native plant movement – Page 9 – Conservation Sense and Nonsense

Vandalism by native plant advocates

In 2010, Timothy Paine, an entomologist at University of California, Riverside, published an article (1) about the introduction of Australian insect predators of eucalyptus into California. Eucalyptus is native to Australia. It was introduced to California in about 1850 and was virtually pest free until 1983. Since then 15 insect predators of the eucalyptus have been found in isolated locations in California.

Professor Paine observes that, “The spatial and temporal patterns of introductions [of these insect pests] do not seem to be random, particularly when taken in perspective of the geographic distribution of the insects in Australia.” For these and other reasons explained in his publication, Professor Paine speculates that “…with no definitive proof, we suggest that the multiple patterns may be nonrandom; instead they suggest the possibility of intentional introductions.”

In a recent interview Professor Paine explains, “We took all of the available information we had on the introduction of eucalyptus pests into California and the conclusion we drew is that there is a very high probability that someone was intentionally introducing [the insect pests of eucalyptus]…There is likely intentional movement of insect pests of eucalyptus into the state. The patterns suggest that.”

Professor Paine agonized about publishing his study. Responsible people are appropriately reluctant to make accusations in the absence of proof. He decided to publish because of the implications of his findings:

“Intentional introductions of insect herbivores onto crop plants, or organisms pathogenic to plants or domestic animals, represent an insidious threat that could severely damage the national agricultural economy, endanger a safe and abundant food supply, threaten water quality or quantity, increase the risk of wild fires, or degrade environmental quality across massive areas.”

Professor Paine has had some success with finding biological controls of these insect pests of the eucalyptus. However, as fast as he can find an effective antidote species of insect, a new pest arrives to attack the eucalyptus. His research is controversial because the native plant advocates who despise eucalyptus and demand its eradication are opposed to any attempt to control the insect infestation. Jake Sigg, our local, prominent native plant advocate is quoted as saying, “I think the University ought not to be going ahead with this research without considering all of the ramifications and hearing from all parties.”

Jake Sigg is a big fan of biological controls to eradicate non-native plants, so we find it ironic—even hypocritical–that he is opposed to research needed to save the eucalyptus from its insect predators. In his Nature News of February 18, 2011, he said, “On this scale, biological control offers the most promise, and–take note–would obviate the need for herbicides. Unfortunately, it is inadequately funded. The beauty of biocontrol is that if the necessary rigorous (and expensive) research is successful the problem of that plant is taken care of for all time–which means it is really inexpensive in the long run.”

So apparently biological controls are highly desirable if they are used to eradicate non-native plants and trees. If they are used to save non-native trees, they are verboten, in Mr. Sigg’s opinion.

The long track record of vandalism by native plant advocates

We can’t prove that Australian insects were intentionally imported to California to kill eucalypts. However, if they were it would not be the first time that native plant advocates have used vandalism to eradicate our eucalypts.

The historical record of vandalism of non-native trees in San Francisco goes back nearly 20 years. In 1994, the Sacramento Bee published an article (2) about non-native Monterey pines and eucalyptus being cut down in public parks by a native plant advocate by the name of Greg Gaar. According to the Sacramento Bee, Mr. Gaar had planted these trees and then changed his mind some 20 years later. (For the record, we note that we don’t approve of such unauthorized plantings any more than unauthorized destruction.)

The California Native Plant Society apparently convinced Mr. Gaar that the trees were a threat to San Francisco’s “natural heritage.” He cut down trees on Mount Davidson and Tank Hill in San Francisco and was sent a bill for $10,996.27 by the Recreation and Park Department. The Bee reported that Mr. Gaar was unemployed and had no intention of paying the bill. Getting caught was apparently the end of that particular method of destroying non-native trees.

Native plant advocates then found a more surreptitious method of destroying the trees. They began girdling the trees in the public parks of San Francisco. Girdling is a method of killing a tree slowly. A band of bark is hacked off the circumference of the trunk with an axe or chainsaw. This prevents water and nutrients from traveling from the roots of the tree into the tree. The tree slowly starves to death. The bigger the tree, the longer it takes to die.

Bayview Hill, 2010 — Girdled trees, Bayview Hill, San Francisco

After girdling the tree, native plant advocates stacked up vegetation around the scar so that it was not visible to the public. Even if the public noticed the scar, they didn’t know what it meant until the tree began to die. By the time the trees started to die several years after the girdling began, about 1,200 trees had been girdled in the parks of San Francisco. Most of them were on Bayview Hill, and many are still visible on Mount Davidson.

According to an article in The Independent, some of the girdling was done by city employees of the Natural Areas Program in the Recreation and Park Department, but much of it was done by native plant advocates, described as “volunteers” by their supporters and “vandals” by their critics. The Independent quotes the head of the urban forestry division of the Recreation and Park Department as saying that trees were also being killed by dousing them with pesticides.

There was a noisy outcry when the public figured out what they were doing. The native plant advocates paid a public relations price for their vandalism and they quit doing it. They are no less dedicated to destroying all of our eucalypts. Perhaps they have moved on to even more nefarious methods such as introducing deadly insects.

We wouldn’t be at all surprised. One of our more memorable debates with a prominent local nativist was about the plan of the Natural Areas Program to reintroduce a legally protected native turtle to a local park that is heavily forested with eucalypts. We knew that rare turtle requires unshaded nesting habitat within 500 feet of its water source. Providing that habitat to this legally protected turtle would have required the destruction of all the trees in that park.

When we objected to the reintroduction of that turtle, the nativist smirked and said, “You know nothing can stop us from putting that turtle in that park whenever we want. And the law provides the same legal protection to that turtle whether it is found there naturally or put there by man.”

Some of these people will stop at nothing. They are appropriately called eco-terrorists.

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(1) Timothy Paine, et. al., “Accumulation of Pest Insects on Eucalyptus in California: Random Process or Smoking Gun,” Journal of Economic Entomology, 103(6): 1943-1949, 2010

(2) “San Francisco garden guerrillas axing alien plants in San Francisco,” Sacramento Bee, February 19, 1994. This article is not available free on-line. However, it can be purchased inexpensively from Sacramento Bee Archives.

The Ruth Bancroft Garden where plants from all over the world are welcome

The Ruth Bancroft Garden in Walnut Creek, California, is a 3-acre remnant of a 400-acre fruit farm started in the 1880s by Hubert Howe Bancroft. Bancroft is a familiar name in the Bay Area because Mr. Bancroft was also a famous historian and publisher who amassed a huge collection of documents about the American West. He donated that collection to University of California at Berkeley, which is the origin of the Bancroft Library there. The Bancroft Library is California’s greatest repository of California history.

When Mr. Bancroft purchased his property, it was oak woodland. These were the venerable valley oaks (Quercus lobata), the largest oak in Northern California. Only one of these oaks remains in the garden. It is estimated to be 350 years old. Its contorted branches create an enormous tent of shade, reaching to the ground. There is not a more beautiful tree, in our opinion.

Valley Oak leaf — Quercus lobata, named for its deeply lobed leaves

Mr. Bancroft’s granddaughter-in-law, Ruth Bancroft started planting her garden in 1972. She had a life-long interest in cactus and succulents, so it wasn’t a good year to begin that venture. The hard freeze of the winter of 1972-73 killed many of the young plants which are not hardy in temperatures below freezing. Fortunately, such hard freezes are rare in the Bay Area and the garden has suffered significant losses only once since then, in winter 1990.

Ghost Gum, Wattzing Australia — Ghost Gum. Courtesy Cynthia Clampitt, Waltzing Australia

There are several eucalyptus trees in the garden, but one is a stand-out. The ghost gum (Eucalyptus pauciflora) is aptly named for its white bark. Coincidentally its ancestral home is the Snowy Mountains in Australia where it is often found standing in the snow. It is one of the few cold-tolerant species of eucalypts. Our opinions of eucalypts are heavily influenced by one particular species, the blue gum eucalyptus, because it is the predominant eucalypt in California. We often forget that there are actually 700 species of eucalyptus and therefore there are a wide variety of forms and horticultural characteristics. The ghost gum in the Bancroft Garden was flowering and swarming with bees collecting pollen and/or nectar. The flowers were close to the ground so we were able to confirm that the nectar was not at all sticky, as critics of eucalyptus often claim.

Flowers of ghost gum — Flowers of Ghost Gum with visiting bee

Touring the garden, we were reminded of many of the themes of the Million Trees blog.

Planting species outside of their range is insurance

The plants in the Bancroft Garden are from all over the world, particularly similar climates such as Australia, South Africa, and Mediterranean countries. Many of the plants come from drier desert climates. Several of the plants in the garden are extinct or nearly so in their native ranges. They continue to exist in the world only because they were exported to new locations before they disappeared from their ancestral homes.

Agave franzosinii is no longer found in the wild in Mexico

Golden Barrel cacti are endangered in the wild due to unscrupulous collectors and the flooding of their habitat by a hydroelectric project,

This is one of many reasons why we do not share the purist vision of the native plant movement, that only plants native to a particular location be allowed to exist in that location. In a changing climate, it is particularly important that plants and animals be allowed to remain where they have been introduced. Their new homes are insurance against their extinction from the Earth.

The characteristics that native and non-native plants have in common

Although most of the plants in the Bancroft Garden are not native to California, there is a section of the garden that is devoted to native plants. Ruth Bancroft had some difficulty establishing that portion of the garden: “When Ruth Bancroft decided to experiment with native California penstemons…many of her plants died. She added even more rock to the bed and planted again. In the improved drainage, that this rocky bed now provides, penstemons thrive alongside such other California native perennials as woolly blue curls and…buckwheats.”

Matilija poppy (Romneya coultera), is another California native in the Bancroft garden, but one which must be watched closely because, “…its major problem is that it spreads underground and can be invasive.” This is a description often applied to non-native plants. However, when the author is a horticulturalist, rather than a nativist, it is sometimes applied to native plants as well.

There is also a native Manzanita in the garden which is a hybrid descendent of two unrelated Manzanita species which have long since disappeared from the garden. Hybrids of native plants are often eradicated by native plant advocates who want to freeze all native species into place. Hybridization represents change and abhorrence of change is a basic tenet of nativism. The existence of this hybrid in the Bancroft Garden is an example of why we are opposed to nativism in its purest form. The hybrid survives, but its two ancestors are gone. Aren’t we better off with this survivor in the Bancroft Garden than with no Manzanita at all?

The Bancroft Garden was an opportunity to revisit these themes of the Million Trees blog:

Native plants are as likely as non-native plants to require tending in the garden, such as soil amendments
Both native and non-native plants are sometimes invasive
Hybridization is another means of insuring the survival of plant genes

This is a particularly good time to visit the Bancroft Garden. There is an exhibit of sculpture by artists from all over the West Coast in the garden until July 14, 2012. It is an interesting and lovely garden which is rich in California history.

Sculpture in Bancroft Garden — Sculpture in the Bancroft Garden

California Academy of Sciences: “Evolution in the Park”

In 2003, when the great debate with native plant advocates about the future of San Francisco’s public parks reached a fever pitch, the California Academy of Sciences stepped into the fray by publishing this article in their quarterly publication, California Wild. This article was written by Gordy Slack, free lance science writer and former editor of California Wild.

Golden Gate Park 1880 — Golden Gate Park in 1880. The trees are about 10 years old. In the distance, looking south, we see the sand dunes of the Sunset District. That’s what most of Golden Gate Park looked like before the trees were planted.

As you will see, “Evolution in the Park” (1) urges the public to consider that the parks of San Francisco have been transformed over the past 150 years from predominantly barren sand dunes to green oases of non-native trees and plants. Using Golden Gate Park as an example, Mr. Slack reminds us that the non-native trees provided the windbreak needed to protect the entire landscape which we admire today. The park has changed and it will continue to change, because nature is dynamic. The forces of evolution are stronger than human desires to freeze-frame our world.

At the time, we were deeply grateful to Mr. Slack and to the Academy of Sciences for taking a position on the controversy. We remember thinking that the opinion of this prestigious institution would surely settle the controversy. But we were mistaken, because native plant advocates would not even read this article, let alone heed its message.

As the Environmental Impact Report for the Natural Areas Program undergoes revision and the controversy heats up again, we reprint “Evolution in the Park.” We can only hope that someday reason will prevail.

Tree Ferns-Golden Gate Park Creative Commons Attribution — Tree ferns from New Zealand are one of many species of non-native trees that make Golden Gate Park the beautiful place it is today. Creative Commons

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“When San Francisco officials asked the great nineteenth-century landscape architect Frederick Law Olmstead how to turn the wind-scoured dunes of the western half of the city into a green, rambling park, he was happy to offer advice: Don’t bother, he said, it’ll never work.

They went ahead anyhow, establishing three-mile-long, 1,107-acre Golden Gate Park on April 4, 1870. The decades that followed saw an almost unbelievable transformation under the strong hand of the park’s first superintendent, William Hammond Hall. He shaped glades and grew forests, dug lakes and planted lawns, until people nearly forgot that under the acres of grass and trees and shrubs lay mountains of sand.

The invention of Golden Gate Park was an amazing engineering and horticultural accomplishment, but it was not an environmental one—at least not in the sense of conserving native natural resources. If the California Native Plant Society (CNPS) had existed then, it would never have allowed Hall to spread tons of exotic barley seed over the dunes as part of his plan to “reclaim” them. The barley achieved what Hall wanted—to create favorable conditions for the thousands of alien trees and shrubs he would soon plant. And yet the CNPS now meets in Strybing Arboretum and botanists love the park. Everyone does. It would seem as silly to criticize the park’s blue gum trees for being out-of-towners as it would be to criticize most of us for being exotics. The park is as much an urban invention as the parking lot or the shopping mall, only much better. There is nothing wild about it…except what goes on there.

Nancy de Stefanis is the Director of San Francisco Nature Education, a group that leads nature studies in Golden Gate Park. She is perhaps best known for her discovery in 1993 that great blue herons were nesting in the park’s Stow Lake, and for her efforts to protect those nests from raccoons and other threats (California Wild, Summer 2002). A few days ago, on an early morning walk in the park, she saw a great blue plucking endangered red-legged frogs out of a pond. She saw feral cats, gray squirrels, and a three-foot-long box turtle. All this, and she had intended to look for birds! She saw those, too: an albino robin, varied thrushes, ravens, white- and gold-crowned sparrows, and a courting pair of red-tail hawks doing loopty-loops and dives. She saw a bevy of seven California quail running through Strybing Arboretum, the only population of quail left in the park. “It was incredible,” she said. “We saw 25 bird species easy.”

Anyone who’s spent much time in Golden Gate Park has wild stories to tell. My own favorite took place a few years ago, after I’d pulled an all-nighter at the magazine and was tired enough to sleep dangling off of Half Dome. Half Dome was too far away, so I walked a few hundred yards east on Middle Drive and up a tiny path back to Lily Pond. I walked the perimeter looking for a place to sleep. The pond had steep vegetated banks all around except for a small, reasonably sloped patch of dirt on the east side. I kicked away some guano, put a newspaper under my head, and fell asleep.

I woke up half an hour later; something soft was tickling my arm. I raised my head slowly to find myself surrounded by mallards. There must have been 20 and they filled every inch of the dirt patch around me. One nestled comfortably between my outstretched arm and my torso.

Each duck had its head swiveled and tucked into the feathers on its back. When I lifted my own head, the birds next to me raised and turned theirs as well, and a couple of them stirred, causing a chain reaction of awakenings in the ultimate morning-after surprise. No one lost his or her cool, though. I tiptoed out of their realm and headed back to work, downy feathers clinging to my sweater and my hair. That was how I became the Man Who Sleeps with Ducks.

Raymond Bandar, a field associate in the Academy’s Department of Ornithology and Mammalogy, grew up in Golden Gate Park and has a thousand wild stories to tell. He says that in the 1940s, when he was a boy, it was a “biologist’s paradise.” He spent long summer days hunting for garter snakes, alligator and fence lizards, bush rabbits, Pacific pond turtles, weasels, and red-legged frogs. Peacocks roamed free in the park, and there Bandar courted his wife, Alkmene. They took long, moonlit walks from the beach to the park’s entrance on Stanyan, stopping to spoon in the Valley of the Moon.

Most old-timers like Bandar long for the good old days, when the park was “less manicured.” It’s hard to tell if this is because the park used to be wilder, or because the old-timers were. But there’s no doubt that the park refuses to cooperate by holding still. As Heracleitus said, “You can’t step into the same river twice.” (Or as Cratylus, Heracleitus’s follower, trumped, ‘You can’t step into the same river once.’)

The park’s “ecosystems” are a moving target, changing with park administrations and larger cycles of growth and death. In recent years, the Parks Department has cleared away much of the undergrowth that had been protecting ground-nesting birds—and homeless humans. Other forces originate outside the park but have an influence by increasing, diminishing, or eliminating the animals that live within. If there are no peregrines anywhere else in California, there aren’t going to be any in Golden Gate Park either.

Late Academy ornithologist Luis Baptista used to talk about the 1980s in the park. California quail were common then, running here and there on urgent business. Native bush rabbits lived here, too. The rabbits are now gone and the quail nearly so. I’ve heard speculation that the rabbit population may have collapsed partly under predation by humans, too. But both are most likely victims of the park’s shifting food web.

Raptors returned when their populations rebounded from the DDT poisoning that largely ended four decades ago. Recently, red-tailed, red-shouldered, and Cooper’s hawks have moved in, according to Douglas Bell, a biology professor at California State University in Sacramento. The park is now “probably a sink for white-crowns” he says. “It draws them in, but because of the intense predation, their survivorship is very low.” But even bigger players in the songbird and quail equation are the park’s resident feral cats. According to Baptista and Bell, white-crowned sparrow deaths in the park are probably due mostly to cats.

In addition to feral cats and other predators, floral changes affect park wildlife as well. Many of the Park’s trees are reaching climax now, says Peter Dallman, who is writing a natural history guide to Strybing Arboretum. The big trees are falling or are being cut down in anticipation of their natural collapse. The pygmy nuthatch, a bird that nests in the park’s climax Monterey pine forest, will likely flee the park when those trees come down.

Today, raccoons are plentiful. So are ravens, though Bell remembers that not long ago no ravens nested here. Exotic cowbirds have arrived, too; they lay their eggs in the nests of other birds, which then raise ravenous cowbird chicks, often at the expense of their own young. Squirrels are multiplying out of control, says Dallman.

Cat populations are strong, but not as strong as their political lobby. The bison herd, introduced to the park in 1894, remains stable at eleven. But the reintroduced grizzly bears (Bandar remembers when there were at least two sad grizzlies in cages in the park’s southeast corner) are long gone. The last Golden Gate grizzly, Monarch, is now stuffed and on exhibit in the Academy’s Wild California Hall.

These changes and conflicts raise some uncomfortable questions about the park and its mission. By what standard can the costs or benefits of these changes be measured? Should we be trying to restore Golden Gate Park systems and populations that are at bottom artificial? Should we simply maintain the species we prefer, and get rid of, or let slip away, the unpopular ones? Should “maximum diversity” be the goal, and mandate mediations of conflicts that arise between incompatible species, such as cat and quail?

To maintain quail in the park for the long term, for instance, would require “intensive and sustained human intervention,” says Bell. “We’d have to rely on the full range of wildlife management techniques.” Predation would have to be monitored and protective habitat cultivated. New quail stocks would have to be introduced, and electrically charged wire cages (through which the quail could fit, but not cats or ravens or raptors) could be built around nesting areas. But without heroic and constant human support, the quails’ days in the park are numbered.

Like its creation, the park’s future will be shaped by human invention, its progression determined by our priorities.”

Golden_gate_park_aerial — Golden Gate Park, aerial view. Gnu Free Documentation

(1) Gordy Slack, “Evolution in the Park,” California Wild, Spring 2003 [reprinted with permission of author]

Pangaea: The first but not the last globalization of ecology

The continents have been sliding about on the Earth since it was “created”(1) approximately 4.5 billion years ago. Although geologists tell us that the continents came together and broke apart several times prior to the formation of the supercontinent geologists call Pangaea, this is the geologic period of most interest to us because life forms were sufficiently complex by that period that we can recognize their modern counterparts.

Pangaea is said to have been assembled about 237 million years ago, during the Early Triassic Period, shortly after the great Permian extinction, the period of the most extensive extinctions of plant and animal species in the history of the Earth. Pangaea began to break apart about 50 million years later, but the African and South American continents remained fused–into a continent dubbed Gondwana–until about 100 million years ago. (1)

During that period of nearly 160 million years, many new life forms emerged and others died out. Cone-bearing plants replaced some spore-bearing plants before Pangaea formed and dominated the Earth during much of Pangaea’s existence. The first true mammals, flowering plants, birds, lizards, and salamanders appeared before the break up of Pangaea was complete.

What are the implications of the development of new species of life on Earth at a time when there was a single, unified continent? That is the question we are considering today. Obviously, the transport of plant and animal species into new territories is facilitated by their proximity. Seeds are more easily transported by wind and animals if they need not cross barriers such as oceans, as they must today. As a result there was greater homogeneity of species during the geologic periods of Pangaea. And species diversified rapidly when Pangaea broke up into the 7 continents of today. (2) These diversified species have common ancestors.

Even after Pangaea began to break up into separate continents, there were land bridges between some of the continents during periods of glaciations when water was locked into ice, draining the oceans. Animals could travel over these land bridges from one continent to another, often bringing plant species with them, usually unwittingly. That’s how the first humans in North America and ultimately South America traveled from Asia about 13,000 years ago at the time of the last ice age.

The common ancestry of many plants and animals is one of many reasons why the concept of “native” is ambiguous and is often debated. We will consider a few examples in which the designation of a particular plant as native or non-native seems debatable.

Is the Dawn Redwood native to California?

Dawn redwood (Metasequoia glyptostroboides) is closely related to our redwood trees, Coast Redwood and Giant Sequoia. Dawn redwood is unique in being a conifer that is also deciduous (loses its foliage in winter), unlike our redwood trees which are evergreen. Dawn redwoods were until recently considered native to remote regions of China where they are considered “critically endangered.”

Dawn redwood in spring. Wikimedia Commons

However, scientists at the Museum of Paleontology at UC Berkeley tell us that there is fossil evidence that dawn redwoods grew in California about 40 million years ago. Dawn redwoods now grow successfully in the Bay Area. There is a famous specimen in front of McLaren Lodge in Golden Gate Park, headquarters of San Francisco’s Recreation and Park Department. Every autumn, when the tree turns red, park staff receives calls from the public expressing their concern that the beautiful tree is dying.

Dawn redwoods died out in California during the last ice age because the climate was cooler than dawn redwoods could tolerate. So, now that the climate has warmed again, and dawn redwoods are back, why not welcome them as a “return of the natives?” That’s the kind of flexibility that makes sense to us, particularly in a time of rapidly changing climate.

Dawn redwood in autumn. Wikimedia Commons

Unfortunately, we don’t find such flexibility in the native plant ideology. Dawn redwoods are rare both in California and in China from which it was reintroduced, and it is therefore not one of the trees that native plant advocates demand be eradicated. Monterey pine and Monterey cypress are not so fortunate. These are also trees for which fossil evidence suggests that they lived in San Francisco in the distant past and their native range is less than 150 miles down the coast in Monterey. Both tree species are also considered threatened in their native range. Yet, native plant advocates demand their eradication in San Francisco.

This is an example of the rigidity of the native plant ideology that has earned them the reputation of fanatics.

Does Rhododendron ponticum “belong” in Britain?

We told our readers in a recent post that Rhododendron ponticum is one of only about a dozen plants in Britain that are considered “invasive.” It is a stunningly beautiful plant which is being aggressively eradicated in Britain. Richard Mabey in Weeds: In Defense of Nature’s Most Unloved Plants offers this explanation for why this particular plant is “invasive” in Britain:

“The next most serious weed is probably rhododendron which, unusually, has the ability to invade existing ancient woodland, especially in the west of Britain. This may be because, if one employs a very long time scale, it is not strictly an alien. The species that forms impenetrable thickets in western Britain is Rhododendron ponticum, whose pollen remains have been found in deposits in Ireland dating back to the last interglacial. The species was plainly accustomed to growing in Atlantic woodland and may have retained a genetic “memory” of how to cope with this habitat and its competing species. But it didn’t grow spontaneously in Britain for the next 30,000 years, and all the current feral colonies are regarded as originating from garden escapes.”(3)

Once again, we wonder if “welcome home” isn’t a more appropriate response to this beautiful plant. We find the definition of “native” as arbitrary as the definition of “invasive.” Both seem to be terms used by people who abhor change. And in a rapidly changing world, does such resistance to change make any sense? We don’t think so.

(1) The use of the word “created” implies no particular origin of the earth, merely its beginning. https://www.usgs.gov/faqs/what-was-pangea-0?qt-news_science_products=0#qt-news_science_products

(2) Crosby,Alfred, Ecological Imperialism, 2^nd Edition, Cambridge, University Press, 2004

(3) Mabey, Richard, Weeds: In Defense of Nature’s Most Unloved Plants, Harper-Collins, 2010

Evolution didn’t stop in 1492

One of the most appealing of the many arguments used by native plant advocates in support of their ideology is the evolutionary concept of “co-evolution.” Co-evolution is defined by Forgotten Pollinators(1) as “The idea in evolutionary ecology that certain mutualistic organisms have directed or redirected each other’s evolutionary trajectory.” The implication of this theory is that plants and animals that have evolved together are interdependent and that loss of a particular plant will result in the loss of the animals with which it evolved. Native plant advocates sometimes describe these relationships as “a lock and key,” implying that native plants and animals fit together in a mutually beneficial relationship which is exclusive.

Those who believe this theory are obviously deeply committed to saving all native plants because they believe the loss of any single plant would inevitably lead to the loss of the animals that are dependent upon it. Likewise, non-native animals are often exterminated based on the assumption that they compete with native animals and that loss of native animals will lead to the loss of native plants.

There are three problems with this theory. First, while there are some examples of truly exclusive co-evolved relationships in which both species cannot survive without the presence of the other, the number of such relationships is quite small. Second, even these relationships are not immutable because evolution has not stopped, and therefore other species may develop mutualistic relationships with the prior exclusively mutualistic species. And third, organisms are opportunistic and are quick to take advantage of any new opportunities, meaning that many interactions observed between species in the wild are not co-evolved at all. For example, the honeybee pollinates hundreds of species of North American plants and it didn’t evolve with any of them (since honeybees were introduced into North America from Europe, which had introduced them from Africa).

Why is “co-evolution” rare in nature?

When defining “co-evolution” Forgotten Pollinators adds this caveat, “Good examples of truly reciprocal coevolution are difficult to find.” Although the concept of “co-evolution” has a certain logical appeal, the explanation for why it is rare in nature is even more logical: it is a risky survival strategy in a world that is constantly changing. If, for example, the specific plant upon which a specific animal depends doesn’t bloom or doesn’t return from its dormant phase because of a sudden, even temporary, change in the climate, the animal that is dependent upon that plant is out of luck. Since such fluctuations of environmental conditions are common, natural selection does not favor the animal that is restricted to a single plant for which there is no substitute. Such exclusive relationships therefore do not persist in nature.

Nature provides “back-ups” that will enable plants and animals to respond to fluctuating environmental conditions. For example, few plants have a single pollinator. Most have several, usually of several different types. One bee may be a particularly effective pollinator of a particular plant, but that plant is probably also visited by a fly, a butterfly, a bird, a beetle, etc. As humans do, plants and animals don’t just give up when conditions change. We all look for and usually find other alternatives.

IMG_5452=2 — Native bumblebee gathering nectar and/or pollen from non-native cotoneaster. Albany Bulb, Albany, California

“Evolution right under our nose”

The Science Section of yesterday’s New York Times features an article about evolution of animals in New York City. In the most densely populated city in the country, founded nearly 400 years ago, 74% of the native plant species that existed when the city was founded in 1624, still exist there.(2) San Francisco has an even lower rate of extirpation of its native plants since it was founded in 1850. Ninety-seven percent of the 714 plant species known to exist in San Francisco in 1850 are still found in San Francisco.

Panorama_Skyline_Manhattan_Empire_State_Building — Midtown Manhattan as seen from the Empire State Building. Creative Commons Attribution Share Alike

The fascinating article in the New York Times reports that the ability of animals to evolve in response to changing environmental conditions has enabled their survival in the urban environment.

The white-footed mouse is an example of a native animal that is thriving in New York City. The urban environment creates isolated urban islands, such as parks. Scientists find that virtually every park in New York City has a population of genetically unique white-footed mice. In fact, “The amount of [genetic] differences you see among populations of mice in the same borough is similar to what you’d see across the whole southeastern United States,” according to the scientist studying this mouse in New York City.

It’s difficult to imagine a more altered, artificial environment than the road medians on Broadway on the Upper West Side of Manhattan, which are composed of landfill used to cover the subway tunnel. However, scientists have found 13 species of ants living in some of these medians. Nine of the thirteen species are native.

Nature is opportunistic and resilient. It isn’t necessary to eradicate non-native plants and animals to ensure the survival of native plants and animals. What greater laboratory to illustrate the resilience of nature than New York City?

(1) Buchmann and Nabhan, The Forgotten Pollinators, Island Press, 1996

(2) Duncan et al, “Plant traits and extinction in urban areas: a meta-analysis of 11 cities,” Global Ecology and Biogeography, July 2011

A dialogue about insects and non-native plants

We received a comment on our “Wildlife” page from “entomologist” that deserves a comprehensive response.

Conversation with “entomologist”

“entomologist:” “Adaptation to exotic species by specialist herbivores is unusual. Those butterflies that switch to exotics tend to be generalists already.”

Webmaster: “Entomologist” is mistaken that the butterflies now using non-native plants are generalists, by which we assume he means that they use many plants, rather than a specific species. According to Professor Art Shapiro (UC Davis), 26 of the 82 species of California butterflies now feeding on exotic plant species, are using only one plant species. In other words, nearly one-third of California butterflies presently using exotic plant species are not generalists.(1) When butterflies have made the transition from a native to a non-native plant, the plants are usually chemically similar.

Anise Swallowtail, Sutro Forest, March 2010

The Anise Swallowtail is a conspicuous example of a California butterfly that is now dependent upon a particular exotic plant, fennel. This relationship between a specific native insect and a specific non-native plant is one of the reasons why the Million Trees blog was created. Non-native fennel is being eradicated by every native plant “restoration” in the Bay Area.

Over ten years ago, a park advocate in San Francisco became enraged by the eradication of fennel in his park because he was aware of the dependence of the Anise Swallowtail upon the fennel. He made every effort to convince the so-called Natural Areas Program to stop destroying the fennel in his park. He enlisted the help of Professor Art Shapiro in that effort. His efforts were ultimately unsuccessful. The Natural Areas Program considered the non-native origins of the fennel sufficient reason to eradicate it, regardless of the needs of a native butterfly. They continue those eradication efforts to this day.

It is such mindless destruction of non-native plants, regardless of their benefit to fauna (or other benefits) that has made the Natural Areas Program so unpopular with people with a broader view of nature. We value the Anise Swallowtail butterfly as much as any theoretical benefit from eradicating a non-native plant.

“entomologist:” “This idea that exotic plants are as good for wildlife as natives is just plain pathetic, especially for anyone who knows about herbivory patterns on native and exotic plants.”

Webmaster: By “pathetic” we assume “entomologist” means that he does not believe that insects eat non-native plants. He is mistaken that insects do not eat non-native plants. Returning to Professor Shapiro, he reports that 82 of 236 (35%) total species of California butterflies feed 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.(2) 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.

Damseflies, Glen Canyon, Janet Kessler — Damselflies (probably Common Blue) mating on non-native ivy in Glen Canyon Park.

We also use our eyes when we walk in our parks. We often find insects in non-native plants. Those non-native plants are often targets for eradication. The damselflies in a San Francisco park are another example of the contradictory strategies of the Natural Areas Program. They have made several attempts to reintroduce the rare Forktailed Damselfly to one of the parks in San Francisco. Although those attempts have not been successful, we see other species of damselflies in that park, using the non-native plants that are repeatedly sprayed with herbicides by the Natural Areas Program. We wonder if the herbicide use in that park is contributing to the failure of attempts to reintroduce the Forktailed Damselfly. Does the right hand know what the left hand is doing?

“entomologist:” “Insects eating plants are at the base of the food chain and native plants have more insect herbivores and support more native birds.”

Webmaster: We can agree that many birds eat insects and those that do are likely to benefit from greater populations of insects. But, there is substantial evidence that insects are as likely to be found in non-native plants as in native plants and we trust that the birds know where to find them. However, unlike “entomologist” we are as interested in the welfare of non-native birds as we are in native birds.

“entomologist:” “Doug Tallamy’s work shows this in the eastern US conclusively.”

Webmaster: Professor Tallamy’s (University of Delaware) publications do not seem to be available on-line, which prevents us from reading his publications. However, since he studies the insects on the east coast we don’t think whatever he reports trumps the studies that we have cited of insect populations here in the Bay Area.

“entomologist:” “I certainly feel for the loss of trees, but the alternative is that we accept a homogenized set of urban-tolerant plants and wildlife. Maybe that’s ok if you don’t know the difference, but for those of us who actually pay attention it is profoundly sad.”

Webmaster: We don’t see the logic of “entomologist’s” vision of a “homogenized” ecology. If we destroy non-native plants and animals, our ecology will be less diverse. And we hope that the readers of Million Trees will agree that we are, indeed, “paying attention.”

The Big Picture

We suggest that “entomologist” and other native plant advocates step back from their deeply-seated prejudices against non-native plants and consider the big picture. The fact is that insects are particularly vulnerable to climate change because they live in relatively narrow temperature ranges. (3) Although they are adjusting well to changes in vegetation, they are not likely to be able to make an equally successful adjustment to changes in temperatures. Therefore, if our top priority is insects, we would be wise to reconsider destroying millions of non-native trees that are sequestering millions of tons of carbon, contributing to greenhouse gases and thereby to climate change.

(1) Arthur M. Shapiro, “Exotics as host plants of the California butterfly fauna,” Biological Conservation, 110, 413-433, 2003

(2) Dov Sax. “Equal diversity in disparate species assemblages: a comparison of native and exotic woodlands in California,” Global Ecology and Biogeography, 11, 49-52, 2002.

(3) “Mountain plant communities moving down despite climate change, study finds,” Los Angeles Times, 1/24/11

Non-native species are NOT the “second greatest threat to species in peril”

One of many doom and gloom scenarios used by native plant advocates to frighten the public into accepting their destructive “restoration” projects is the claim that “non-native species are the second greatest threat to the survival of species in peril.”(1) Although the statement originates with a scientific study published in 1998, the context in which it was originally reported has long since been lost as it has been cited more than 700 hundred times in scientific studies according to Mark Davis.(2)

The original 1998 article in BioScience by Wilcove et.al. clearly states that the claim is not based on any actual data:

“We emphasize at the outset that there are some important limitations to the data we used. The attributes of a specific threat to a species is usually based on the judgment of an expert source, such as a USFWS employee who prepares a listing notice or a state Fish and Game employee who monitors endangered species in a given region. Their evaluation of the threats facing that species may not be based on experimental evidence or even on quantitative data. Indeed, such data often do not exist.”(3)

This caveat is rarely repeated when the claim is invoked by native plant advocates to justify their crusade against non-native plants and animals. In fact, since the statement was originally made over a decade ago, it is now repeated without reference to the original source. It has acquired the status of a mantra amongst native plant advocates that requires no citation to substantiate its “truthiness.”

The Wilcove et.al. article in BioScience in which this statement was made was heavily influenced by selecting a geographic area which is not representative of the United States as a whole. Although Hawaii is a part of the United States its rates of extinction are not typical of the contiguous states of the union. Rates of extinction are substantially higher on islands because they contain many more endemic (unique) species that do not occur elsewhere. These endemic populations are small and vulnerable to the introduction of competing species. Native populations on islands are not supplemented by immigrations as they are elsewhere.

coqui — Coqui frog is being eradicated in Hawaii. USDA photo

If Hawaii is removed from the anecdotal information in the Wilcove article, the rates of extinction are comparable to those in Canada where introduced species are considered the least important of six categories of causes of extinction (habitat loss, over-exploitation, pollution, native species interactions, and natural causes such as storms) identified in a similar article in 2006(4). This list doesn’t include climate change, which is now considered a serious threat for extinction. Similar studies in the continental United States have reached similar conclusions.(5)

At the time the Wilcove et. al. article was published there was no evidence of a single extinction (or even local extirpation) of a native plant in the continental US resulting from competition from an introduced species of plant. Clearly, the authors of this study were guilty of exaggeration.(6)

Although native plant advocates have misused this publication by taking it out of context, the authors were complicit in its misuse by selecting a geographic area that is not representative of the United States. Non-native species are NOT the second greatest threat to the survival of endangered native species. In fact, they probably aren’t the third, fourth, or fifth greatest threat to native species.

We wish that native plant advocates would examine the origins of their assumptions more carefully. We believe if they did so they would modify their destructive projects to reflect a more inclusive view of nature.

(1) Wilcove, DS, Rothstein, D., Dubrow, J., Phillips, A., and Losos, E, “Quantifying threats to imperiled species in the United States,” BioScience, 48, 607-615, 1998.

(2) Davis, Mark, Invasion Biology, Oxford University Press, 2009, page 181.

(3) Ibid.

(4) Venter, O, et. al., “Threats to endangered species in Canada,” BioScience, 56, 903-910, 2006.

(5) Ibid., page 182

(6) Ibid., page 183

A dialogue about the living roof on the California Academy of Sciences

We encourage native plant advocates to comment on our posts because we learn from them. We learn more about their ideology and the assumptions that support it.

These dialogues with native plant advocates are embedded in our posts and are therefore not as accessible to our readers as they often deserve to be. Occasionally, we will create a post from these exchanges so that all of our readers can benefit from them. In so doing, we hope not to discourage native plant advocates from posting comments, as they are essential to improving our mutual understanding of the complex issues we are debating.

We recently received a comment from someone who seemed to believe that our post about the green roof on the California Academy of Sciences is essentially fraudulent. His accusations deserve a response.

P1010026 — California Academy of Sciences, April 2011

Comment from “Name Here”

May 6, 2011 11:43 am

Name Here: “Since you don’t have the confidence to post your identity, I thought it only fitting to return the favor. Your argument would have much more strength if you were not anonymous.

You claim on your home page to provide citations, yet in this article you fail to tell us who “We had the privilege of meeting the ecology consultant who designed the plant palette for the living roof for the academy and many other institutions around the world.” is referring to. The “ecology consultant” does not have a name? By then throwing out Peter Del Tredici’s name it would appear as though you wish your reader to assume that he was the “ecology consultant” you refer to.”

Webmaster: The ecology consultant for the living roof on the Academy was Paul Kephart of Rana Nursery. He is the person we are quoting in our post about planning for the living roof. Our readers can confirm Mr. Kephart’s role in the design of the roof by reading this article: “High Maintenance Superstar,” Linda McIntyre, Landscape Architecture, August 2009. This article is not available on-line, but the edition of the magazine in which it was published can be purchased on-line. However, Mr. Kephart’s statement quoted in our post was made in a lecture to a group and does not appear in this publication.

Our post did not state, nor did it imply that Peter Del Tredici was the ecology consultant for this project. He is a scientist who has published articles about native plant “restorations,” particularly in urban settings. We quote him in our post because his observations about native plant gardens are directly relevant to the living roof.

Name Here: “On another note, you mention this third predominant species on the roof as “a moss” and then tell us it is non-native, yet offer no proof of this. Citing another blog with no standard of journalistic integrity is not a valid source. You might want to present the scientific name of this moss to prove your point, though I do not believe, judging by your writing, that you actually know the name, or you would have presented it.”

Webmaster: At the time that we published our posts about the living roof, we did not know the names of the mosses on the roof, which is why we quoted the “From the Thicket” blog. The author of the “From the Thicket” blog, Heath Schenker, is Professor of Landscape Architecture at UC Davis. Her background and credentials are described on her blog. She wrote her post about the living roof at the California Academy of Sciences after attending a symposium at the Academy about their monitoring project. Our readers can judge for themselves if this was a credible source of information to document our post at the time it was published.

Name Here: “There are many different species of mosses out there, some native, some non-native. Many moss are very cosmopolitan in their range and therefore may occur natively all over the world. The actual quote from InTheThicket is as follows: “Nobody knows where the mosses came from, but they appear to be varieties of early-succession mosses, the types that commonly show up in disturbed soil.” I challenge you to show me where this says they are non-native.”

Webmaster: After we published our post, the Academy made their monitoring report available on-line: http://www.calacademy.org/pdfs/living-roof-project-results.pdf. The report contained the names of the mosses on the roof: Bryum sp., Rosulabryum sp., Ceratodon purpureus, Leptobryum pyriforme. We took that list to the Jepson Herbarium at UC Berkeley to confirm that our description of the mosses was accurate. The staff at the Herbarium looked up those mosses for us and described them as “cosmopolitan,” which means they are widespread and cannot be considered either native or non-native. Since these mosses were not amongst the 9 species of native plants originally planted on the roof, we felt comfortable with our original description of them. They are clearly “volunteers,” not part of the original roof top planting.

Name Here: “I think it is important for anyone reading this blog to be reminded that it is just that, a blog. It is written by an anonymous source who can say whatever they like with no fear of reprisal other than these comments, and with no need to live up to journalistic standards of any kind.”

Webmaster: Yes, the Million Trees blog is “just a blog.” However, I invite our readers to consider the difference between this accusatory comment from “Name Here” and the information we present. We provide citations for most statements we make. Those citations are usually of publications by academics at major universities, published in peer-reviewed journals or journalistic articles about their publications. We often resort to journalistic articles because they are easier for non-scientists to comprehend.

We know that we are confronting firmly held beliefs in the community of native plant advocates. Therefore, we cannot expect to challenge their assumptions without providing well-documented information. And since we have often been on the receiving end of ad hominem attacks by native plant advocates, we do our best to protect ourselves from such attacks by standing on firm scientific ground and by remaining anonymous. (One wonders what “reprisals we should fear” for providing information with which “Name Here” disagrees.)

In contrast, “Name Here” questions our credibility without providing any evidence to substantiate his claim that we are fabricating information. Therefore, his comment seems more an attempt to discredit than to illuminate.

Celebrating the first anniversary of the Million Trees blog

We are celebrating the anniversary of our first year of the Million Trees blog by reporting our progress and what we have learned.

Our readership has grown steadily in the past year, particularly in 2011. Daily visits have increased 200% since December 2010.

Of our 50 pages and posts, the three most popular posts, in descending order of visits, are presently:

A more recent post “The Living Roof: A failed experiment in native plant gardening” is in fourth place, but gaining ground quickly. There is apparently considerable interest in the green roof on the California Academy of Sciences.

We have had over 200 comments from readers, most in support of our perspective on the native plant movement, but many critical of our approach to this issue. We have posted most, but not all of the critical comments.

This comment is typical of those few that we chose not to post: “This entire website is essentially just a cesspool of misinformation.” We responded to that reader: “If you would be more specific, we might post your comment. You should also cite your sources as we do on Million Trees. At the moment, your comment contains no information.” He did not respond, so we did not post his comment.

Most native plant advocates who post comments are more specific, but they have never provided references for the generalizations that are the underpinnings of the native plant movement, such as:

Native grassland stores more carbon than forests (Since carbon storage is proportional to biomass, this is a physical impossibility.)
Native plants produce: “Better soil function resulting in improved air quality and hydrology and pollination” (We have seen no scientific evidence to support any of these claims.)
Wildlife prefers native plants (Most wildlife has adapted to non-native plants and is sometimes dependent upon them)

We responded to these comments with scientific references that contradict these claims and we invited the authors to provide us with scientific references that support their view. We did not receive any replies to these requests for information about the sources of their statements.

In one case, we had a long email dialogue with a native plant advocate who filled pages with such generalizations. We repeatedly asked him to cite his sources. Finally he sent us a 12 page bibliography, none of which he claimed to have read. Nor did he make any connection between this lengthy bibliography and the statements he made in support of his arguments. That was the end of the dialogue.

We conclude that these unsupported generalizations about the superiority of native plants are symptomatic of the native plant movement, which is an ideology, not a science. The ideology persists because it is a victim of incestuous amplification, the sharing of misinformation by a group that isolates itself from dissenting views. They hear their assumptions repeated so often that the assumptions are eventually transformed from fiction into fact in their minds.

Unlike native plant advocates, we read all available literature on the subject, particularly publications in support of the native plant movement, such as the newsletters of the California Native Plant Society, Nature in the City, as well as Jake Sigg’s Nature News. When we see new claims of the benefits of native plants, we research those claims by comparing them to the scientific literature.

It is our research of the scientific literature that gives us hope that the native plant movement is losing its credibility. In the past few years, more and more scientists have published their research refuting many of the assumptions of the native plant movement. We have reported on Million Trees the research of some of these scientists: Mark Davis, Peter Del Tredici, Hugh Raffles, and Dov Sax. The publications of these scientists have enabled us to provide our readers with the evidence that many of the assumptions of the native plant movement are unsupported by scientific research.

Thank you to the readers of the Million Trees blog for visiting and commenting. We invite our readers to correct any misstatements of fact, as we try our best to avoid the incestuous amplification that can accompany advocacy. We provide citations of scientific literature whenever possible to avoid that trap. We renew our appeal to native plant advocates to supply us with the scientific literature that they believe supports their ideology and we commit ourselves to reading and reporting such evidence.

P1010138 — Our inclusive view of nature: native and non-native plants at Oyster Bay

For the record, we repeat Million Trees’ primary appeal to native plant advocates: please plant native plants if that is your preference, but quit destroying non-native plants, trees and animals.

P1010137 — Destructive "restoration" at Oyster Bay

Hybridization: “Genetic pollution” or a natural process?

: Presidio variety of California poppy. NPS photo

The San Francisco Chronicle’s gossip columnist, Leah Garchik, recently published a story about California poppies in the Presidio. Apparently, someone planted the “wrong” poppy, or it migrated there. The poppy that is native to the Presidio is small and yellow. This “alien” poppy is the large orange poppy that most of us consider the classic California poppy. The historical record indicates that this classic poppy grew elsewhere in San Francisco, but since it didn’t grow in the Presidio it must be removed because the Presidio’s Vegetation Management Plan “contains the requirement to remove any plants that could jeopardize the integrity of the genetics of native plants in the Presidio.”

: The “wrong” poppy

This incident reminded us of an article published in the newsletter of the local chapter of the California Native Plant Society several years ago, entitled “Contaminating the Gene Pool.” In this article Jake Sigg instructs gardeners to beware of planting the wrong variety of a native plant because it will cause “genetic pollution.” The California poppy is one of the examples he gives of a variety of California native being planted in San Francisco that doesn’t belong here. It isn’t sufficient in his opinion, to plant a California native if that specific variety of the species didn’t historically occur in San Francisco. He asks gardeners to “think in terms of preserving the genetic integrity of the local landscape.” And he speculates many negative consequences of selecting the wrong variety, such as “genetic swamping, you’ve got all these foreign genes that are going to overwhelm the native population.” We were reminded of Mr. Sigg’s vocal opposition to human immigration.

For the benefit of our readers who aren’t gardeners, we should explain what Jake Sigg and the Presidio are worried about. In a word, they are worried about hybridization, defined as “to breed or cause the production of a hybrid,” which is defined as “the offspring of two animals or plants of different breeds, varieties, or species.” Hybridization is as likely to occur between two native plants as two non-native plants, but native plant advocates are concerned about the possibility of a native and a non-native plant producing a hybrid variety that is distinct from the native plant. Hybridization is not inevitable, but it does occur naturally as well as through human manipulation. The “From the Thicket” blog recently told the fascinating story of the development of a valuable garden cultivar variety of a favorite California native, ceanothus or California Lilac.

Aside from the unpleasant association with eugenics, Mr. Sigg’s advice raises several practical questions. How is the gardener supposed to know exactly which variety of a native plant “belongs” in San Francisco or even in a specific neighborhood within San Francisco, such as the Presidio? And, in the unlikely event that gardeners might have such esoteric knowledge, where would they get the seeds of this specific variety? Jake Sigg acknowledges this practical obstacle, but advises gardeners to get their seeds and plants only from the annual plant sale of the local chapter of the California Native Plant Society. One wonders how many gardeners will follow this rather restrictive advice.

However, the more important question is the scientific question. Is hybridization an inherently harmful process that always reduces species diversity? We turn to Mark Davis for a less gloomy view of hybridization. Like most scientific questions, there is evidence of both positive and negative effects of hybridization on species diversity. Since you’ve heard the negative view from Mr. Sigg, we’ll let Mark Davis speak for the positive view. Professor Davis reports in his book Invasion Biology* that “the fossil record generally shows that following the invasion of new species, the number of species resulting from adaptive radiations and evolutionary diversification exceeds the number of extinctions.” And he concludes his discussion of hybridization and evolution by saying, “…a fair appraisal must also acknowledge that species introductions can enhance diversity as well, through hybridization, and the creation of new genotypes.”

The native plant movement has a narrow view of nature, which we do not share. Their ideology is based on dire predictions of ecological disaster if we don’t follow their restrictive advice. And when the managers of public lands choose to follow their advice, the consequences are usually the destruction of plants and animals that we value, in this case a field of California poppies.

* Mark Davis, Invasion Biology, Oxford University Press, 2009, page 78-82.