National Academies Press: OpenBook

Control of Invasive Species (2006)

Chapter: Chapter Two - Invasive Species A Growing Problem

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Suggested Citation:"Chapter Two - Invasive Species A Growing Problem." National Academies of Sciences, Engineering, and Medicine. 2006. Control of Invasive Species. Washington, DC: The National Academies Press. doi: 10.17226/14020.
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Suggested Citation:"Chapter Two - Invasive Species A Growing Problem." National Academies of Sciences, Engineering, and Medicine. 2006. Control of Invasive Species. Washington, DC: The National Academies Press. doi: 10.17226/14020.
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Suggested Citation:"Chapter Two - Invasive Species A Growing Problem." National Academies of Sciences, Engineering, and Medicine. 2006. Control of Invasive Species. Washington, DC: The National Academies Press. doi: 10.17226/14020.
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Suggested Citation:"Chapter Two - Invasive Species A Growing Problem." National Academies of Sciences, Engineering, and Medicine. 2006. Control of Invasive Species. Washington, DC: The National Academies Press. doi: 10.17226/14020.
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Suggested Citation:"Chapter Two - Invasive Species A Growing Problem." National Academies of Sciences, Engineering, and Medicine. 2006. Control of Invasive Species. Washington, DC: The National Academies Press. doi: 10.17226/14020.
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Suggested Citation:"Chapter Two - Invasive Species A Growing Problem." National Academies of Sciences, Engineering, and Medicine. 2006. Control of Invasive Species. Washington, DC: The National Academies Press. doi: 10.17226/14020.
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Suggested Citation:"Chapter Two - Invasive Species A Growing Problem." National Academies of Sciences, Engineering, and Medicine. 2006. Control of Invasive Species. Washington, DC: The National Academies Press. doi: 10.17226/14020.
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5WHAT ARE INVASIVE SPECIES? STATE AND FEDERAL DEFINITIONS For the purpose of this report, invasive plant species are defined as those found outside of their native range and, owing to certain characteristics, are able to move into an area and become dominant numerically, in cover, resource use, or other ecological impact. E.O. 13112, “Invasive Species” defines invasive as “alien (non-native) species whose introduction does or is likely to cause economic or environmental harm or harm to human health” (4). Invasive species can be plants, animals, and other organisms (e.g., microbes). The large majority of non-native species—those occur- ring in locations beyond their known historical natural ranges and/or brought in from other continents, regions, ecosystems, or habitats—do not pose a threat to the natural or human systems in which they are introduced. However, a small percentage of non-native species that become established have the potential to become invasive and cause significant economic, environmental, and human health consequences (5). After introduction in a new environment, invasive species may establish easily and quickly, compete aggres- sively, and grow rapidly, presenting a threat to native species and habitats. As transportation corridors enable people and vehicles to move from place to place, highways have become pathways or vectors for the spread of invasives. Human actions are the primary means of invasive species introductions. For exam- ple, Canada thistle, Cirsium arvense, arrived from Europe in the 1600s as a contaminant in crop seed. It is now on most noxious weed lists in North America. Purposeful introduc- tions of invasives have resulted from the use of such species as ornamental, pasture grasses, or to solve erosion control problems. Both intended and unintended introductions are now equally common. Most states confine their noxious weed lists to agricultural concerns rather than using the definition of invasive to expand coverage of the laws and regulations beyond those species with a wider span of harm. Noxious weeds are plants deemed by a state’s Department of Agriculture (DOA) and/or Department of Natural Resources (DNR) as harmful to agriculture, human health, or the environment. RISING COSTS IMPOSED BY INVASIVE SPECIES Introduced organisms are the second greatest cause, after habitat destruction, of species endangerment and extinction worldwide (6). In the United States, nonindigenous species do more than $130 billion a year in damage to agriculture, forests, rangelands, and fisheries, as estimated by Cornell University biologists (7). According to an Office of Technol- ogy Assessment study, a selection of just 79 of these non- native species cost the American taxpayer some $97 billion in damages to natural resources and lost industrial productivity during the 20th century (8). Some of these costs arise from both roadway management needs and impacts on adjacent landowners (9): • Contamination or competition with crops, • Decrease in forage value of rangeland and pastures, • Change in aesthetics of the landscape and degradation of natural heritage and educational value, • Increase in fire threats, • Compromise of roadside visibility and safety, • Attraction of wildlife to roadside, and • Additional costs of roadside maintenance. Such costs are increasing as invasive plants spread into an estimated 4,600 acres daily (9). In the 2002 report, Invasive Species: Clearer Focus and Greater Commitment Needed to Effectively Manage the Problem (10), the U.S. General Accounting Office (GAO) found that most economic esti- mates do not consider all of the relevant effects of non-native species or the future risks that they pose, but that a more comprehensive analysis could help decision makers make better resource allocations; that is, allocate more resources to the task. A number of DOTs noted that access to information about the costs and benefits of treating invasive species could bolster their ability to get resources allocated to address the problem. Invasive species and their management impose substantial costs on DOTs, and a number of states, associations, and sci- entific entities have begun to compile these data. Historically, roadside vegetation restoration and maintenance has been a lower priority than safety-related issues such as pavement management and snow and ice control. However, in recent years, public scrutiny has broadened from these core issues to the effect and appearance and ecological function of the road- side as well. CHAPTER TWO INVASIVE SPECIES—A GROWING PROBLEM

FEDERAL CONTEXT, PRIORITIES, AND DRIVERS IN INVASIVE SPECIES CONTROL Invasive species are an increasing concern for all public agencies. In many cases, the control of invasive species is mandated by state and local law and policy; in others, con- trol of invasives depends on voluntary efforts and the public interest missions of public agencies. Presidential Executive Order 13112 on Invasive Species and FHWA Guidance E.O. 13112 directs all federal agencies to address invasive species concerns and refrain from actions likely to increase invasive species problems. It also directs agencies to “pro- vide for restoration of native species and habitat conditions in ecosystems that have been invaded.” On August 10, 1999, FHWA provided field guidance on implementing the execu- tive order, which specified that (11): • Federal funds cannot be used for construction, revegeta- tion, or landscaping activities that purposely include the use of known invasive plant species as listed by some states or the National Invasive Species Council (NISC). • National Environmental Policy Act (NEPA) analyses require determinations of the likelihood of introducing or spreading invasive species and a description of mea- sures being taken to minimize their potential harm. • With regard to construction and maintenance, federal- aid funds can be used for new and expanded invasive species control efforts under each state DOT’s roadside vegetation management program. Despite allowances for use by maintenance, thus far redi- rection of federal-aid funds by states for this purpose has been limited. The executive order and implementing guid- ance also recommended prevention and eradication measures such as: • Statewide, right-of-way (ROW) inventories of vegeta- tion that map existing invasive plant infestations; • Inspection and cleaning of construction equipment; • Commitments to ensure the use of invasive-free mulches, topsoils, and seed mixes; and • Eradication strategies to be deployed should an invasion occur. A number of DOTs have started completing invasive species surveys for all projects (state and federal) with ground- disturbing activities. If weeds are found and adjacent lands are federal, the DOT coordinates with that agency for more effec- tive control of invasive species. Special mitigation measures to prevent the spread of weeds found and to prevent the intro- duction of invasive species are incorporated into NEPA docu- mentation and contract specifications. Coordination among environmental, design and landscape architecture, and con- struction staff is on the increase, addressing environmental 6 impacts and eradication and control of invasive species during and after construction. For example, New York State DOT (NYSDOT) and Utah DOT (UDOT) are including invasive species in NEPA decision-making processes, documenting potential environmental impacts, and listing appropriate best management practices (BMPs) as mitigation commitments for all projects that have the potential to spread or introduce listed weeds. Interagency Invasive Species Council and National Invasive Species Management Plan E.O. 13112 also created an interagency Invasive Species Council and called for a National Invasive Species Manage- ment Plan to better coordinate federal agency efforts. The National Invasive Species Management Plan identifies trans- portation facilities as sites of invasive species or the means for introduction and spread of invasive species. Some of the other activities of the Council include: • Identification of sanitation and exclusion methods for preventing the spread of invasive species (e.g., restric- tions on use of contaminated soils and fills, cleaning firefighting equipment before deployment to new areas, requiring pest-free forage and mulch and weed-free sod, washing construction equipment, and managing ballast water). • Development of draft legislation to authorize matching federal funds for state programs to manage invasive species, including a provision to provide assistance to states for the development of state invasive species management plans. The draft legislation proposal may also include tax incentives or other provisions to encourage voluntary participation of private landown- ers in control programs and to promote their actions to prevent the spread of invasive species. Consideration will also be given to extending current federal author- ity to conduct control activities on state and private lands where invited by the landowner. • U.S. Department of Agriculture (USDA) leadership, in consultation with regional, state, tribal, and local agen- cies, in the formation of a proposal for accelerating the development, testing, assessment, transfer, and post- release monitoring of environmentally safe biological control agents and submit the proposal to the council for review. • Development of guidance for ranking the priority of invasive species control projects at local, regional, and ecosystem-based levels. • Federal Interagency Committee for the Management of Noxious and Exotic Weeds (FICMNEW) is currently updating the Weed Fact Book (12) and has proposed an Invasive Biological Control Fact Book. The Federal Inter- agency Committee for Invasive Terrestrial, Animals, and Pathogens is a newly formed interagency committee undertaking projects similar to FICMNEW (13).

7A 2003 GAO report claimed that “the federal government had made little progress in implementing many of the actions called for by the plan” owing to delays in establishing teams to be responsible for guiding implementation of the planned actions, the low priority given to implementation by the NISC and federal agencies, and the lack of funding and staff responsible for doing the work” (14). State officials who responded to GAO’s survey identified a number of gaps in, or problems with, existing legislation addressing invasive species along with other barriers to managing invasive species, including a lack of legal requirements for controlling invasive species that are already established or widespread. Also lacking were federal funding for state invasive species efforts, public education and outreach, and cost-effective control measures (14). Existing Federal Legislation The most recent transportation legislation, SAFETEA-LU, Section 606, makes existing National Highway System/ Surface Transportation Program funds available for partici- pation in the control of noxious weeds and establishment of native species. Environmental restoration may be carried out for “environmental degradation caused wholly or partially by a transportation facility.” Such restoration costs are not to exceed 20% of the total cost of the reconstruction, rehabili- tation, resurfacing, or restoration of the facility. Section 329 details eligibility for control of noxious weeds and establish- ment of native species, if related to transportation projects. Plant establishment and “management of plants which impair or impede the establishment, maintenance, or safe use of a transportation system” are also eligible. This establish- ment and management may include: • ROW surveys to determine management requirements to control federal or state noxious weeds, as defined in the Plant Protection Act (7 U.S.C. 7701 et seq.) or state law, and brush or tree species, whether native or non- native, that may be considered by state or local trans- portation authorities to be a threat with respect to the safety or maintenance of transportation systems. • Establishment of plants, whether native or non-native, with a preference for native to the maximum extent pos- sible, for stormwater abatement, soil stabilization, and aesthetic enhancement. • Control or elimination of plants that impair or impede establishment, maintenance, or safe use of a transporta- tion system. • Elimination of plants to create fuel breaks for the pre- vention and control of wildfires. • Training. These activities “may be carried out concurrently with, in advance of, or following the construction of a project funded under this title.” Thus, invasive species control and native revegetation projects may be conducted essentially independently of a transportation improvement project, but should be associated with a current, past, or future project, in some way, not to exceed 20% of the total cost of that project. Because SAFETEA-LU was just recently passed, FHWA has yet to issue guidance to states on the imple- mentation of these provisions. The Plant Protection Act (2000) replaced the Federal Noxious Weed Act and consolidates and modernizes all major statutes pertaining to plant protection and quarantine (Federal Noxious Weed Act and Plant Quarantine Act). It permits the Animal and Plant Health Inspection Service (APHIS) to address weed issues, increases the maximum civil penalty for violations, and authorizes APHIS to take both emergency and extraordinary emergency actions to address incursions of noxious weeds. In general, this legisla- tion deals with quarantine and inspection, rather than wide- ranging species. A few exceptions have occurred by state request. The National Invasive Species Act (1996) reautho- rized and amended the Non-Indigenous Aquatic Nuisance Prevention and Control Act of 1990 to mandate regulations to prevent the introduction and spread of aquatic nuisance species into the Great Lakes through ballast water and autho- rized funding for research on aquatic nuisance species pre- vention and control for the Chesapeake Bay, Gulf of Mexico, Pacific Coast, Atlantic Coast, and San Francisco Bay–Delta Estuary. It required a ballast water management program to demonstrate technologies and practices to prevent non- indigenous species from being introduced. The legislation also modified the composition of the Aquatic Nuisance Species Task Force. Federal Weed Lists The federal noxious weed list falls within International Plant Pest Convention rules for international trade. Federal listing makes a plant a quarantined pest and an interdiction target. The federal noxious weed listing is designed for species that are not widely distributed and are under official control. Plants would be unlikely to be added to the list if they were widely distributed, unless present in relatively few states. Even then, the federal noxious weed focus of exclusion and eradication does not match well with state noxious weed lists and objectives, which are oriented to the control and man- agement of pest species. In most cases state-listed noxious weeds are widespread, although some states may also have identified a relative few eradication and Early Detection and Rapid Response (EDRR) targets. There are federal procedures for listing species that are known to be invasive. Such listings may be petitioned and involve stakeholders and the public in the course of the rule- making process. Importation and interstate transport is pro- hibited for species that are federally listed as noxious weeds or injurious wildlife, although enforcement of prohibitions on listed species and exclusion of invasive species is limited

and largely dependent on inspection services at ports of entry. Federal lists and regulations include the following: • Federal Noxious Weed List (9/8/00), Plant Protection and Quarantine, APHIS, USDA. • Federal Plant Quarantine Summary (March 2003), Plant Protection and Quarantine, APHIS, USDA. • Injurious Wildlife Species List (50 CFR 16.11-16.15), Division of Environmental Quality, U.S. Fish & Wildlife Service (FWS). • Plant laws and regulations, National Plant Board. • APHIS regulations (Title 7, Subtitle B, Chapter III, 2000 ed.), USDA. • APHIS Regulated Plant Pest List, USDA. STATE AND LOCAL CONTEXT AND PRIORITIES Given diverse environments, state DOTs attend to state and often local priorities in the management of weeds and/or nox- ious species. In particular, DOTs may focus on species of concern to safety and/or existing vegetation where the DOT is responsible for managing in the ROW. State Noxious Weed Laws and Weed Lists Most state legislatures have enacted noxious weed laws to limit economic loss resulting from the presence and spread of noxious weeds. The laws mandate the control of weed species. A typical noxious weed definition is “A plant which when established is highly destructive, competitive, or diffi- cult to control by cultural or chemical practices.” State- specific laws and regulations pertaining to noxious weeds and invasive species are available for review on the Internet. A complete overview of state legislation regarding invasive species may be found in the Environmental Law Institute report, Halting the Invasion: State Tools for Invasive Species Management (15). Of the thousands of introduced species, each state with a noxious weed list specifies a small number of its own priorities, lending much fragmentation to the pur- suit of interstate invasive species priorities. More than half of responding state DOTs (23) reported that they have an enforceable invasive species law, whereas one-third noted that there was no enforceable invasive species control law. Where a state law does not exist, execu- tive orders by the governor have been issued, as in the case of New Mexico. Elsewhere, as in New York, bills have required the convening of an Invasive Species Task Force to assess the issue and existing programs and recommend future actions to the governor. In Wisconsin, there is a noxious weed law with penalties; however, no agency has been given the authority to enforce it. Missouri DOT (MoDOT) reports that legislation or state legislative allocations have “blurred the picture,” cutting support to counties or at the state level. Some DOTs noted that important invasive species are not listed with regard to their state’s noxious weed law. 8 State noxious weed laws often establish weed control boards, which update the state’s noxious weed lists. Most states develop and maintain noxious weed lists particular to issues and species of concern in their state, and these are pre- dominantly agricultural. Eleven states still do not have lists and many state weed laws are not enforced. In the past, a lack of coordination has resulted in some DOTs continuing to plant species that are contained on state noxious weed lists. Lists are sometimes divided into multiple categories. Class A weeds, for example, are usually of the highest prior- ity. They are non-native species with a limited distribution. Prevention and eradication may be required for Class A species. Class B species may be designated for control in regions where they are not yet widespread to prevent further infestation in the state. Where Class B species are already abundant, containment is the primary goal. Class C weeds may already be established throughout much of a state. Long-term programs of suppression and control are a local option, depending on local threats and the feasibility of con- trol in local areas. Local and Regional Weed Control Efforts Fragmentation and diverse focus characterize existing local and regional weed control efforts. DOTs often become involved in other regional weed control or cooperative weed management projects. DOTs partner with other major landowners and weed control organizations to more effec- tively limit the introduction and spread of invasive weed species. Some states, such as Washington, have a strong locally based organization and legal process for managing invasive plant species; the existence of noxious weed control boards in all 39 of Washington’s counties creates a frame- work for coordination of weed management across property lines and political boundaries. Weed Management Areas (WMAs) are developed by landowners and managers in a common local area to facilitate cooperation in managing common weed problems and pre- venting the reproduction and spread of weeds into and within the WMA. They bring together landowners and managers (pri- vate, city, county, state, and federal) in a county, multicounty, or other geographical area to coordinate efforts and expertise against invasive weeds. The WMA functions under the author- ity of a mutually developed Memorandum of Understanding (MOU) and is subject to statutory and regulatory weed control requirements. In some states, such groups are initiated by the county agricultural commissioner’s office or a federal agency employee, and voluntarily governed by a chairperson or steer- ing committee. WMAs are unique because they attempt to address both agricultural weeds and wild land weeds under one local umbrella organization. A WMA replaces jurisdictional boundaries that are barri- ers to weed management programs in favor of natural or

9more logical boundaries that facilitate weed management and control. WMAs typically have similar characteristics such as geography, weed problems, climate, common inter- est, or funding support. Boundaries may be a watershed or other geographic feature. Stakeholders in a WMA jointly pri- oritize weed management efforts based on species or geo- graphical area. They then work together to manage the weeds within the WMA (16). Regional weed control efforts may cross state and even international borders. The Weeds Across Borders project in the Okanogan region of north-central Washington State and south-central British Columbia involves agencies and major landowners on both sides of the international border. Initi- ated with partial funding by FHWA, the project has included: • Development and maintenance of a geographic infor- mation system (GIS) inventory of the most problematic weed species. • Coordination of on-ground treatments of all significant infestations. • Introduction of a biological control program for several of the widespread invasive weed species. • Development and implementation of an education pro- gram for the public and for lawmakers at the local, state, and federal levels. The Cooperative Weed Management Area (CWMA) Cookbook (17) is a guide to help organize, develop, and oper- ate successful WMAs. Statewide Invasive Species Councils or Task Forces Statewide invasive species councils or task forces have been formed in 30 states, according to the 40 state DOT respon- dents, with the DOT actively involved in all but 4 of those cases. However, only 16 of the 30 state DOTs with such task forces view the council or task force as a success. When asked for further comment on the key strengths, successful approaches, or accomplishments that may serve as models to others, DOTs noted that, at a minimum, the networking paid off. Additional strengths were/are: • Statewide focus and inclusion of a wide range of inter- ests (e.g., aquatics, horticulture, agriculture, forestry, academics, private land owners, government agencies, extension, industry vendors, and private consultants), their expertise, and the willingness of each member to participate in the council and its subcommittees. • Creation and wide circulation of a brochure featuring the state’s “10 Worst Invasive Weeds.” • Initiation of the production (largely funded by the DOT—Alabama, in this case) of a one-hour documen- tary on the impact of invasive weeds on the state, to be aired on public broadcasting stations throughout the state and then made available, with text curriculum, for use in all state schools. • Bringing legislative focus to the issue of invasive species, and the most troublesome species in particular. • Fostering education and cooperation across multiple jurisdictions. • Hosting regional, multistate meetings. • Stopping the sale of invasive plants in the state and compiling a list of noninvasive replacement plants (Connecticut). • Sponsoring a central and very active website and very active listserv/e-mail list (Hawaii). In a few cases, “affected parties, such as those responsi- ble for managing ROW are not included in the state’s efforts.” In another case, the DOT noted that the group “needs to finish the plan and strategies so we can do a better job suppressing/preventing the (species) that we all agree on.” The participants typically have “limited time available— most members are busy with other commitments and respon- sibilities”; however, “with limited budgets the Council is able to address statewide concerns and utilize the limited monetary resources where they will be most effective.” STATE DEPARTMENT OF TRANSPORTATION DRIVERS, PRIORITIES, AND CHALLENGES For years, DOTs have been managing species that affect roadway safety, sign visibility, and roadside maintenance and operations. The further spread of invasive species, the impact on vegetation management, and increasing attention devoted to the topic by other agencies and stakeholders con- cerned with the loss of natural habitats have driven additional efforts. Impact of Executive Order 13112 on State Departments of Transportation Of all respondents, 33% indicated that E.O. 13112 has notably changed how they do business. A DOT for whom business has changed significantly as a direct result of the executive order had this to say: The issuance of E.O. 13112 has changed the program from mainly a control program to some movement towards an inte- grated management approach. This movement is in its infancy with limited projects and results. The New Mexico DOT stated that, “As a result of the 1999 E.O., NMDOT adopted a statewide program that includes preventative measures, mechanical control, chemical control, and integrated methods”—characteristic of an IRVM pro- gram. Other program changes cited included conducting inva- sive species surveys for all projects with ground-disturbing activities and coordination with agencies that manage adja- cent lands. Special mitigation measures to prevent the spread

of identified patches of invasives and to prevent introduction elsewhere are incorporated into NEPA documentation and contract specifications. In planning and development, more emphasis is being placed on identifying and controlling or eradicating invasive species before and during construction. For example, UDOT formed a Quality Improvement Team to identify appropriate strategies to implement E.O. 13112 after FHWA issued its guidance. Individuals from FHWA and UDOT design, con- struction, maintenance, and environmental divisions partici- pated on the team, which agreed to address invasive species on both the state and county noxious weed list. In addition to addressing and proposing mitigation for potential impacts from invasive species as part of the NEPA process, the team identified BMPs to minimize the introduction and spread of listed noxious weed species. These BMPs are included in plans and specifications through a special provision on Inva- sive Weed Control. UDOT has enhanced training for staff to understand the executive order and its implications, current invasive species problems, and how to incorporate BMPs. Many DOTs had already begun to require the use of native species; however, the executive order provided a def- inition of invasive species and elevated attention to the issue at an earlier point in the transportation process. Several DOTs reported that the executive order has given them more justification for actions already underway. NYSDOT noted that, “The E.O. added emphasis and formality to an issue that although recognized as important, had not been formally addressed in Department policy, guidance, and procedure.” Although most DOTs noted that E.O. 13112 had not really changed how the agency does business, many of these noted that it has added steps or work in planning or project development. Twenty-five percent indicated that their agency is currently incorporating invasive species assess- ments in all NEPA evaluations. Another 18% ensure that invasive species assessments are at least incorporated in Environmental Impact Statements (EISs) or environmental assessments (EAs). Although overall business practices may not have changed much in ways that can be directly attributable to E.O. 13112 for two-thirds of the respondents, DOTs have increased their activity and attention in the area and new policies and procedures have been added in recent years. Many DOTs are now targeting specific species rather than weeds more generally. One DOT indicated that it is attempt- ing to include invasive species as a bid item for federal-aid projects. DOTs are eliminating the use of invasive plants and removing some existing plants as part of landscaping projects. Certified weed-free hay or mulch is now required. At the Colorado DOT, maintenance staff is now included in construction project final inspection. Some DOTs men- tioned that they could do more to implement E.O. 13112, but resource availability is a major issue. 10 State Department of Transportation Priorities in Invasive Species Control Transportation agencies manage approximately 12 million acres of land surrounding state, interstate, county, and municipal roads. In the survey conducted for this synthesis, responding state DOTs identified 68 different invasive species, nationwide, in their lists of “top five” invasive species in each state. Some top priorities are widespread; one-third of the respon- dents placed Canada thistle and 30% placed Johnsongrass (Sorghum halepense) on their lists of top invasives. Twenty- five percent are fighting kudzu (Pueraria montana), which has been moving westward, and 20% and 18% are targeting Japa- nese knotweed [Fallopia japonica (syn polygonum cuspida- tum, F. x. bohemica, F. sachalinensis) and Purple loosestrife (Lythrum salicaria)], respectively. With regard to non-plant and weed species, 13% of respondents control for mosquitoes to prevent the spread of West Nile Virus and 13% control for red imported fire ants (Solenopsis invicta). Of responding DOTs, 8% control for gypsy moth (Lymantria dispar) and 5% for oak wilt (Ceratocystis fagacearum). Eight percent control zebra mussels (Dreissena polymorpha). However, weed species occupy a larger part of the time, energy, and budget of invasive species control and are the primary focus of this report. Primary Department of Transportation Drivers in Addressing Invasive Species More than two-thirds of all respondents (68%) reported that internal, rather than external policies drive their efforts at invasive species control. Figure 1 details the percentage of respondents citing different categories of drivers in address- ing invasive species. For several DOTs, state laws on invasive species or nox- ious weeds drive their efforts. Other agencies may require DOTs to address invasive species as a condition of acquiring permits. State DOAs often play a key role. In addition to a coordinating role, some DOAs have helped implement con- trols on DOT ROWs. Invasive species committees, task forces, and weed management groups also provide input. Despite these important inputs, leadership from within propels many DOT invasive species efforts. Members of roadside management teams or landscape architects were mentioned as being instrumental in guiding invasive species policies and finding ways to further invasive species control in a low-resource environment. DOTs also identified specific concerns and objectives as drivers, such as reducing herbi- cide use, protecting rare or threatened species, and carrying out formal roadside vegetation management plans. Cost- efficiency and environmental concerns are also increasingly

0 10 20 30 40 50 60 Pe rc e n ta ge o f re sp on de nt s La ck o f s ta te fu nd s Co nt ro l li m ite d to R OW Li m ite d fe de ra l h ig hw ay fu nd s D iff e rin g pr io rit ie s of fe de ra l, st at e, a n d lo ca l a ge nc ie s La ck o f t em pl at es o r g ui da nc e Pe rc e pt io n of n at ive g ra ss e s Fi nd in g su ita ble n at ive gr o u n dc ov e rs Su pp ly of n at ive s e e d La ck o f i nd ep en de nt c er tif ica tio n o f w e e d- fre e m u lc h 0 10 20 30 40 50 60 70 Pe rc e n ta ge o f r es po nd en ts In te rn a l D OT p ol ici es En vi ro nm en ta l s te w a rd sh ip M ai nt en an ce co st s av in gs Pu bl ic in pu t, su rv ey s, cu st om er c om pl ai nt s O th er a ge nc y po lic ie s or re qu es ts E. O. 13 11 2 an d FH W A M in im iz in g he al th o r s af e ty h az ar ds O th er in te rn a l O th er 11 an issue. One DOT cited invasive species control as an important factor in pavement preservation. Primary Obstacles to Control of Invasive Species Many DOTs were quite vocal about the obstacles con- fronting the control of invasive species. For many, a simple lack of resources—both dedicated funding and dedicated personnel—is at the heart of insufficient invasive species control. As NYSDOT stated, “[c]urrently, staffing, and funding for invasive species management must compete against other priorities for the same staff time and funds— dedicated line items and a separate funding source would be a great benefit.” The frequency at which respondents cited various categories of obstacles is illustrated in Figure 2. Fifty-three percent of responding DOTs cited a lack of state funds as an obstacle in invasive species control, 50% cited a lack of control over lands adjacent to the ROW, and 38% reported that limited federal highway funds were a primary obstacle. Another major hurdle is that the concept of invasive species has not been adequately defined, if at all, and there is little legal impetus or even guidance for addressing invasive species control. The laws of many states still only address noxious weeds identified for agricultural purposes. Thirty- five percent of responding DOTs cited differing priorities of federal, state, and local agencies as obstacles to invasive species control. Inadequate or incomplete inventories of invasives, as well as the means to track those species identi- fied, remain obstacles for others. Other obstacles cited by individual DOTs included the following: • Mitigation measures, such as washing equipment before and after construction and site-specific collabo- rative mitigation, all add cost, usually to the construc- tion budget, and monitoring these measures during construction is difficult. • Inadequate specific guidelines or policies on a pro- grammatic scale. • Poor soil, compacted soils, disturbed and degraded roadsides. • Lack of an easy (commitment) tracking system for seg- ments of ROWs that come under federal funding for purposes of compliance with E.O. 13112 at any given moment. The status needs to be easily accessible to maintenance personnel as projects close and landscap- ing and maintenance projects start and close. Getting the right information to the right people was a concern for some DOTs. As one noted, the problem is “[l]ack of communication, lack of training for contractors, and over- all lack of awareness in the organization, especially in that this is a serious issue.” Others lack good training materials or management guidelines. FIGURE 1 Drivers in addressing invasive species. FIGURE 2 Obstacles faced by departments of transportation.

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TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 363: Control of Invasive Species explores the extent to which state departments of transportation are identifying actions that affect the spread of invasive species, preventing introduction, tracking status and locations of “invasives” in a timely and ongoing manner, controlling found populations, restoring invaded habitats, conducting research, and sharing lessons learned. The report documents successful practices and lessons learned. It also synthesizes the state of the practice in developing Integrated (Roadside) Vegetation Management, along with physical, chemical, biological, and cultural control mechanisms.

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