either landscape type.” (2)
This finding that insects are equally likely to eat native and non-native plants may be new to Professor Tallamy, but it isn’t new to the readers of Million Trees. We have reported many studies which are consistent with this finding.
- Professor Arthur Shapiro (UC Davis) reports that 82 of 236 (35%) total species of California butterflies have been observed either laying their eggs or feeding on non-native plants.
- Professor Dov Sax (Brown University) compared insects living in the leaf litter of the non-native eucalyptus forest with those living in the native oak-bay woodland in Berkeley, California. He found significantly more species of insects in the leaf litter of the eucalyptus forest in the spring and equal numbers in the fall. Professor Sax also reports the results of many similar studies all over the world that reach the same conclusion.
- The California Academy of Sciences finds that several years after planting its roof with native plants, it is now dominated by non-native species of plants in the two quadrants that are not being weeded, replanted and reseeded with natives. Their monitoring project recently reported that there were an equal number of insects found in the quadrants dominated by native plants and those dominated by non-native plants. (Correction: Should read “…equal number of orders of insects…”)
- Jennifer Owens (Ph.D., University of Michigan) reports 30 years of observing her garden in Wildlife of a Garden (Royal Horticultural Society, 2011). She found that non-native species were better as food plants for moth larvae than native species. Moth larvae used 27% of the native species in the garden as food plants, and 35% of the alien plants.
Specialists vs. Generalists
When debating with native plant advocates, one quickly learns that the debate isn’t ended by putting facts such as these on the table. In this case, the comeback is, “The insects using non-native plants are generalists. Insects that are specialists will not make that transition.” Generalists are insects that eat a wide variety of plants, while specialists are limited to only one plant or plants in the same family which are chemically similar.
Professor Tallamy offers in support of this contention that only “…about 10 percent of the insect herbivores in a given ecosystem [are not specialists],” implying that few insects are capable of making a transition to another host plant.
However, categorizing insects as specialists or generalists is not a dichotomy. At one extreme, there are some insects that choose a single species of plant as its host or its meal. At the other extreme, there are insects that feed on more than three different plant families. It is only that extreme category which has been estimated at only 10% of all phytophagous (plant-eating) insects. The majority of insects are in the middle of the continuum. They are generally confined to a single plant family in which the plants are chemically similar.
Putting that definition of “specialist” as confined to one plant family into perspective, let us consider the size of plant families. For example, there are 20,000 plant members of the Asteraceae family, including the native sagebrush (Artemisia) and the non-native African daisy. In other words, the insect that confines its diet to one family of plants is not very specialized.
Professor Tallamy offers his readers an explanation for why specialist insects cannot make the transition from native to non-native plants. He claims that many non-native plants are chemically unique and therefore insects are unable to adapt to them. He offers examples of non-native plants and trees which “are not related to any lineage of plants in North America.” One of his examples is the goldenrain tree (Koelreuteria paniculata). This is the member of the soapberry (Sapindaceae) family to which the soapberry bug has made a transition from a native plant in the soapberry family in less than 100 generations over a period of 20 to 50 years. Professor Tallamy’s other examples of unique non-native plant species are also members of large plant families which probably contain native members. Professor Tallamy is apparently mistaken in his assumption that most or all non-native plants are unique, with no native relatives.
The pace of evolution
Even if insects are “specialists” we should not assume that their dependence on a native plant is incapable of changing over time. Professor Tallamy’s hypothesis about the mutually exclusive relationships between native animals and native plants is based on an outdated notion of the slow pace of evolution. The assumption amongst native plant advocates is that these relationships are nearly immutable.
In fact, evolution continues today and is sometimes even visible within the lifetime of observers. Professor Tallamy provides his readers with examples of non-native insects that made quick transitions to native plants:
- The hemlock wooly adelgids from Asia have had a devastating effect on native hemlock forests in the eastern United States.
- The Japanese beetle introduced to the United States is now eating the foliage of over 400 plants (according to Professor Tallamy), some of which are native (according to the USDA invasive species website).
These insects apparently made transitions to chemically similar native plants without evolutionary adaptation. If non-native insects quickly adapt to new hosts, doesn’t it seem likely that native insects are capable of doing the same? That is both logical and consistent with our experience. For example, the native soapberry bug mentioned above has undergone rapid evolution of its beak length to adapt to a new host.
Although Professor Tallamy tells us that the relationship between insects and plants evolved over “thousands of generations,” he acknowledges much faster changes in plants when he explains why non-native plants become invasive decades after their arrival: “Japanese honeysuckle, for example, was planted as an ornamental for 80 years before it escaped cultivation. No one is sure why this lag time occurs. Perhaps during the lag period, the plant is changing genetically through natural selection to better fit its new environment.” Does it make sense that the evolution of plants would be much more rapid than the evolution of insects? Since the lifetime of most insects is not substantially longer than the lifetime of most plants, we don’t see the logic in this assumption.
Beliefs die hard
Although Professor Tallamy now concedes that there is no evidence that insects are dependent upon native plants, he continues to believe that the absence of native plants will cause “ecological collapse.” In the same book in which he reports the study of his graduate student, Professor Tallamy repeats his mantra: “…our wholesale replacement of native plant communities with disparate collections of plants from other parts of the world is pushing our local animals to the brink of extinction—and the ecosystems that sustain human societies to the edge of collapse.”
This alarmist conclusion is offered without providing examples of any animals being “pushed to the brink of extinction.” In fact, available scientific evidence contradicts this alarmist conclusion. (3)
Here are more articles about the mistaken theories of Doug Tallamy:
- Doug Tallamy claims that non-native plants are “ecological traps for birds.” HERE is an article that disputes that theory.
- Doug Tallamy claims that native and non-native plants in the same genus are not equally useful to wildlife, but he is wrong about that. Story is HERE.
- Doug Tallamy advocates for the eradication of butterfly bush (Buddleia) because it is not native. He claims it is not useful to butterflies, but he is wrong about that. Story is HERE.
- Doug Tallamy publishes a laboratory study that he believes contradicts field studies, but he is wrong about that. Story is HERE.
- Doug Tallamy speaks to Smithsonian Magazine, Art Shapiro responds, Million Trees fills in the gaps: HERE
- Doug Tallamy’s Nature’s Best Hope perpetuates the myth that berry-producing non-native plants must be eradicated because they are less nutritious than the berries of native plants. Available HERE.
- Doug Tallamy believes we must prevent hybridization. Hybridization is a natural process that increases biodiversity and enables plants and animals to adapt to changes in the environment. Available HERE.
- There is NO evidence to support Doug Tallamy’s claim that insect populations are declining because of the existence of non-native plants. Available HERE.
(1) Tallamy, Doug, Bringing Nature Home, Timber Press, 2007
(2) Tallamy, Doug, “Flipping the Paradigm: Landscapes that Welcome Wildlife,” chapter in
Christopher, Thomas, The New American Landscape, Timber Press, 2011
(3) Erle C. Ellis, et. al., “All Is Not Loss: Plant Biodiversity in the Anthropocene,” http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0030535
33 thoughts on “Doug Tallamy refutes his own theory without changing his ideology”
Thank you. Very informative with useful citations.
Interesting and important article. Nativists sometimes make it difficult for any insect or animal to dine on native plants when they insist on caging them, after they plant them, to “protect” them from being eaten. Strange but true, and hard on any animal or insect who is looking consciously for food, or “unconsciously” for a flower to pollinate, especially if the area has previously been cleared to plant the natives.
why do you call them alarmists
Webmaster: Predicting “ecological collapse” in the absence of evidence seems alarmist to us.
The trouble with using secondary sources is that the probabilities for misinterpretation grow exponentially. Such is the case with Erin Reed’s work cited here. It is better to check her original work:
These are some of her conclusions: “I found moderate evidence to support the prediction that pest populations will remain lower and more stable in native-based landscapes. Native properties supported a higher diversity of herbivores and natural enemies in the herbaceous layer than properties landscaped with non-native plants.”
This may not be strong evidence, but it is the opposite of refuting Doug Tallamy’s arguments. In the meantime evidence keeps accumulating to support the fact that native plants are better for native wildlife. Take these two examples:
Webmaster: I read Erin Reed’s thesis before writing this post, but I did not quote from it in this post. Rather I quoted verbatim Professor Tallamy’s description of the thesis. Since Professor Tallamy was Erin Reed’s thesis advisor, we can safely assume that he is accurately describing its content and conclusions. I could cherry pick several quotes from the thesis which would confuse and obfuscate the issue as the thesis is all over the map, including unsubstantiated speculation about why more evidence of greater insect populations in native gardens wasn’t found.
Amanda M. Conover. The Impact of Non-native Plants on Bird Communities in Suburban Forest Fragments http://ag.udel.edu/enwc/faculty/Williams/Amanda%20Conover%20MS%20Thesis.pdf
“The proportion of native plants was the best variable in predicting Wood Thrush occupancy. Forest structure variables were the strongest predictors of presence for American Robin, Carolina Chickadee, and Gray Catbird. Both forest structure and native plant proportion were important variables in predicting the occupancy of Eastern Towhee, Northern Cardinal, and Ovenbird. For Carolina Wren, invertebrate abundance was the most important variable in predicting occupancy.”
Beal Christy, Ph.D. Bird foraging preferences and caterpillar biomass on suburban landscape trees. http://gradworks.umi.com/34/40/3440456.html
“I found that (1) native trees supported significantly more foraging than non-native trees; (2) migratory bird foraging choices were best explained by the amount of caterpillar frass collected in drop cloths but foraging choices of residential birds were best explained by tree nativity; and (3) bird foraging was highest on the Fagaceae in both studies.”
This is just the tip of the iceberg. I listed additional evidence published by many authors here: http://nativeplantwildlifegarden.com/the-science-behind-our-passion-for-native-plants/
Webmaster: We could play dueling citations here, but we won’t because we have provided our readers with plenty of scientific studies that reach other conclusions. We clearly won’t change your mind by engaging in such an exercise.
And last but not least, this is not ‘Professor Tallamy’s hypothesis that native insects require native plants because they have evolved together “over thousands of generations.”’ You should do well to heed the comments submitted in this very blog by people who know the subject:
“A preference for native over introduced plant species is not a “movement” but a reflection of the combined knowledge biologists have acquired over the years. Every PhD, MSc, or even BSc knows species richness and diversity relies on the equilibrium reached by different species co-evolving over time.” (mycos July 26, 2011)
Webmaster: The phrase evolved together “over thousands of generations” is a verbatim quote from Tallamy’s first book Bringing Nature Home. If it’s not his hypothesis, why did he say that while explaining his theory to his readers?
Every Ph.D., M.Sc. and B.Sc. does not know this because there is presently precious little support in the scientific community for equilibrium theory. It is a theory that has largely been overturned by more recent studies. Likewise, more recent research has found substantial evidence of rapid evolution in response to changes in the environment.
Since I am not a scientist I submitted my draft for review by a distinguished professor of evolution and ecology at a major university. He said, “All of your arguments are valid.” He suggested a few qualifications and I made the revisions he suggested. I stand firmly on the arguments I made in this article.<
Unfortunately, you have badly misrepresented the facts from the get go of this article and you do a disservice to the public by being uninformed or intentionally misleading. Yes, I could be more polite but I’m sorry but there is little reason to sugar coat this. The above article is rife with cherry picked facts or errors. I’ll just point out a few.
1) “Professor Tallamy freely admits that his theory is based on his anecdotal observations in his own garden, not on scientific evidence”.
You took his quote out of context because he regularly cites this large body of literature and has contributed articles himself. If you even visited his website you’d see this. Moreover, there are literally hundreds of recent articles demonstrating how native herbivores fare worse (or cannot survive in most cases) on non-native plants. A Web of Science or Google Scholar search will turn up a large number of hits on the subject using any relevant terms. This isn’t a matter of warring citations. The overwhelming majority of research on the subject demonstrates that introduced plants reduce biodiversity and ecosystem functioning.
2) You gave several examples of evidence that non-native plants are equally good (or better) than native plants for butterflies etc. Each of these can be taken apart but we’ll start out with one that you unfortunately misinterpreted.
“Professor Arthur Shapiro (UC Davis) reports that 82 of 236 (35%) total species of California butterflies have been observed either laying their eggs or feeding on non-native plants.”
Even at a first glance this says that 2/3rds of California butterflies have not been observed laying eggs on or feeding on non-native plants. So the 1/3rd that do lay eggs or feed on non-native plants… how well do they fare? Not very well in many of those instances. I suggest you read some of the Lepidoptera literature (including Shapiro’s research which you must have just skimmed the abstracts). Since you told an earlier poster that you don’t want long lists of references, I’ll spare you, but I urge you to look into this. It’s not actually an unknown and it’s very well-documented that the majority of herbivores are specialists. And yes, some of this is obvious to evolutionary biologists, especially those that study co-evolution.
3) Some of these studies don’t even show what you claim they do, as pointed out above. But even if they did, you can always cherry pick a small number of examples that show contrary results, but these are decidedly in the minority. This is literally akin to the intelligent design debate. One can always find a few scientists taking a contrarian point of view (prominently Dov Sax, and a few others), but the majority of theory won’t support the position that herbivores suffer no impacts or are generally going to benefit from species introductions. This is basic co-evolutionary theory and one need not go far to find the myriad reasons why it wouldn’t even make sense for the majority of herbivores to be generalists and why it’s the very small minority of species that can quickly adapt (see any of a number of papers by Futuyma. List can gladly be provided).
Dr. Ron Obvious
We have read all the studies we have cited, including Mr. Tallamy’s book, the thesis of his student, and the chapter he wrote in another book. All the quotes from the cited studies are accurate and have not been “taken out of context.” We have discussed Dr. Shapiro’s study of California butterflies with him and have not misrepresented his study.
Dr. Obvious has not provided any studies in support of his opinions, which contradict the scientific literature we have cited. His statements about co-evolution, specialization and other assumptions that are the underpinnings of invasion biology are not consistent with empirical evidence. Invasion biology is quickly becoming the “contrarian viewpoint.”
Well good, let me just tell the monarchs we are being alarmists and everything will be fine.
We are unsure about the meaning of this comment. We hope Jennifer is aware of the fact that the monarch requires non-native trees for its winter roost in California: https://milliontrees.me/2013/11/01/monarch-butterflies-in-california-need-eucalyptus-trees-for-their-winter-roost/
Yay! Common sense! Rare these days.
This article is reminiscent of a Christian scientist cherry picking facts to make an argument. It’s common sense that insects from the Americas are dependent on the plants they’ve evolved with. Walk in to almost any natural area east of the Mississippi and you’ll quickly see how exotic landscape plants have decreased biodiversity irreperably. Burning bush, multi flora rose, various honeysuckles, oriental bittersweet, Norway maple, kudzu, buckthorn, etc. have destroyed large chunks or our remaining natural areas. Now we’ll just wait for butterfly bush, Japanese maple, and whatever hgtv flavor of month degrades what’s left. Viburnum, beech, elm, chestnut, ash, dogwood all either gone or under attack from foreign insects/fungus. The greater point of his book was how people should embrace ample native choices.
Million Trees does not “cherry pick” facts. We have read hundreds of books and studies and we provide references for virtually every statement we make so that our readers can read those sources if they wish. In fact, we have yet to have a comment from a critic of our viewpoint which has provided any references in support of their belief in nativism. Nativism is an ideology, not a science.
When reality contradicts your “common sense,” it is time to re-evaluate your viewpoint. Countless empirical studies consistently report that equal numbers of insects and other animals are found in native and non-native vegetation. There is also ample evidence of rapid evolution which disproves the belief that “co-evolution” is required for animals to benefit from introduced vegetation.
Non-native plants are not destroying anything. They are there because they are adapted to present conditions. Their removal will not change the underlying conditions which are long gone and it is therefore pointless to destroy them, particularly with the herbicides that are damaging the soil, the environment, and the animals that live here now.
Plant native plants if you prefer, but understand there is no science which supports your belief in their superiority.
Reblogged this on livfullyblog and commented:
I enjoyed hearing Doug Tallamy speak at the Salisbury Forum in Lakeville Ct at the Hotchkiss School, but his message was truly alarming. We didn’t want to have to go back to the real world and take up our spades and get plantin’ (the right variety of a few main trees which he said held the key to buy us time and maybe prevent the steep decline of birds leading in short order to us perishing as well…) Not your normal horror film talk, since the slides were of lovely moths and the caterpillars they fed on when the right tree habitat was found. There was one extra wild orange tufted caterpillar called “The Donald” in honor of Trump’s hair style and taht helped us keep the faith and yet at the same time reminded us that power concentrated in the wrong hands was like the major climate issue we face only even more frightening in ways. So we need to hear more A Lot More about the theories and findings, what can help and what won’t. Permaculture and http://www.gaia.org are two things I asked Doug Tallamy to look into so he could give people more helpful resources and he appreciated the thought. Now, onto that post I am reblogging from A Million Trees… Doug says we need to plant about half of all the lawns and cleared areas to reclaim the habitat that can serve nature and clean the air. Whose game to pick up the challenge with a great team and donations and funds flowing in from untapped resources? We need to Dream Big and Follow Through… such is the advice of many successful folks and prayers…for all to be served in meeting basic human needs with ethical means. Happy Planting!
Interesting to have found this today. I have another example of insects’ adaptability. As you probably know Doug Tallamy is instructing folks to get rid of their butterfly bushes. Part of the argument is that they serve only as nectar, not host plants. I have living proof this is changing. Here’s my story. http://plantwhateverbringsyoujoy.com/never-pull-up-and-discard-what-you-cannot-identify/
Kathryn, Thank you for your visit and for your comment. The title of your book suggests that you might share my cosmopolitan attitude toward the natural world. I am glad to see that you have enlisted the help of Art Shapiro to answer your questions about butterflies.
I didn’t know that Doug Tallamy advises against planting buddleia, but I am not surprised. He does not seem to appreciate the adaptability of plants and animals to the changing environment. Please visit my latest post to see another approach to the thorny question of the evolving relationships between plants and insects in our rapidly changing world. https://milliontrees.me/2017/07/01/the-natural-history-of-americas-urban-forests/
This still doesn’t quite sway me away from my preference towards native plants. I think the author is making some good arguments and points but is missing the bigger picture. Yes our native insect population can adapt to these non-native plants, but it’s my understanding that the number that can do this is very limited even if the new plant is in the same plant family. Furthermore, even if the non-native IS a great host for the insect, that doesn’t mean it provides nectar for pollinators and fruit/seeds for birds and mammals the same way that native plants do. And even if they DO provide lots of good food/nectar for wildlife, that doesn’t mean they provide them at the appropriate time of year for the lifecycle of the consumer. And even they do ALL of this, we’re still seeing issues of non-native plants outcompeting native ones. And even if the non-native does a better job than the native version, I still want the native one to exist and thrive.
The last sentence is the main point of Mr. Bishop’s comment. He has a preference for native plants. We all have a right to our horticultural preferences. The mantra of the Million Trees blog is that everyone should be free to plant whatever they want, for whatever reasons. We only ask that they quit destroying the plants they don’t like, especially on public land that belongs to everyone and especially with herbicides that are damaging the environment and its inhabitants.
Mr. Bishop is mistaken about some of his beliefs. Non-native plants are providing valuable habitat and food for many insects and animals. For example, 75% of overwintering monarch butterflies in California roost in eucalyptus trees. Non-native vegetation prolongs the blooming period in California, which provides nectar to birds and insects year around. Anna’s hummingbird has greatly expanded its range in California because of the availability of winter nectar provided by blooming eucalyptus. The Anise Swallowtail butterfly is now found in California year around because of the availability of blooming non-native fennel. The berries found on non-native plants are as nutritious as those on native plants. There are many more examples. If you want to read the scientific studies that corroborate these statements, put the key words in the search box and you will find the evidence you require.
We do not begrudge anyone’s preference for native plants. However, we object to the fabrication of “evidence” used to justify that preference. There is no need to justify a preference for native plants, but when inaccurate statements are made to justify that preference, Million Trees was created to report the accurate evidence that native plants are not superior to non-native plants with respect to the ecological functions they perform.
I would like to hear the author’s thoughts on the ever degrading landscapes along roadways where unchecked growth and spread of vines (mostly non-native) have resulted the death of numerous trees and forests. I recently read that the cost associated with repairing downed power lines and cleaning up the mess left behind is in the millions – or maybe it was billions and billions. lol. In any case, those are tax dollars going down the drain.
There seem to be several unrelated themes in your comment.
(1) “degraded landscapes along roadways…” I agree that non-native vegetation usually occupies disturbed ground such as roadways. The expense of controlling that vegetation is the consequence of the disturbance, not the vegetation.
(2) “…resulted [in] the death of numerous trees and forests.” There is no evidence that such vegetation “kills trees.” The exception to that rule is when herbicides that kill trees are sprayed on the unwanted vegetation by those who aren’t following the manufacturer’s label that advises against spraying herbicides under non-target trees. There are many examples of trees killed by inappropriate use of herbicides. Here is an example in Michigan: https://milliontrees.me/2013/03/12/when-the-cure-is-worse-than-the-disease-incompetent-pesticide-use/ Here is an example in Oregon: https://www.opb.org/news/article/odot-ponderosa-pine-pesticide-logging-sisters-highway-20/
(3) “cost associated with downed power lines and cleaning up the mess left behind.” Downed power-lines are caused by negligent maintenance of power lines by utilities companies. Non-native vegetation is not the cause of failed power-lines.
(4) “tax dollars going down the drain” You fail to make the case that non-native vegetation is costing taxpayers money. If anything, the futile and damaging attempt to eradicate harmless vegetation is wasting taxpayers’ money.
My comment was an inquiry into your thoughts on a quantifiable and known problem documented by the federal government and local governments throughout the US…namely the cost of invasive species. I am sorry that you couldn’t follow the theme.
Thank you for clarifying your question. This is the study that is quoted by the government: Pimentel, David, “Update on the environmental and economic costs associated with alien-invasive species in the United States,” Ecological Economics, 52:273-288, 2005. The study claims the economic impact of alien plant and animal species in the US is over $120 billion per year.
Here is one of many critiques of that cost estimate: Hamilton, Garry, The New Scientist, January 20, 2011. Here is Mr. Hamilton’s critique of Pimentel’s estimate: “The study has been roundly criticized for ignoring major economic benefits [of non-native plants and animals] and for including the cost of controlling species that may not need controlling, as well as factoring in events of questionable relevance, such as bird deaths caused by domestic cats.”
Since most of what is being done by eradication projects seems unnecessary to us, we have always assumed these cost estimates are more a reflection of money wasted than a report of actual economic harm. For example, if hundreds of gallons of herbicide are used to kill plants just because they aren’t native, the harm is more in the herbicide use, than in the money wasted on it. In any case, the waste of money is not being caused by the non-native plants, but rather by the ideologues who choose to destroy them.
So the EPA seems to think the high numbers of non-natives are a problem. Maybe Tallomy overstated things a bit but this article seems to act like invasive species are a good thing.
First make a distinction between non-natives and invasives, as the EPA article does: “Not all non-native species become pests, or even survive, in new locations (see the Ten Percent Rule).” Tallamy makes the same mistake. In his most recent book, Nature’s Best Hope, he says there are 3,300 invasive plant species, a number that is difficult to defend.
The perspective of this website is that there are advantages and disadvantages to non-native plants and that both should be taken into consideration before launching eradication projects that usually damage the environment by using herbicides. When non-native plants become invasive, there is often an underlying reason that isn’t reversed by eradicating the plant, such as the warmer climate, pollution, disturbance, etc. If the underlying problem isn’t resolved, the plants return.
The first thing I do is look for conflict of interest from the author of an article. And look at this, the author is called Webmaster – Red lights going off. The cherry picking of facts is not useful, and of course in the world of real science hypotheses are long standing until extensive confirming (or nonconforming) studies are done. I look and say where is more damage done, agreeing or denying this current hypothesis. I’ll stick with Tallamy and have the courage to share your name and expertise in the future Mr. Webmaster.
What conflict of interest? I derive no economic benefit from my website. I don’t sell books or make paid presentations to the public. I don’t use my name on my website because of comments like yours. I must use my name when I write or speak at hearings about projects on public lands, so I have experience with the name-calling and personal attacks that those provoke. I have been chased down the hallways of city hall. I have had a rock thrown through my car window. I have had threatening letters delivered to my home.
I don’t owe anyone my name. Your personal attack is solely an attempt to intimidate. It only makes my arguments look stronger. If you weren’t afraid that my work is effective, you wouldn’t need to intimidate me.
What is your conflict of interest? Are you earning your living in the “restoration” in industry?
To Mr./Ms. Webmaster,
It’s remarkable you’d spend this much time misinterpreting and cherry-picking so many sources to defend an idea that nonnative plants are just as functional as native species, if not more so. A quick look into “Conservation Sense and Nonsense” reveals why this is the case. You have taken a project near and dear to you and have attempted to identify as many “statements” that back up your view on whether Eucalyptus should be removed in San Francisco. This was then expanded into an idea that “other nonnative plants have a role to play” too. Sure, some fauna and other biota adapt to form relationships with nonnative plants; however, that make ups a small percentage of an area’s overall biodiversity especially when compared to the existing relationships between native biota.
Webmaster: What is the percentage of “existing relationships between native biota?” You can’t answer that question and neither can I. Claims about the superiority of native plants are not based on data. They are based on the opinions of people who prefer native plants. I can only provide a “small percentage” of non-native plants forming relationships with “fauna and other biota” because my examples are based on actual empirical studies that prove those relationships. I don’t rely on my opinions. I rely on studies done by academic scientists. They are limited in number because of limited resources.
For example, let’s use your take on “nonnative invasive species being capable of forming new relationships with native plants”. First, these species that are wildly “successful” at forming these unhealthy relationships do not facilitate healthy ecologies.
Webmaster: The concept of successful non-native species forming “unhealthy relationships” is a moral judgment that has no scientific meaning. The success of all species is measured by science as reproductive success. That’s evolution at work. We cannot control evolution nor should we try. I leave it to religious dogma to condemn relationships as “unhealthy.”
Second, consider the percentage of nonnative species that end up being capable of forming healthy ecologies with native vegetation? Most certainly fewer than those that become invasive and “successful” for themselves rather than the community. You seem to pick out an overwhelmingly small number of examples to support your claims, but what’s worse is you then have the audacity to try to dismiss the importance of the robust ecologies our native biota have formed with their environments.
Webmaster: Again, I provide as many examples as are available in scientific literature. I also read the literature of invasion biology and the activist advocates such as California Native Plant Society and California Invasive Plant Council, attend their conferences and report what I learn from them. I find more evidence in their literature of the failure of their eradication efforts than I do of their success.
In doing all of this you have demonstrated your devotion to your pet project and your lack of objectivity to the subject. If your ego allows, I hope you’ll use your platform in the future to find and discuss real solutions to the issues plaguing our ecosystems, because buying into the idea that nonnatives perform on the same level natives do is just silly.
Webmaster: This is another indication that you have not read enough of the 459 articles on this website to pass judgment. If you would read further you would find many articles about solutions. A few examples: (1) Spend our limited time and money on addressing the causes of climate change because climate change will ultimately kill the plants you prefer; (2) Quit using herbicide on non-native plants because they are damaging the soil and killing the plants you prefer; (3) Before making commitments to eradication, conduct a cost-benefit analysis that weighs both the costs and the benefits of the non-native species and add to that analysis the costs and damage caused by the eradication effort. And many others.