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A Strategic Plan for Managing Invasive Nonnative Plants on National Park System Lands
U. S. Department of the Interior
National Park Service
August 1996
The National Park Service prepared this document to describe the impacts of invasive nonnative plants on the National Park System's natural resources and to outline strategies and tactics to help prevent and manage their spread on National Park System lands. This plan describes for National Park Service managers and partners the management challenges facing the agency and outlines ways to better coordinate all National Park Service programs in the fight against invasive nonnative plants.

For more copies of this publication, contact Associate Director, Natural Resources Stewardship and Science, National Park Service, P.O. Box 37127, Washington, D.C., 20013-7127.

Contibutors to this document include Roger Andrascik, Terry Cacek, Robert Doren, Lissa Fox, Ron Hiebert, Gary Johnston.

Nonnative plants are invading the national parks, causing tremendous damage to park resources. Called exotics, aliens, non-indigenous species, and weeds, these invasive nonnatives get into the parks by various means. Seeds and plant parts are brought into the parks by wildlife, wind, water, and humans. Fast-growing nonnative plants encroach from populations established outside park boundaries.

Once inside park boundaries, the most aggressive of these nonnatives spread like wildfire into undisturbed as well as disturbed areas. These invasive plants often cause irreparable damage to natural resources. The ecological balance of plants, animals, soil, and water achieved over many thousands of years is destroyed. As native plants are displaced, animal populations that rely on the plants for food and shelter also decline. Nonnative plants may reduce or deplete water levels, or alter runoff patterns and increase soil erosion, thus diminishing both the land and water quality. Some nonnatives release toxic chemicals into the soil or harbor diseases, increasing the stress on native plants. Some nitrogen-fixing nonnatives increase soil fertility, allowing other nonnatives to outcompete plants that have evolved in the nutrient-poor native soils. Nonnatives that interbreed with native species can swamp native gene pools. The growth and spread of nonnatives can also change fire patterns and intensities, resulting in an altered ecosystem.

Estimates indicate that nonnative plants infest 4,600 new acres of federal land each day. Each year, nonnatives spread into an area larger than the state of Delaware. Invasive nonnative plants currently infest an estimated seven million acres of National Park System lands. The National Park Service spends millions of dollars each year combatting these plants in an effort to preserve park resources, and still the problem is not solved. Outside park boundaries, federal, state, and local agencies fight the same battles. Farmers lose millions more trying to control nonnative plants that drastically reduce land use and productivity.

Managing invasions of this magnitude requires a coordinated strategy based on cooperation among all land managers and on the principles of integrated pest management. Since nonnative plants do not recognize political or other jurisdictional boundaries, they can only be managed if all land managers, both private and public, work together. Given the extent of nonnative plant infestations and the associated costs for management, all available resources should be shared and used efficiently. This strategy, which emphasizes cooperation, education, and science, and is based on integrated pest management techniques, can provide a blueprint for successful management of invasive nonnative plants on National Park System lands.

Management commitment
The National Park Service is required by law to keep the parks as unaltered by human activities as possible. As early as 1933, National Park Service policy recognized the harmful effects of nonnative plants and animals. Today, the National Park Service has a strong and clear policy on managing nonnative species in the park. This policy is strengthened by a definition of nonnative species that is unique. The National Park Service defines nonnative species as any animal or plant species that occurs in a given location as a result of direct, indirect, deliberate, or accidental actions by humans. This definition allows the National Park Service to recognize and distinguish between changes to park resources caused by natural processes of animals and plants, such as natural range expansions, and those changes caused by animals and plants introduced by humans.

The concepts of integrated pest management and adaptive management underlie National Park Service nonnative plant management policies and this strategy. Integrated pest management is a proven approach to managing pest problems, including invasive nonnative plants. Integrated pest management is based on a sound understanding of the ecology and biology of a pest and its environment, and is a form of adaptive management. In adaptive management, information about the resources managed is continuously developed and used to make adjustments to management approaches.

The National Park Service has already shown a commitment to managing nonnative plants through cooperation and partnerships. The National Park Service helped to organize several invasive nonnative (exotic) pest plant councils. These councils bring together resource management professionals from local, state, and federal governments, private organizations, universities, and the public to coordinate and focus nonnative plant management efforts and eliminate duplication of effort. The National Park Service also participates actively in developing multi-agency and multi-jurisdictional nonnative plant management plans. The National Park Service cooperates with the Department of Transportation and the Natural Resources Conservation Service to produce native plant materials for use in revegetation projects during road construction in parks. In Florida and Hawaii, the state governments, the Agricultural Research Service, the U.S. Forest Service, and the National Park Service are developing and testing biological control agents.

Inside park boundaries, park managers are instituting integrated pest management techniques to control the spread of nonnative plant species while causing minimal impact on the environment. As part of that program, the National Park Service is testing mechanical, chemical, and cultural management methods and biological control techniques.

Management strategies
Unfortunately, these efforts have not stopped the flow of aggressive nonnative plants into new areas of the parks or adjoining lands. More must be done. The National Park Service needs an adequately funded management program based on strong partnerships, cooperation, and credible science. The National Park Service workforce and the public must be made aware of the disastrous impacts aggressive nonnative plant infestations have on ecosystems, so that they will be supportive of and join management efforts. The National Park Service must consider nonnative plant management in all planning and project development and implementation, and have an integrated pest management program that is adopted and applied throughout the National Park System. Since some nonnative plants are relatively benign, emphasis should be put on the plant species that cause the most resource and ecosystem damage. However, vigilance is required because environmental or other conditions could change allowing nonnative plants that appear benign to become invasive.

This document lays out strategies for reaching the above invasive nonnative plant management goals. All action items are intended to be examples, rather than a comprehensive list of all that should be done to manage invasive nonnative plants.

Strategy: Prevent invasion.
Nonnative plants are continuously introduced to our lands and waters. Preventing the introduction of these nonnative plants is the first line of defense in protecting ecosystems from degradation. It is also the most economical and efficient means of management.

The National Park Service prevention program must have both internal and external components. The Service must prevent introduction of nonnative plant species into National Park System units and work with partners to develop national, regional, and local prevention strategies.

Preventing nonnative plant introduction requires constant vigilance. Seeds of nonnative plants arrive in parks in the tire treads of cars, buses, trucks, planes, bicycles, and even on shoes. Nonnative seeds attach to the fur or feathers of wildlife and pets that routinely move in and out of parks. Plant materials such as native grasses or earth fill materials brought in to revegetate disturbed ground or for other valid management reasons can contain the seeds of nonnative plants. Physical forces such as wind and water also transport seeds and other parts of invasive plants.

Preventing invasion of nonnatives depends on an active and informed public and workforce. Everyone must understand and do their part to ensure a park environment free of invasive nonnative plant species. A workforce skilled in the principles and techniques of nonnative plant management is a critical component of effective prevention and management. Contractors, concessioners, permittees, and holders of rights-of-way must also understand the influence their actions have on park resources.

Target: Develop and implement a park-based prevention program.
Develop an early warning system to identify and eradicate new infestations of nonnative plants in the park. Train appropriate personnel to identify invasive nonnative plants.
Create and maintain a park-based list of plant species that have not yet invaded the park but that are known to occur in the region and are likely to invade.
Cooperate with other regulatory agencies in expediting listing of invasive nonnative plants on state and federal noxious plant lists.
Work with the Denver Service Center and the Natural Resource Conservation Service to develop 'Best Management Practices' for ground-disturbing activities.
Ensure all feeds used on National Park System lands are free of invasive nonnative plants materials, in concert with state programs.
Ensure all materials used in revegetation projects on National Park System lands, including organic fertilizers and plant materials, are free of nonnative plant seeds or materials.
Use locally-grown native plant materials where available in all appropriate vegetation projects in order to maintain genetic integrity of local species.
Require inspections of contractor's equipment and materials to prevent importation of nonnative seeds into the park.
Specify responsibilities for nonnative plant management in permits and concessions contracts. Require commercial users that disturb established vegetation to provide bonds that are retained until sites are returned to specified vegetative conditions.

Target: Provide park managers and the public with acceptable native alternatives to non-native plant materials
Create guidelines for park managers describing appropriate uses of commercial varieties of native seeds and plant materials when seeds cannot be collected locally.
Work with commercial and other interests to develop programs, regulations, or legislation prohibiting the sale of plants known to be highly invasive or that are on prohibited lists.
Work with commercial and other interests to develop and ensure availability of acceptable plant materials. Disseminate information on sources of materials.
Target: Modify National Park Service policy and guidelines to include nonnative plant management issues, as needed.
Clarify the circumstances under which National Park Service resources may be used to manage nonnative plants on adjacent non-federal lands as part of a preventive strategy.
Incorporate nonnative plant management issues in all appropriate policy documents and guidelines, including planning/design, maintenance, fire, law enforcement, construction, and resource management.
Develop park guidance concerning uses of nonnative plants in park residences, including a list of permitted and non-permitted imports.

Target: Educate National Park Service employees and commercial users (permittees, concessioners, rights-of-way holders, etc.) about invasive nonnative plant impacts on park resources.
Incorporate nonnative plant management information at all levels of Park Service training, including planning/design, management, construction, interpretation, maintenance, law enforcement, and resource management.
Use established media (electronic media, publications, permits and contracts, etc.) to educate Park Service employees and commercial users about nonnative plant management issues.
Work with universities, state and federal agencies, and private organizations, to develop educational programs and courses for resource managers and others responsible for managing nonnative plants.
Participate in and conduct seminars or workshops on nonnative plant management.
Communicate and interpret the results of the latest research on nonnative plants to resource managers, interpreters, maintenance personnel, and others.
Encourage National Park Service employees to join and participate in professional organizations or societies concerned with nonnative plant management issues.
Work with responsible agencies and the concerned public to incorporate nonnative plant management techniques into pesticide applicator training courses.

Strategy: Increase public awareness
For any prevention or management effort to be successful, the public must understand the threats posed by nonnative plant species, change behavior that results in the spread of nonnative plants, and provide support for management efforts. To bring about this understanding, the National Park Service must reach a broad audience with a clearly articulated message.

The interpretation and education program in the National Park Service reaches millions of people annually, providing the Service with a broad-reaching, well-established educational net work. Working closely with natural resource managers, interpreters can present current and accurate information. When integrated with other agencies' educational networks, such as the U.S. Department of Agriculture's Extension Service and the Natural Resources Conservation Service, the National Park Service will be able to build support for nonnative plant management strategies.

Target: Increase public awareness of invasive nonnative plant threats and build support for National Park Service management efforts.

Create and disseminate, through all available outlets both locally and nationally, educational materials that increase awareness of, understanding of, and support for the full range of nonnative plant management activities.
Develop a model code of ethics concerning the use of plant materials through cooperative efforts with other concerned groups, industries, and agencies.
Participate in or create local area field days and other types of meetings to highlight partners' nonnative plant management projects or programs.
Cooperate with other agencies to develop and disseminate educational materials (publications, posters, videos, World Wide Web, etc.) to the public, interested organizations, and agency employees.
Encourage public support through volunteer nonnative plant management projects and other activities.
Work with the plant production industry to prepare educational materials that encourage the use of native plant species in revegetation and landscaping.

Strategy: Inventory and monitor nonnative plants.
Early detection and treatment of new infestations of invasive nonnative plants is an effective and ecologically sound management approach. Strong inventory and monitoring programs in the parks provide the information needed to direct prevention activities. Inventories provide baseline information on presence, distribution, and size of extant nonnative plant populations. Inventories also provide essential information for planning, budgeting, and setting priorities. Regular monitoring will spot nonnative plant encroachments in time to take effective action and can be used as a tool to measure the effectiveness of management efforts. Monitoring is also needed to determine whether land use and program objectives are being met and whether specific management methods are effective. This information can then be used to make adjustments to the overall program or to specific on-the-ground treatments.

Baseline information important for making decisions includes species identification; locations of infestations; acreage infested; density of plants; general plant community makeup and presence of rare native plants; environmental conditions such as soils, slopes, and proximity to surface or groundwater; and level of disturbance and current land use.

Target: Assess the distribution and extent of invasive nonnative plant populations
Work with the Servicewide Inventory and Monitoring Program to initiate inventories that would gather information needed to make invasive nonnative plant management decisions.
Incorporate monitoring for invasive nonnative plants into park resource management programs.
Work with the National Biological Service [now the Biological Resources Division of the U. S. Geological Survey], Agricultural Research Service, and others to develop standards for nonnative plant inventories that would be used by all federal land management agencies. (Until new standards are developed, the inventory and mapping guidelines in the 'Guidelines for Coordinated Management of Noxious Weeds in the Greater Yellowstone Area,' USDA and DOI, 1992, are recommended.)
Support development of remote sensing and GIS technologies for detecting and monitoring nonnative plants.
Incorporate standardized data related to nonnative plants into National Park Service planning and data management tools such as NR-MAP and the Resource Management Plan Database.
Create partnerships with adjacent land holders and with county weed districts to share resources in the preparation of landscape inventory maps.
Ensure that site-specific monitoring is included in plans for construction, habitat manipulation, and other activities that might increase the risk of nonnative plant infestations.

Target: Assess trends in time and space and assess effectiveness of management programs.
Cooperate with the Agricultural Research Service and National Biological Service [now the Biological Resources Division of the U. S. Geological Survey] in the development of monitoring technologies that are efficient yet sensitive to rapid changes in nonnative plant populations.
Work with the National Biological Service [now the Biological Resources Division of the U. S. Geological Survey], Agricultural Research Service, and others to develop a standard database for storage and retrieval of invasive nonnative plant inventory data from all federal land-managing agencies.
With other agencies, develop a technical manual describing how to monitor and evaluate various treatment techniques.
Inventory or inspect high-risk areas to detect new invasions or range expansions. These areas include construction sites and other disturbed areas, roads, trails, livestock holding areas, and streams that enter the park.
Monitor control programs to assess not only the reduction of the targeted plant, but also the maintenance or restoration of the native vegetation and fauna.

Strategy: Conduct research and transfer technology.
Ecological understanding is essential for successful adaptive and integrated management of invasive nonnative plants. Individual plant species respond to a particular environmental condition based upon life history, special adaptations, and ranges of tolerances. It has also been demonstrated that the vulnerability of habitats to invasion varies among types and levels and frequency of disturbance. Management priorities need to be based upon ecological criteria and the feasibility of control. To set these priorities, managers need sound scientific information, including information on dispersal, the life history of specific species, and the ecological effects of specific nonnative plants on given systems.

Under the principles of adaptive management, new management techniques should be treated as experimental and evaluated and adjusted accordingly. Working together, scientists and resource managers must gather sound scientific information, use the information to develop management techniques, monitor the results of the management activities, determine if clearly stated objectives are being met, and modify activities as indicated.

The National Park Service will rely upon the scientific expertise of cooperating research agencies and institutions to develop sound scientific information for managing invasive nonnative plants. Agencies such as the Agricultural Research Service and the National Biological Service [now the Biological Resources Division of the U. S. Geological Survey], as well as universities, can provide invaluable support for National Park Service management activities.

In addition to obtaining research, the National Park Service should make efforts to share information. Transferring research and resource management information to other researchers, National Park Service employees, and the public will improve research and management effectiveness at all levels. Technologies communicated to research peers will increase the knowledge base, avoid duplicative effort, and provide information for synthetic and modeling activities. Research information communicated to land managers can be applied directly to management. Research results communicated to educators and trainers will increase public awareness and the skills of technical staffs.

Target: Base species-based management priorities on scientific and other resource-related information.
Classify nonnative plants based on potential impacts to the ecosystem.
In cooperation with federal, state, and regional authorities, rank nonnative plants on local, regional, and national scales based on potential impacts to ecosystems.

Target: Develop methods and models to predict the invasiveness of nonnative plants.
Develop case histories of highly invasive nonnative plants that elucidate characteristics of invasiveness.
Develop models to predict invasiveness. Test these models on known invasive and innocuous nonnative plants.
Obtain research to improve restoration techniques and methodology.

Target: Understand what factors influence the vulnerability of specific habitats to invasion and the effects of nonnative invasions on ecosystems.

Cooperate on studies of invaded and non-invaded habitats to determine characteristics of vulnerable habitats.
Conduct literature searches and prepare abstracts of ecosystem effects of invasive nonnative plants found in national parks and their environs.
Determine types and degree of ecosystem effects of high-priority nonnative plants or highly threatened habitats.

Target: Develop techniques to detect and prevent nonnative plant invasions and to manage established nonnative populations.

Work with cooperating agencies to identify key corridors of invasion and transporters of nonnative plants.
Test management alternatives that will improve an uninfested ecosystem's ability to resist invasion by nonnative plants.
Test alternative methods to retard nonnative plant invasion of disturbed sites pending restoration or recovery of the site.
Work with cooperating agencies to develop and test integrated invasive nonnative plant management programs for use in infested areas.
Support research and testing of new biological control agents and development of biological control technologies. Participate in multi-agency regional weed technology centers.

Target: Communicate technologies, status, and trends.

Work with other organizations to develop risk assessment models and other decision-making tools.
Publish research and resource management information in professional and popular periodicals.
Advertise management successes to provide models for other areas and agencies.
Cosponsor and present research results at appropriate regional, national, and international workshops and conferences.

Strategy: Integrate planning and evaluation.

Integration of invasive nonnative plant management into every aspect of planning-whether local, regional, national, or project related-contributes directly to the ultimate goal of prevention and management of these invasive pests. Partnerships that integrate planning are the key to success in the management of invasive nonnative plants, since these plants invade lands regardless of political or organizational affiliation.

Target: Create partnerships designed to integrate planning.

Develop multi-agency groups to assist with the development of nonnative plant management partnership plans and program development. Ensure that planning incorporates the concerns and issues of land managers with similar invasive nonnative plant problems and management issues.
Coordinate use of resources such as personnel, equipment, expertise, and information where appropriate.
Make sample contracts, partnership documents, and invasive nonnative plant management plans available to parks as examples.
Provide sufficient financial support for successful nonnative plant management programs.

Target: Create management plans based on sound science.

Include scientific experts in planning efforts to ensure that ecological considerations are incorporated into management, operational, and funding elements of planning.
Participate with other agencies to develop uniform criteria for measuring accomplishments in all major areas of nonnative plant management.

Target: Increase program efficiency and consistency in the parks.

Incorporate nonnative plant management issues into planning considerations in park and multi-park management plans.
Improve information transfer among resource management, operations, and planning staff in the parks to ensure that plans are comprehensive.
Develop inter- and intra-agency cross-cutting budgets that reflect the amount and aim of each organization's funding toward nonnative plant management. Incorporate the funding plans into program, project, and operational planning.
Develop multi-agency funding requests that embody the total nonnative plant program(s) being implemented by all agencies within the identified area of operations and management.
Evaluate the effectiveness of nonnative plant control programs and projects by developing criteria and schedules for program and project evaluations for all nonnative plant management programs.
Include other plans or programs that may affect or be affected by nonnative plant issues.

Strategy: Manage invasive non-native plants.
Many park units throughout the National Park System have instituted projects to manage individual species of invasive nonnative plants. However, there are still many parks that do not have a viable nonnative plant management program. The National Park Service must put nonnative plant management high on the list of resource management priorities, and see that every park with invasive plants has a management program in place.

Target: Reduce populations of invasive nonnative plants through an integrated pest management program that incorporates chemical, biological, cultural, and physical (mechanical) operations.

Create National Park Service guidance for invasive nonnative plant management.
Develop regional integrated pest management programs in cooperation with partners. Share scientific expertise, organizational skills, and administrative support among partners.
Participate in the development of local invasive nonnative plant management units.
Fund locally developed management strategies.
Ensure that professional technical assistance is readily available to every park.
Maintain a system for reviewing, approving, and reporting herbicide uses.
Use new technologies and strategies to minimize the adverse consequences of management practices on the ecosystem, paying special attention to water quality and threatened, endangered, or sensitive species.
Promote and support biological control efforts. Support careful pre-release testing of biological control agents on non-target (native) species to detect possible unwanted impacts.

Visit the Federal Interagency Committee for the Management of Noxious and Exotic Weeds Webpage.


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