Invasive Species Impacts and Management

Invasive species are one of the leading threats to fish and wildlife, with potential to degrade entire ecosystems. Among the most insidious plant invaders on national wildlife refuges are salt cedar, leafy spurge, whitetop, thistles, Brazilian pepper, purple loosestrife, Australian pine, Chinese tallow trees, old world climbing fern, and melaleuca. Many approaches and techniques are used to control plants, including application of chemicals, mechanical removal, prescribed burning, and biological control. In addition, a variety of exotic/nonindigenous animals such as tilapia, Norway rats, asian carp, nutria, asian swamp eels, feral goats and wild pigs are also a problem throughout the Refuge System. In 1998, combined invasive plant and animal control operations cost the Refuge System nearly 94 FTE’s and 12.7 million dollars. However, these efforts addressed only a fraction of the enormous invasive species problem in the Refuge System. Based on national interagency estimates, over 6 million acres of the National Wildlife Refuge System are infested with exotic plants that interfere with the achievement of crucial wildlife management objectives on nearly 50% of all refuges. Nationwide, the rate of spread of invasive plants, alone, is estimated to be 5,400 acres per year. Estimates of the rate of spread of invasive animals vary significantly throughout the nation. Refuges are significantly impacted by these aggressively spreading populations of invasive species. Refuges from Alaska to the Caribbean are affected by this problem that knows no boundaries. Since most refuges have significant wetland components, aquatic invasive species are particularly damaging to refuge habitat management efforts.

The cost of fighting invasive species increase each year, nationwide and within the Refuge System. As if we were battling a wildfire out-of-control, we barely have the ability to conduct preventative measures because we are overwhelmed with the bombardment of new and expanding infestations. National Wildlife Refuge System staff and equipment, and financial, resources are extremely limited. A recent "test run" of the new Refuge System Threats and Conflicts Database indicated that invasive species problems ranked as the #1 threat or conflict affecting the Refuge System, scoring almost double that of the next lowest problem listed...which was illegal activities.

Ecologically, refuges are finding that much of their biological and habitat management efforts are spent on battling with these exotic species, not enhancing the quality of native wildlife habitats. Another indication of the rapid progression of this ecological disaster is the change in Refuge Operations Needs projects. In February 2000, refuges identified approximately $44 million in invasive species management projects. By July 2000 those problems grew to almost $120 million. Currently the fastest growing component of the Refuge Operations Needs System (RONS) database, invasive species management projects total nearly $150 million (almost 15%) of the nearly over $1 billion backlog for refuge operations. Refuges are striving to keep up with the rapid degradation caused by invasive species infestations. The "hole" in our refuge management budget "bucket" is growing wider because of these invasive species impacts and efforts to increase overall Refuge System management funding cannot keep up with the leak.

A portion of the Refuge System’s effort to fight invasive species includes projects to document the extent, rate of spread, and impacts of invasive plants and animals on Service lands and ensure that the best and most appropriate management practices are available for use by managers in the field. System-wide research partnerships between the USGS - BRD, Invasive Species Program Element and the Refuge System are underway to accomplish an updated inventory/survey of the status of invasive species infestations throughout the Refuge System. Information provided from these research partnerships must provide science that is directly applicable to the land managers. Information must be coordinated, rapid, accurate, adaptable, integrated, predictive, and must be provided at both a site-specific level as well as a landscape scale. The need for a clearer understanding of invasive species behavior and physiology is frequently a limiting factor in developing integrated management plans for control. The refuge system will look toward building partnerships with researchers to develop the necessary tools for better management of invasive species.

Additionally, the Refuge System Fulfilling the Promise Invasive Species team has undertaken the development of a National Strategy for refuge invasive species management. This strategy will include regional and national organization guidance, assessment information, inventory guidance, mapping and monitoring recommendations and best management practices. Regional organization for Refuge System invasive species management has been proposed and would be accomplished by establishing full-time Refuge Invasive Species Coordinators in each region. These coordinators would help assess the current status of invasive plants and animals, assemble nationwide data on the problem, and help develop strategies to respond to those invasions. When established, these coordinators will review existing control methods and assist field staff in identifying and implementing the best available and most appropriate control techniques. The coordinators would also provide recommendations for future research and development of new monitoring and control methods. In support of Executive Order 13122, Section 2, research will be supported in the Refuge System to develop technologies for the prevention of and ecologically sound control of invasive species under a fully integrated pest management program.

Aquatic Invasive Species Control

The control of aquatic invasive species (plants and animals) on refuges is critical for the protection of native fish and wildlife populations and to prevent significant habitat degradation in wetland areas. Some aquatic species of concern include nutria, purple loosestrife, zebra mussel, brown tree snake, parrotfeather, water hyacinth, hydrilla, round goby, Eurasian watermilfoil, Tilapia, and water lettuce. Coastal and river corridor regions are typically the most affected, however many inland wetlands and waterways have become infested with these species. Control operations are needed on over 300,000 aquatic acres each year throughout the Refuge System, not including river systems. Integrated pest management techniques for invasive species control will be applied and may include mechanical, chemical, and biological controls where appropriate. Prevention efforts are critical to reduce the impacts of aquatic invasive species threatening the Refuge System, and a Emergency/Rapid Response Program for the System is the key to preventing to newly discovered infestations from gaining a foothold on refuges.

There is a need to devote significant efforts to on-the-ground control and prevention of invasive plants and animals on Refuge System units. Control operations will incorporate integrated pest management techniques and may include methods such as mechanical, chemical, biological, and prescribed fire control. Nearly 1,000,000 acres of habitats throughout the Refuge System will benefit from invasive species control efforts if a sound process is developed to improve efficacy. The majority of these operations will address the control of invasive plants impacting refuges and surrounding lands and will benefit native fish and wildlife and their associated habitats. Some of these species of concern include saltcedar, exotic thistles, Russian olive, whitetop, miconia, melaleuca, yellow starthistle, leafy spurge, Chinese tallow, exotic knapweeds, Brazilian pepper, tropical soda apple, and fountain grass. Control of invasive species plays a major role in ecosystem restoration and benefit threatened and endangered species that rely on healthy ecosystems. Refuges pay considerable attention to restoration of terrestrial habitats impacted by wildfire, for those disturbed areas are prime locations for invasive species infestations to get started and expand.

With any refuge management issue, there is an educational component. The invasive species issue is no different and perhaps needs significantly more education and outreach support than other more understandable biological issues. The National Wildlife Refuge System has significantly improved its internal and external outreach efforts for invasive species and developed educational materials related to the invasive species problem. The Refuge System works in concert with other Service programs to expand the understanding of the invasive species problem and coordinate our efforts with other local, state, and federal entities. Cooperation with research offices in USDA and USGS have enabled Refuge System invasive species awareness issues to be promoted nationwide. Prevention efforts (including education) are significant components of a fully functional invasive species management program and education and outreach are directly linked to preventing expansion of or new infestations of invasive species. An active education and outreach component, the Refuge System Invasive Species Program must be maintained in order for us to meet our obligations outlined in the Presidential Executive Order 13112 and other mandates related to aquatic and terrestrial invasive species management. The Refuge System has included the invasive species issue as one of the priorities of the national outreach strategy/plan recently developed. Congressional outreach efforts underway by the Service have resulted in expanding support for Service invasive species operations. Cooperation with other DOI agencies to develop cross-cutting budget packages will help agencies such as USGS-BRD to work closer with the Service to solve on-the-ground invasive species management problems.

USGS, Biological Resources Division
Denver Federal Center, P.O. Box 25046, Bldg 20, Mail Stop 300
Central Regional Office, Denver, CO 80225-0046

Contact: jcoffelt@usgs.gov
Updated: 11/21/01