November 2014 – Conservation Sense and Nonsense

Where does it belong?

The advent of molecular genetic analysis about 50 years ago is making it possible to determine the relationships between species of plants and animals. As this analytic method becomes more sophisticated and more accessible, we are slowly learning more about how plants and animals have been dispersed around the earth, often great distances, sometimes crossing oceans. Here is an illustration of some of the long-distance dispersal of species across oceans which have been identified (1):

Look closely at the dispersal labeled “b.” This line describes the travels of a genus of plant (Lepidium) in the mustard family (Brassicaceae) which arrived in Australia from California and Africa in two separate dispersal incidents: “This [molecular] pattern is likely explained by two trans-oceanic dispersals of Lepidium from California and Africa to Australia/New Zealand…” (2)

Lepidium flavum found alongside the road in Tecopa, California. Creative Commons - Stan Shepp — Lepidium flavum found alongside the road in Tecopa, California. Creative Commons – Stan Shepp

Calibration of the molecular trees indicates the arrival of this plant in Australia/New Zealand in the Pleistocene geologic era, between .3 and 1.3 million years ago. The authors of this study speculate that mucilaginous (sticky surface) seeds were carried by birds: “…sea bird migration pathways between coastal California and Australia/New Zealand and South Africa and Australia/New Zealand are fully compatible with the proposed colonization scenario.” (2)

Flowers and seed capsules of Blue Gum eucalyptus

We know that eucalyptus seeds were brought to California in the mid-19^th Century by humans who came by boat. But can we imagine a scenario in which the seeds could have been carried in their protective seed capsules on ocean currents? And is the fact that the seeds were carried in a ship across the ocean really so very different from them being carried on the currents?

Few of these long-distance dispersals have been identified so far, but many more are likely to be identified in the future as this analytic method becomes more widely available.

Next time you hear a nativist say, “It doesn’t belong here” when explaining why a plant or animal must be killed, please think about this example of the natural dispersal of plants and animals across the oceans to new homes. Who is to say that it doesn’t belong here?

Alan de Queiroz, “The resurrection of oceanic dispersal in historical biogeography,” Trends in Ecology and Evolution, 20 No. 2, February 2005
Klaus Mummenhoff, et. al., “Molecular evidence for bicontinental hybridogenous genomic constitution in Lepidium sensu strict (Brassicaceae) species from Australia and New Zealand,” American Journal of Botany, February 2004

Do insects prefer native plants?

We follow Doug Tallamy’s publications closely because he is the academic scientist most often quoted by native plant advocates to support their belief that insects require native plants and that the absence of the native plants will result in the collapse of entire ecosystems: “…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.” (1)

Main fountains of Longwood Gardens. Creative Commons - Share Alike — Main fountains of Longwood Gardens. Creative Commons – Share Alike

Tallamy co-authored his most recent publication, The Living Landscape: Designing for Beauty and Diversity in the Home Garden, with Rick Darke, curator of plants at Longwood Gardens for 20 years. Longwood is a formal garden outside of Philadelphia, which seems at odds with the exclusively native gardens for which Tallamy advocates. And so we were intrigued by this unlikely team. Darke’s introduction to the book implies a departure from Tallamy’s usual mantra:

“Is this a book only about gardening with native plants? No. It’s a book about how native plants can play essential roles in gardens designed for multiple purposes, with a focus on proven functionality. For better and worse, the native plant movement in North America has evolved in the last decade…One of the most important functionalities is durability: the capacity to thrive over a long time without dependence on resource-consuming maintenance regimes. Claims that natives are always better than exotics fail to take into account radically altered environmental conditions in many suburban landscapes…In most cases and most places, the design of broadly functional ecologically sound, resource-conserving residential gardens requires a carefully balanced mix of native and non-native plants. It’s time to stop worrying about where plants come from and instead focus on how they function in today’s ecology. After all, it’s the only one we have.” (2)

Tallamy writes his own introduction to The Living Landscape, which suggests a softening of his hard-line insistence upon gardening exclusively with native plants:

“What is native in any given place today wasn’t native if we look back far enough in time, and it is certain that what will be native in that same place in the future will be different from what is native now. Functional ecological relationships take a long time to evolve—often thousands of years—but they do evolve. Humanity’s challenge is to reduce its introduction of rapid environmental changes that are currently causing extinctions to occur faster than the evolution of new species.” (2)

Has Tallamy’s viewpoint evolved?

When we reported on Tallamy’s previous publication in 2012, we quoted him as saying that a graduate student under his direction could not find any evidence that native plants were eaten by insects more frequently than non-native plants:

“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 landscapes 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.” (1)

May we conclude that Tallamy no longer believes that native plants are required by insects? No, we may not. In Living Landscape he takes a different approach to this question. He collaborated in three studies which found more insects in native gardens than in non-native gardens:

Significantly more caterpillars of butterflies and moths were found in suburban gardens of predominantly native plants compared to gardens of predominantly non-native plants. This study also quantified the number of birds found in these gardens and concluded that “…the negative relationship between non-native plant abundance and bird community integrity is apparent in managed ecosystems as well, regardless of whether the non-native species are invasive.” This seemed a leap of faith, given that the inventory of insects was done in a six-week period in August and September and the inventory of birds was done in a six-week period in June and July, rendering a cause-and-effect relationship dubious.
Two other studies were conducted in a constructed garden in which native and non-native plants were paired for comparisons. Some of the pairs were in the same genus. Again, significantly more caterpillars and other plant-eating arthropods were found on native plants, although the differences were much smaller when the plants were in the same genus, which are often—but not always–chemically similar.

Reconciling apparent contradictions

So, how are we to reconcile these studies which find more insects on native plants with other studies which report otherwise?

Here in the San Francisco Bay Area, we rely on the research of Professor Arthur Shapiro to inform us of which plants are useful to our butterflies. He tells us: “Most California natives in cultivation are of no more butterfly interest than nonnatives, and most of the best butterfly flowers in our area are exotic.” (3) The difference between Professor Shapiro’s studies and those cited by Professor Tallamy is that Professor Shapiro has been studying butterflies in “natural areas” rather than cultivated gardens. Most of the plants that he finds butterflies using are considered weeds, such as non-native fennel and star thistle, which we wouldn’t find in suburban gardens. We speculate that this difference accounts for some of the difference in findings.
Furthermore, the studies reported by Professor Tallamy only seem contradictory. In fact, if we look at them closely we find that one reports no difference in what caterpillars eat, but considerable difference in where they are found. And this strange difference is consistent with the scientific literature. A meta-analysis of hundreds of studies of insect-plant interactions published by Annual Review of Entomology reports these findings: “Herbivore densities are lower on invasive plants than on native plants, but there is no evidence that invasive plants overall suffer from less damage inflicted by native herbivores.” (4)

Go figure! More herbivores are found on native plants, but they don’t eat more native plants than they do non-native plants.

A parting shot

Professor Tallamy urges suburban gardeners to take insects into account when making their gardening choices and, of course, we agree. However, he closes his pitch for gardening with natives in The Living Landscape with a story which seems superficially compelling but doesn’t hold up to close scrutiny.

Eumaeus atala butterfly laying eggs on coontie. Creative Commons - Share Alike — Eumaeus atala butterfly laying eggs on coontie. Creative Commons – Share Alike

There is a beautiful butterfly (Eumaeus atala) in Florida that was historically dependent upon a particular native plant, coontie, which is a species of cycad. Coontie was popular with early settlers as a food flavoring and was nearly wiped out early in the 20^th century, along with the atala butterfly which was dependent upon it as its host plant. Tallamy claims that the atala made a comeback when coontie became a popular plant for suburban gardens. This makes a powerful case for how suburban gardeners can participate in efforts to conserve our native butterfly fauna.

Coontie. Photo by Dan Culbert, University of Florida

But is it true? Wikipedia says it’s not: “The atala is now common locally in southeast Florida rebounding to some extent as it has begun to use ornamental cycads planted in suburban areas.” This is an example of how chemically similar plants can be useful to native insects, whether they are native plants or introduced, non-native, ornamental plants.

Sago cycad palm is an example of an ornamental cycad

We apologize for being repetitive, but for the record we will close with the reminder that Million Trees urges everyone to plant whatever they want in their own gardens. In public open spaces, which belong to everyone, we ask only that land managers quit destroying trees and using pesticides for the sole purpose of attempting to eradicate non-native plants. The audience for Professor Tallamy’s publications is private gardeners, so we don’t really have a beef with him. We critique his rationale for his preference for native plants only because it is often cited by those who demand the eradication of non-native plants and trees in our public open spaces.

The Living Landscape is a beautiful book, which we recommend to our readers for its lovely photos of naturalistic landscapes.

Doug Tallamy, “Flipping the Paradigm: Landscapes that Welcome Wildlife,” chapter in Christopher, Thomas,The New American Landscape, Timber Press, 2011
Rick Darke and Doug Tallamy, The Living Landscape: Designing for Beauty and Diversity in the Home Garden, Timber Press, 2014
Arthur Shapiro, Field Guide to Butterflies of the San Francisco Bay and Sacramento Valley Regions, University of California Press, 2007
Martijn Bezemer, et. al., “Response to Native Insect Communities to Invasive Plants,” Annual Review of Entomology, January 2014.

A defensive tirade from invasion biologists

Pesticide use by land managers in California. Source California Invasive Plant Council

An international team of invasion biologists has just published a defense of their academic turf, invasion biology. (1) Daniel Simberloff, an American member of the team, is the most relentless defender of the crusade to eradicate all non-native species, wherever they are found, all over the world. Their publication acknowledges the mounting criticism of this crusade and attempts to respond to that criticism, but what is most notable is what is missing from their attempt to defend their opinions. They make no mention of the harmful methods used to eradicate non-native species:

Pesticides are used to eradicate non-native species. Pesticide use is damaging the environment and the animals that live in it, including humans.
Prescribed burns are used to eradicate non-native species as well as to prevent natural succession from grassland to shrubs and ultimately to forest. These fires pollute the air and endanger our lives and property
Non-native insects and pathogens are introduced into our landscapes for the purpose of killing non-native species of plants and animals. These biological controls have a track record of killing unintended targets.
Healthy, mature trees, which store tons of carbon, are being destroyed, thereby contributing to climate change.

Keep these damaging methods in mind as we visit the hypocritical and contradictory arguments used to justify the projects for which these invasion biologists advocate. They set up “novel ecosystems” as the straw man to which they compare the goals of invasion biology. They define novel ecosystems as “a new species combination that arises spontaneously and irreversibly in response to anthropogenic land-use changes, species introductions, and climate change, without correspondence to any historical ecosystem.”

“Lack of rigorous scrutiny”

Their primary criticism of the concept of “novel ecosystems” is that it has not been “subjected to the scrutiny and empirical validation inherent in science” and its definition is “impaired by logical contradictions and ecological imprecisions.” These criticisms apply equally to invasion biology.

An international team of scientists analyzed 371 empirical studies which tested six major hypotheses in invasion biology. They found that empirical evidence for these hypotheses is uneven and declining. The scientists counted the number of studies that support, question/oppose, or are undecided/inconclusive about each hypothesis. They also compared the number of supporting studies when the hypothesis was new with the number of supporting studies published recently to determine the decline in support for the hypothesis. Here’s what they found:

Hypothesis	n	% of supporting studies	% of decline in support
Invasional meltdown	30	77%	41%
Novel weapons	23	74%	25%
Enemy release	106	54%	10%
Biotic resistance	129	29%	5%
Tens rule	74	28%	10%
Island Susceptibility	9	11%	25%

Although support is strongest for the invasional meltdown hypothesis, recent studies are less supportive than early studies, indicating substantial decline in supporting evidence. Declining evidence of invasional meltdown is consistent with the fact that exotic species are eventually integrated into the food web which reduces their populations, stabilizing their spread. There is apparently little evidence that islands are more susceptible to invasion than continents and few studies have been done to test the hypothesis.

A survey of invasion biologists in Europe found no consensus regarding the definition of “native” or “invasive.”

If empirical validation and semantic precision are required to establish the credibility of scientific hypotheses, invasion biology has failed that test.

“Precautionary principle of conservation and restoration”

These invasion biologists define the precautionary principle of conservation and restoration as follows: “we should seek to reestablish –or emulate, insofar as possible—the historical trajectory of ecosystems, before they were deflected by human activity.” This is an unusual use of the precautionary principle, which is more typically defined as avoiding damage to the environment by not using potentially harmful methods, even in the absence of solid evidence of such harm. The precautionary principle was not used when the following “restoration” projects were defined or implemented:

California Clapper Rail. British Wikipedia

The precautionary principle was clearly not used before the population of endangered California Clapper Rail was decimated by the eradication of non-native spartina on the entire West Coast, which was providing superior nesting cover for this rare, shy bird. The precautionary principle also would have precluded the use of an herbicide in that project which was untested on shore birds.
Nor was the precautionary principle used when plans were developed to aerial bomb 1.3 metric tons of rodenticide on the Farallon Islands for the stated purpose of killing mice that are the preferred prey of an average population of six burrowing owls, which are accused of eating the eggs and chicks of a rare bird.
If the precautionary principle had been employed, 15 native moth species in Hawaii might not have been lost when biological controls were introduced to control non-native species. This is just one of many examples of the unintended consequences of such dangerous introductions.

Ivy in the Conservatory in Central Park, New York City

In 1996, Daniel Simberloff made this statement in his publication about the hazards of biological controls: “…are there any protocols for biological-control introductions that would prevent all disasters? Probably not…” (2) Yet, in 2013, he expressed his support for the introduction of non-native insects to control cape ivy at a conference at UC Davis sponsored by the California Department of Food and Agriculture. Although cape ivy is despised by native plant advocates, it is not an agricultural pest and therefore causes no economic damage to ecosystems, unless money is wasted on attempts to eradicate it.

“All ecosystems should be considered candidates for restoration”

In response to those who find value in novel ecosystems, these invasion biologists find none. They reject the possibility that there is ever a point at which it may not be possible to re-create a historical landscape. They continue to believe that ANY and ALL radically altered landscapes CAN and SHOULD be considered candidates for restoration. Their only caveat to this universal goal is that “damaged ecosystems…should be evaluated for feasibility, desirability, and cost-effectiveness, on a case-by-case basis, so that informed and science-based policy decisions can be made, in consultations with scientists, restoration practitioners, stakeholders, and advisors.”

These criteria for potential “restoration” have nothing to do with reality:

Most projects in the San Francisco Bay Area have not provided cost estimates when they were planned. The public demanded cost estimates for the projects of the Natural Areas Program in San Francisco, but these demands were ignored. Therefore, “cost-effectiveness” is not usually considered when these projects have been shoved down the public’s throat.
We consider the public to be “stakeholders” in decisions to radically alter our public open spaces. We are the visitors to these areas and our tax dollars pay for their acquisition, maintenance, and “restoration.” Yet, managers of public land are consistently making those decisions without taking the public’s opinion into consideration. Most projects are planned and executed without any public participation. In the few cases in which there are environmental impact reviews, the projects are implemented regardless of overwhelming opposition of the public.

“Human-damaged ecosystems can be at least partially restored”

The demonstrated futility of “restoration” projects is one of many reasons why there is waning public support for attempting them. Yet, invasion biologists who authored this diatribe claim that “restored sites recovered on average 80-86% of biodiversity and ecosystem services…and showed improvements of 125-144% over degraded ones.” This claim is contradicted both by other scientific studies and by experience with local projects:

“…this paper analyses 249 plant species reintroductions worldwide by assessing the methods used and the results obtained from these reintroduction experiments…Results indicate that survival, flowering and fruiting rates of reintroduced plants are generally quite low (on average 52%, 19%, and 16% respectively). Furthermore, our results show a success rate decline in individual experiments with time. Survival rates reported in the literature are also much higher (78% on average) than those mentioned by survey participants (33% on average).” (3)
Dunnigan Test Plot, August 2011. The result of an eight-year effort to restore native grassland. Does it look “biodiverse?” ecoseed.com.

There is frequently a discrepancy between the success rates claimed in papers and those actually observed. For example, Cal-Trans gave researchers at UC Davis $450,000 to restore 2 acres of non-native annual grassland to native grassland. UC Davis researchers spent 8 years and used multiple methods to achieve this transition. When they ran out of money, they declared success in their published report. They defined success as 50% native plants which they expected to last 10 years before being entirely replaced by non-native annual grasses again. Do you consider that a success?
On a more anecdotal level, we watch established landscapes that have required no maintenance in the past being transformed into weedy messes by failed “restoration” projects. Then, adding insult to injury, we hear those who are responsible for these failures tell us how successful they are.

“Inadequate political will”

The authors of this publication conclude:

“No proof of ecological thresholds that would prevent restoration has ever been demonstrated. Often the threshold that obstructs a restoration project is not its ecological feasibility, but its cost, and the political will to commit to such cost.” (1)

We are reminded of an old football adage: “The best defense is a good offense.” In other words, invasion biology is under fire, but the reaction of invasion biologists is to demand more….more money, more effort, and the commitment of public land managers to “restore” all ecosystems, regardless of what the public wants. And in support of that aggressive strategy, they refuse to acknowledge the damage that is being done to the environment and the animals that live in it, by the projects they demand.

The authors of this defensive tirade have hammered another nail in the coffin of invasion biology.

Carolina Murcia, James Aronson, Gustavo Kattan, David Moreno-Mateos, Kingsley Dixon, Daniel Simberloff, “A critique of the ‘novel ecosystem’ concept,” Trends in Ecology and Evolution, October 2014, Vol. 29, No. 10
Daniel Simberloff and Peter Stiling, “How Risky is Biological Control?” Ecology, 77(7), 1996, pp 1965-1974
Sandrine Godefroid, et. al., “How successful are plant species reintroductions?” Biological Conservation, 144, Issue 2, February 2011

Where does it end?

It is our pleasure to republish with permission a post from the website of Flood Creek Non-Nativist Landcare Group. Flood Creek is located in Braidwood, New South Wales, Australia. Across Australia, Landcare is a popular volunteer-based environmental movement which enjoys general support from government in the form of occasional financial grants. Over the last 25 years, many Landcare groups have undertaken projects with the stated goal of eradicating non-native plants based on a belief that native plants and animals would benefit. That strategy will sound familiar to our readers, as will the damage to the environment which it causes.

The Non-Nativist Landcare Group is a small team of people with a history of participation in Landcare who want to foster a discussion of current nativist approaches to environmental management, and question their outcomes. Based on their experiences with conventional Landcare projects, the Non-Nativist Landcare Group has concluded that these often do more harm than good. The Group describes their mission: “Above all, this discussion is inspired by the goal of taking a more ecologically-based and functional approach to Australian socio-ecological systems and their health. We seek to highlight the inconvenient-truth that rational environmental management can never be based upon a simple mantra of “natives good, non-natives bad”. Extermination is rarely an effective way to promote landscape diversity and resilience.”

Please visit their website and wish them well in their effort to find a less destructive approach to land management.

When you look at the willful and wanton environmental destruction conveyed in these photographs you must ask yourself: ‘how could anyone do this in the name of environmentalism?’ After all the disturbance we’ve already inflicted upon this biosphere, how is this really helping?

In this example of willow demolition, the trees were cut down and dragged away and the stumps were poisoned. Then (for some unfathomable reason) a drainage ditch was excavated into the floodplain. In the photo below, the main flow-line is 40m off to the left.

Apart from the economic motives at play (a theme for a future post), I can think of only one reason why an ‘environmentalist’ might condone this kind of damage and disturbance. It must be to do with that old adage, ‘the end justifies the means‘.

The reasoning seems to be: ‘Sure, it makes a big mess and causes erosion, and nutrient release, and carbon emissions, and local temperature increases, and loss of habitat, but it’s necessary because we’re going to make Australia a place for natives-only again.’

So that’s the end we’re aiming for: a ‘native-only’ Australia. And these photos show the means we must accept along the way. It seems we’re just going to remove all of the non-natives from this continent so the environment is back to ‘pristine’ again and then we can stop with the chainsaws and excavators and herbicides in the name of ‘saving’ the environment.

We just want 1788-Australia back. Presumably without the dingoes and without the previous intrinsic Aboriginal management; plus with a few minor additions like cattle; and sheep; and horses; and apples; and asparagus; and hops; and wheat; and rice; and trout; and tomatoes; and lettuce; and cats; and dogs; and goldfish; and maybe just one or two other things, but that’s it! And we want all the ‘invasive’ natives, like Cootamundra Wattle, and Sweet Pittosporum, and Kookaburras to know their place and to go back where they were when Europeans first arrived….And stay there forever and ever….And not move just because the climate or fire regime has changed. And this won’t happen by itself so we’ll need funding and legislation and heavy machinery. And we’re going to fix it all ‘real good’ without knowing what it was actually like or exactly what species existed in many parts of the country back in 1788. And….and…..

….And then again……When you think about it…..Are we ever actually going to achieve anything even remotely approaching a native Australia?…..really?

I doubt it.

And I’d doubt the sincerity (or sanity) of anyone who says that we could. Surely nobody actually believes this?

So, given this impossibility, it seems pretty reasonable to ask ourselves: ‘how can the end justify the means, when it’s clear there really is no conceivable end?’ If it just goes on and on forever, then how do we justify these means to no end at all? How do we live with this permanent state of expensive self-congratulatory environmental vandalism?

More importantly, given how well-supported the above activities currently are, how do objecting grassroots Landcarers begin to articulate new ways to work with the adaptive living-landscapes around us? And how do we influence the direction of our own movement so that participation in Landcare is not assumed to mean support for this destruction?

All the death and destruction in these photographs is familiar to us here in the San Francisco Bay Area. The only difference is that the trees that were destroyed in this project were willows, which are native in California, but not native in Australia. That difference helps us appreciate the arbitrariness of nativism, which treats eucalyptus as demons and willows as the “good” trees in California.

We have yet to witness a “restoration” that wasn’t far more destructive than constructive. And based on our experience in the San Francisco Bay Area, we can venture an answer to the rhetorical question, “Where does it end?” It doesn’t end because every “restoration” is quickly occupied again by the plants that were destroyed by herbicide applications. As long as the objective continues to be to kill everything non-native and re-populate a landscape with native plants, the project will never be complete.

Therefore, it only ends when the goal is revised and/or the effort is no longer funded. And the only way to achieve that revised goal is for the public to object to the destruction of their public lands. So, if you are tired of witnessing these destructive projects, speak up! Tell your elected representatives that you don’t want your tax dollars spent on the pointless ruin of public open space.