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National Park Service FIRST-CLASS MAIL
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P.O. Box 25287 National Park Service
Denver, CO 80225-0287 Permit No. G-83
Integrating Research and Resource Management
Volume 22, Number 2, Fall 2004
U.S. Department of the Interior
National Park Service
Associate Director, Natural Resource Stewardship and Science
Betsie Blumberg, under cooperative agreement CA 4000-8-9028
Katie KellerLynn, under cooperative agreement CA 1200-99-0009
Glenda Heronema—Denver Service Center
Ron Hiebert (chair)—Research Coordinator, Colorado Plateau CESU
Gary E. Davis—Visiting Chief Scientist, Ocean Program
John Dennis—Biologist, Natural Systems Management Office
Bobbi Simpson—Supervisory Biologist and California Exotic Plant Management Team Liaison, Point Reyes NS
William Supernaugh—Superintendent, Badlands NP
Judy Visty—Natural Resource Management Specialist, Continental Divide Research and Learning Center, Rocky Mountain NP
National Park Service
P.O. Box 25287
Denver, CO 80225-0287
Park Science is a resource management bulletin of the U.S. National Park Service that reports recent and ongoing natural and social science research, its implications for park planning and management, and its application to resource management. Published by the Natural Resource Information Division of the Natural Resource Program Center, it appears twice annually. Thematic issues, such as this one, that explore a topic in depth are published occasionally. Content is reviewed for usefulness, basic scientific soundness, clarity, completeness, and policy considerations, but does not undergo anonymous peer review.
Letters that address the scientific content or factual nature of an article are welcome; they may be edited for length, clarity, and tone.
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Articles, comments, address changes, and inquiries should be directed to the editor by email; hard copy materials should be forwarded to the editorial office.
Park Science is also published online (ISSN 1090-9966). All back issues, article submission guidelines, and other useful information can be accessed from www.nature.nps.gov/parksci.
Park Science accepts subscription donations from non-NPS readers to help defray production costs. A typical donation is $10 per subscription per year. Checks should be made payable to the National Park Service and sent to the editorial office address.
Sample article citation
Benjamin, P., and R. Hiebert. 2004. Assessing the invasive plant issue. Park Science 22(2):27–31.
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ON THE COVER
Pieces of a mosaic, invasive plant and animal species are transforming the landscape of our national parks, disrupting native species, altering habitats, and compelling science-based control programs. What long-term effects will invaders have on parks, their natural systems, and our enjoyment of these special places? The articles in this special issue delve into many of these troubling questions.
WATERCOLOR—SANTA MONICA MOUNTAINS NRA; BY PHILIP THYS, DENVER SERVICE CENTER, NPS.
= = = = Contents = = = =
Volume 22 • Number 2 • Fall 2004
(1) From the Guest Editor
(3) Information Crossfile
(4) Nature Out of Place: Biological Invasions in the Global Age
(5) A Plague of Rats and Rubbervines: The Growing Threat of Species Invasions
(6) Meetings of Interest
(7) The challenge of effectively addressing the threat of invasive species to the National Park System
A look at the scope of the invasive species problem in national parks highlights the tremendous threat to native biodiversity and the serious choices facing policy makers and park managers.
By Lloyd Loope
(8) A retrospective on NPS invasive species policy and management
With a long history of recognizing and combating the threat of exotic species, the National Park Service has evolved innovative prevention and control programs, improving its capabilities.
By Linda Drees
(9) Assessing the invasive plant issue
An array of assessment tools is being developed to help NPS resource managers target the control of the highest priority invasive plants, in areas of greatest value, and with the highest potential for restoration.
By Pamela Benjamin and Ron Hiebert
(10) The role of fire and fire management in the invasion of nonnative plants in California
Researchers with the U.S. Geological Survey seek to understand how fire and fire management strategies may be aiding the invasion of nonnative plants.
By Kyle E. Merriam, Tom W. McGinnis, and Jon E. Keeley
(11) Invasions in the sea
Though long known in harbors, bays, and estuaries, marine invaders have been turning up in waters of the outer coast, raising the threat to coastal national parks.
By Andrew N. Cohen
(12) Under water and out of sight: Invasive fishes in the United States
Implications for national parks
Introduced for sport fishing, as biological controls or other purposes, and as a result of illegal activity, nonnative fishes occupy national park waters where approximately 118 species now compete with native aquatic organisms.
By Walter R. Courtenay, Jr., and Pam L. Fuller
(13) Ecological effects of animal introductions at Channel Islands National Park
Based on research, park managers are adopting a holistic approach to island restoration that includes eradication of nonnative species, restoration of native plant habitats, and monitoring.
By Kathryn McEachern
(14) Hemlock woolly adelgid and the disintegration of eastern hemlock ecosystems
An alien insect is causing decline in eastern hemlock forests, leading to the loss of native biodiversity, and opening the way for invasions of alien plants.
By Richard A. Evans
(15) The Florida/Caribbean Exotic Plant Management Team Partnership
By Tony Pernas, Dan Clark, and Chris Furqueron
(16) Impacts of West Nile virus on wildlife
By Emi Kate Saito and Margaret A. Wild
(17) Understanding relationships among invasive species and soils
By Pete Biggam
(18) Invasive species: a biological wildfire
By Tom Stohlgren
(19) The health of our forests and what we are doing about it
By Terry Cacek
(20) Zebra mussels threaten native mussels of the St. Croix National Scenic Riverway
By Randy S. Ferrin
(21) Salamanders and introduced fish in mountain lakes of two Pacific Northwest parks
By Gary Larson and Robert Hoffman
(1) = = = = From the Guest Editor = = = =
Invasive species management: Are we doing enough?
Inspiration for this special issue of Park Science came from discussions among participants in a workshop to develop guidelines for inventory and monitoring of invasive plants held in Ft. Collins, Colorado, in June 2002. As Lloyd Loope states in the cover article, “Given the seeds of catastrophic loss already planted and those yet to come, invasive species pose a highly significant threat to the biodiversity of the U.S. National Park System in the early decades of the 21st century.” The purpose of this issue is to communicate the breadth and depth of the invasive species issue, to document impacts, and to report what has and is being done by the National Park Service and its partners to control this “biological wildfire.” This edition also serves as a springboard to discuss the role of the National Park Service in this global issue and to plot a course of action for the future. All articles were solicited to assure that a cross-section of invasive taxa was addressed and that impacts to terrestrial, aquatic, and marine systems were considered.
The cover article by Loope, the “biological wildfire” piece by Tom Stohlgren, and the books reviewed by Pamela Benjamin and Neil Cobb document increasing biological invasions resulting from a breakdown of natural geographical barriers in an age of globalization. They sound the clarion for coordinated efforts in research, education, prevention, control, and restoration that must be components of any action plan to preserve the biodiversity in the National Park System. The NPS Organic Act implies that a key mission of the Service is to protect biodiversity. As Pam Benjamin and I state in our article, we need to place more effort on assessing the distribution, abundance, and impacts of invasive species in the national parks. More importantly, in my opinion, we need to identify those areas of high ecological value that are relatively free of exotic invasives, and make heroic efforts to keep them that way.
Recognition of invasive species as a problem in the National Park System is far from new as Linda Drees, my coeditor for this issue, points out. George Wright noted the negative impacts of nonnative species in the 1930s. Policy against introductions of exotics and control of existing exotics in natural zones dates back to the 1960s. The documentation of resource impacts of feral pigs and brook trout in the Great Smoky Mountains and burros in the Grand Canyon were some of my first exposure to the invasive species issue. Articles in this special issue exemplify the disruption of soils, forests, and wildlife caused by invasive species, and their deleterious effects on marine, aquatic, and terrestrial systems. Kathryn McEachern illustrates the amplitude of impacts of introduced exotics on entire ecosystems. Kyle Merriam and his coauthors investigate how fire management may catalyze exotic plant invasions in some ecosystems.
We certainly have big problems, but we also have some success stories to share. An ambitious program to prevent zebra mussels from migrating into the upper reaches of the St. Croix River has helped preserve the 40 or more species of freshwater mussels in that system. The African oryx has been removed from White Sands National Monument. Leafy spurge is under control as a result of an integrated control program in the Little Missouri River watershed, including Theodore Roosevelt National Park. The National Park Service now has an invasive species coordinator and targeted funding for invasive species management. Exotic Plant Management Teams have treated more than 73,000 infested acres in and around parks.
Are we doing enough? Linda Drees, NPS invasive species coordinator, states that “management of invasive species is in our grasp.” I appreciate her optimism, as optimism, good science, adequate funding, and hard work will help us manage invasive species. But we must do more. Battling the likely largest threat to the biodiversity of the National Park System is not a collateral duty.
National Park Service, research coordinator, Colorado Plateau CESU, Flagstaff, Arizona
Editor’s Note: Park Science accepts proposals for the development of thematic issues, like this one, to be coordinated by a guest editor. Contact editor Jeff Selleck for further information.
(2) = = = = Highlights = = = =
TEAM Leafy Spurge and Theodore Roosevelt National Park:
A partnership for the management and control of leafy spurge
TEAM Leafy Spurge, an integrated pest management (IPM) research and demonstration project, is based on the premise that IPM provides the flexibility needed to control agricultural plant and insect pests across broad regions. To demonstrate the effectiveness of the IPM approach for controlling the noxious weed leafy spurge (Euphorbia esula L.) over a wide and varied expanse, TEAM Leafy Spurge chose the Little Missouri River drainage, which spans portions of North Dakota, South Dakota, Montana, and Wyoming, as its primary study area because of its complex variety of ecological conditions, all impacted by this invasive plant species (fig. 1). Fortunately, Theodore Roosevelt National Park (North Dakota) occurs within the TEAM Leafy Spurge study area.
Figure 1 [photo]. About 120 miles (193 km) from Theodore Roosevelt National Park, this landscape in the Missouri River drainage is colored by the yellow bracts of the invasive alien, leafy spurge. The plant displaces native vegetation in prairie habitats.
AGRICULTURAL RESEARCH SERVICE
TEAM Leafy Spurge is cochaired and overseen by the USDA Agricultural Research Service in cooperation with the USDA Animal and Plant Health Inspection Service. Together these federal partners make a powerful team to address the leafy spurge problem on a multistate basis. Additional federal bureaus participating in the project are the Bureau of Land Management, USDA Forest Service, National Park Service, Bureau of Indian Affairs, Bureau of Reclamation, and U.S. Geological Survey. State partners are state departments of agriculture and other agencies, cooperative extension services, land grant universities, and county weed managers; private-sector representatives include landowners and ranchers.
Over its six-year life, the project’s collaborative emphasis has enabled participants to share resources and expertise, aptly demonstrating how partnerships and teamwork can be used to implement IPM strategies and achieve successful leafy spurge control over broad regions. In particular, the effort has helped demonstrate how Aphthona spp. flea beetles can be affordable and sustainable biocontrol agents of leafy spurge in much of the study area (fig. 2), with further containment accomplished through judicious herbicide applications and multispecies grazing.
Figure 2 [photo]. Aphthona lacertosa, flea beetles used in TEAM Leafy Spurge’s integrated pest management project, gobble up leafy spurge. Over 15 years, more than 18 million of the beetles have been released within Theodore Roosevelt National Park.
AGRICULTURAL RESEARCH SERVICE
An instrumental partner in the project was Theodore Roosevelt National Park, a park with serious leafy spurge problems. Over the past 15 years the park has released more than 18 million Aphthona flea beetles at 3,534 sites for leafy spurge control. In addition, the park is a strong advocate for the judicious use of herbicides, applied from sprayers attached to backpacks, all-terrain vehicles, and trucks. Helicopter spraying is also conducted in remote backcountry areas. The park has also held numerous field days involving the collection and redistribution of Aphthona flea beetles for local farmers and ranchers. This has resulted in a win-win situation for the National Park Service and local communities.
Leafy spurge is a formidable opponent that cannot be controlled or eliminated by any single entity or management practice. Rather, a collaborative, integrated, and regional approach is essential to solving this costly problem. Projects such as the one being conducted at Theodore Roosevelt National Park are using scientifically valid, ecologically based IPM strategies that can achieve effective, affordable, and sustainable leafy spurge control.
—C. W. Prosser, ecologist, Theodore Roosevelt National Park, Medora, North Dakota, firstname.lastname@example.org.
* * *
Last African oryx removed from White Sands National Monument
[Photos of oryx and helicopter translocating an oryx]
African oryx (Oryx gazella or gemsbok) were released near White Sands National Monument on the U.S. Army–White Sands Missile Range by the New Mexico Department of Game and Fish in the 1960s. The purpose was to establish a population for public hunting on military land. Oryx proved more successful in New Mexico than expected. The original herd of approximately 100 animals increased to more than 4,000 in southern New Mexico despite an active hunting program. Factors such as not requiring surface water, fecundity (i.e., females becoming pregnant soon after calving every nine months), and ineffective predation contributed to the success of the species.
The National Park Service (NPS) completed a 67-mile boundary fence in 1996 to exclude oryx from White Sands National Monument. However, animals contained within the fence increased in population, with concomitant impacts by the 450-pound animals to soil and vegetation. At the time the population was increasing at a rate of 20 to 30% per year; if left uncontrolled the situation would have caused severe resource degradation. Removing the oryx from NPS land was complicated by the lack of roads in the 144,000-acre (58,320-ha) monument and the oryx’s habit of disbursing widely over the desert.
A draft environmental assessment was prepared in 1998, presenting the preferred alternative of NPS staff shooting the estimated 140 to 190 animals. Thereafter, a critical news article resulted in an organized letter-writing campaign with 161 respondents from coast to coast objecting to the proposed management action.
As a result of public input, oryx removal plans shifted to more expensive and dangerous nonlethal management methods. These included the use of helicopters and all-terrain vehicles for herding oryx to openings in the fence, and also shooting them with anesthesia-filled darts followed by loading the drugged animals in a sling attached to a helicopter for transport out of the monument. Park staff and partners tried constructing one-way gates in the boundary fence that would allow the animals to leave the monument, but the attempt was not successful. Contraceptive drug darting to prevent further expansion of the population was not considered feasible.
Several partners assisted monument staff in carrying out the helicopter sling-loading operation over several years. They included the NPS Biological Resource Management Division, Carlsbad Caverns and Mesa Verde National Parks, New Mexico Department of Game and Fish, U.S. Army–White Sands Missile Range, and the U.S. Fish and Wildlife Service. Funding for the operation came from the Natural Resource Preservation Program and the Recreational Fee Demonstration Program. The initial herding and sling-loading operation was effective, resulting in the removal by nonlethal means of 174 oryx from White Sand National Monument from 1999 to 2001. Nevertheless, helicopter search time to locate oryx increased greatly as the animals became scarcer, and the cost per animal escalated. Subsequently, the National Park Service publicly released an environmental assessment in November 2001 recommending complete removal of the relatively few remaining oryx by lethal means, with support of the New Mexico Department of Game and Fish. The monument received 39 letters supporting the project and 9 that either opposed it or confused it with other management issues, and the National Park Service signed a “Finding of No Significant Impact” to begin the final phase of control.
The project was well covered by regional media, as well as the Wall Street Journal and High Country News. Twenty-five animals have been shot to date and no fresh sign has been detected, suggesting that oryx no longer roam within the fenced portion of White Sands National Monument. Long-term, annual maintenance by tracking and shooting (if any oryx are detected) is planned, as is maintaining the 67-mile fence indefinitely.
—Bill Conrod, biologist, White Sands National Monument, New Mexico; email@example.com.
(3) = = = = Information Crossfile = = = =
The costs of invasion
Resource managers face the difficult task of picking and choosing which ecological problems, among many, they can actively address. In a crisis-laden field, how can we prioritize resource needs? Where do invasive species rate among the myriad threats facing the National Park System? Two frequently cited articles provide justification for moving invasive species management near the top of the list. A 1998 study of threatened and endangered species in the United States found that alien species are second only to habitat destruction and degradation as a threat to imperiled species (Wilcove et al. 1998). The authors quantify threats to imperiled species in the United States. In summation, exotics affected 57% of plant species and 39% of animal species analyzed overall, and the figures jump to nearly 100% when considering only Hawaiian species. Investigators also found that invasive species affect aquatic systems in the West in particular.
In addition, Pimental and others (2000) tally the economic costs of biotic invasions at approximately $137 billion annually in the United States alone. In the article “Environmental and Economic Costs of Nonindigenous Species in the United States,” the authors combine the losses and damages caused by alien invasive species with the costs of control for exotic plants, vertebrates, invertebrates, and microbes to obtain a rough estimate of the total cost. Often no data concerning the costs of an invasion were available; therefore, the true cost of invasive species almost certainly is underestimated in this study. However, information from these two studies shows that allocating funds to invasive species management projects has both high economic and ecological value.
—R. Harms, graduate student, College of Environmental Science and Education, Northern Arizona University, Flagstaff.
Pimental, D., L. Lach, R. Zuniga, and D. Morrison. 2000. Environmental and economic costs of nonindigenous species in the United States. BioScience 50(1):53–65.
Wilcove, D. S., D. Rothstein, J. Dubow, A. Phillips, and E. Losos. 1998. Quantifying threats to imperiled species in the United States. BioScience 48(8):607–615.
* * *
Trade policy and prevention of nonnative species invasions
Approximately half of the invertebrate and disease pests imported into the United States come in on live plants; most of the other half of pests comes in on raw wood and wood packaging. Quantities of these items are increasing with increasing trade. Horticultural imports are not only risky because of the small (1–2%) but highly significant numbers of invasive exotics that escape, but also because of the hitchhikers on these imports. Because biological invasions are rarely reversible, prevention seems desirable. However, the current process in the United States and most other countries is to try to balance native biodiversity protection and trade promotion. The rules established by the United States and its trading partners are based on the premise that phytosanitary regulations should not be more restrictive than necessary to achieve a country’s chosen level of protection. Furthermore, the World Trade Organization regards phytosanitary measures as a potentially unjustified barrier to free trade. Therefore, the burden of proof is placed on advocates for the prevention of exotic species invasions and the protection of native biodiversity.
Recent articles detailing the major pathways of pests entering the United States may be useful for resource managers in achieving a broad understanding of invasions and options for improvement in U.S. strategy, policy, and techniques for prevention. Campbell (2001) examines U.S. and international policies governing the structure and implementation of invasive species prevention programs, and recommends approaches for addressing the huge consequent problems that arise for protection of biodiversity. Campbell and Schlarbaum (2002) provide much detail on the biological outcome of prioritizing trade above protection—which results in forests, especially those of eastern United States, dying because of introductions of damaging foreign pests and diseases. Campbell and Kriesch (2003) review and outline pathways for invasive species into the United States.
—L. Loope, Haleakala Field Station, USGS, Pacific Island Ecosystems Research Center, Maui.