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UNDERSTANDINGS OF INVAS IVE SPECIES IN THE UNITED STATES BY CINDY LI A THESIS Submitted to the Division of Environmental Studies New College of Florida in partial fulfillment of the requirements for the degree Bachelor of Art s Under the sponsorship of Professor Margaret D. Lowman Sarasota, Florida March 2010
ii Acknowledgements Thank you to the following individuals, for sh arin g your wisdom and support. Professor Lowman your excitement and expertise in environmental have guided me through my academics, thesis and baccalaureate exam. I appreciate your willing ness to engage with all of the projects that I have pursued at New College. Mom and Dad t hank you for letting me study at a strange little liberal arts school in Florida. I always have confidence in your love and support. Who else has parents who over night them twenty pound packages of home made Chinese food ? Caroline thank you for always making me laugh You inspire me! Jaclyn t hank you for sharing meals, ideals, family, kindness, adventure s and quiet times with me these past four years. Thank you, also, for showing me how to be a better person and teaching me how to write a paper. Jessica Jenna and Nath an, thank you for your help writing and editing my thesis. A ll of my friends : Jackie, Persephone, Letitia, an d everyone else thank you for making New College a spectacular experience. My committee: Margaret Lowman, Elzie McCord and Bob Johnson.
iii TABLE OF C ONTENTS Acknowledgements Table of Contents ..............................................................................................................iii Abstract Foreword Introduction Chapter One: Cultural Perceptions of Invasive Species .. ..5 English Sparrow .. Hybridized Honey Bee. 11 .. 1 4 Chapter Two: The Science of Invasive Phenomena 17 The Scientists Study and Prediction ... 18 Environmental Conse 28 .36 Chapter Three: 42 43 46 .5 1 Prevention Discus sion ...60 Works Cited 62
iv UNDERSTANDINGS OF INVASIVE SPECIES IN THE UNITED STATES Cindy Li New College of Florida, 2010 ABSTRACT Invasive organisms hold a certain place of notoriety to many who know and deal with them, an d in recent years, legislation from federal to county levels has been passed to reduce or eradicate their populations. These efforts are spearheaded by ecologists and industries negatively affected by invasive organis ms; however, they are not the only forces influencing how we think about invasive exotics. This thesis will attempt to draw connections between the cultural values and science that affect such policies and offer alternative ways of thought. Does our histor ically nativist view on nature carry through to today? How can alternative view s benefit our interactions with invasive organisms? Margaret Lowman Environmental Studies
1 Foreword What first sparked my interest in the topic of invasive species was the disdain for them that I observed in environmentalists and the prevalence of programs that attempt to eradicate populations of invasive species. I went on a nature walk soon a fter I moved to Florida, and the leader of this walk showed us Cuban anoles, Brazilian pepper, and a host of other non native species that thrive in Florida. When we came across a patch of air potato plant s with heart shaped leaves familiar to all Floridi ans, she immediately began to tear them all down, and explained that she was pocketing the bulbs to destroy later This idea of environmentalist s ripping down plants and expressing a personal hatred for them le ft me feeling a certain discord. What circumst ances justify the mass eradication of a species? Is the negative image of these species more prominent than positivity for the ecosystem? These questions began to complicate my understanding of environmentalism and led me to question what environmentalist values can represent Introduction When the topic of invasive species comes up in conversation, it is more often than not to speak about how they destroy ecosystems and threaten native species However, to discuss them in only this way ignores many comple xities. It is important to consider how one species comes to travel around the world, find a suitable habitat to establish a population and then intera ct with the species around them Additionally, one must consider how and why humans attempt to manage the se changes in the ecosystem. In industry and agriculture, most of the impact of invasive species is quantifiable and the management strategies are in line with mainstream agricultural pest control techniques. Industries want to make a product and generate revenue through the sale of that product,
2 but new problems arise as new species interact with this process T hese problems require funding to get managed and ameliorated. In wild environments, however, the new interactions that arise from growing populatio ns of non native species are more difficult to quantify and qualify as entirely detrimental or beneficial. For example, the growth of the zebra mussel population in the Great Lakes Region is correlated with the decline of native mussel populations but also with the increase of small mouth ba ss and yellow perch populations (MacIsaac 1996) Before diving into the bulk of this thesis, I will first briefly discuss some of the complexities that arise when thinking about invasive species, wilderness and environm entalism. First, the terminology used to speak about invasive species in both a cultural and academic context is not standardized T he terms exotic, non indigenous, and invasive can all be used to signify the exact same or completel y different statuses of species (Colautti and MacIsaac 1999) species that have been recorded to come to an ecosystem that they have not historically occupied, regardless of the vector or their dispersal or the extent of their est ablishment; native species establishing a population in a new environment; and I will use the term are considered pests and also denote the broader concept of non native species that impact environment negatively. William Throop attributes the wide spread importance of preserving wilderness to awe and limitation onto nature. Anna Tsing (1994) also connects the significance of nature to religion.
3 Nature, like God is both lawful and mysterious; it requires human efforts to know yet always slips away from full knowledge. Thus, although cultural analysts over and over demonstrate the cultural shaping of so called natural attributes, we can wrongly labeled by human cultural efforts; this is what gives nature its majesty ( 11 4 115 ) Wilderness can be defined land as that embodies this particular type of majesty, but a discussion of the significance of wilderness management requires something more concrete. The 1964 Wilderness Act provides a baseline definition, which describe s wilderness as land removed from human control or population. The management of non native species populations in wild lands in order to preserve those lands brings to light the problem of the It juxtaposes the concept of wilderness as land untrammeled by humans with the control that humans must exert at times to restore a natural landscape. In the case of invasive species, the eradication of their populations from wild lands usually requires either a significant corps of h uman workers or a significant amount of chemical pesticide or herbicide application. These but they certainly do not remove it from human control. It is important, then, to consider why these are some of the most prominent and recommended strategies for both wilderness and invasive species management. I argue that cultural concepts of xenophobia and nativism have influenced the popular framework of how to assign value to and interact wit h various elements in nature. Furthermore, this framework has come to have a hegemonic authority over how these species are managed in public, natural spaces. This thesis is an analysis of the interdisciplinary discourse o n invasive species through examini ng the development of the cultural narrative, invasion biology and the implementation of management strategies. The purpose of this tripartite
4 division is to isolate and analyze three popular topics of debate in invasive species management: cultural values scientific objectivity and the struggle to find consensus in applying these knowledges. I n essence, I will analyze how we perceive study, and interact with invasive species In the first chapter, I will attempt to trace the cultural significance of inva sive species in the United States after European colonization through nature writing, journalism and social critiques. I will also introduce three invasive species to consider in the framework of the rest of the text. In the second chapter, I will analyze the discourse of the field of invasion biology, beginning with the work of Charles Elton and continuing to current publications from invasion biologists who still are muddling through how to embody both scientific objectivity and environmentalist values. F inally in the third chapter, I will examine management plans and actions to show how interests and agency of the stakeholders involved with invasive species have come to shape ways that they are managed in the wild.
5 Chapter 1: Cultural Perceptio n s of Invasive Species To begin thinking about invasive species, it is important to first consider how they have come to exist in a cultural context, i.e. how they have appeared in nature writing or journalism rather than in scientific papers or government publications. Changing cultural values and the role of the environment in the United States have led to an evolving narrative of the invasive species. Typically, organisms are considered non native in the United States today if they arrived after initial European colonization in the 16 th century. (Gordon 1998) Prior to this point in history, Native Americans had already lived in America for at least 12,000 years. Despite cultural imagery to the contrary, they did not live in perfect harmony with nature and indeed affected the environment in the United States in significant ways. They imported non native crops such as corn, beans, squash and pepper from the Caribbean to the United States and also altered the landscapes through hunting fire regimens and agri culture (Winters 1967) (Peretti 1998) However, upon European colonization, up to 90% of the indigenous population in the Americas was lost due to introduced disease and conflict as a new scale and regime of human in fluence began (Crosby 2003 ) This marks an important point in history to begin discussion of how introduced species are understood in the United States. In the famous Columbian Exchange, an enormous number of plants, animals, foods, diseases and people crossed the Atlantic Ocean from the Eurasia n and African continents to the Americas and vice versa. Christopher Columbus, the namesake of this global phenomenon, began an era of widespread global travel and trade when his ships a rrived in the Caribbean in 1492 (Crosby 1972) Some of the organisms, such as livestock and food crops, were introduced intentionally, while others, such as the brown rat and
6 zebra mussel, arrived to their new homes as stowaways. Most of the livestock and food crops could be controlled by their human companions, so they were and still are considered to be domestic species S imilarly, the stowaways remain unmanageable invasives. The number of species transported from the Old World to the New World was much higher than those transported the opposite direction. European settlers were eager to bring crops and livestock to the New World so that they could grow familiar food for their own consumption as well as for economic gain as exports. In addition to the species brought to the New World as crops and livestock, others were broug ht to release into the wild to recreate familiar European landscapes. Many of these imported species did not benefit the landscape as predicted and instead became a nuisance to European settlers. Peter Coates (2007) comments that as people increasingly b egan to observe the effects of non native plants in altering the environment, they began to connect this phenomenon with the stigmas associated with human immigrants. He quotes Roderick The Ecological Approach to the Study of Human C ommunity Just as in plant communities successions are the products of invasion, so also in the human community the formations segregations and associations that appear constitute the o utcome of a series of invasions (74) Although many ecologists were ca reful in their discussion of ecological invaders and colonizers to distinguish these terms from those used in a social context, it was unavoidable that they would become understood that way by at least some of the public. Nativism refers to the defense of native residents that a rises in response to the perception of an immigrant threat. This social concept has also been tied to the public understanding of invasive species.
7 In response to his observation of nativism in the natural gardening movement, Michae l Pollan (1994) writes: antihumanist, particularly in the way it seeks to erase people and history from the land. Yet this can't be more than a conceit, since even a natural garden n eeds pe ople to create and cultivate it ( 2 ) Although Pollan acknowledges that his accusation of antihumanism towards nativists is exaggerated, it does raise complex questions regarding the role that humans play in altering the environment. His perspective represents a popular one that challenges the claim that species dispersed by human vectors are any less natural than the ones dispersed by non human vectors. Pollan questions how the actions of humans are less natural than the ac tions of other organisms o n Earth, and claims that global species migration is simply the current state of natural history. Based on this contention, he argues that the mixed use of native and non representative of American m ulticulturalism. Many arguments against ecological nativism, such as against human discrimination. In this argument, a ccepting and even inviting the presence of non native species in the American landscape is akin to accepting cultural diversity in human communities. The three invasive species described below have caused controversy in America for a variety of reasons. Each has affected different stakeholders and elicited different responses from the public, but they all share the status of being foreign invaders. Below, their natural histories in the United States as well as public reactions to their establishment will be described in order to offer further insight into how Americans understand invasive species. 1.1 The English Sparrow
8 Late in the nineteenth century, populations of English Sparrows (also called House Sparrows, European Sparrows or Passer domesticus ) began to expand in the Northeastern United States. English Sparrows are not the same as American sparrows, which a re a group of bi rds from the family Emberizidae. In fact, American sparrows are only called sparrows by colonists because of their physical resemblance to the English Sparrow. In the United States, English Sparrows were originally imported from England in the autumn of 1850 by the directors of the Brooklyn Institute of Arts and Sciences; they did not thrive upon this initial release. Another release by the Brooklyn Institute in 1852 proved again to be unsuccessful. In the spring of 1853, eight pairs of spar rows were set free in Brooklyn and successfully began to reproduce (Barrow 1889) By 1880, at least another 100 releases of sparrow mating pairs were reported by ornithologists, acclimatization societies and other local and civic forces. What spurred this mass, persistent release of sparrows? In New York City and other U.S. cities that were developing in this time period, crowded conditions and urban trees fostered large, unattractive population of insects, of which canker wor ms were especially bothersome. According to some accounts, the canker worms fell from trees onto pedestrians or were crushed and left to mar the streets and sidewalks. Groups such as the Brooklyn Institute and the American Acclimatization Society were eager to curb the population of can ker worms by introducing insect eating birds from the Old World. And while the Brooklyn Institute was a proponent of sparrow introduction for primarily utilitarian purposes, the American Acclimatization Society imported European flora and fauna in order to recreate a landscape for which many Eur opean immigrants felt nostalgic (Coates 2007). A considerable part of our population, and especially that of the newer parts of our country, consisted of Europeans who naturally remembered with pleasure
9 many of the s urroundings of their former homes and doubtless longed for the familiar chirp of the Sparrow. They had no strong associations connected with our American birds and our treeless cities and uncultivated prairies contrasted strongly with the thickly settled c ountry half garden, half city which so many of them had left. (Barrow 212 ) This quot ation explaining the s entiment that English Sparrows aroused comes from Walter Bradford Barrows, a Harvard professor of biology, in a report on the birds to the United States Department of Agriculture in 1889. Isidore Geoffry Saint Hilaire, a French zoologist, founded the first acclimatization society in Paris in 1854. These societies became widespread in the United States and other countries colonized by Europeans at th e time. The organisms that European ex patriots valued and decided to import were not only familiar faces from home but also considered more useful or perfect than the ones in their current locations. European birds with familiar songs and functions, the refore, were particularly desirable in the United useful as food or otherwise which we had not here (New York Times 1877) Despite t he presence of suitable fish in American waters, it was not enough to have some fish in some waters and other fish in others T he U.S. Fish Commission commonly redistributed fish species around the United States (Rhymer and Simberloff 1996) In hindsight, it is easy to see that the population redistribution efforts accomplished by acclimatization societies did not successfully result in their idealized environments. Rather, the organisms they relocated were treated as resources and commodities that European immigrants living in the United States could use at their own discretion. In the case of English Sparrows, they were imported for pest control and as a reminder of the atmosphere of the Old World.
10 English Sparrows were received warmly when they first bega n to populate U.S. cities after they showed that their appetite was voracious enough to visibly reduce canker worm populations (Coates 2007) control abilities, citizens began to build nest boxes in hopes of attracting the b irds and their beneficial services. The sparrow population grew steadily through the initial years of introduction and became an established member of many American urban ecosystems. Breathing with quiet pleasure the cool air cleansed by the night, lacki ng all will, To let such happiness go, not thinking the least thing ill, In me for such indulgence, please with the day and with myself. How sweet, The noisy chirping of the urchin sparrows from crevice and shelf Under my window, and from down there in the street, Announcing the advance of the roaring competitive day with the city bird song. (Millay 230) This poem by Edna St. Vincent Millay illustrates her camaraderie with the sparrows, but also foreshadows the problems to come with their growing po pulations. Sparrows are creatures with high behavioral adaptability, so as the number of canker worms began to decrease, and the sparrow population increased, sparrows needed to search for more food sources. In cities, they consumed the undigested grains i n horse manure. At this time, of course, horses and horse drawn carriages were very popular forms of transportation Horse excrement scattered all over the streets was evidence of their ubiquity This food source drew the sparrows into the streets. People observed that the sparrows seemed to eat more grains while the canker worm population seemed to rebound, but the correlation was not tested scientifically. Untested as it was, this development still changed the perspective of those who wanted sparrows to k eep feeding on worms. The sparrows also
11 appetite for grains was even less acceptable. In cities, they were merely a nuisance, but in rural areas, they became a financ ial liability to farmers. At this point, people who had spoken out against sparrow import and advocated native species found a more receptive audience. This included the American ited argument that many of these scientists made for the favorability of native organisms is a precursor to current science of invasive organisms. Popular opposition to the spa rrows appealed to a lingering resentment Americans felt towards England as well as a growing fear of human immigrants. o T he basis of these monikers, race and class, indicate s that the fear of foreign intruders has been a historical influence in the consideration of the environment. Anti sparrow advocates drew more supporters when citizens realized that sparrows had more agency than they expected and did not limit themselves to simply ea ting pests and singing songs. Farmers found that sparrows had an appetite for anything that they could grow ; as city dwellers found that sparrows would nest in any small nook or crevice in a building, often too close for comfort. Distaste for these sparrow s grew so great that by 1880, the state of Michigan began to offer a bounty of one cent per head on English Sparrows in an effort to reduce their population Some towns also offered bounties and many farmers took individual initiatives to curb sparrow popu lations themselves through firearms, trappi ng, poison and nest destruction (Barrow 1889) 1.2 Hybridized Honey Bee
12 Beginning in the late 1980s, a hybrid species (between African and European races) of honey bees began to migrate into the United States fro m Central America. Known as killer bees or Africanized bees, the actions and migration of these insects have been well publicized to the American public ever since Time magazine coine in 1965 (Time 1965) The bees were first bred in Sao Paolo, Brazil by Dr. Warwick E. Kerr in the 1950s, who was attempting to breed a bee that would make more honey in tropical environments than European bees, which are more suited to temperate climates. Kerr did not find any luck succeeding in this proj ect, and furthermore 26 African honey bee ( Apis mellifera scutellata ) queens were accidentally released in 1957. They began to breed with European honey bee ( Aplis mellifera ligustica ) drones in the wild and in domestic hives. The African honey bee has beh avioral characteristics more adapted to and suited for the tropical climate from which they originate. The European and American tradition of beekeeping has selected for t hrough breeding, behaviors that help apiarists. They wanted bees that were less aggr essive and tended to hoard honey, a behavior that in natural settings helps them to prepare for winter in Europe. In Africa, however, honey procuring traditions lean more towards hive hunting rather than hive keeping. These bees, thus, do not have the same history of breeding. Their habits of swarming, absconding and hoarding less honey are more suited for environments with human (and other) predators, rather than maintainers. A colony can quickly relocate to another location without too much consequence. M any of these African honey bee qualities occur in the hybrid species, which makes them unfamiliar and undesirable to apiarists.
13 Killer bees began to appear in popular culture, as sports mascots and especially in the media. In The Swarm a big budget film p roduced in 1978 by Irwin Allen, a swarm of killer bees wreak havoc on American cities by disrupting trains, attacking an Air Force base and causing a nuclear meltdown. Although the plot is obviously fictitious, the film draws upon and magnifies actual publ ic fears: the contamination of gentle, Europe derived honey bees by fierce, tropical bees; their increased tendency to swarm; and the insidiousness of a small creature with such a dangerous stigma. In October 1990, the first swarm of hybridized bees was c aptured in a trap in Hidalgo, Texas. Other private reports in the early 1990s included a construction worker who reported that he observe d a swarm of bees kill a rabbit (Tsing 1995) News reports had characteristics were reduced after further breeding with European honey bees while other reports stated that the bees were unquestionably vicious and dangerous. Statements such as the following, published by Bayard Webster in the New York Times in 1982, used very racialized language to describe the bees. Dr. Taylor's data also showed that African drones mated with both European and African queens, but the European drones tended to mate only with European queens. As a result, over several generations an area's population of European bees tended to be come Africanized ( 1 ) One main problem in the public discourse of these bees is the use of the term, try of the bees meaning that honey bees have a default status as European honey bees, and that hybrids between them and African honey bees must be labeled as Africanized to mark them as other than the default.
14 While the danger of hybridized bee attacks has been sensationalized to the public, another more economically pressing threat is the effect that the hybridized bee would have on commercial hives. Their aforementioned inability to survive harsh winters and lowered production of honey in cold climates made them unwelcome in northern apiar ies Many hives have been shut down in fear of hybridization, but the Florida Department of commercial and wild bee hives shoul d be maintained and protected instead. They and the U.S. Department of Agriculture fear that decreasing European honey bee populations will open a niche for hybridized bees to exploit. New reports on the suggested management of hybridized bees attempt to r educe the public fear of their danger and point to cases in Brazil, where beekeepers now favor the hybridized bees for their suitability for tropical climates (Winston 1992) In the 1960s, many South American beekeepers abandoned their hives in fear when t he hybridized bee population began to grow, but in recent years, new beekeeping techniques have made hybridized bees an improvement over European bees in many tropical areas. 1.3 Australian Pine Australian pine was introduced to Miami Beach in the 1890s an d planted along canals and beach fronts as windbreaks and as erosion control. It was also planted in hope that a timber industry could develop with it. The three most prevalent species of Australian pine in Florida are Causarina litorea C. glauca and C. c ristata Despite the these species are actually angiosperms rather than gymnosperms. They have become naturalized in Florida and have spread to areas beyond their original introduction, primarily to sites of significant human activity. Beginni ng in the 1980s, the
15 Florida Park Service and the Florida Exotic Pest Control Council (FLEPPC) began state wide efforts to reduce Australian pine populations in Florida. Although many citizens accepted plan or were ignorant of it, some who felt an emotion connection to the trees Many of the projects to clear areas of the Australian pines were met with public outcry. Ken Ellis, in 1999, published a personal website conveying his horror as he observed the park service clearing Australian Pines I was appalled at what I saw! The beauty of South Beach Park had been destroyed destroyed by butchers with chain (Ellis 1999) Others have accused the state of Flor ida of having a vendetta against these trees (Morgan 2009) Ellis accounts a dissatisfying interaction with the Florida State Park Service. He portrays the park ranger, Jeff Borick, whom he spoke with as confused, vague and generally uncertain of how the A ustralian Pines were harming the ecosystem. I asked Mr. Borick why the Australian pines were considered a pest and needed to be removed. His answer seemed vague to me. He referred to th e Australian pines that needed to be removed. He indicat ed that the needles that they drop on the ground seem to discourage other native plants from growing nearby. He implied that the Australian pines spread and take over whole areas. I asked if they were being removed because they might blow over in a hurrica ne, but he said that was not one of the main reasons. (Ellis 4 ) Of course this statement is not representative of all interactions between the Florida State Park Service and the public; however, it does show the opportunities for gaps in knowledge communi cation among scientists, the park service and the public. Mr. Borick somebody who is already familiar with the complex systems that su pport such scientific arguments, but it may be lost on many who have learned to appreciate the environment
16 through leisure or other experiential ways. Many people have positive interactions with the shade and scenery that the trees provide, so they understandably demand justification when the pa rk service plans to remove them. So what effects do Australian pines have on the environment in Florida that would justify such a vendetta? In Florida, they can grow up to eighty feet in ten years, much faster than in Australia. Many people fear that Aust ralian pines due to their large size, could damage property and surrounding flora during hurricanes and strong winds (Department of Environmental Management 2006) Their shallow roots compound this problem. Their rapid growth is also suggested to preempt the growth of other plants because they can establish themselves on a patch of land first. After they become established, they can prevent other plants from growing beneath their canopy because their leaf litter has allelopathic qualities (Parotta 1995) T hey have a high rate of nitrogen uptake, which prevents other plants from growing near them as well. Habitats created by red mangrove prop roots have been a key environmental feature of Key Biscayne, FL and all around the Biscayne Bay. Since the 1970s, tho ugh, Australian pines have been observed to grow on the same lands as mangroves. Although currently, one might find that the dominant reasoning for the rem oval of invasive exotics is based on ecology, one can see that many other players, including agricul ture, journ alists, poets, and naturalists have contributed to the dialogue surrounding invasive organisms. Each of them has played a role in complicating and changing the interactions between humans and non native species. In the following chapters, I will explore further how these players affect the production of facts and management strategies regarding invasive exotics
17 Chapter 2: The Science of Invasion Phenomena Invasion biology became a distinct area of study in the late twentieth century and is often now categorized under the broader field of conservation biology. This field of study has used a synthesis of methodology and theory from a wide range of other scientific studies, including ecology, bioinformatics, evolutionary studies, zoology, botany, and many other related fields. Invasion biology has also created its own distinct methodology by focusing on the phenomenon of non native primarily plant and animal species establishment in new environments (Vermeij 1996 ) This type of study is fairly nov el to the broader field of ecology and can be classified under conservation biology due to the focus of invasion biology on human affected environments, rather than the traditional focus of ecology on wild environments. Scientists working in this field are still working to determine how to standardize the major concepts of the field, qualities such as invasibility and invasiveness. These terms refer to the susceptibility of an environment to establishment by foreign species and the ability a species has to become established: key qualities that define the interactions of the two natural players the species themselves and the environment in invasion biology. Invasion biology, being a relatively young and also applied field of study, still lingers in the stage of exploring how to incorporate social values with scientific knowledge production. Some scientists in this area work to defend the rigor of invasion biology as an objective science, while others value the social impact that invasion biology receives and imparts. Critics of this field are from many different backgrounds, including other ecologists and scholars from o utside fields. Most of these critiques do not deny the validity of studying invasive species; however, they do reevaluate the methodology
18 language and application of the science. As an applied science, defined as one that applies scientific knowledge to the physical world, invasion biology has the potential of affecting global regulations of trade and the environment. Being mired in these global interactions, invasion biology is steeped with cultural values and other societal influence. I argue that these influences have resulted in a xenophobic and nativist application of the science. Some of the scientists who contribute to the discourse of the application of invasion biology critically engage with this social influence, many are too quick to dismiss these complexities. Through further engagement with both the research and application aspects of it, the study of invasion phenomena can simu ltaneously embody the positive values of preserving wilderness without pursuing a prejudiced agenda and still retain its scientific rigor. 2.1 The Scientists Study and Predictions Charles Elton has been described as the father of invasion biology after h is influential book, The Ecology of Invasions by Animals and Plants persuaded other scientists to consider the harmful effects of foreign species on an ecosystem (Elton 1958) He describes many instances of great ecological change occurring as foreign spe cies were introduced to various ecosystems and makes predictions about the future of biological invasions. In this text, Elton does not present his own scientific study of non native species as much as he recollects cases of foreign species establishing po pulations in new environments. In later interviews, he himself lamented the fact that the book was a collection of anecdotes rather than a more methodical work. Current scientists do acknowledge that the value of the seminal text was to present a set of i nductive generalizations for others to explore. Elton highlighted an environmental issue and made
19 an urgent call for other scientists to study and act upon it, similar in intent to Rachel d as a scientist, he also drew from his cultural and emotional background to form his conservation ethic. Preserving the imagery and memories of the British landscape that he grew up with was important to Elton, in addition to his desire to preserve biodi versity and stable ecosystems. This sense of protection and care that he had for his home was the tool he used to pull at the heartstrings of other scientists and inspire invasion biology. Much of the work of the United States Soil Conservation Service is concerned with putting back what had been lost or creating entirely new kinds of habitat interspersion, whereas in Britain we might still have the chance of keeping our own remarkable landscape before it loses its ecological variety. ( 33 ) Besides the inhe rent value of the plants and animals themselves in an ecosystem, Elton cherishes the imagery and ideals that the landscape represents. Even as a rigorous scientist, national pride has influenced his conception of conservation and ecology to a great degree. Although he is advocating the preservation of wilderness, he emphasizes in the final chapte r of The Ecology of Invasions that the manmade hedges and rural landscapes are environments with important ecological and economic functions as well. This sentiment demonstrates clearly the value that native species hold for Elton, even in a heavily disturbed landscape. 2.1.1 Invasibility Simberloff, one of the most prolific publishers of inv asion biology literature wrote an introduction for the 2000 edition of Elt The Ecology of Invasions This piece is significant despite its briefness, in that is acts as a jumping off point to discuss the development of the field since Elton. Simberloff notes his considerable appreciation of
20 made to the field since the 1950s. Although he noted that invaders sometimes got into natural habitats, Elton felt that sites dis turbed by humans roadsides, agricultural fields and the like received much more than their share. Most researchers today would agree with this contention but many would question his explanation. ( viii ) Elton believed that the disturbed landscapes wer e more damaged, more ill, so to speak, so they were more invasible (susceptible to invasive species establishment). This theory was based upon his own observations, corresponding to a popular ecological idea in the 1950s and 1960s that a strict causal rela tionship exists between the increased number of native species in an ecosystem and the increased stability of that ecosystem, diversity stability. Simberloff states that current studies seem to show that propagule pressure, simply defined as the repeated e xposure of an environment to a new species, rather than the diversity stability relationship, is the cause of the trend that Elton noticed. The idea of stability is still a heavily contended one, and thinking has changed since the 1950s. So to speak furth er of stability in ecosystems, we must first define the term and its importance. In ecology, stability is most often defined in two ways: first as resilience, an changes ( Hansson and Helgesson 2003 ) Aldo Leopold describes stability as the 49 ) This idea is furthermore based on an underlying assumption in ecology that equilibrium is optimal in population dynamics. The consideration of environmental stability in ecology, and more specifically conservation biology, is important in a social context so that humans can draw resources from the environment without completely depleting the sources. Elton and other ecologist s also value the continued existence of wilderness for its inherent worth in
21 addition to the continued economic value of natural resources (Elton 1958 Simberloff 2000 ) Quite a few scientists began to challenge the notion of diversity stability in the 19 70s and 1980s, notably May (1973), Yodzi s (198 1 ) and Pimm (1984). May used mathematical modeling to run linear stability analysis on randomly constructed community models with random interaction strength. In his community models, he found that diversity te nded to destabilize the communities rather than stabilize them. This finding, although revolutionary in its implications, was limited by being a mathematical model rather than a field study. Yodzi s found that in models based on existing food webs, the inte current field studies that attempt to quantify stability through these mathematical models, the results are still ambiguous and inconclusive at best. To further complicate the consideration of stability in environments affecting the establishment of invasive species, Pimm creates a compilation of eleven defined variables in environmental stability and offers a basic proposition of stability patterns he has drawn from his own wor k and the work of others, including May and Yodzi s His eleven defined variables, furthermore, do not contribute predictably to stability in an environment, that is to say, factors such as resilience and resistance in an ecosystem are not necessarily confo unded, despite them both being factors that contribute to stability. Boiled down, he states that in theory, populations with great species variety should be more stable if they have less connectance, i.e. the number of actual interspecific interactions div ided by the number of possible interspecific interactions, and that a community with higher connectance should have higher stability with lower species variety. This influential work in ecology and
22 necessity of a continued effort to connect theory and field work. 2.1.2 Invasiveness On the other side of the issue, scientists are attempting to isolate the qualities of foreign species that allow them to establish populations in new environments. Data from these findings have been used to enact specific and effective quarantines. In Australia, potential for invasion in their respective regions (Daehler and Carino 2000 ) Australia and New Zealand were the first nations to develop a weed risk assessment (WRA) system to screen foreign plant species. The criteria for invasiveness are influenced by both geopolitical considerations, in that the plants are screened for entran ce to the nations of Australia and New Zealand, and also biogeographical ones in the analysis of what kind of ecosystems may be susceptible to the foreign species. The WRA uses eights types of criteria: domestication of the species, climate and distributio n, pest elsewhere status, unappealing qualities (toxicity, allel opathy, high growth density, etc.), plant type, reproduction, dispersal mechanisms, and persistence attributes (seed production rates, susceptibility to herbicide use, etc). One weakness of th e WRA is in its use of the pest st atus elsewhere criterion (Rejm nek et al. 2004) In most Australian cases, the status of whether or not a species has become invasive elsewhere in the world is the primary determinant of whether or not it is invasive in th e WRA system. This weakness does not negatively affect screening plants that have already become established as invasive elsewhere but does present an issue for the identification of novel invasive species as well as for the determination of a general set of criteria for invasiveness. The effectiveness of
23 the WRA has been tested on species that have already established as invasive in Australia, New Zealand, Hawaii and Florida. In each of these areas, the system had the highest success rate confirming specie s that have become pests, but also classified many non pest species as invasive as well. Fewer qualities that determine invasiveness in animals have been identified and evaluated compared to those in plants. This is due in part to the lack of methodology, as well as lack of study. For example, research has found that non native bird populations are more likely to establish if they are non migratory, with a larger body mass. Due to the absence of re s earch supporting these claims, they are not comprehensive e nough to successfu lly predict invasibility (Kolar 2001) A better understood factor has been linked to the increased success of non native bird establishment is increased instances and quantity of birds released, propagule pressure (Cassey 2004 ) This noti on of propagule pressure is of increasing importance in the current framework of invasion biology. Propagule pressure is not used as a predictive model for determining future invasives, but rather works at finding the root cause of invasion phenomenon. Ins tead of relying exclusively on either the stability of an ecosystem or the inherent qualities of a species to predict the success of species establishment, this idea uses the number of instances a species is released in the environment (propagule number) a success. Greater propagule numbers and propagule sizes seem to result in greater success in most cases, and qualities of both the environment and the foreign species can also be incorporated into the explanation of each phenomenon ( Novak and Mack 1995; Rejmanek 2004 ) Beyond this simple correlation, the explanatory power of propagule
24 pressure has the flexibility to include a variety of other environmental and species f actors: the amount of genetic variation in an establishing invasive population, the vectors and pathways that affect the environment, flow of nutrients and also interaction with other species (Lockwood 2005) increased invasion phenomena in disturbed areas such as agricultural fields or roadsides through increased exposure to human traffic bring intentional or unintentional foreign carry ons. Innumerable instances of species introduced through repeated human r elease in developed areas exist. Just a few examples include zebra mussels, native to the Black and Caspian Sea, being transported unintentionally through ballast water to find great success in the waters North America and Western Europe; the English sparr ow, which was released intentionally repeatedly in the 19th century in the Atlantic Northeast region of the United states as a predator for native insect pests; and the melaleuca, a genus of plants in the myrtle family that was intentionally released repea tedly during the 20th century in Florida to dry out the Everglades for real estate development. Additionally, propagule pressure has gained validity through the explanation of instances of invasion stability th eory. Levine, et al. (2000) examines the trend of greater invasion phenomenon in less disturbed areas of a California riparian system. He explains the greater invasibility of areas downstream, which have greater biodiversity, due to the flow of nutrients a nd seeds in the river settling further downstream. The combination of higher nutrient density with higher propagule pressure in that ecosystem increased the success of all plants, native and non native. The ecosystem downstream, despite being physically fa rther removed from human
25 disturbance, experienced the impact of increased traffic flow through the pathway of the riparian system. 2.1.3 Environmental consequences the devel opment of how scientists evaluate the consequences of non native species establishment. He begins his text by introducing the idea of ecological explosions, which restrain explosion, including flare ups of the plague in humans due to the flux of their rodent vector populations, and pandemic influenza that arose in Europe and North America after World War I, but brings his focus to the ecological explosions that he observed from non native species in an environment. The main consequences that Elton observes for local ecosystems are the economic harm that non native species have had on agriculture damage to cotton crops and also the damage that they do to other species in the wild, such as defoliating or killing trees. Elton predicts that non native species that thrive in disturbed environments will come to dominate them. He also predicts that some non native species will out compete similar native species for the same resource and become more successful, as in the case of Cuban anoles pushing the populations native green anoles out of their original habitat ( Nicholson et al. 2005) Finally, on a global scale, Elton predicts that with repeated and increasing transport of foreign species to new environments, ecological systems around the world will experience a pronounced decline in biodiversity and stability. The way that Elton frames these consequences under
26 the ultimate consequence of destabilizing global ecosystems points readers to a conclusion that non native species can only harm an environme nt. Since then, many invasion biologists have tried to steer away from jumping to this conclusion because of the aforementioned change in stability theory and through the study of beneficial effects of non native species to their new environments ( Johnson and Padilla 1996 ); but does it still affect the value system of invasion biology nonetheless? Simberloff and Rhymer describe problems that can from a non native species evolving in its new home (Rhymer & Simberloff 1996) Evolution can occur through repr oduction within the population of non native species or through hybridization with native species. They then introduce an effect that they call genetic pollution, which results from the hybridization of native species with non native ones. He points to Gam busia amistadensis a fish once found in only at the Goodenough Spring in Val Verde, Texas, and charges introduced Gambusia species of hybridization to the point of the G. amistadensis valu able in conservation biology; however, it is important to contextualize population changes on the broader scale of the ecosystem. In 1968, only a few years prior to the observed extinction of the fish (Peden 1973), the newly constructed Amistad Reservoir f looded the Goodenough Spring with over 30 meter of water. This event was what initially flushed G. amistadensis from Goodenough Spring and brought in other fish from the same species group, G. nobilis If the continued existence of a certain set of genetic information is valued, then certainly the effect of the new species on G. amistadensis can be considered detrimental, but what makes genetic preservation important and how does it affect the broader ecosystem?
27 Broadly speaking, ecologists agree that grea ter biological diversity on many levels genetic, species and ecosystem is socially important because of the inherent value of sustaining life (Ehrlich & Ehrlich 1992) Though this value is shared among most ecologists, there are many arguments for how to preserve biodiversity and what levels of biodiversity are more important. The Endangered Species Act of 1973 reflected the environmentalist trends at the time to focus on fostering threatened populations of individual species. Current thinking on the to pic of preserving biodiversity shows a shift in focus away from individual species to the scale of ecosystems. A focus on maintaining the health of matrices that support ecological systems can help support greater species variety that a focus on pr eserving individual populations (Franklin 1993) In the case of G. amistadensis the factor that caused its initial population decline was not the hybridization with non native species but the construction of the Amistad Dam, which submerged acres of land under wa ter. Additionally, because the original ecosystem of Goodenough Spring was completely lost, it is not completely accurate to say that the other G. nobilis species are non native. In this case, the ecological explosion did not put new species in an existing ecosystem but instead destroyed it and created a completely new one. The loss of the wild population of G. amistadensis is indeed unfortunate, but hybridization with non native species was not the main causal factor as Rhymer and Simberloff presented. Non native population establishments do affect many systems within ecosystems. At times, they occupy the same niche as a native species and out compete them. In environments of primary succession, this success over native species often results in the incre ased reliance of other species on the non native species instead of the native species
28 (Titus 200 2 ) (Bellingham 2005) The establishment of some non native species also alters the cycles of natural phenomena. In ecosystems that are maintained by natural c yclical fires, invasive species have changed the timing and dispersal of the fires. The introduction of cheatgrass in the American Southwest has expanded the range of fires and helps to maintain a grassier landscape rather than a shrubby one (Brooks and Py ke 2002) Stands of Tamarix a genus of trees native to Eurasia and Africa, in the Great Plains have been shown to consume greater quantities of water than native cottonwood stands (Sala 1996) In Florida, the melaleuca, introduced to the Everglades, has a lso been shown to consume higher quantities of water than native plants. Whether the success of Tamarix is because of active displacement of native species or the result of existing human disturbance is the subject of current deb ate (Everitt 1998) ( Birken and Cooper 2006 ) 2.2 Critique As a developing applied science, invasion biology is still in the midst of creating inductive generalizations, finding appropriate methodology and defining its role in affecting society. This is an important period to study the development of the field and the directions that different scientists wish to take it. Many current invasion biologists continue to publish literature that attempts, through productive struggle, to create clarity in the muddle of information and opini on regarding how to properly study invasion phenomena and apply that knowledge. These publications provide important insights into the factors that influence this discursive construction of invasion biology. Most studies of invasion phenomena strive for t wo types of validity, explanatory power and predictive power (Lockwood 2005 Kolar 2001 ) The idea of propagule pressure is one that tries to explain the root of invasion phenomena. At this point, the
29 ideas of environment invasibility and species invasiven ess attempt to predict the location and species of invasion phenomena. The pursuit of understanding each of these ideas results in varying levels of application. Scientists have more readily recommended predictive theory and management strategies in applic ation to reduce and prevent invasive populations, but these are also the aspects of the study that draw the most cultural criticism for being xenophobic and nativist, as discussed in Chapter 1. It is unsupported and unfair to accuse invasion biology of ha ving an exclusively xenophobic agenda, but the discussion of such issues is necessary in a field that deals in the management of foreign populations in natural environments. Most invasion biologists try to distance themselves from negative allegations of x enophobia and nativism: some by denying that culture has a significant effect on the science, some by engaging with cultural concerns, and some by working to instill more rigor and objectivity in invasion biology. For example, early on in the history of in vasion biology, scientists considered the pathways of species over geopolitical boundaries, but now, most scientists think about invasion phenomena biogeographically instead (Simberloff 2000) One critique of invasion biology focuses on the charged termi nology; words such as invasive, alien, noxious, all carry heavy cultural associations. In addition to their popular references, the aforementioned terminology is problematic among scientists because of its ambiguity. Different authors might each use the te rms invasive, non indigenous, and introduced to describe the same phen omenon or completely different; from Colautti and MacIsaac (2004): various derivatives (Richardson et al., 2000a). Explicit or implicit definitions for Radford & Cousens, 2000); (2) an adjective for native or indigenous species
30 (NIS) that have colonized natural areas (e.g. Burke & Grime, 1996); (3) those established in natural habitats (e.g. Reichard & Hamilton, 1997); (4) NIS that are widespread (e.g. van Clef & Stiles, 2001); or (5) widespread NIS that have adverse effects on the invaded habitat (e.g. Davis & Thompson, 2000; Mack et al., 2000). ( 136 ) invasive species in order to work towards greater objectivity in the discipline. What does objectivity mean in this situation? Their conception of objectivity uses criteria that can be observed in any species to determine its stage of invasion. Species in stages 0 2 are in areas with significant transportation vectors or on pathways to a new location but have not yet arrived. Species in stages 3 5 are those that have reached a new environment and distinguished through their abundance there. In a later publication, Colautti and Richardson (2009) suggest refining objecti vity in invasion biology by creating a dichotomy between methodological questions and motivational questions about non native species. They define the methodological questions as ones directed towards why and how invasive phenomena occur, and motivational questions as those directed towards how humans can respond to the phenomena. And although they note that neither type of question can be studied completely objectively, Colautti and Richardson st ate that the methodological questions can be constrained by t he bounds of scientific theories and paradigms. The validity of biological methods and analysis is defined by historical scientific consensus whereas the answers to motivational questions are determined by what social interests are at stake. This distincti neutral pursuit of knowledge.
31 In Confronting introduced species: a form of xenophobia? Simberloff (2003) denies that the modern study of invasion biology has its roots in racism and claims that the altruistic goal of preserving the environment morally overrides any critiques of racialization. However, the mechanisms of population establishment ar e not fully understood, and the strategies for population c ontrol are not always effective Therefore, the pursuit of preserving the environment and the presentation of racial critique are not mutually exclusive. For example, not all species foreign to a region have success becoming established, and the qualities that make one species more inva sive than another are not yet fully determined. Also, both ecologically and culturally, the mass application of chemical herbicides/pesticides to eradicate a population of plants or animals is problematic. In these cases, the marking of a species as invasi ve leads to the elimination of their population in the new environment. We must question if this framework of applying scientific knowledge is because of based upon an existing xenophobic prejudice. Brown and Sax (2005) argue that this prejudice against in vasive species exists widely among scientists, policy makers and lay people. They, like Colautti and MacIsaac suggest that scientists reduce prejudice in their work through eliminating any type of subjective value system when studying invasion phenomena. T hey propose that invasion biologists should value the status they have as purely objective observers without tainting it by wielding its power. What are the implications of using neutral terminology and greater objectivity in invasion biology? Colautti & M acIsaac posit that neutral terminology will help invasion biology shed cultural baggage and thus increase its scientific validity. While it is true that
32 invasion biology draws criticism because of this terminology, cultural implications run deeper than the terms themselves. Optimally for objectivists, neutral terminology in invasion biology would allow scientists to observe trends and identify phenomena without the influe nce of their cultural knowledge and societal upbringing. In application, however, the standardization of terms without discussion of the effects of cultural influence on the discipline may just be masking the symptoms without engaging with the source of th e problems at hand. Removing the leeway for discussion of invasive species in a cultural context in the science elevates its authority over other stakeholders. Additionally, it gives this particular form of objective science a hegemonic sort of authority o ver other methods of knowledge creation. Larson (2006) argues for the simultaneous embodiment of biodiversity values and objectivity in invasion biology in a response paper to Brown and Sax (2005). He discusses the flaw of creating and believing in a stric t dichotomy between fact and value in correspondence to science and society. He uses a brief emotional appeal to defend his inextricable link between fact and science by arguing that what else inspires one to become an ecologist than a personal connection to the environment and nature then delves into a more methodical and critical approach. He begins by presenting the arguments of Colautti & MacIsaac and Brown & Sax in favor of objectivity in science, and then questions the motivation and implications of s uch a goal. Larson accuses the models of purely reportive science of using objectivity to obscure any social biases the scientists may have under the guise of factual information and presents the idea that facts need to be understood through various frames of reference rather than holding inherent truth. He then describes his idea of a synthesis of science and society, which is directly
33 not only a fact finder but also an information interpreter and decision maker. This conclusion empowers scientists to actively contribute to societal decisions but does it through wielding the authority of objective knowledge. Larson ultimately makes it clear that he is not attempting t o deconstruct the authority of invasion biology but is rather defending its clout in affecting conservationist policy. He accuses, through the work of Soule and Lease ( 1995 ), Brown and Sax of using postmodern theory to undermine contemporary conservation e fforts through the denial of any ultimate value systems. This accusation is problematic many ways. First, the accusation is inaccurate in its accusation: Brown and Sax emphasize that as scientists, they strive to eliminate the effect of social values on th eir work but that private citizens should certainly develop their own value systems informed by their perspective and knowledge. It is further problematic in its conflation of critique with invalidation and the insistence that one dominant theory of conser vation needs to maintain broad authority. Donna Haraway (1988) offers a strategy for science to strive for some sort of objectivity and also allow multiple perspectives to theorize and present arguments without one maintaining an unchallengeable authority She maintains a belief in the meaningfulness that a scientist finds in the world, b ut to deconstruct the notion that their perspective is a complete one. Instead, their perspective is partial like any other and situation rather than some disembodied per spective. What makes then makes the
34 this term to categorize instruments and technologies that work to aid our interaction with natural phenomena and turn it into meani ng, much like a hearing aid for the hard of hearing or a cane for the blind. Much like these examples, prosthetic devices in science, according to Haraway, empower scientists to gain insights to the world in ways that our bodies alone cannot. This perspect ive is still a partial perspective, so the engagement with others regarding this situated knowledge that one has is necessary to work toward a fuller communal conceptualization. Her deconstruction of the notion of objectivity in science emphasizes that it one that can be partially shared and that is friendly to earthwide projects of finite freedom, adequate material abundance, modest meaning in suffering and limited From the se authors who have created a bulk of the discourse surrounding invasion biology, we can conceptualize that the main issues at hand include the incorporation of many environmentalist ideal and the development of invasion biology as a rigorous science. Thes e issues are further complicated by the social influence of xenophobia in invasion biology. An attempt to move away from xenophobia and nativism does not necessarily deny the existence or effect of invasion phenomena, instead it attempts to achieve the opp osite to support and reimagine the importance of studying how new species interact with new environments. I argue that invasion biologists cannot remove their subjective experience from their scientific exploits, as Brown and Sax would suggest, because t heir knowledge is situated knowledge. An acknowledgement of partial perspective instead of defending a claim of universal truth can serve to both
35 broaden the scope of a rigorous scientific study of invasion biology and refine its effect on the preservation of wilderness. Primarily, it is very difficult to separate the use of racialized language from racialized understandings of the world. In invasion biology, this use of racialized language is compounded with the action of targeting and the mass eradicatio n of many non native species to create an uncomfortable and problematic situation. Furthermore, the reform of charged terminology does not address the broader issue at hand or change the framework for the application of scientific knowledge. In Colautti an imagination of neutral terminology, the conflation of all non native species as harmful invasives is reduced through structured categorization, but this structure also works to focus more negative attention on species whose populations have gr own too large to control easily. Contributing to this reimagining, the actors involved in invasion biology must acknowledge to a greater extent the human actions that have set the stage for invasion phenomena, in addition to focusing on the damage by spe cies themselves. In popular literature on invasive species, the primary issue addressed is the potential for harm that the species present more often than the problems of channels that human globalization opened for mass transport of biota and the reductio n of wilderness through human encroachment. In this situation, the explanatory power of propagule pressure can also contribute significantly to the prevention of harmful invasion phenomena by creating a strategy that attacks the root of the problem. Some s cientists debate whether the definition of an invasive species requires it to be carried to new environments by humans (Brown and Sax 2005 Larson 2007 ), but there is consensus that global human traffic has
36 significantly increased the combination of new en vironments with new species. Increased globalization of industry is the key source of new vectors and pathways for invasive species and increased propagule pressure (Lockwood 2005 ) Additionally, land development and the reduction of nationally preserved l ands increase the systematic flow of new human traffic to previously wild land. To clarify, this distinction of wilderness as minimally affected by systematic human traffic is meant to separate the idea of wild land from such a strictly structured and ener gy intense force rather than to deny the nature in humans or encourage a naturalist argument. In this conceptualization, the preservation of wild lands can be maintained through the reduction or reform of human traffic, and the further study and acknowledg ement of the human role as a significant actor and also observer in invasion phenomena. This acknowledgement gives further accountability to how new human actions affect ecological interactions in addition to how new species affect them. 2.3.1 English Spar row The English sparrow became established in the United States before the advent of modern invasion biology, and the scientific literature published about them is much different in style and approach than current literature about invasive species. To begi n with, scientists at the turn of the 20th century had not yet created the distinction of non natives as a group of species that had the potential to affect great change on the ecosystem level. Therefore, factors such as diversity stability and succession were not as thoroughly considered or studied as those such as distribution, individual species interactions and agricultural damage when releasing novel species. Furthermore, much of the influential data on distribution and environmental effect collected o n the English
37 sparrow in the early twentieth century relied on survey and anecdotal data from amateur birders or other lay people rather than scientists themselves (Barrow s 1889) The DOA nsultation on the management of English Sparrows because of their history of vocalizations against the import of the species. Walter B. Barrow, a professor of biology at Michigan State Agricultural College, now Michigan State University, wrote a report on the effect English Sparrows in the United States to the United States Department of Agriculture (DoA) (Barrow s 1889) His methodology for determining the distribution, rate of increase, damage to buds and foliage, damage to gardens, damage to grain crops, relations to other birds and relations to other insects was to send a survey through the AOU and compiling the responses. Barrow compiled the results for each categorization in two groups, one for those that responses that he deemed satisfactorily descript ive and one for those that he deemed insufficiently descriptive. Oddly, the group of satisfactorily descriptive answers always had many more negative experiences with English Sparrows while the group with unsatisfactorily descriptive answers always had man y more neutral or positive experiences. Other scientists studied the question of why the English Sparrows were so successful in their new environment, but again, in a much different way than current scientists. Studies were published that studied whether o r not the English Sparrows were more intelligent than native birds that it outcompeted, and what aspects of its intelligence led to its success (Porter 1906) Porter studied the memory and maze skills of the English sparrow, and ranked their intelligence o n the level of the white rat, above the level of the cowbird or pigeon. This study influenced many nature writers and conservationists, who
38 published more popularly read literature, to cite this increased intelligence as the source (Dearborn 1912, Estabrook 1907) The idea of determining invasiveness in the sparrow species is apparent in this early study, despite the differences in research methodology and focus. 2.3.2 Hybridized hone y bee Most recent scientific studies have shown t hat hybridized bees do not deserve a and killing people have maintained a strong and persistent presence. The most commonly feared quality of hybridized honey bees is their defensive stinging behavior. Although African honey bees are on average more likely to sting en masse in response to threats against their hive than European honey bees, it is important to recognize that each hive has its own proclivity to this beha vior and that some European honey bees will be more aggressive while some African honey bees will be less aggressive. Genetically, scientists believe that this behavior is polygenic and that aggressiveness is controlled by a variety of dominant and recessi ve genes, thus resulting in hybridized bees that have varying levels of aggression rather than only very aggressive ones (Collins and Rinderer 1991) but the reputati on as a killer bee remains strongly tied to the cultural understanding of the hybridized honey bee. Another discrepancy between the public understanding and scientific understanding of the hybridized honey bee is dispersal and evolution of their populatio n. The bee is a hybrid of the African honey bee and the European honey bee both of the same species, Apis mellifera and the two types of bees are commonly referred to as
39 breeds or races. The spread of these hybridized bees in the Americas is due to bot h the mating of the hybrid drones with the existing European honey bee queens and also the dispersal of hybridized bee swarms (Hall and Muralidharan 1989) Perhaps some of the lingering fear lies in the racialized language used in science to describe the h ybridized hybridization and expansion of the bee population in the America. As in popular literature, the use of racially charged words to describe the bees is problematic in the markedness of the African bees as a harmful other. In a scientific context, despite a technical definition of the term, it still conceptualizes the spread of hybridized honey bees as a tainting of European honey bee genes by African honey bee genes ra ther than a mutual intermingling. Furthermore, scientific objectivity in this case can be harnessed as an authority to reinforce this racialization rather than as a critical eye to examine the effect of cultural influence. 2.3.3 Australian Pine The Austral ian pine, various species of the genus Casuarina has become a common species in the Florida landscape. Since the Australian pine has been understood as a non native species since the point of it initial introduction, the ways in which it is studied is fra med by how it is different from native species. Scientists have debated whether the growth of its population has affected local fauna detrimentally without a common consensus: some argue that the tree out competes native coastal trees for land and nutrient s while others argue that the trees are becoming integrated with the native ecosystems withou t great detriment (Mazzotti et al 198 1) Furthermore, because of the question of whether the introduction of Australian pine is harmful to Florida ecosystems
40 as a whole, much of the research on it has been to compare the interactions between Casuarina species and other native coastal trees, such as mangrove and cypress. Many native animals have come to use the Australian pine as part of the ecosystem. Wood storks have increasingly used the trees as nesting sites as their population experienced resurgence in the last forty years (Ogden 1991) In natural and altered landscapes, the wood stork nested more on native trees, cypress, willow and mangrove. In artificial en vironments, defined as those created by humans with heavy maintenance, wood storks nested primarily in Casuarina. Additionally, three rodent species, Peromyscus gossypinu Sigmodon hispidus and Oryzomys palustris are supported in stands of Australian pine (Mazzotti et al. 19 8 1) This study concluded that although these species can survive in Australian pine habitats, in comparison to their greater prevalence in habitats dominated by native trees, the Australian pine habitats are able to support smaller pop ulations. 2.4 Conclusion Invasion biology is at a critical point in addressing social values that affect its development as a field and application. Different voices in the field have different ideas of how to find fidelity in their practice, some by look ing for objectivity through stricter methodology and some by trying to muddle through integrating social value or perspective with that methodology. Since the study and application of invasion biology have historically been very closely tied, it is impossi ble to speak of the discourse without accepting, to a great extent, that the values of fact finding and conservation have become deeply connected in its practice. In attempting to work through problems of how to integrate scientific knowledge with conserva tion values and efforts, invasion biologists
41 have also put critical thought into dealing with influences of xenophobia and nativism. These two ideas have strongly influenced the large scale conservation efforts for the eradication and prevention of new pop ulations of non native species, but they also have influenced the framework of creating scientific knowledge about them as well. Many studies of the effect of these species on their new environments are conceived with the presupposition that there are detr imental effects to uncover because of the non native species. Furthermore, the development of systems to predict the pest status of geopolitically non native species implies that there are qualities of foreign species that make them inherently different an d more harmful. The spread of species through new vectors and pathways to new environments have however certainly changed ecosystems, sometimes to a great extent. It is important, thus, to work for a study of these new interactions without the prejudgment of non native species as inherent pests for the sake of scientific knowledge and also positive social applications. Finally, further critical focus on the importance of systematic human vectors and pathways in the global dispersal of species is necessary f or conservation efforts to reform the root of this issue.
42 Chapter 3: Managing Invasive Species Populations Stakeholders and experts from many fields come together to conceptualize and implement strategies for minimizing the effect of invasion phen omena on the a different framework of values and goals regarding how humans and non native species can co exist. Additionally, the different types of land that they r epresent private or communal property, agricultural and industrial lands, and wild ecosystems all hold different types of values to the stakeholders and to the general public. The ways that they work together in government and private efforts to create plans that manage invasive species illustrate how power is distributed among the various stakeholders and how the value of different types of land are assessed. In the United States, the federal government plays a major role in coordinating the communicat ion between various stakeholders and developing management plans to control the impacts of invasive species. In 1999, President Clinton issued Executive Order (EO) 13112, which defines invasive species as, an alien species whose introduction does or is li kely to cause economic or environmental harm or harm to human health, that they have had on a range of American stakeholders. The order acknowledges past statutes that took into account the effects and management of invasive spec ies the Lacey Act of 1900, the Federal Plant Pest Act of 1957, the Endangered Species Act of 1973, the Federal Noxious Weed Act of 1974, and the Nonindigenous Aquatic Prevention and Control Act of 1990 and focuses federal invasive species management ef forts into a centralized entity, the National Invasive Species Council (NISC) and its advisory committee, the Invasive Species Advisory Committee (ISAC). These two councils are
43 charged with the duty of developing science based processes to determine and ma nage the threat that invasive species pose to the health of the economy, people and the environment, as well as managing interagency budgets for invasive species management ( EO 13112 1999) Many argue that the use of science based processes is beneficial because they reduce conflicts of interest in the process of deciding on invasive species management policy (Blossey 1999); however, this is problematic because it works under the presupposition that scientists agree on how to quantify certain impacts and r isks associated with invasive species and if they even can be quantified in certain cases. Furthermore it assumes that conflicts arise from lack of knowledge rather than from different value systems. This helps to develop and implement management plans fo r stakeholders who are currently able to quantify the impact invasive species have on them; however, it draws focus away from those that cannot yet be quantified because of their complexity. 3.1 The Stakeholders The NISC, chaired by the Secretaries of Comm erce, Agriculture and the Interior, exists to set the standards and evaluate the success of invasive species management in the United States. In addition to the three co chairs, NISC members include the Secretaries of State, Defense, Homeland Security, Tre asury, Transporta tion, Health and Human Services; and the U.S. Trade Representative and the Administrators of the U.S. Environmental Protection Agency, National Aeronautics and Space Administration and the U.S. Agency for International Development. The NI SC is advised by the Invasive Species Advisory Council, which is responsible for implementing management strategies
44 as well as coordinating cooperation and knowledge sharing among federal agencies. The ISAC is made up of scientists, land managers and other experts and stakeholders appointed by the Secretary of the Interior. The 2008 2012 ISAC is composed of 11 advisers representing universities; 8 advisers representing agriculture, commerce, and industry; 7 advisers representing public land management agenc ies; and 2 each representing private, environmentalist and tribal interests. The United States agriculture sector has been heavily impacted economically by the introduction of new species, and the impact can be quantif ied as revenue gained or lost. 98% o f the crops grown and livestock raised in the United States are non native, including wheat, rice, soy, pigs, cattle and bees, and are worth over $250 billion per year. In contrast to this positive economic force, other non native species have damaged crop s and caused agricultural losses. 73% of the plant weeds and 40% of insect pests in crop systems are non native. The combined value of the agricultural loss they cause is estimated at about over $35 billion each year (Pimental et al. 2005) In these cases, the distinction between desirable and undesirable non native s pecies in agriculture is based o n the element of control or domestication that can be applied to them in addition to their potentia l for consumption, rather than o n their effect on the natural ecosystem. Non native species that can be grown as edible crops and livestock and contained by human systems are positive and not invasive from an agricultural perspective. Those that damage edible crops without providing any additional economic benefit ar e invasive. Non agricultural industries have also been affected by the growth of non native species populations, and their impact is similarly quantifiable. The zebra mussel, Dreissena polymorpha is one of the most well known examples of invasive specie s.
45 F acilities that operate in areas with substantial populations of zebra mussel electric power plants, water treatment facilities, and other agencies and industries all reported il l 1997) Unlike the sedentary adult form of the mussel, the larva l form is free swimming and microscopic. Thus, they can travel through water flow in uptake pipelines and then establish adult colonies within the facilities. The adult zebra mussels fo rm v ery dense colonies that cause problems by blocking pipelines and damaging industrial machinery. Conversely, some other companies have come to benefit economically from the pest status of many new non native species populations. For example, Dow Agroscience s, part of the Dow Chemical Company, makes the bulk of its revenue through supplying farms with chemical pesticide and herbicide, designer seeds and other types of agricultural biotechnology T hey have now also expanded their market to target those who wan t to control invasive pests with chemicals designed for non cropland use. Despite the economic benefit of invasive species to Dow and other chemical pesticide companies, they still rely on the aforementioned value system to sell their products. In addition to their use in industry, chemical pesticides and herbicides are also used to manage populations of non native species in wild ecosystems. Another group of industries also ha s a significant but separate stake in invasive species management. These are the ones that have facilitated the dispersal of species to new environments and include shipping and travel industries, the exotic pet industry and the nursery industry. The uptake and release of ballast water from international cargo ships has been recognize d as one of the most significant vectors of aquatic species dispersal. Many Burmese pythons and Nile monitors originally imported as exotic pets
46 have been released into the wild by their owners and have become pest s in Southern Florida. More than half of t he invasive plants in the United States were imported as horticulture plants (Randell and Marinelli 1996) Though these industries have generally not been directly affected by the establishment of species that they dispersed, they do stand to be significan tly affected by invasive species management. One very different framework of concern for invasive species regards the ecological effects of invasive species in wild lands. This stake in managing invasive species is perhaps the most complex. Although many groups share a common goal of protecting the environment, they differ in what they want to preserve in the environment and how they want to accomplish their goals As we have seen from the discussion of invasion biologists, environmentalist perspectives do not necessarily equate non native with invasive. For some, a non native species is considered invasive if it threatens the population of native endangered species, and for others, it must be detrimental to the stability of the ecosystem. The U.S. National Park Service (NPS) maintains over 84 million acres of land in the United States, so the power it has to implement invasive species management is spread very wide. Its mission is to preserve historic landscapes and the biodiversity within them for the cont inued enjoyment of future Americans (Department of the Interior 2008 ) Thus the introduction of any non native species to lands under its jurisdiction is considered, in theory, to be detrimental to the historical landscape that it tries to protect. 3.2 Man agement Strategies Most invasion biologists categorize invasive species management into three main goals (Rejmanek 2000) The first is prevention, which is most often implemented through
47 preventing the intentional import of foreign species. Other preventi on strategies include predictive measure s for determining which species are more likely to become established and preventative measures for the accidental import of foreign species. International transport of known invasive species into the United States i s prohibited, and the dispersal of these species within the nation is banned as well. After a species becomes successfully established, early detection and rapid assessment are optimal so that the process of physically managing its populations can begin. F or species whose populations are still small but rapidly expanding, complete eradication is the management objective. This often becomes too costly and laborious for species whose populations are already large and widely dispersed, so control and containme nt become the primary objectives. National Invasive Species Management Plan (NISMP) This document guide s federal effort s to prevent and control invasive species populations and t heir effects from 2008 2010. The two remaining strategic goals are restoration and organizational collaboration. term goals for the management of invasive species. Each of these five goals is further divided into objectives, which describe what the NISC hopes to achieve in its five year plan. The objectives are finally divided into implementation tasks for its member agencies to accomplish and more concrete ards achieving their duties. The NISMP addresses a wide range of concerns regarding invasive species. The primary goal at this level of management is not to implement policies that physically control invasive species populations but to determine the priori ties and standards for other agencies to follow. The current co chairs of the NISC Control and Management
48 W orkgroup are Nelroy Jackson of Monsanto Company and Robert Nowierski of the USDA. This workgroup recommends that groups prioritize management initiat ives that have proven techniques for managing species specifically and effectively. Additionally, it write s that the eradication of species with more economic, social and environmental benefits should be prioritized over those that have fewer (Jackson and Nowierski 2005) Although these recommendations follow conventional wisdom against implementing under researched management plans, the policies that they favor and fund would be those that control populations with simpler environmental impacts and more tan gible results. This trend is reflected in the ISAC Performance Budget, in which the highest expenditures are through the USDA to control agriculture pests (ISAC 2004, ISAC 2005, ISAC 2006) The development of management plans in industry and agriculture is relatively direct in most cases. Although the strategies may be costly, they decrease profit losses and have clear objectives: eradicate pest species and prevent future ones. In the case of the zebra mussel, affected industries rely on chlorine and filtra tion to prevent the uptake of the mussel larvae and use high heat and mechanical scraping to remove colonies that have already established (MacIsaac 1996) Out of all species initiatives, the ISAC Performance Budget has allocated the most money to controll ing Agrilus planipennis the emerald ash borer, which threatens the $25.1 billion per year ash timber industry. Trees at risk are treated yearly with insecticide, and efforts are being undertaken to hybridize the American variety of ash with Asian varietie s, which are resistant to the emerald ash borer (ISAC 2006)
49 The strategy for managing invasive species in natural settings is more complicated, in theory and execution. In preserving land for the sake of wilderness rather than for resource conservation, o human influence at the risk of creating a managed landscape or take a hands off approach at the risk of lettin g a problem grow uncontrollably. The United States Wilderness Act of 1964 defines wilderness as follows : A wilderness, in contrast with those areas where man and his own works dominate the landscape, is hereby recognized as an area where the earth and its community of life are untrammeled by man, where man himself is a visitor who does not remain. An area of wilderness is further defined to mean in this Act an area of undeveloped Federal land retaining its primeval character and influence, without permanent improvements or human habitation, which is protected and managed so as to preserve its natural conditions. (1) In this definition, the paradox applies in attempting to restore both the wild, untrammeled qualities as well as the primeval qualities of an en indicates that an area is not controlled or confined by human influence. In many cases of restoring disturbed environments, significa nt human control, i.e. trammeling, is needed in order to recreate a historical ecosystem. Without this interference, ecological processes may allow an ecosystem to become wild again, but without the historical variety of species. In the management of invas ive species, it is important to consider this paradox in order to recognize the motivations and goals behind management strategies, and whether they are in line to achieve healthy existences of humans in nature. Higgs (2003) describes two standard goals of wildlife restoration: ecological integrity and historical fidelity. Those who strive to restore ecological integrity want to restore an ecosystem's ability to
50 function in a dynamic and resilient way. Those that want historical fidelity want to remain loya l to the conditions of the environment at a point in its history prior to human disturbance. The mission of the National Park Service is not explicitly to preserve lands for wilderness but to maintain historical natural landscapes. However, its considerati on of what constitutes a historical landscape in the United States often ignores indigenous or beneficial land use practices that shaped the landscape ( Cronon 1983 ) Additionally, the efforts taken to control invasive species populations are often not reco gnized for their intrusive force on the environment. Strict enforcement of eradicating invasive species in wild areas puts human decisions and technology in control of determining the landscape but also removes the possibility of humans to exist in nature and the wild beneficially. Invasive species management is dominated by this type of technological control; the ISAC prioritizes the funding of management techniques that can be implemented once and then not need oversight or further interaction in the futu re (Jackson and Nowierski 2005) An alternative to technological control in wilderness restoration is through focal practice. Higgs (2003) prefaces his description of this practice with an explanation of two ways that people relate to objects around them. First, he describes things that are a focal point for social and physical engagement, such as a music venue, which offers live music and a center fo r people to congregate. These interactions generate conversation and lively coexistence. The other type of r elationship is with devices, or commodities that can offer certain functionalities, such as a CD player. Devices may make life more convenient, but they do not generate the same level of social engagement or the same sense of fulfillment. In wildlife resto ration, focal practices require people to take part in restoration efforts in
51 communities that they have a stake in, instead of delegati ng tasks to private contractors. They also require people to consider the broader scope of human actions that cause envi ronmental degradation. Integrating more focal practice into the management of invasive species in the United States can serve to bring a more holistic understanding of how humans interact with the environment. Instead of separating the lives of humans into one realm and the existence of wilderness into another, this understanding helps us to address the effects that they have on each other. 3.3 Management Implementation and Problems ve species control: cultural practices, restraining dispersal, mechanical removal, chemical control, biological control and interfering with reproduction. In the eradication and control of non native plants and animals in wild lands, examples of the techni ques, respectively, could include controlled burns, barrier construction, bulldozing large stands of trees, herbicide spray, introducing new herbivorous or predaceous organisms and pheromone baited traps. These techniques require extended human control to be exerted on the landscape. In wild ecosystems, the optimal targets of eradication efforts are animals that have been shown to have a detrimental effect on populations of native species through predation or herbivory. In these situations, the pressure lif ted from the native species can result in the successful recovery of their populations without further consequence to them or the environment (Zalvaleta et al. 2001) In the search for effective management strategies, ecologists and land managers have im plemented techniques that have more negative consequences than positive ones. In the 1980s, the Florida Exotic Pest Plant Council undertook expensive and labor
52 intensive efforts to apply herbicide to individual Melaleuca quinquenervia trees. The herbicide treated trees were nearly all eradicated, however upon death, their crowns released massi ve amounts of seeds (Myers et al. 200 2 ) Furthermore, many effective strategies have unintended consequences on the environment. On a basic level, traditional control techniques require significant human influence in controlling the landscape and often leave a physical footprint. The excessive use of poison to control invasive species does not always remain contained on the targeted species; poisoning non target species as well as contaminating soil and water. Pesticide and h erbicide use can also result in bioaccumulation (Innes and Barker 1999) which occurs when the rate of toxin accumulation in an organism is higher than the rate that it loses the toxin. This affects species at higher trophic levels that consume the initially poisoned species. More difficult problems arise when considering non native species that have already developed complex interactions with many other species and systems within an ecosystem. At thi s point, it is difficult to isolate and ameliorate the effect of the invasive species through simple eradication techniques, and the implementation of them can cause further damage to the ecosystem. In ecosystems that have non native species at many trophi c levels, i.e. at different levels in a food web, the elimination of one non native that preys on another may result in an explosion of the prey population. The elimination of the non native prey may also result in the predator targeting native species for pre y (Zavaleta et al., 2001) Tamarix has been considered invasive in the American Midwest for over a century. They have been present there for nearly two centuries but became dominant in formerly riparian regions that were altered by dams, such as the Ri o Grande River Valley, because they are more resistant to drought than native species, such as cottonwood.
53 Although Tamarix support communities of native species, ecologists and land managers worry that it they are less dense and less diverse communities Tamarisk alters fire regimens and soil hydrology and has also increased soil salinity, which prevents the growth of native plants that are salt sensitive (Jackson et al., 1990) After eradication, the salinity of the soil remains elevated, so the effect of the salt cedar lasts beyond the duration of its lifespan. Furthermore, many avian species, including the endangered southwestern willow flycatcher, have come to nest in Tamarix (Department of Forestry 2004) The eradication of these species of salt cedar could very likely be detrimental to the flycatcher population if simultaneous efforts to restore soil conditions and native flora are not planned or effective. Current management strategies for Tamarix have not been very successful in coordinating both as pects of land restoration. One of the most effective strategies involves the controlled burning of saltcedar stands followed by application of herbicide ( Taylor 1998 ) In Ouray National Refuge, the most successful case of this application, all of the plant s were eliminated upon burning and only 1% resprouted the following season. Although this statistic seems to indicate a high level of success, the complications lie in the ability for other species to grow on the treated land as well as the high cost of th e treatment. Anderson argues that at this point, the overall ineffectiveness of these strategies should convince land managers to reduce eradication efforts and instead consider strategies to more successfully integrate tamarisk into the natural ecosystem (Anderson 1998) Others argue that tamarisk populations have not grown past the point of human control, citing the developing success of using the tamarisk beetle to eradicate the
54 tree. This introduces another problematic strategy of invasive species manag ement, biocontrol. Biocontrol is the use of predation, parasitism or herbivory to control pest populations. In managing invasive species through biocontrol, an associated antagonist ce. Additionally, biocontrol is one of the key methods of invasive species management that should not require continued human control. Early examples of biocontrol were primarily for the purpose of reducing agricultural pests. One very early example was th e use and sale of Oecophylla smaragdina a species of ant, to control citrus pests in China in the third century (Simmonds 1976) In the United States, westward expansion in the late nineteenth century spurred an American interest in biocontrol for agricul ture. Chemical pesticides were not yet highly developed or effective, so biological agents were used heavily to control agricultural pests. In some cases, the biocontrol agents were successful in their task of controlling pest populations, such as in the c ase of Rodalia cardinalis the Australian Vedalia ladybeetle. This insect was imp orted by Charles V. Riley, then head of the USDA Department of Entomology, in 1889 to control populations of Icerya purchasi an Australian scale insect that was ravaging Cali fornia citrus groves. In this instance, a non native species was imported to control the growth of another non native invasive species and resulted in success because both populations remain ed within the threshold of human tolerance. Additionally, this was implemented in a citrus grove in California, which does not have native citrus populations, with insect species that are specific to their host or prey. This allowed all of the non native species involved to remain easily contained. The National Park Serv ice has also taken up the use of
55 biocontrol. It has experienced success, in limited trials, using the tamarisk beetle to control the dispersal of saltcedar. The use of biocontrol agents also has its own risks and complications. At times, the introduction of a species for biocontrol results in the re duction of non target species as well. Rhynocyllus conicus was introduced in many parts of the United States in the 1970s to control musk thistle populations, but has also contributed to the decline of many nati ve thistl e species (Rose et al. 2005) 3.4 Prevention Strategies The problems associated with invasive species control techniques emphasize the importance of prevention strategies. Prevention strategies are often much cheaper than management, however they require an initial investment before the onset of a problem. Models estimate that prevention efforts for all American lakes with power plants from problems with zebra mussels would cost $324,000 a year whereas the management plans for lakes that are alrea dy affected cost the US Fish and Wildlife Service over $800,000 per year (Leung et al 2002) Additionally, the opportunity for invasive species to impact an environment is very often made possible by human effects on the environment, such as in the case s of tamarisk and Gambusia amistadensis. Curre nt trends in ecology suggest that invasive species and their effects on the environment are the passengers rather than the drivers of ecological change (Didham et al. 2005) (MacDougall and Turkington 2005), meani ng that they are part of a larger force of ecological change, such as the construction of a dam or the draining of a wetland. This makes it critically important to address prevention techniques as well as the root of the problems a ssociated with invasive s pecies.
56 Prevention is the second least funded Strategic Goal in the ISAC budget, after restoration. The NISMP has three objectives for improving the prevention of invasive species: prevent the establishment of intentiona lly introduced invasive species; pre vent the establishment of unintentionally introduce d invasive species through high risk pathways; and improve the international, federal, state and tribal standards and guidelines to protect the United States from invasive species. Currently, the United St ates prohibits the intentional import of invasive species as well as their domestic distribution. Additionally, imported non native plants are screened for parasites and other pests. Some screening systems have been developed to assess the risk of non nati ve species becoming pests to the environment or the economy, however none can quantify the risks definitively. Additionally, there is debate in the scientific community on whether or not it is possible to determine inherent qualities of invasiveness in spe cies (Kolar 2002) Screening methods are thus not yet a high priority for NISC funding; their development has received virtually no funding by the ISAC (ISAC 2006) The current foc i of government funds in creating preventative measures are researching and implementing methods to reduce dispersal of invasive species through ballast water (ISAC 2005) (ISAC 2006) The water and sediment taken in for ballast in international cargo ships are the leading vector s in the global dispersal of aquatic organisms (Fires tone 2006) The ISAC has initiated projects to target this problem including the testing of ballast water at port before emptying the tanks and also the treatment of discharged ballast water as any other type of fouled water. These projects do not address the problem of the volume of traffic that occurs globally, which is the root of
57 the global dispersal of these species; however, limiting traffic or reducing trade is of course detrimental to the economy. 3.5.1 English Sparrow In 1887, New York State amende d a law that forbade intentional harm on wild birds. It excluded the English sparrow from that protection and added that intentionally feeding or housing the sparrows Union suggested that all of the individua l control methods like trapping and shooting should be combined with the use of grain poisoned by arsenic and strychnine by states wishing to combat En glish sparrow populations. The proposal was accepted by ten states by 1907 (Coates 2007 ) These efforts t o eradicate the population of sparrows had variable and debatable levels of success, but the factor that most definitively controlled their growth was the replacement of animal power by the gasoline engine (Fitzwater 1981) As animal feed and animal waste became less prevalent in agricultural areas and non existent in urban areas, the main food source of the sparrows diminished and so did their populations. It was the change in large scale human traffic that reduced the population of sparrows in the United States rather than control and management. Limited populations of these birds continue to live in the United States, and public distaste for them is virtually nonexistent. 3.5.2 Hybridized Honey Bee The Florida Department of Agriculture and Consumer Servi ces (FDACS) issued an Africanized bee action plan in 2005. Instances of the bees have been confirmed in many counties across Florida, but no attacks have been reported yet, and the bees are not yet considered established in the state. The action plan first emphasizes the importance of
58 public awareness of the hybridized bees in order to ensure public safety and assist in early detection and rapid response. It established a directory of pest control officials (PCOs) in the state that are trained in the remova l of the bees and encourages private citizens to report swarms to them. PCOs are instructed to then send samples of the bees in question to FDACS labs to determine what type of bees they are. Furthermore, the action plan encourages beekeepers to maintain h ives of European honey bees so that the hybridized bee does not become dominant in Florida (Bronson 2005) At this stage, the plan focuses on the prevention of human harm and economic damages that could occur out of public fear e.g. the destruction of api aries and native hives, if hybridized bee populations become established in Florida. 3.5.3 Australian Pines The only wide spread management strategies for Australian pine removal in Florida are manual removal of seedlings and saplings or the use of herbic ide and mechanical removal to treat more mature stands. The removal of leaf litter and cones is also effective for preventing allelopathic effects and seed dispersal. Shell Key Preserve in Pinellas County, Florida specifies that invasive species preventio n and management are a key part of its management plan. Since 2003, private contractors have been hired to remove over 700 Australian pines from the preserve. Additionally, 700 native trees, including live oak, buttonwood, coco plum, red cedar and longleaf pine, have been planted in their place. In response to public concern regarding the risk of rapidly removing several hundred established trees to create soil erosion Shell Key Preserve officials maintain that erosion is a natural phenomenon in barrier is lands and that they must follow their management objectives. These projects have cost Pinellas County and
59 the state of Florida over $100,000 (Department of Environmental Management 2006) Australian Pines still remain on Shell Key Preserve in areas where t hey provide shade for visitors, but plans are in place for their removal in the near future. 3.6 Conclusion Michael Pollan (1994) writes: As a nation, we've never been sure whether to dominate nature, in the name of civilization, or worship it untouched, a s an escape from civilization. It's always been all or nothing with us: parking lot or wilderness preserve; crew cut lawn or untended meadow; culture or nature. Neither extreme suggests a particularly useful model for our relations with nature. ( 4 ) This h as been the case with invasive species management. The prioritization of science based strategies in evaluating and managing the impacts of invasive species supports increased human control of the landscape. To promote a healthier human understanding of na ture, it is necessary to further explore the gray area of how humans can exist within wilderness and ameliorate negative human impacts through salutary interactions rather than technical management. Additionally, it is important to recognize invasive speci es as a human caused environmental change, similar to increasing carbon dioxide in the atmosphere or the endangerment of biodiversity due to habitat loss. Human trade is the primary vector of species dispersal, and human alterations on the environment have in many cases set the stage for new species establishment. Reducing the negative effects of invasive species requires careful consideration of human actions and taking steps to build a healthier human relationship with nature and the wilderness
60 Discus sion T he wide spread and often negative ecological effects that have resulted from the global dispersal of species to new environments are undeniable but the problems affecting these environment s lie deeper than the organisms themselves. The effect of hum ans in the environment increases the exposure of non native species to new environments. Human disturbances often also initially prepare ecosystems and populations of native species for non native species to become dominant. It is thus important to recogni ze that the problem of global ecosystem change by invasive species is largely reliant on greater human changes on the environment. Many different people have a stake in understanding and managing the effects of these species, but some have much more power in enacting management plans than others. Scientists have authority in determining the effect of invasive species and developing control techniques, and economic interests have authority in determining which management strategies are funded. S takeholders that receive the greatest economic harm from invasive species also have the most financial resources to fund management efforts D espite the tremendous role that trans national and domestic pathways of trade have in the dispersal of species it is against e conomic interests to reduce and restrict them. Additionally, efforts to manage the effects of invasive species in wilderness settings rely on strategies that are more economically efficient with quantifiable results rather than those that promote a healthi er relationship between human systems and ecological systems. This reinforces the importance for invasion biologists and other scientists to recognize how their knowledges are situated within the contexts of social values and decision making. If their prio rities for invasive species study lie in
61 ameliorating economic problems associated with invasive species, then they are in line with the current course of invasive species management. However, since many are both conservationists and scientists they must a lso empower the knowledges of this simultaneous embodiment in order to apply their authority for the benefit of meaningful and beneficial coexistence of human systems and wilderness.
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