Thinking about Invasive Species, Plants and Definitions

Initial damage appears as thinning and dieback in the upper canopy of the tree as larvae feed under the bark they damage the conductive tissue  http://www.entomology.wisc.edu/emeraldashborer/  . 

               Some plant species are introduced by human activity into new ecosystems at such a rate that they can overcome the odds and establish themselves in the landscape. A few of these plant species do more than just establish they multiply so fast and so aggressively as to crowd out any other plant species creating a biological desert bereft of diversity. Some of these species have become notorious in the last few decades such as kudzu (Pueraria montana (Lour.) Merr. var. lobata (Willd.) Maesen & S. Almeida) and the various salt cedars or, tamarisks (Tamarix spp.); some such as common barberry (Berberis vulgaris L.) in the 18th century or field bindweed (Convolvulus arvensis L.) in the 20th century began their rise to pest status even before we used the term invasive species. Interestingly enough the colony of Connecticut tried to ban barberry in 1726 way before there even was a United States. [Connecticut keeps trying to ban plants. 2010]

               These plants are not indigenous to North America and so by extension we begin think all alien non native plants are suspect. The cognitive dissonance that arises when we find out wheat (Triticum spp.) is also not native is disturbing to a native only perspective. Then there is the little problem of impact, benefit and harm when it comes to judging a species place in the ecosystems in which we find ourselves. And just to layer on the complications, the non native exotic plant itself may be harmless but maybe a host for invasive hitchhikers (insects and pathogens) The native ash tree. for exmaple, can be a vector or a transport platform for the non native emerald ash borer (Agrilus planipennis Fairmaire) which destroys both native and non native ash species. [A Menacing Discovery Of the Emerald Ash Borer in Moscow. 2007]  

               Defining invasive species is the first step to finding solutions.  A good resource is the  Invasive Species Definition Clarification and Guidance White Paper from 2006 which defines an invasive species as: 

“an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.” In the Executive Summary of the National Invasive Species Management Plan (NISMP) the term invasive species is further clarified and defined as “a species that is non-native to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health.” To provide guidance for the development and implementation of the NISMP, the National Invasive Species Council (NISC) and the Invasive Species Advisory Committee (ISAC) adopted a set of principles outlined in Appendix 6 of the NISMP. Guiding Principle #1 provides additional context for defining the term invasive species and states “many alien species are non-invasive and support human livelihoods or a preferred quality of life.” However, some alien species (non-native will be used in this white paper because it is more descriptive than alien), for example West Nile virus, are considered invasive and undesirable by virtually everyone. Other non-native species are not as easily characterized. For example, some non-native species are considered harmful, and therefore, invasive by some sectors of our society while others consider them beneficial. This discontinuity is reflective of the different value systems operating in our free society, and contributes to the complexity of defining the term invasive species.[1]

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[1] Invasive Species Defined in a Policy Context: Recommendations from the Federal Invasive

Species Advisory Committee. 2006. K. George Beck, Kenneth Zimmerman, Jeffrey D. Schardt, Jeffrey Stone, Ronald R. Lukens, Sarah Reichard, John Randall, Allegra A. Cangelosi, Diane Cooper, and John Peter Thompson*

What is an Invasive Species?

What is an "invasive species"?

               An answer will depend whom you ask, and to a large extend what outcomes the person asked expects.

That was not a very helpful answer. Could you give a few answers that show different definitions of an "invasive species"?

               Sure.  First let's look at some words that are used to describe a change in species distribution that upset existing ecosystem balances and cause changes in ecosystem services that lead or may lead to system resource change or collapse:  adventive, alien, casual, colonizing, cryptogenic, escaped, endemic, established, exotic, foreign, immigrant, imported, introduced, invasive, native, naturalized, nonindigenous, noxious, nuisance, pest, spreading, temporary, tramp, transferred, transformer, transient, translocated, transplanted, transported, travelling, waif, and weedy. (Colautti & MacIsaac, 2004) Brendan Larson's thirteen meta categories to consider when we try to come to grips with a definition are: invaders, terrorists, piggy-backers, opportunists, spawn, mirrors of ourselves, providers, hybrids, tricksters, matrix elements and dynamic matrices, transients, founts of life and creation, teachers and instructors that force us to think about our assumptions. (Larson, 2007)   

Yes that is all very nice, but I want a simply straightforward definition.   

               Well, because of the complexities that arise from the ecosystems themselves and the many stakeholders and interested parties, there are many definitions. This happens because it is easier to start with an outcomes and work backwards to a definition. In other words we color the definition with preconceived ideas and concepts. This even our choice of words predisposes us to a view of the problem even before we have a definition. The very choice of the word invasive presumes a pejorative meaning, because natural system stakeholders so the negative impact of what to them looked like invasions.

Yeah Yeah Yeah, but I am just passing through and I do not have a lot of time for this, just give me a definition.

               The International Union for Conservation of Nature, (IUCN) describes invasive species as “animals, plants or other organisms introduced by man into places out of their natural range of distribution, where they become established and disperse, generating a negative impact on the local ecosystem and species.” Invasive species can negatively impact human health, the economy (i.e. tourism, agriculture), and native ecosystems. These impacts may disrupt the ecosystem processes, introduce diseases to humans or flora and fauna, and reduce biodiversity.

               Invasive Species Definition Clarification and Guidance White Paper Submitted by the definitions Subcommittee of the Invasive Species Advisory Committee (ISAC) in 2006 sought to make clear the US Executive Order 13112  which defines an invasive species as “an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.” In the Executive Summary of the National Invasive Species Management Plan (NISMP) the term invasive species is further clarified and defined as “a species that is non-native to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health.”   (Beck, et al., ISAC 2006)

               In California an invasive plant is defined by Cal-IPC as  invasive non-native plant species that threaten wildlands and are are not native to, yet can spread into, wildland ecosystems, and that also displace native species, hybridize with native species, alter biological communities, or alter ecosystem processes.   This definition does not address diseases, insects or animals, just plants and only if they invade California wildlands with native habitat values. The invasive plant definition does not include plant species found solely in areas of human-caused disturbance such as roadsides and cultivated agricultural fields.  For these human disturbance areas the terminology or word would be weed. The California Native Plant Society has a straight forward definition of an invasive exotic plant, to wit: "a plant which is able to proliferate and aggressively alter or displace indigenous biological communities."

               The European Commission on the Environment states that "Invasive Alien Species are animals and plants that are introduced accidently or deliberately into a natural environment where they are not normally found. They represent a serious threat to native plants and animals in Europe, causing € millions worth of damage every year."

Great now I need to understand what a native species is? I don't suppose there is a simple definition. is there?

               That would be a different blog posting. Definitions of native run into the same fuzzy definition problem  that we are skirting in this blog. The closer you look the harder it is to pin down exactly what the term means. What exactly is native at 650 ppm CO2 for example is a question no one is talking about. Suppose we move an endangered species to a new site; is it native now?

This invasive business requires too much thinking. Can't you make this simpler?

               Sure: an invasive species is the wrong pathogen, plant, animal in the wrong place at the wrong time.

Works Cited

Beck, K. G., Zimmerman, K., Schardt, J. D., Stone, J., Lukens, R. R., Reichard, S., et al. (ISAC 2006). Invasive Species Definition Clarification and Guidance White Paper. Retrieved March 2009, from http://www.invasivespeciesinfo.gov/docs/council/isacdef.pdf

Colautti, R. I., & MacIsaac, H. J. (2004). A neutral terminology to define ‘invasive’. Diversity Distrib. , 10, 135-141.

Larson, B. M. (2007). Thirteen ways of looking at invasive species. In D. R. Clements, & S. J. Darbyshire (Eds.), Invasive plants: Inventories, strategies and action. Topics in Canadian Weeds Science (Vol. 5). Canadian Weed Science Society – Société canadienne de.

Ruminations on the Complexities of Invasive Species

The blog posting, Biologists as engineers of the living world, offers an opportunity to expand on my theme of the wicked inconvenience of invasive species.[1] Should we engage in biological engineering to solve invasive species problems? Invasive species are a wicked problem, a type of problem that is found in many social and physical systems. A very well know wicked problem intrinsically related to invasive species is climate change. In two sentences I have described two complex systems that are regularly reduced or simplified into complicated explanations with associated multiple conflicting solutions. In a complicated system, on the other hand, the members or parts and their interactions or connections are equally important. Unless redundancy is built in, when one part or connection fails, the entire system fails. In a complex system on the other hand the members or parts are of no individual importance, and a loss of one is not critical. However, the connections are important and it is the loss of a connection or interactive pathways that can dramatically alter the whole system. In a complicated system simple rules give simple predictive results whereas in a complex system, simple rules result in unpredictable outcomes. 

Invasive species are, in some sense, a symptom of a perturbation in or a disturbance of ecosystems. Ecosystems are dynamic networks of interactions and relationships that are most assuredly not collections of static, predictable entities. One does not predetermine the exact flight path of a bee or the precise flow of a stream but rather one describes the most probable direction and boundaries in which the system may be found in the future. More specifically it is possible estimate the probability of certain outcomes weighing one against another but it is not possible to say for certain which outcome is certain in all cases for all time.

Ecosystems are also adaptive which means that their individual and collective activities, actions and behavior change as a result of inputs, interactions and behaviors. Invasive species are the result of some action or sequence of actions that result in the movement of one species into a new region. By definition, invasive species are the harmful-to-humanity, non-indigenous pathogens, plants or animals that are introduced as a result of human activity into a novel ecological system – into our backyards and homes. It is worth noting that as a rule it takes more than one introduction event, so the establishment of an invasive species through human activity enhances the portability of success. The complexity lies in part within the many assumptions that I just made in trying to define what the problem is, and I have not yet discussed cascading effects of species introduction on ecosystem services.

To engineer a solution, we start with an identification of a need or problem, and then work to develop a tool or process that becomes the solution. We try to economize costs, which usually but not always means some linear answer more or less in a straight line preferably with as few gaps as possible. A prosaic example is a plow. The need is to break up the soil and the ecosystem so that a food source can be easily planted. The engineered solution today is a metal shape that cuts or rips through the land in a straight line. The plow works wonders if you keep your eye on the goal which is to make planting easy and short term yields. At the same time the engineered solution creates unintended new problems such as erosion and soil nutrient run off. This is the fear inherent in the linear approach to biology.

The interesting side product of the engineering marvel we know as the plow is the ability to disturb the earth inexpensively, repeatedly and, therefore, chronically produce a disturbance pattern that favors certain species over others. And these species are either called weeds by farmers and gardeners or invasive plants by natural area managers and ecologists. This unintended product is possible anytime one applies linear thinking to non linear systems and is even in an ironic twist guaranteed by definition. The unexpected outcomes from engineering in a straight line should not be a reason not to consider engineering complex systems. Rather it is an invitation to think first and consider using applied complex system theory as an integral part of the engineering process. 

Historically, when faced by a problem in landscaping we engineer a simple, cost effective solution. Since landscaping usually includes plants, the landscape architect will engineer a plant solution if he or she can. The discipline of horticulture admits to the need from time to time of other expert professionals, but the ultimate design engineering rests with the landscape architect. The odds are slight that the client will pay for a comprehensive team of equals including hydrologists, ecologists, biologists, entomologist, and a dozen other specialties in advance of identifying a particular problem. In other words, we do not set out to identify potential problems that may affect the common ecosystem, but restrict of future externalities, our deliberations are directed to the landscape at hand to keep costs from quickly becoming prohibitive. And so we specify English ivy, Hedera helix, as a general purpose groundcover to minimize planting costs as well as maintenance cost in the near future. 

Linear engineered solutions are not solely found in ornamental gardening. In order to meet the insatiable demand for goods, the wooden shipping pallet is a simple engineered platform. Take a tree from the fields near where a product is made, create a pallet, and send the product on the pallet to a new ecosystem. Hidden on board on or in the pallet may be living hitchhikers foreign and deadly to the receiving ecosystem. This is straightforward, simple and deadly to ahs trees. The emerald ash borer is eating the ash trees of North America. The borer most likely arrived on wooden pallets or shipping craters which, had an interdisciplinary team been assembled might have been avoided. And with identification of a risk, protocols could have been put in place to reduce the risk of millions of acres of dead trees.

Biological systems may perhaps be engineered if we keep a few key things in mind. First complicated linear and determined systems produce controllable and predictable outcomes, while complex adaptive systems can produce novel, creative, and emergent outcomes.[2] Biological systems are complex systems of the latter type, and will require a sympathetic engineering strategy that changes some aspect of the system and then works with the biologic system while it adjusts to the change. The traditional assumption of straight-line thinking will be dangerous if applied to complex biologic systems. The dependable ascertain that every observed effect has an observable cause will lead inevitably to unintended consequences. A belief that the whole can be understood by taking the system apart and studying the pieces will tend to produce surprises many of which could be unpleasant. The problem of complex systems, the challenge of biology is that they are rooted in chaos theory and wickedly defy any predictive detail modeling.

We should not be afraid of engineering. We should be afraid, however, of treating biologic systems like cars. We can tool a solution to a door lock with every reasonable expectation of a predictable outcome; we cannot tool biologic systems in the same way and expect to predict the result. On the other hand, this is not a reason, to adapt engineering to a process of nudging complex systems, pushing their constraints, and observing the results in an endless dance with our universe.

[1] Link to multiple posting on the wicked inconvenience theme of invasive species: http://ipetrus.blogspot.com/search?q=wicked+inconvenience

[2] Jones, Wendell. "Complex Adaptive Systems." Beyond Intractability. Ed. Guy Burgess and Heidi Burgess. Ocotber 2003. Conflict Research Consortium, University of Colorado, Boulder, Colorado, USA.

Invasive species - rambling thoughts

Discussion today about invasive species are couched in reports, papers and research that stretch all the way back to the 1980s with roots reaching even to the late 1950s. Conflated with all the complexities inherent in invasive species is the idea that invasive species are somehow a new public policy issue. When combined with the inverse issue of endangered (native) species the perfect storm of suspended disbelief comes into focus as today’s ecologists find themselves continuously thwarted in every policy effort at the level of the disinterested, unengaged, fully uninformed voter. Amazingly no matter how dire the issue, how carefully the disaster and damage are described, the public is unmotivated and unconcerned, and unwilling to spend the funds to combat and mitigate the problem.

Buried deeply in the American psyche and to some extend Western Culture is the problem of nature. Defining nature, natural, naturalized, native, artifice and artificial, as well as art and international and cosmopolitan rises above the domain of science. Knowing the hardships of the European attempts to establish communities in North America such as the Norse colony of Vinland is crucial to understanding invasive species issues today. In current discussions there unspoken ideas surface that European settlement was a foregone condition and that nature therefore is something that was “losing” the contest from the beginning. This view however is hindsight of John Muir, expounded upon by Aldo Leopold and codified by Charles Elton, amplified by the modern students of ecology. Unremarked is the fact that at least until 1800 there was every reason to believe that the great experiment would fail; the experiment of surviving on this unrelenting, wild continent.

John Muir saw that technology was ‘winning’ the battle, and that at the present rate the last great “untouched” places could be gone if a new value system could not be created to delimited special places. Aldo Leopold refined what it could meant by the idea of a landscape and more importantly to create and manage one, and Elton among many achievements grabbed the idea of invasive species harm so that a new generation could begin to understand the critical importance of finding a away to control the aexotic, alien, newlydefined 'unnatural' invasions. In doing so the three seers of the ecological preservation movement led a revolution describing a new value system that taught a new generation how to see and understand the world. And this new world view seemed to its followers to overturn the basics of gardening and farming. The old ways must be at best uniformed and at worse lacking in scientific rigor.

However the early colonists were not scientific ignoramuses, and in fact were rather more well philosophically grounded, understanding that science was a tool to help with value system management. They were not part of the Age of Enlightenment for nothing; for concurrent with the efforts to survive in the wilderness went the debates as to what constituted a native, and under what conditions a non native could become naturalized, if ever. Participants in the community discussion included prominent Americans such as Jefferson and European thinkers such as Raynal as well other European and American natural philosophers who happened to be practitioners of the science of horticulture and therefore accomplished gardeners. In addition the conversations of native and naturalized were wrapped around the concept of resource appropriation and use as well as reconstitution, revitalization or as we now call the concepts and dynamics of sustainability. The first Europeans thought the idea of species included humans and therefore applied the labels native and naturalized both to themselves and to their surroundings. For them it was self-evident that if a person could become naturalized then so could a plant or animal. Early European settlers and thinkers did not see mankind as apart from nature but solidly in the middle of nature as a participant.

CO2 Increase Impact - A Question of Complexity

CO2 is Green, a pending 501(C)(4) non-profit organization whose mission is to support scientifically and economically sound public policy on environmental issues. Currently, the non profit organization is attempting to sway public opinion by refuting “claims that CO2 is a pollutant…” To accomplish this CO2 is Green makes its own claim that facts support the position that “…lowering levels of carbon dioxide would actually inhibit plant growth and food production.” CO2 is Green claims the facts of carbon reduction advocates are “… a myth and are absolutely false.” CO2 is Green is not the only organization or group asking us to make decisions based upon their arrangement of information. What we have here, then, is a failure to communicate wrapped in a classic wicked problem, surrounded by a selective use of knowledge.

Challenged as to where to begin, a definition of carbon dioxide seems in order. From the web site of Lenntech Water treatment & purification Holding B.V we read:

“Joseph Black, a Scottish chemist and physician, first identified carbon dioxide in the 1750s. At room temperatures (20-25 oC), carbon dioxide is an odourless, colourless gas, which is faintly acidic and non-flammable. Carbon dioxide is a molecule with the molecular formula CO2. The linear molecule consists of a carbon atom that is doubly bonded to two oxygen atoms, O=C=O. Although carbon dioxide mainly consists in the gaseous form, it also has a solid and a liquid form. It can only be solid when temperatures are below -78 oC. Liquid carbon dioxide mainly exists when carbon dioxide is dissolved in water. Carbon dioxide is only water-soluble, when pressure is maintained. After pressure drops the CO2 gas will try to escape to air. This event is characterized by the CO2 bubbles forming into water.”

Glossing over the many uses that carbon dioxide offers to mankind including decaffeinated coffee, we turn to plants and man and the regulating function such as the gas cycles of ecosystems. Although this discussion is focused on carbon dioxide, we need to keep in mind that the “…principal greenhouse gas concentrations that have increased over the industrial period are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and chlorofluorocarbons CFC-11 (CCl3F) and CFC-12 (CCl2F2)” [Hansen et al., 1998; Schimel et al., 1996]. These increases are not in dispute but, importantly for this discussion, the mechanisms of the increase are contested by some. If the increases are by the hand of man there may be a way back from the brink; if the increases arise from a natural cycle then a much of humanity is in even bigger trouble.

CO2 is Green offers the proposition that more carbon dioxide is good and will have broad across the board positive benefits to plants and therefore mankind through increased production of ecosystem service resources. The ideas of more of anything is always better lurks beneath the claim and is supported by some plants benefitting from increased carbon dioxide. Some plants will benefit, however the CO2 is Green claim is a blanket statement of benefit, and assumes the reader will jump to the conclusion that carbon dioxide is good for all plants and plays upon most of us not recalling or ever learning about plant physiology and processes of photosynthesis.

Almost certainly, CO2 is Green is thinking of Sylvan Wittwer who observed in ‘Food, Climate and Carbon Dioxide’ that “[t]he effects of an enriched CO2 atmosphere on crop productivity, in large measure, as positive, leaving little doubt as the benefits for global food security …. Now, after more than a century, and with the confirmation of thousands of scientific reports, CO2 gives the most remarkable response of all nutrients in plant bulk, is usually in short supply, and is nearly always limiting for photosynthesis … The rising level of atmospheric CO2 is a universally free premium, gaining in magnitude with time, on which we can all reckon for the foreseeable future.”
(applet-magic.com Thayer Watkins Silicon Valley & Tornado Alley USA)

It turns out that plants are not all alike and that there is a distinct worth considering between agricultural monocultures and diversity rich natural ecosystems. Leaving out the fact that too much carbon dioxide can harm a person directly through suffocation, kidney failure or even in extreme conditions, frostbite, more carbon dioxide is not necessarily a good thing for all plants. Because some species evolved solutions to hot dry climate conditions, some plants already maximize the carbon dioxide available and will not measurably benefit from increased carbon dioxide. These are the C4 and CAM plants, many grasses, succulents and cacti of mild and desert ecoregions. This of course does not negate the CO2 is Green claims, but does strongly suggest that in ecosystems with both plant types the C3 species may, if temperatures and light conditions remain the same, become more efficient and therefore dramatically out compete changing the resources of the system at hand. If that change results in top predator degradation or loss, the entire ecosystem will collapse.

The large elephant running freely through out CO2 is Green’s argument involves temperature and photosynthesis. Keeping in mind that photosynthesis and respiration, one the reverse of the other, play an important role in the carbon cycle and are at equilibrium with one another, and that carbon dioxide levels influence atmospheric temperature, we know that as temperatures go up photosynthesis goes down in plant species which most benefit from the extra carbon dioxide. It follows that CO2 is Green is allowing its target audience to assume that the additional carbon dioxide will be taken up by the plants as a super carbon sink thereby preventing the rise in temperatures. CO2 is Green’s imbedded claim is that increased carbon dioxide is a simple linear process with no feed back loops and no interaction with other processes such as temperature. And most tellingly, CO2 is Green fails to mention that for many terrestrial land plant species, there is a process called photorespiration which occurs at high light intensities and temperatures and competes with photosynthesis limiting further increases in the rate of photosynthesis, notably when the supply of water is limited. Thus CO2 is Green might correctly claim that a rising concentration of carbon dioxide will not materially augment, neither will it limit food production for ten billion people nor lessen the land that can be spared for Nature however, the effects on ecosystem outside of agriculture cannot be foreseen and the importance of limiting factors are not considered.

The claims of CO2 is Green are built upon a few broad based truths or facts that ignore inconvenient data or processes in order to justify an a priori desired outcome, the classic position of stakeholders in a wicked problem. The simple direct linear proposition that correlates better photosynthesis in some plant species to a better world; a complicated reality that falls a little short in the complex fuzzy fractal world of wicked problems. According to Farrar & Williams (1991), although “…[l]ittle information is available for interactions between temperature and CO2. Cold-adapted plants show little response to elevated levels of CO2, with some species showing a decline in biomass accumulation. In general though, increasing temperature will increase sucrose synthesis, transport and utilization for CO2-enriched plants and decrease carbohydrate accumulation within the leaf.” Bunce & Ziska (1995) measured carbon dioxide impact among soy bean cultivars and found that “…increasing atmospheric carbon dioxide concentration may reduce respiration in soybeans, and respiration may be insensitive to climate warming.”

But our carbon-dioxide-increase elephant is larger than even these important biochemical functions for every process is part of a higher level system, and current research strongly suggests that while in some plant species carbon dioxide certainly enhances photosynthesis, at the level of leaf canopy, the level of the plant as a whole, the increase carbon dioxide will lead to higher leaf canopy temperatures. And this increase in temperature will lead to an increase in sterility. If this were true just for annoying pest plant species, we would stop reading, however, the research is focused on and the sterility is in, grain species. At the very least this means more land to produce the same resource, and more likely it means just less food.

If we move to the next level of system complexity we enter the plant community, the biome. Here we must note that increased carbon dioxide will not only cause large leaf and plant structures for our desirable agricultural species, but of course for the weed species that have co-evolved with the crop and humans. The current reduction in farm out-puts (harvests) in Asia could feed over 50 million people. With larger and more vigorous growth of C3 plants including the weeds which compete with the desirable plants, our needed resource yields will go down and starvation will go up.

In closing, we must find a way to balance the intricate mechanisms and complexities of ecosystem services and try to refrain from making simple carte blanche statements of the one size fits all variety. Mankind must find ways to adapt or die; evolutionary forces have no moral grounding, and we must not be fall into the trap of paralysis through analysis. We need to find a pathway between doing nothing at all and waiting until there is nothing to be done.
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Invasive Species: Simple at First Glance

Invasive species issues seem simple at first glance. A species is introduced, establishes reproduces and begins to alter the new ecosystem, or negatively impacting human health and well being. Direct, strong adverse interactions that effect human health rise to the forefront of community awareness and efforts to reduce or eliminate the threat. Much is spent to prevent or ameliorate the introduction or control of invasive species such as:

Asian longhorned beetle (Anoplophora glabripennis)
Asian tiger mosquito (Aedes albopictus)
Brown citrus aphid (Toxoptera citricola)
Codling moth (Cydia pomonella)
Colorado potato beetle (Leptinotarsa decemlineata)
Cotton aphid (Aphis gossypii)
Diamondback moth (Plutella xylostella)
Emerald ash borer (Agrilus planipennis)
European corn borer (Ostrinia nubilalis)
Formosan subterranean termite (Coptotermes formosanus)
Glassy-winged sharpshooter (Homalodisca coagulata)
Gypsy moth (Lymantria dispar)
Hemlock wooly adelgid (Adelges tsugae)
Insect Biocontrol
Japanese beetle (Papillia japonica)
Mediterranean fruit fly (Ceratitis capitata)
Mexican fruit fly (Anastrepha ludens)
Oriental fruit fly (Bactrocera dorsalis)
Pink bollworm (Pectinophora gossypiella)
Pink hibiscus mealybug (Maconellicoccus hirsutus)
Red imported fire ant (Solenopsis invicta)
Russian wheat aphid (Diuraphis noxia)
Silverleaf whitefly (Bemisia argentifolii)
Wheat stem sawfly (Cephus cinctus)

Things get more complicated when the invasive species threat is not direct. The difficulties of the science, and the lack of absolutes, lead to statements of concern and even desperation as desired outcomes collide. Nan Wishner, Chair Emeritus of the City of Albany Integrated Pest Management Task Force and a member of the Stop the Spray East Bay Steering Committee writes that the total elimination “.. LBAM(light brown apple moth) is not feasible, the state plans to carry out a multi-year eradication program involving mass pesticide applications; that program’s first year cost an estimated $97 million.”

As the level of complication and complexities rise, the wicked inconvenience of invasive species issues seems to compel stakeholders to define their perceived problem in terms of their own unique a priori outcome desires. This means that each group of stakeholders has a slightly different working definition of invasive species making it very hard to reach consensus. The end game then becomes one of my way or the highway.

Any farmer or gardener will tell you that pests such as pathogens, insects and weeds are eternal; they do the best they can to control and eliminate the daily invasion that reduce monetary or aesthetic yield, knowing full well that the task is akin to sticking a finger in a dike. If farmers were to decide that weeds cannot be eliminated and gave up, we all would starve. Why then is it different when we set out to protect a natural area? Some would say we should just allow the invasion to create a new balance in time in a new, novel ecosystem and learn to live with it. In deed that is one option. It is the option of the property owner who chooses not to landscape, and cuts the brush around the buildings only to prevent fire and rodent damage. The neighbor who chooses to install and maintain an ornamental work landscape that requires endless removal of invaders is no less wrong in his choice than the former. So too our natural areas are like garden, rich in complexity and under constant and it would seem permanent attack. The issue at this level is one of limited resources as well as competing goals. Don’t use chemicals to control invaders in natural areas, and therefore allow a dramatically altered ecosystem, and deal with the unintended unexpected consequence later. Use chemical and reduce the impact, but suffer the affects of chemical pollution of air, earth or water.

So far we are speaking about the easy side of invasive species management and politics. Mark A. Davis writes in his new book, Invasion Biology, Oxford University Press, 2009, that ” …it is usually much easier to assess impact than it is to determine the series of ecological causes for it.” (White et a. 2006) Because current science has focused on the assessment of impact and not upon the mechanisms of ecological cause, certain stakeholders can reasonably claim that there is either no science or not enough science to support the dedication of resources. The present reliance on science as religion with the concurrent expectation that scientist-priests will rule on great issues ex cathedra and never ever change their minds fails to recognize that science is a tool for use in public discourse and public valuation exercises; science is not the end of the conversation but the beginning.

As Davis point out on page 151 of “Invasion Biology”, the ever-changing dynamic relationship between an ecosystem (itself ever-changing) and social systems (also in a constant state of flux) provides an overwhelming set of choices for environmental decision makers, land managers, and public policy deciders. Solutions and recommendations for invasive species will never be static and the casual observer will be endlessly confused. The tendency to throw up one’s hands in surrender will be powerful and the call to do nothing will be loud.

Controlling an invasive species or even eradicating it is most cost effective before it has actually done anything harmful. The idea that the LBAM should be allowed to spread because it has not yet wiped out a crop demonstrates the difficulty of getting people to care about something that has not actually happened yet. USDA has asked for more funding but because the problem is not pandemic begging is the order of the day. We as a society are loathe to spend money on something that has not happened yet. Better to wait til someone turns to crime and then incarcerate them than to pay less up front in education and work force development is our motto and so it is with invasive species

“Light brown apple moth is a recognized agricultural pest. Moths, such as light brown apple moth (LBAM) (Epiphyas postvittana), banana moth (Opogona sacchari), and nettle caterpillar (Darna pallivitta), are [known] pests of various tropical /subtropical crops, limiting production, and may severely disrupt trade if not detected and allowed to become established in primary growing areas. LBAM also attacks temperate crops and has recently been identified in California as a new invasive species. Because LBAM threatens a multibillion dollar industry in California, alone, CDFA and APHIS, have asked ARS scientists to help develop methods for LBAM control. Research Gaps including effective management of moth pests of tropical /subtropical crops requires the development of: 1) user-friendly, economical, and environmentally acceptable technologies; 2) area-wide integrated pest management (IPM) systems for moth suppression; and 3) systems approaches to prevent pest movement on export commodities.” (http://www.ars.usda.gov/SP2UserFiles/Program/304/ActionPlan2008-2013/2h.pdf)

If gardeners waited until the weeds crowded out the tomatoes we would never have spaghetti sauce. Gardeners know that early detection and rapid response is the key to a a successful harvest and react without waiting to see if the scientist can publish; invasion of the garden are dealt with summarily. But on an ecosystem level we sometimes choose to wait until the kudzu covers the telephone poles of a million acres before buying the special machinery needed to keep the roads clear. We will carefully not try to reduce the level of the apple moth so that we have a reduction in chemical impact, as we loose the harvest of the fields, hoping that when the moth is finished it does not adapt to our natural areas and begin to be a factor in the wild fires of California as other invasive species already are. The call is to find consensus and to work together towards a common management goal using the tools of science and the techniques of IPM to reduce the toxicity of the solution and the level of the pest simultaneously.

Somehow we need to find away between do nothing at all and waiting until there is nothing to be done. But I digress…until another species catches my attention.

An either/or of Invasive species

As with many difficult problems in life, the issues invasive species are usually framed in a yes/no - either/or framework. War or peace, life or death, feast or famine, farms or forests, sustainable ecosystems or economic development highlight and delimit the choices which we debate and discuss. The suspension of a restoration plan in favor of farming crops, prompted by increasing concerns over feeding world's largest population is presented as an either/or choice. (China suspends reforestation project over food shortage fears. Guardian, June 23, 2009) “The sacrifice of a key environmental restoration project for crop production highlights the growing problem of feeding the world's biggest population as cities expand into farmland and urban residents consume more meat and vegetables.” Most urban centers for historic reasons developed and grew on the best farm land compounding the problem.

Invasive species’ issues are framed similarly. The casually involved stakeholder finds the options that may be applied to invasive species policies described in terms of two diametrically opposed choices. Save the earth by planting non natives or contribute to the destruction of the universe by gardening with alien exotics. In actuality, a continuum of possibilities exists. From complete eradication through partial control, to slowing the invasion’s spread, to even doing nothing. The fuzzy rainbow of possible solutions is rendered even more complex by the problems of scale that are associated both with the ecological considerations as well as economic calculations. A new book investigates this dual partnership between economics and ecology in depth. (Bioeconomics of Invasive Species; Integrating Ecology, Economics, Policy, and Management Edited by Reuben P. Keller, David M. Lodge, Mark A. Lewis and Jason F. Shogren. 2009. Oxford University Press)

Invasive species’ partisans operate in related but different arenas of interest. Aesthetic discussions on matters of taste arouse considerable emotions. Questions of beauty and personal subjective interest spill over into political considerations. Property rights and ownership color the conversations about species restriction and market regulations surrounding gardening options and pet choices. Many have heard the claim that there is no authority that can dictate what animal may be kept as a companion or what flower may be proscribed from a landscape. The beauty aesthetic drives a market in new species introductions.

Another arena of disagreement is the use of natural resources. For some, there is a deeply held belief that resources are for all practical reasons, infinite. Ludwig von Mises explains in Liberalism: The Classical Tradition that “[h]uman labor by itself is not capable of increasing our well-being. In order to be fruitful, it must be applied to the materials and resources of the earth that Nature has placed at our disposal.” This sometimes religious imperative coupled with the foundational concept of resources beyond measurement makes possible technological advances that in turn deplete the available resources at an ever faster rate. The entire system is dependent upon technology accessing more difficult to reach resources ever faster. On the other side are the naturalists supported by many ecologists who warn of a spiraling increase in the decline of ecosystem services, or at the very least an accelerated change that is outpacing humanities ability to adapt.

Assessments of harm either to one’s personal subjective senses or to the resources supplied by ecosystems and the environment are stumbling blocks to finding consensus. Dr. Milton Friedman sums up the concerns of same constituencies by saying that “there's nothing that does so much harm as good intentions.” Aphorisms explain in part the reluctance to action on the part of those who would be financially or aesthetically restrained.

Annapolis Maryland proposes to ban invasive species - plants

The City of Annapolis, Maryland has decided to enter the war on invasive species - plants only. Introduced by Alderman Paone, ORDINANCE NO. O-05-09 is offered for “…the purpose of prohibiting invasive plants on lots or parcels within the City unless completely contained to control growth and prevent encroachment.” Unfortunately for the conversation and dialogue among interested parties, the Council thus far has decided to overlook the United States federal advisory committee definition white paper as a source for its working concept of “invasive species”. Instead, quoting from the proposed legislation, “…Invasive plants, as defined in “Invasive Plants of the Eastern United States” by the U.S. Department of Agriculture and the University of Georgia, are not permitted on any lot or parcel of land within the City unless completely contained so as to control growth and prevent any encroachment upon or interference with neighboring properties, utilities, streets, sidewalks, or structures of any kind.”[1] Clarity in legislation and sources of definition for wicked messy problems are a wicked inconvenience for some.

Wicked problems by their nature become a definitional struggle among stakeholders and woe to the policy arbiter who ignores this part of the controversy. The United States government recognizing the myriad definitions and fragmentation of the discussion by producing a white paper intended to provide a non-regulatory policy interpretation of the term invasive species by identifying what is meant, and just as important, what is not meant by the term. Executive Order 13112 – defines an invasive species as “an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.” In the Executive Summary of the National Invasive Species Management Plan (NISMP) the term invasive species is further clarified and defined as “a species that is non-native to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health.” [2]

The city of Annapolis has selected a well know and respected source of invasive species information. Invasive.org is a joint project of some of the following organizations and agencies: The Bugwood Network, USDA Forest Service & USDA APHIS PPQ.. The University of Georgia - Warnell School of Forest Resources and College of Agricultural and Environmental Sciences - Dept. of Entomology. The proposed bill is based on the Center’s statement that at least in part is not referenced in the legislation: “While this is not an official list of "invasive" plants throughout the eastern United States, it includes Federal Noxious Weeds and those listed by State regulatory agencies, pest plant councils and other organizations. Some of the plants on this list are often found in ornamental plantings and landscapes. In fact, many non-native plants introduced for horticultural and agricultural use now pose a serious ecological threat in the absence of their natural predators and control agents. This publication will aid landowners, foresters, resource managers, and the general public in becoming familiar with invasive plants in their area to help protect our environment from the economic and ecological impacts of these biological pollutants.”[3] Maryland’s own MISC (Maryland Invasive Species Council) list could have been cited, but was not.

Invasive species issues are controversial and problematic. Dr. Robert Lackey proposes nine generalities, all of which may come into play with the proposal:[4]
(1) the policy and political dynamic is a zero-sum game;
(2) the distribution of benefits and costs is more important than the ratio of total benefits to total costs;
(3) the most politically viable policy choice spreads the benefits to a broad majority with the costs limited to a narrow minority of the population;
(4) potential losers are usually more assertive and vocal than potential winners and are, therefore, disproportionately important in decision making;
(5) many advocates will cloak their arguments as science to mask their personal policy preferences;
(6) even with complete and accurate scientific information, most policy issues remain divisive; (7) demonizing policy advocates supporting competing policy options is often more effective than presenting rigorous analytical arguments;
(8) if something can be measured accurately and with confidence, it is probably not particularly relevant in decision making;
(9) the meaning of words matters greatly and arguments over their precise meaning are often surrogates for debates over values.

Dr. Lacey continues: “Wicked, messy ecological policy problems share several qualities: (1) complexity
— innumerable options and trade-offs;
(2) polarization — clashes between competing
values;
(3) winners and losers — for each policy choice, some will clearly benefit, some
will be harmed, and the consequences for others is uncertain;
(4) delayed consequences
— no immediate "fix" and the benefits, if any, of painful concessions will often not be
evident for decades;
(5) decision distortion — advocates often appeal to strongly held
values and distort or hide the real policy choices and their consequences;
(6) national vs. regional conflict — national (or international) priorities often differ substantially from those at the local or regional level; and (7) ambiguous role for science — science is often not pivotal in evaluating policy options, but science often ends up serving inappropriately as a surrogate for debates over values and preferences.

List from Invasive Plants of the Eastern United States: Identification and Control
alligatorweed
Alternanthera philoxeroides (Mart.) Griseb.
waterhyacinth
Eichhornia crassipes (Mart.) Solms
hydrilla
Hydrilla verticillata (L. f.) Royle
parrot feather watermilfoil
Myriophyllum aquaticum (Vell.) Verdc.
Eurasian watermilfoil
Myriophyllum spicatum L.
waterlettuce
Pistia stratiotes L.
giant salvinia
Salvinia molesta D. S. Mitchell
water chestnut
Trapa natans L.
Japanese climbing fern
Lygodium japonicum (Thunb. ex Murr.) Sw.
old world climbing fern
Lygodium microphyllum (Cav.) R. Br.
garlic mustard
Alliaria petiolata (Bieb.) Cavara & Grande
plumeless thistle
Carduus acanthoides L.
musk thistle
Carduus nutans L.
winged plumeless thistle
Carduus tenuiflorus W. Curtis
spotted knapweed
Centaurea biebersteinii DC
Canada thistle
Cirsium arvense (L.) Scop.
bull thistle
Cirsium vulgare (Savi) Ten.
tropical spiderwort
Commelina benghalensis L.
cypress spurge
Euphorbia cyparissias L.
leafy spurge
Euphorbia esula L.
goatsrue
Galega officinalis L.
orange daylily
Hemerocallis fulva (L.) L.
giant hogweed
Heracleum mantegazzianum Sommier & Levier
shrubby lespedeza
Lespedeza bicolor Turcz.
Chinese lespedeza
Lespedeza cuneata (Dum.-Cours.) G. Don
purple loosestrife
Lythrum salicaria L.
marsh dewflower
Murdannia keisak (Hassk.) Hand.-Maz.
small broomrape
Orobanche minor Sm.
Japanese knotweed
Polygonum cuspidatum Sieb. & Zucc.
lesser Celandine
Ranunculus ficaria L.
wetland nightshade
Solanum tampicense Dunal
turkeyberry
Solanum torvum Swartz
tropical soda apple
Solanum viarum Dunal
Asiatic witchweed
Striga asiatica (L.) Kuntze
coltsfoot
Tussilago farfara L.
giant reed
Arundo donax L.
deeprooted sedge
Cyperus entrerianus Boeck.
cogongrass
Imperata cylindrica (L.) Beauv.
tall fescue
Lolium arundinaceum (Schreb.) S.J. Darbyshire
Nepalese browntop
Microstegium vimineum (Trin.) A. Camus
Chinese silvergrass
Miscanthus sinensis Anderss.
common reed
Phragmites australis (Cav.) Trin. ex Steud.
golden bamboo
Phyllostachys aurea Carr. ex A.& C. Rivière
itchgrass
Rottboellia cochinchinensis (Lour.) W.D. Clayton
Johnsongrass
Sorghum halepense (L.) Pers.

Japanese barberry
Berberis thunbergii DC.
butterflybush
Buddleja spp. L.
thorny olive
Elaeagnus pungens Thunb.
autumn olive
Elaeagnus umbellata Thunb.
winged burning bush
Euonymus alata (Thunb.) Sieb.
Japanese privet
Ligustrum japonicum Thunb.
glossy privet
Ligustrum lucidum Ait. f.
Chinese privet
Ligustrum sinense Lour.
European privet
Ligustrum vulgare L.
sweet breath of spring
Lonicera fragrantissima Lindl. & Paxton
Amur honeysuckle
Lonicera maackii (Rupr.) Herder
Morrow's honeysuckle
Lonicera morrowii Gray
Tatarian honeysuckle
Lonicera tatarica L.
sacred bamboo
Nandina domestica Thunb.
jetbead
Rhodotypos scandens (Thunb.) Makino
Macartney rose
Rosa bracteata J.C. Wendl.
multiflora rose
Rosa multiflora Thunb. ex Murr.
wine raspberry
Rubus phoenicolasius Maxim.
Japanese spiraea
Spiraea japonica L. f.

Norway maple
Acer platanoides L.
tree of heaven
Ailanthus altissima (P. Mill.) Swingle
mimosa
Albizia julibrissin Durazz.
paper mulberry
Broussonetia papyrifera (L.) L'Hér. ex Vent.
Russian olive
Elaeagnus angustifolia L.
melaleuca
Melaleuca quinquenervia (Cav.) Blake
chinaberrytree
Melia azedarach L.
white mulberry
Morus alba L.
princesstree
Paulownia tomentosa (Thunb.) Sieb. & Zucc. ex Steud.
Bradford pear
Pyrus calleryana 'Bradford'
sawtooth oak
Quercus acutissima Carruthers
Brazilian peppertree
Schinus terebinthifolius Raddi
tallow tree
Triadica sebifera (L.) Small
Siberian elm
Ulmus pumila L.

fiveleaf akebia
Akebia quinata (Houtt.) Dcne.
Amur peppervine
Ampelopsis brevipedunculata (Maxim.) Trautv.
oriental bittersweet
Celastrus orbiculata Thunb.
purple crownvetch
Coronilla varia L.
Japanese dodder
Cuscuta japonica Choisy
swallow-worts
Cynanchum spp. L.
water yam
Dioscorea alata L.
air yam
Dioscorea bulbifera L.
Chinese yam
Dioscorea oppositifolia L.
winter creeper
Euonymus fortunei (Turcz.) Hand.-Maz.
English ivy
Hedera helix L.
Japanese honeysuckle
Lonicera japonica Thunb.
skunk vine
Paederia foetida L.
mile-a-minute weed
Polygonum perfoliatum L.
kudzu
Pueraria montana (Lour.) Merr.
bigleaf periwinkle
Vinca major L.
common periwinkle
Vinca minor L.
Chinese wisteria
Wisteria sinensis (Sims) DC.
Japanese Wisteria
Wisteria floribunda (Willd.) DC..


[1] http://www.ci.annapolis.md.us/upload/images/government/council/Pending/O0509.pdf
[2] Invasive Species Definition Clarification and Guidance White Paper, Submitted by the Definitions Subcommittee of the Invasive Species Advisory Committee (ISAC), Approved by ISAC April 27, 2006; http://www.invasivespeciesinfo.gov/docs/council/isacdef.pdf
[3] Charles T. Bargeron, David J. Moorhead, G. Keith Douce, Richard C. Reardon and Arthur E. Miller The University of Georgia, USDA APHIS PPQ and USDA Forest Service Forest Health Technology Enterprise Team. FHTET-2003-08; http://www.invasive.org/eastern/
[4] Lackey, Robert T. 2006. Axioms of ecological policy. Fisheries. 31(6): 286-290.

Invasive Species Definitions Defined

Reading through some web postings, I note a tendency to define invasive species vaguely, a sort of know-one-when-I-see it vernacular. Akin to this laissez-faire definitional approach is the nigh unto gospel ‘resignational’ sigh that every plant is invasive somewhere so what is the problem. This resignation percolates into unexpected quarters, even rumored to infect the Nature Conservancy itself. Yesterday, we were told that there was no scientific evidence of invasiveness; today we are told that the non existent problem of yesteryear is far too big to be solved, and therefore logically we should continue as before, somewhat ostrich-like.

Difficult non linear problems, in the case of invasive species, a wicked inconvenience, need working definitions which are build by stakeholders finding common ground upon which to build consensus. As with making laws and sausage, the construction of common definitions is not a pretty sight and for some the resulting definition is too wide, to small, too unwieldy, to narrow, too inoperable, too controlled, too inaccurate; however it is something agreed upon which allows for a starting point in efforts to move forward together.

Executive Order 13112, for better or worse, currently, defines an invasive species as “an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.” To clarify somewhat the term invasive species is further clarified and defined as “a species that is non-native to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health.”( Invasive Species Definition Clarification and Guidance White Paper Submitted by the Definitions Subcommittee of the Invasive Species Advisory Committee (ISAC), Approved by ISAC April 27, 2006 )

At the heart of the defintional challenge are the complications explained in the white paper “…concerning the concept of invasive species (arising) from differing human values and perspectives. Differing perceptions of the relative harm caused or benefit gained by a particular organism are influenced by different values and management goals. If invasive species did not cause harm, we would not be nearly as concerned. Perceptions of relative benefit and harm also may change as new knowledge is acquired, or as human values or management goals change.”
The definition white paper explores the seeming incongruous notion that white-tailed deer are not invasive species on the east coast of the United States, and more importantly why they are not form a definitional point of view. I of course think of them as a scourge when they eat all the sweet corn but that is a different posting. The paper discusses feral animals versus domesticated herds, opening the door for irate supporters of the rights of feral cat to infest natural areas and decimate the ecosystem rather like the activities of the humans which brought them in the first place.

The white paper examines the negative impacts on ecosystem services which invasive species cause. The examples are extensive and worth reading in order to gain a context for the issues. The summary does a good job of laying out the case: “Invasive species are those that are not native to the ecosystem under consideration and that cause or are likely to cause economic or environmental harm or harm to human, animal, or plant health. Plant and animal species under domestication or cultivation and under human control are not invasive species. Furthermore for policy purposes, to be considered invasive, the negative impacts caused by a non-native species will be deemed to outweigh the beneficial effects it provides. Finally, a non-native species might be considered invasive in one region but not in another. Whether or not a species is considered an invasive species depends largely on human values. By attempting to manage invasive species, we are affirming our economic and environmental values. Those non-native species judged to cause overall economic or environmental harm or harm to human health may be considered invasive, even if they yield some beneficial effects. Society struggles to determine the appropriate course of action in such cases, but in a democratic society that struggle is essential.

Many invasive species are examples of "the tragedy of the commons," or how actions that benefit one individual's use of resources may negatively impact others and result in a significant overall increase in damage to the economy, the environment, or public health. In ISAC’s review of Executive Order 113112, the public domain is specifically represented; however, the implementation of the NISMP has prompted concerns over the rights of personal and private property owners. Property rights are of great importance in the U.S. and one outcome of the NISMP should be to recognize the right to self determination by property owners and promote collaboration on invasive species management. The right to self determination is an important concept in a democratic society, however, with that right comes personal responsibility and stewardship, which includes being environmentally responsible. The natural environment that our society enjoys, recreates in, and depends upon to support commerce must be conserved and maintained. Effective invasive species management is just one aspect of conserving and maintaining our nation’s natural environment, the economies it supports, and the high quality of life our society enjoys.” http://www.invasivespeciesinfo.gov/docs/council/isacdef.pdf

If you are new to invasive species issues, then the white paper is a good place to start your reading.


Invasive Plant Science and Management 1(4):414-421. 2008 doi: 10.1614/IPSM-08-089.1
Invasive Species Defined in a Policy Context: Recommendations from the Federal Invasive Species Advisory Committee
K. George Beck, Kenneth Zimmerman, Jeffrey D. Schardt, Jeffrey Stone, Ronald R. Lukens, Sarah Reichard, John Randall, Allegra A. Cangelosi, Diane Cooper, and John Peter Thompson*
*Professor, Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO 80523; Lone Tree Cattle Company, P.O. Box 910, Bellflower, CA, 90707; Florida Department of Environmental Protection, 3900 Commonwealth Blvd., Mail Station 705, Tallahassee, FL 32399; Professor, Oregon State University, Department of Botany and Plant Pathology, Corvallis, OR 97331; Gulf States Marine Fisheries Commission, P.O. Box 726, Ocean Springs, MS 39566; Associate Professor, Center for Urban Horticulture, University of Washington, Box 354115, Seattle, WA 98195; The Nature Conservancy, University of California–Davis, Mail Stop 4—Robbins Hall, Davis, CA 95616; Northeast Midwest Institute, 218 D Street S.E., Washington D.C. 20003; Taylor Shellfish Farms, SE 130 Lynch Road, Shelton, WA 98584; The Behnke Nurseries Company, 11300 Baltimore Avenue, P.O. Box 290, Beltsville, MD 20705. Corresponding author's E-mail: george.beck@colostate.edu
Approved by ISAC April 27, 2006
Received: April 16, 2008; Accepted: August 2, 2008

Invasive species and ecosystem services; good and bad?

Invasive Species: Not Always a Bad Thing? makes the case for the ecosystems service matrix which I began to explain in an earlier posting; Ecosystem services are nested hierarchical processes with two fundamental parts, one being the "natural" system services and the second nested higher level systems being the human, or artificial (artifice-cial) services. for more on this please link to: Sunday, February 15, 2009, Sustainability's Ecosystem Service Matrix

The two parts of ecosystem services are not exclusive from a human perspective, they are linked together as necessary for the continuation of the human species with a quality of life expectation assumed.