Slowing the insect invasion: wood packaging sanitation policy yields US $11.7 billion net benefit
Jun06

Slowing the insect invasion: wood packaging sanitation policy yields US $11.7 billion net benefit

Risk analysis finds savings for homeowners and local governments of excluding invasive pests like the emerald ash borer outweigh added cost to imported goods.

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Managing non-native invasive plants

 This post contributed by Terence Houston, ESA Science Policy Analyst Many invasive species can have a domino effect of throwing an entire ecosystem off balance by diminishing native plant or animal species that function as an important resource for both natural ecosystems and human communities. According to the Nature Conservancy, the estimated damage from invasive species worldwide totals over $1.4 trillion, five percent of the global economy. Invasive species that have gained notoriety in the United States include the Burmese python, Asian carp, Northern snakehead fish,Asian tiger mosquito, emerald ash borer and  brown marmorated stink bug. Non-native  invasives from the plant kingdom can be just as damaging, if not more so. Invasive plant species have the ability to reduce the amounts of light, water, nutrients and space available to native species in an ecosystem. Their ability to affecthydrological patterns, soil chemistry, soil erosion and fire frequency can also have disastrous economic consequences for human society, particularly the agricultural industry. Federal management of invasive species is primarily handled by the United States Department of Agriculture along with the National Park Service.  According to the U.S. Forest Service, invasive exotic plants constitute eight to 47 percent of the total flora of most states in the nation. Of the approximately 4,500 exotic species currently in the U.S., at least 15 percent cause severe harm. Examples of the detriments of invasive plants include alteration of food webs, degradation on wildlife habitat, changes of fire and hydrological regimes and increases in erosion rates. The Forest Service estimates that the United States spends approximately $145 million annually in its attempt to control non-native invasive plants. In a recent edition of the Ecologist Goes to Washington podcast, ESA Graduate Student Policy Award winner Sara Kuebbing discusses her work on invasive plant species at the University of Tennessee in Knoxville. In addition, Kuebbing serves on the Tennessee Exotic Pest Plant Council (TN-EPPC). Her work has included some of the most problematic invasive plant species in the state of Tennessee and the greater United States. During the podcast, Sara touches on her research and efforts by TN-EPPC and affiliated state entities to educate communities on invasive plant species and manage both existing and potential threat species. Perhaps among the most renowned invasive plant species is kudzu, which currently inhabits 30 states and the District of Columbia. According to scientific studies, kudzu’s nationwide invasion costs about $100-500 million per year in forest productivity loss. Kudzu can grow on top of structures and even other plants, including trees, basically suffocating them by obstructing their access to light and other necessary resources.  Power companies spend about $1.5 million annually to control...

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Shrubs Bred for Sparse Seeds Still Spread

This post contributed by Celia Smith, ESA Education Programs Coordinator In response to growing concern about the ecological and economic impact of invasive species, there has been increasing interest in developing cultivars of ornamental shrubs that produce few or sterile seeds. However, in a study published in the October issue of BioScience, researchers at Washington University in St. Louis and the Chicago Botanic Garden found that many cultivars currently marketed as “safe” are still potentially invasive. Invasive plant species present an ecological paradox. Many popular woody plants used in horticulture and landscaping grow readily in varied moisture and soil conditions; display numerous, long-lived blooms; and produce succulent fruits that attract birds and other backyard visitors. Yet the same characteristics that allow these species to easily adapt and thrive can also lead to invasive growth beyond the confines of a carefully managed garden. In an effort to evade laws controlling the spread of invasive plants, the selection of  common woody shrubs such as Japanese barberry and burning bush to produce fewer seeds has become popular, resulting in cultivars that are advertised as ‘safe’ or ‘non-invasive.’ Yet there is very little research to define what makes a cultivar ‘safe,’ let alone confirm whether or not it could be used to effectively control population growth of a species. Given this lack of evidence, the authors reasoned that population modeling of 19 common species of shrubs, trees, herbs and grasses could yield much needed data on the effects of seed reduction. Their results were illuminating: simply limiting seed production in cultivars was insufficient to reduce invasive potential, because seed abundance is just one of many traits that influence how fast or densely a species can grow (case in point: click here for another timely blog post about a study documenting the effects of plant height on seed dispersal).  For example, according to the BioScience article, reducing the seed production of long-lived species—like the shrubs and trees at your local nursery— by even 95% would still fail to control population increases. Furthermore, the offspring of cultivars do not necessarily produce fewer seeds themselves; in fact, they could prove significantly more fecund than their parents if they were to cross-breed. Based on these results, the most effective way to manage the dispersal of invasive plant species may be to invest the time and funds necessary to research, develop and market more varieties that are completely sterile. An alternative solution may be to encourage gardening using native plant species. Of course, this study is predicated on the assumption that invasive species are inherently harmful; indeed, the authors lead off by stating: : “Invasive woody plants pose...

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Green Forests?

This post contributed by Heather Kirk, a post-doctoral researcher at the Institute of Agricultural Sciences in Zurich, Switzerland When a 9.0 magnitude earthquake caused a series of nuclear accidents in Japan back in March of this year, there was nervousness in North America that nuclear fallout could blow across the Pacific Ocean to reach coastal cities in Canada and the US.  While those fears were largely unfounded according to health officials, West Coast residents have certainly received air-borne “gifts” from Asian countries in the past. Every year, China and a number of other Asian countries are the source of massive dust storms that spread over large portions of the Asian continent, and sometimes even cross the Pacific.  These storms have intensified over the past century as a result of deforestation, overgrazing, and poor water management.  In 2010, East Asia experienced particularly bad droughts that led to food shortages and massive dust storms that lasted for days and traveled thousands of kilometers. In order to address these storms and their causes, China has implemented a tree-planting policy that aims to reduce erosion and evaporation of precious water resources, while providing new sources of economic growth (via timber and tree-fruit production).  The most internationally publicized of these initiatives is the “green wall of China” project, which was initiated in 1978 as part of a larger plan to stop the expansion of the Gobi desert.  The project aims to develop a green belt more than 4000 km in length along the edge of the desert. In the September 22, 2011 issue of Nature, Jianchu Xu, a senior scientist at the World Agroforestry Centre and a professor at the Chinese Academy of Sciences, comments on the detrimental effects of the widespread planting of non-native trees in China, which comprise a large portion of reforestation projects.  Most reforested areas are planted with crop species that include fruit trees, eucalyptus, and rubber, and not with native mixed forests that promote biodiversity and are better suited for providing ecosystem services such as erosion control. Additionally, new forests are being planted in areas that were not historically forested such as grasslands. In his paper, Xu states: “I would like to see China establish parallel forest-management programmes for recovery and restoration of natural forests, and for incorporating working trees into farmlands. Each should include best practices from ecosystem science; a clear definition of tree crop plantations for timber or non-timber products would clarify the separate systems”. Afforestation is an important strategy for carbon sequestration, and can play a valuable role in both ecosystem remediation and economic development.  However all forest are not created equal: some are greener than...

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New grants promote greater understanding of infectious disease

This post contributed by Lindsay Deel, a Ph.D. student in geography at West Virginia University and Intern with ESA’s journal Frontiers in Ecology and the Environment Infectious diseases won’t know what hit them. A massive new collaborative effort between funding sources in the United States (US) and United Kingdom (UK) takes aim at infectious diseases from ecological and social perspectives, reported the National Science Foundation (NSF) in a recent press release. The overall goal of the suite of eight projects is to improve understanding of the factors affecting disease transmission, said NSF, but a major focus will also be on building models to help predict and control outbreaks. Each of these projects examines different themes within the global context of infectious disease. For example, Tony Goldberg (Professor of Epidemiology, University of Wisconsin–Madison) and colleagues will investigate the spread of HIV from its origin in monkeys to humans by examining similar viruses that are currently impacting wild monkeys in Uganda. This project will also study human social factors – such as awareness, beliefs, and behaviors – surrounding the transmission of such diseases. Another project helmed by David Rizzo (Professor of Plant Pathology, University of California–Davis) will explore how interacting forest disturbances – such as fire and drought – may control the emergence, persistence, and spread of invasive pathogens using the case of sudden oak death – a disease caused by a non-native pathogen, Phytophthora ramorum. “Over the past 10 years, potentially millions of trees in California and Oregon coastal forests have died as a result of this emerging disease,” explains Rizzo. “The goal of this new grant is [to] link this new disturbance agent (sudden oak death) with pre-existing disturbance agents (fire, drought) in coastal forests.” Samantha Forde (Professor of Ecology and Evolutionary Biology, University of California – Santa Cruz) will lead a project using a simplified laboratory system of E. coli bacteria and its viruses as a model to study why some viruses have evolved the ability to infect multiple host species, while others can only infect one.  “This will further a general understanding of the dynamics of disease in natural systems and help to improve public health initiatives,” she says. From the modeling perspective, Armand Kuris (Professor of Biological Sciences, University of California at Santa Barbara) and colleagues will delve into the complexity of ecological systems and how the level of complexity might influence disease dynamics.  Kuris and colleagues hope to bring the role of infectious diseases into the core of ecological thinking, comparable to the roles of predation, competition, disturbance and resource quality. Joseph Tien (Professor of Mathematics, Ohio State University) will examine the recent cholera epidemic in Haiti. ...

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Speaking of species and their origins

An essay published in the June 8 issue of Nature is causing something of a stir. Eighteen ecologists who signed the essay, titled “Don’t judge species on their origins,” “argue that conservationists should assess organisms based on their impact on the local environment, rather than simply whether they’re native,” as described in a recent Scientific American podcast. In the essay, Mark Davis from Macalester College, St. Paul, Minnesota and colleagues argue that adherence to the idea of non-natives as “the enemy” is more a reflection of “prejudice rather than solid science,” wrote Brandon Keim in a Wired Science article. As the authors wrote, the “preoccupation with the native–alien dichotomy” among scientists, land managers and policy-makers is prohibitive to dynamic and pragmatic conservation and species management in a 21st century planet that is forever altered by climate change, land-use changes and other anthropogenic influences. As a result of this misguided preoccupation, claim the authors, time and resources are unnecessarily spent attempting to eradicate introduced species that actually turn out to be a boon to the environment; the authors cite the non-native tamarisk tree in the western U.S. as an example of this. But some other ecological scientists believe that the authors of the essay are barking up the wrong tamarisk tree, so to speak. Not only is there a disagreement with the paper’s premise that there is an unjust bias against all non-natives, but other scientists assert that the harm non-natives are capable of causing should not be overlooked. Jessica Gurevitch, an ecologist at the State University of New York Stony Brook, stated that the authors “downplay some of the problems and uncertainties,” and she insists that the “just get used to [non-natives being the norm]” attitude is misguided. David Pimentel, an entomologist at Cornell University, has estimated invasive species damage in the U.S. at between $100 billion and $200 billion. Nevertheless, the essay authors argue that “being indigenous doesn’t grant a species special rights to inhabit an ecosystem,” according to the Scientific American podcast, and Razib Khan from Discover’s blog Gene Expression reminds readers that “we [humans] are after all an invasive species oursel[ves]!” Furthermore, not all natives are economically and ecologically beneficial. For example, British Columbia has recently had one of the largest infestations of the mountain pine beetle, a species indigenous to pine forests of western North America, on record—an issue that has caused significant ecological impacts. And according to Mark Davis, many non-natives can actually boost biodiversity. But is biodiversity always the ultimate goal? David Lodge, an ecologist at the University of Notre Dame, argues otherwise. While local biodiversity may at times increase with the introduction...

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