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Chapter 9
Roadside Vegetation Management
9.3. Practices for Prevention of Roadside Infestations

The first-line of defense and the most cost-effective strategy against invasive species is preventing them from invading and becoming established in the first place. Once an infestation becomes well-established, management is expensive and eradication is difficult and unlikely. One of the most important components of prevention is the detection of individual plants or small groups of plants after seed germination. The second is eradication before they produce seed or develop an established root system. According to a 1995 survey, very few DOTs feel they have developed and implemented systems for prevention, detection, analysis, control, and management. [N] Eleven DOTs, just over a quarter of respondents, said they had mapped or were currently tracking/monitoring areas of infestation as part of efforts to prevent the spread of invasive species. [N] A similar number had developed policies and procedures to support control efforts and/or implemented integrated roadside vegetation management plans, statewide or by district. [N] Six DOTs (15% of respondents) said they are reviewing the ROW and treating annually for control of invasive species. [N]

Early Detection, as applied to invasive species, is a comprehensive, integrated system of active or passive surveillance to find and verify the identity of new invasive species as early after entry as possible, when eradication and control are still feasible and less costly. It may be targeted at areas where introductions are likely, such as near pathways of introduction, and sensitive ecosystems where impacts are likely to be great or invasion is likely to be rapid. [N] After invasive species become established, they often grow deeper root systems and may reproduce by rhizomes as well. Control after weeds have gone to seed may begin a long process, since many seeds are viable for years. Control of non-plant species requires equally attentive action, and may reach out to law enforcement, recreational users, and travelers, especially aquatic vehicles that may carry infested water from one location to another.

Focusing resources on preventing and detecting new invasions, to the extent possible, can be far more cost-effective than containing existing populations. As the National Invasive Species Action Plan notes, "[e]ven the best prevention efforts cannot stop all introductions. Early detection of incipient invasions and quick, coordinated responses are needed to eradicate or contain invasive species before they become too widespread and control becomes technically and/or financially impossible. Populations that are not addressed early may require costly ongoing control efforts."

The remainder of this section focuses on Early Detection and Rapid Response (EDRR), identification of aspects of operations that spread invasive species, roadside inventory, risk assessment, priority setting, and information management.


9.3.1 Assessment and Management
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Management of invasive alien species generally includes:

  • Initial assessment of the situation
  • A process of identifying the species of highest priority for a management program
  • Detailed information on methods for eradication, containment, control, and mitigation
  • An introduction to monitoring approaches
  • Identification of principal approaches to the project
  • Activities to secure resources
  • Stakeholder commitment and involvement
  • Training in control methods

The first step of a management program is to assess the current situation by determining the management goal, the extent and quality of the area being managed, the invasive target species affecting the area, and the native species threatened. The management goal should be the conservation or restoration of intact ecosystems that support the delivery of ecosystem services and cost-effective maintenance of the area. Eradication and control options need to be evaluated on the basis of the likelihood of success, cost-effectiveness, and any potential detrimental impacts.

Prioritization of invasive species control projects takes into consideration the extent of the area infested by the species, its impact, the ecological value of habitats invaded, the difficulty of control, and management costs. Species with the highest priority would be those known or suspected to be invasive but still in small numbers, species which can alter ecosystem processes, species that occur in areas of high conservation value, those imposing or with the potential to impose high costs on the DOT, and those that are likely to be controlled successfully.

Eradication, containment, and control are all approaches to management of populations of invasive species. When prevention measures have failed, an eradication program is considered to be the most effective action, because of the opportunity for complete rehabilitation of the site and long-term minimization of costs. Since eradication programs can be initially costly and require full commitment until completion, the feasibility of this approach requires careful consideration. Eradication has been achieved using mechanical, chemical and biological control, as well as habitat management. These methods are discussed in detail in Chapter 4: Construction Practices for Environmental Stewardship.


9.3.2 Identifying Major Pathways and Managing Risk
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The most common approach for prevention of invasive organisms is to target individual species. A comprehensive approach also targets major pathways that lead to harmful invasions and manages the risks associated with these. While some have argued that certain pathways, such as ship ballast water, have already been used for centuries, current attention to control is still important. Establishment rates can vary over time. For example, with faster transport times, some invasive species can establish in new environments more easily now. Climatic changes and changes in disturbance in the area of introduction (e.g., construction opening new areas of land or salinity and nutrient changes in bays) also affect an area's susceptibility.

Pathways for introduction of invasive species are both intentional and accidental introductions. Most plant and vertebrate species introductions have been intentional for various reasons, e.g. plants as ornamentals or for erosion control, mammals as game, birds for enjoyment, fish for sport fishing. In contrast, most invertebrates (including marine organisms) and microbe introductions have been accidental, often attached to other species introduced intentionally. Often agricultural weeds have been introduced as contaminants of crop seeds, whereas most of the environmental weeds were purposefully planted as ornamentals, for soil stabilization, or for firewood. Education is a key component of successful prevention and management methods. DOTs, weed management areas, and federal agencies have roles in informing the public why prevention measures are taken and what impact failure can cause. [N]

Identifying Aspects of DOT Operations that Promote Invasive

E.O. 13112 mandates a risk-based approach, including consideration of the likelihood that an invasive species will establish and spread, as well as the degree of harm it could cause. To do this, it helps to start with a master list of the DOT's work activities that may inadvertently promote the spread of invasive; a risk assessment identifies the most significant issues and helps decide where to focus. A few DOTs are identifying infestations on-site for treatment before ground disturbance, over multiple years if necessary. Increasingly, measures are being taken to conserve valuable topsoil, instead of having it collected and sold by contractors, leaving deficient soils more vulnerable to infestation by invasive species. DOTs are checking and treating permanent water control for West Nile Virus and considering inadvertent creation of such environments as part of current planning processes.

Identification of aspects of operations that may impact the environment is a step in development of a system to manage environmental impacts, often called an Environmental Management System (EMS). In an EMS, the transportation agency identifies environmental aspects of its activities, products, or services that it can control and over which it can be expected to have an influence, to determine those which have had or can have significant impacts on the environment. With respect to invasive species and other environmental impacts, the DOT can then prioritize pathways and controls according to significance, available funding, risk, or any other factors the DOT deems important.

While research has indicated that off-road vehicles are among the largest offenders in transport of seeds of invasive species, construction projects, transportation systems, spraying and mowing operations can inadvertently spread invasive as well. The following are just a few common mechanisms:

  • Use of forage mulches that have not been certified weed-seed free mulches and other erosion control products.
  • Planting of species now controlled as invasive for erosion control purposes, including aggressive sweet clovers, alfalfa, smooth brome, trefoil, and perennial rye.
  • Placement of spoil or importation of topsoil contaminated with invasive, such as ragweed, thistles, and sweet clovers.
  • Ill-timed maintenance disturbances like blading, mowing, ditch dredging, and bare-grounding, which have been known to increase invasive.
  • Indirect mechanisms such as drainage flows, wind, vehicles, people, and wildlife.
  • Movement of construction equipment from a weedy site to a non weedy site, which can transport undesirable seeds. [N]

DOT earthmoving, erosion control, water quality, wetland restoration, endangered species protection activities, landscaping, snow storage, utility line and signage placement, volunteers, recovery zone maintenance, and other maintenance and operations activities all affect invasive species and native habitats. Best management practices (BMPs) are used to reduce the introduction or spread of invasive species.

The spread of invasive species caused by sub-standard vegetation or revegetation and the transport of weed seeds by vehicles are particularly well documented. [N] An Australian study found that approximately half of cars were carrying seeds. [N] Exotic species cover and the number of exotic forb species decreased as distance from roads increased, particularly on certain soil types (non-serpentine soils in particular). [N]

Most DOTs (26 states, 65% of respondents) are not formally identifying aspects of activities that may impact/promote invasive species. Some DOTs said they are already "very cognizant of some of the detrimental activities and need to incorporate steps to minimize spread through BMPs." Nine DOTs (23% of respondents) are explicitly identifying aspects or risk areas. In Arizona and New York State DOTs, at the district level, engineers and supervisors are identifying activities such as mowing, blading and cut cleaning that promote or spread invasive species and devising BMPs to reduce these impacts.

DOT Example of Environmental Aspect/Risk Identification: NSW RTA Assessment of Construction, Operation, and Maintenance Activities

The New South Wales, Australia, Roads and Traffic Authority (RTA) undertakes environmental impact assessments for its construction, operation, and maintenance activities, in addition to project development. The RTA has committed to addressing environmental aspects in all of its activities and to continuously improving the authority's environmental performance. The RTA-wide environmental management system ( EMS) has been a primary vehicle for accomplishing this commitment. It "provides a structured management system to achieve and demonstrate our environmental performance." [N] The RTA prepares a Review of Environmental Factors to identify and consider environmental impacts, which may prompt development and/or implementation measures to address them.

Standard maintenance activities are assessed on a regular basis, usually annually. [N] Other maintenance activities are assessed in a similar way to construction activities. [N] For maintenance by contract, requirements for environmental impact assessment are to be incorporated in contract requirements and reviewed by the RTA. [N] RTA uses tables to summarize construction and maintenance activities and associated environmental aspects and impacts at the NSW RTA. Activities entailing ground disturbance or use of vehicles and equipment off the roadway have been particularly identified as potentially causing the spread of invasive species.

Risk Assessment

A risk assessment process assesses species based on their perceived risk and potential impact. The objective of assessment is to predict whether or not a species is likely to become established and be invasive and to generate a relative ranking of risk. Entire pathways may also be analyzed for risk. This may be a more efficient procedure where many possible species and vectors are involved. Though the lack of knowledge and ability to predict consequences may lead to substantial reliance on assumptions, risk assessment provides a logical process for gathering, analyzing, synthesizing, comparing and communicating information, which can improve the quality of decision-making. [N]

Processes for setting priorities often incorporate risk assessment. One such process is reviewed in the following section. Other risk assessment resources include:


9.3.3 Setting Priorities
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DOTs set priorities in the hope of minimizing the total, long-term workload, and hence cost of an operation, in terms of money, resources and opportunities. Therefore, invasive species control activities may be focused on prevention of new infestations and on existing infestations that are the fastest growing, most disruptive, and affect the most highly valued or costly to maintain areas. Also considered is the difficulty of achieving satisfactory control, giving higher priority to infestations the DOT thinks most amenable to control with available technology and resources. A detailed priority-setting system for weeds is presented in the Handbook for Ranking Exotic Plants for Management and Control. [N]

The priority-setting process can be difficult, due to the need to consider multiple factors. It may be helpful to group these factors into four categories, as a filter to identify the worst invasive. This process is recommended by the Global Invasive Species Program: [N]

  1. Current and potential extent of the species on or near the site. (primary consideration). Under this category, priorities are assigned to species in order to first, prevent the establishment of new invasive species, second, eliminate small, rapidly-growing infestations, third, prevent large infestations from expanding, and fourth, reduce or eliminate large infestations. To do this, assign priorities in the following sequence:
    • Species not yet on the site but which are present nearby. Pay special attention to species known to be pests elsewhere in the region.
    • Species present on the site as new populations or outliers of larger infestations, especially if they are expanding rapidly.
    • Species present on the site in large infestations that continue to expand.
    • Species present on the site in large infestations, which are not expanding.
  1. Current and potential impacts of the species. The order of priorities under this category is based on the management goals for your site, but the following order of consideration may be helpful:
    • Species that alter ecosystem processes such as fire frequency, sedimentation, nutrient cycling, or other ecosystem processes. These are species that "change the rules of the game", often altering conditions so radically that few native plants and animals can persist.
    • Species that kill, parasitize, hybridize or out-compete natives and dominate otherwise undisturbed native communities.
    • Species that do not out-compete dominant natives but: prevent or depress recruitment or regeneration of native species; or reduce or eliminate resources (e.g. food, cover, nesting sites) used by native animals; or promote populations of invasive non-native animals by providing them with resources otherwise unavailable in the area; or significantly increase seed distribution of non-native plants or enhance non-native plants in some other way.
    • Species that overtake and exclude natives following natural disturbances such as fires, floods, or hurricanes, thereby altering natural succession, or that hinder restoration of natural communities. In areas of repeated disturbances, DOTs may want to elevate the importance of this category.
  1. Value of the habitats/areas that the species infests or may infest. Priorities may be assigned in the following order:
    • Infestations that occur in the most highly valued habitats or areas - especially areas that contain rare or highly valued species or communities and areas that provide vital resources.
    • Infestations that occur in less highly valued areas. Areas already badly infested with other pests may be given low priority unless the species in question will make the situation significantly worse.
  1. Difficulty of control and establishing replacement species. Priorities may be assigned in the following order:
    • Species likely to be controlled or eradicated with available technology and resources and which desirable native species will replace with little further input.
    • Species likely to be controlled but will not be replaced by desirable natives without an active restoration program requiring substantial resources.
    • Species difficult to control with available technology and resources and/or whose control will likely result in substantial damage to other, desirable species and /or enhance other non-indigenous species.
    • Species unlikely to be controlled with available technology and resources.

Species can be ranked numerically (1, 2, 3…n) or by classifying invasive groups by worst, moderate, and minor. Invasive species whose populations are decreasing or those that colonize only disturbed areas and do not move into (relatively) undisturbed habitats or affect recovery from the disturbance can be assigned the lowest priorities.

Other tools and organizations are readily available to assist DOTs in prioritizing invasive species to target. NatureServe is an independent non-profit providing scientific information and technology, affiliated with the State Natural Heritage Programs (NHPs). NHPs are often located at state universities and provide support to other government agencies as well as The Nature Conservancy. NatureServe developed an Invasive Species Assessment Protocol, in cooperation with The Nature Conservancy and the National Park Service. The criteria develop Invasive Species Impact Ranks (I-Ranks) at the national and state level. Assessment criteria include: Ecological Impact, Current Distribution and Abundance, Trend in Distribution and Abundance, and Management Difficulty. Species ranked "high" present a severe threat to native species and ecological communities.

NatureServe plans to evaluate at the U.S. national level all of the estimated 3,500 non-native vascular plant species established outside cultivation in the U.S. using this new assessment methodology. That work is expected to assist land managers in prioritizing their work and to support decision making related to prevention, monitoring, management, research, and identifying conservation/preservation areas. FHWA and other federal agencies contributed to development of this system. Ultimately, the system will:

  • Allow management of data through the NHPs' network, using their software, Biotics and provide access to data through web site.
  • Link non-native species to Ecological Systems.
  • Develop more invasive species management information.
  • Encourage growth of Early Detection/Rapid Response pilot project.
  • Model potential sites for non-native invasions.
  • Identify invasions that are critical to regional biodiversity resources.

Most DOTs (26 states, 65% of respondents) are not formally identifying aspects of activities that may impact/promote invasive species. Some DOTs said they are already "very cognizant of some of the detrimental activities and need to incorporate steps to minimize spread through BMPs." Nine DOTs (23% of respondents) are explicitly identifying aspects or risk areas. In Arizona and New York State DOTs, at the district level, engineers and supervisors are identifying activities such as mowing, blading and cut cleaning that will promote or spread invasive species and devising BMPs to reduce these impacts.


9.3.4 Prevention
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Prevention involves attention to the most common vectors of transmission, including contaminated seed, mulch, or soils; movement of unlearned equipment or machinery from an invasive weed-contaminated area to a non-contaminated area; lack of restoration or revegetation after construction. Prevention depends upon limiting the introduction of new weeds through:

  • Minimizing the disturbance of desirable plants and soils.
  • Maintaining desired plant communities through good management.
  • Monitoring high-risk areas such as transportation corridors and bare ground.
  • Revegetating disturbed sites with desired plants.
  • Evaluating the effectiveness of prevention efforts and adapting plans for the following year.
  • Early detection and eradication of small patches of weeds through regulatory inventory and corrective action.

Early detection (ED) consists of identifying and documenting the newly introduced invasive weed species in an area. Then, rapid response (RR) may be employed to eradicate new infestations and methods may be taken to prevent movement to non-infested areas. Some prevention practices are presented in greater detail in the section of this document on Cultural Control Methods.

Early detection of incipient invasions and quick coordinated responses are needed to eradicate or contain invasive species before they become too widespread and control becomes technically and/or financially impossible. Populations that are not addressed early may require costly ongoing control efforts. For example, spotted knapweed (Centaurea biebersteinii) was introduced to Montana in the 1920s, and by 1988, had infested more than 4.7 million acres. The economic impact is approximately $42 million annually. [N]


9.3.5 Eradication
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Eradication is the elimination of the entire population of an alien species, including any resting stages, in the managed area. Efforts at eradication often follow failure to prevent introduction of invasive species on construction and other vulnerable sites. Eradication as a rapid response to an early detection of a non-indigenous species is often the key to a successful and cost-effective solution. Once invasive species have spread, eradication becomes much more difficult and costly, to the point of being infeasible in many circumstances. Feasibility should be assessed before attempting eradication. Successful eradication programs in the past have been based on:

  • Mechanical control, e.g. hand-picking of snails and hand-pulling of weeds. Plants are often best eradicated by a combination of mechanical and chemical treatment.
  • Chemical control, e.g. using toxic baits against vertebrates and spraying insecticides against insect pests.
  • Biopesticides, e.g. Bacillus thuringiensis (BT) sprayed against insect pests.
  • Sterile male releases, usually combined with chemical control.
  • Physical habitat management controls such as grazing and prescribed burning.
  • Hunting of invasive vertebrates.

If an eradication program is feasible, it is the preferred choice for action against an invasive non-indigenous species. Eradication has the advantage of long-term control, no long-term costs outside of follow up monitoring and prevention measures, and the opportunity for restoration of pre-invasion conditions. However, eradication requires adequate funding and commitment from the stakeholders involved. Well-established populations and large areas of infestation may be unsuitable for eradication programs and may have unintended side effects in addition to very high cost. For example, in the case of the attempt to eradicate South-American fire ants in southern states, the insecticide initially was ingested by wildlife and cattle. The ant bait subsequently developed also had non-target effects, and proved to be more effective against native ant species than the intruder, ultimately enhancing the populations of the non-indigenous species due to a decrease of interspecific competition with the native ant species. [N]

Eradication (or control) of well-established non-indigenous species, which have become a major element of the ecosystem, will influence the entire ecosystem. Predicting the consequences of the successful elimination of such species, including the synergistic effects, of the invasive species to indigenous and non-indigenous species can be difficult but such efforts are important for avoiding unexpected problems. Cases have been reported where one invasive species replaces another, following an effort to eradicate the primary target.

Successful eradication programs tend to involve:

  1. Small, geographically limited populations of non-indigenous species are easiest to eliminate. Thus, immediate eradication is the preferred option for most species found in early detection surveys. It is crucial that the early warning program has funds available for these actions.
  2. Eradication is considered feasible and adequate support from stakeholders must be present (this is easier to achieve on construction sites with existing contracts or on other land over which the DOT has control).
  3. Sufficient funding is secured for an intensive program (allowing for contingencies) to make sure that eradication can be pursued until the last individual is removed. Expectations must be realistic in terms of the processes required for successful eradication programs e.g. low visible returns for high investments late in the program.
  4. Immigration of the alien species is zero, something DOTs and contractors can help achieve through vehicle washing and weed-seed-free mulch requirements. Potential pathways for the species between infested areas and the management area must be controlled to prevent new invasions.
  5. All individuals of the population are susceptible to the eradication technique.
  6. Effective team management and motivation are present. Teamwork is required to achieve an eradication success, with a core of field and research expertise to maximize efficiency and help maintain administrative support.
  7. A technique to monitor the species at very low densities, at the end of the program, needs to be designed to ensure detection of the last survivors. Organisms that have less obvious stages, which can survive for long periods, e.g. seed banks of weeds, need a monitoring period to make sure that eradication has been achieved.
  8. Methods to minimize the chances of re-invasion and early detection of the eradicated species should it re-establish need to be in place.
  9. Development and use of field methods are usually an iterative process since implementation needs to be monitored and methods may need to be adapted as conditions change and eradication is approached.


9.3.6 Containment
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Containment of non-indigenous invasive species is a special form of control. The aim is to restrict the spread of an alien species and to contain the population in a defined geographical range. The methods used for containment are the same as those described for prevention, eradication and control. Containment programs also need to be designed with clearly defined goals: barriers beyond which the invasive species should not spread, habitats that are not to be colonized and invaded, etc. In order to establish these parameters, a clear understanding of why the containment is being done in the first place is necessary; e.g. to protect particular areas or habitats from invasion or to allow time to mobilize other control or eradication measures etc.

An important component of a containment program is the ability to rapidly detect new infestations of the invasive species both spreading from the margins of its distribution or in completely new areas, so that control measures can be implemented in as timely a manner as possible. These new infestations will initially be at very low densities so early detection can be challenging. The invasive species population is suppressed using a variety of methods along the border of the defined area of containment; individuals and colonies spreading beyond this are eradicated, and introductions into areas outside the defined containment area are prevented.

A species most likely to be successfully contained in a defined area is a species spreading slowly over short distances. The nearest suitable habitat for the species should be preferably separated by a natural barrier or an effective artificial barrier. The most suitable cases for containment are habitat islands without suitable connections that would allow the easy spread of invasive species. The spread of alien freshwater species between different parts of watersheds is a good example where containment may be possible.

If containment of an invasive species in a well-defined area is successful, habitats and native species are safeguarded against the impacts caused by the harmful alien species outside this area. In cases where eradication is not feasible and the range of the invasive species is restricted in a rather isolated area, containment of the species in that area can be highly effective, to save other parts even if the species is harmful in the containment area. Containing a species in a defined area will, however, need constant attention and control of the species at the border.

The chances for successful containment of invasive species are relatively good for species living in freshwater habitats, e.g. fish spread limited to specific water catchment areas, unless human activities such as artificial canals connect catchment areas and allow alien species to spread between systems.

A related but different approach is exclusion, which aims to protect a sensitive area against invasive species by fencing them out. This method often combines eradication, prevention and fencing techniques. An area of high conservation value is fenced with an animal-proof fence and if the invasive species occurs inside, it will be eradicated. This mainland-islands concept is very effective in supporting crucial populations of endangered species, if eradication of the invasive species within the containment is possible but eradication on a large-scale is not feasible. Again feasibility and potential unintended consequences of the solution need to be examined.

9.3.7 Early Detection and Rapid Response
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Early detection of non-indigenous species should be based on a system of regular surveys to find newly established species. Methods to detect species differ between taxonomic groups, and their success depends largely on how conspicuous species are. A drawback of general surveys is that only well-trained staff will be able to identify non-indigenous species in many taxonomic groups.

A 2005 survey found that thirteen DOTs (33% of respondents) had implemented rapid responses to discovered locations or patches of invasive species. [N] Subsets of these had developed Early Detection/Rapid Response programs. In Illinois and Maryland, District Landscape Architects notify the local Maintenance Yard, who responds as soon as they are able. State agriculture department staff also contacts the DOT when infestations are observed. Texas DOT utilizes rapid response statewide. Washington State DOT (WSDOT)'s EDRR efforts utilize an e-mail list of field staff. DOTs are more likely to employ early detection and rapid response for species that are new to the state, to eliminate and avoid new burgeoning problems (Nevada DOT, New Hampshire DOT, Oregon DOT). EDRR is also used when a big push is on, for elimination or reduction of priority species. For example, Mn/DOT is attempting to eradicate common reed (Phragmites australis) and Grecian foxglove (Digitalis lanata ) from the ROW; early detection and rapid response are employed to "hold the line" on weed spread into new counties or from gaining a foothold in new segments of highway. Caltrans and FHWA have partnered to address exploding populations of the Sahara Mustard plant in the Mojave and Sonora deserts, where highway corridors have been blamed for the weed's spread. FHWA was instrumental in gathering federal and state partners to work with Caltrans as part of a rapid response effort and in funding a workshop. Caltrans is inventorying the plant on the ROW, which will be used as a benchmark for subsequent control. [N]

Practices for Effective Early Detection Programs

A crucial part of early detection is a contingency plan, which determines the action to be taken when an alien species is been found. Given the diversity of potential new incursions, an initial plan will be rather general. It should summarize the stakeholders and experts who need to be contacted for a more detailed action plan. Contingency plans targeted at specific high-risk species can be very efficient, with an exact schedule for what to do. For a contingency plan to work, the equipment needed must be ready at the designated place and funding must be available for emergency eradication or control.

Rapid response is a systematic effort to eradicate, contain or control invasive species while the infestation is still localized. It may be implemented in response to new introductions or to isolated infestations of a previously established organism that is non-native to the ecosystem. Preliminary assessment and subsequent monitoring may be part of the response. It is based on a system and infrastructure organized in advance so that the response is rapid and efficient. [N]

Looking at models of EDRR from oil spills to fire to invasive species and diseases, some of the general features associated of effective EDRR programs are: [N]

  • Strong interest by localities or states in detection and response.
  • Federal leadership through means in addition to funding (science, training, logistics, and leadership itself).
  • Effective communication of ideas and data with stakeholders and partners.
  • Clear organization, authority and responsibility.
  • Exploitation of the most effective means of detection for the particular system.
  • Adequate funding.
  • Advance, detailed planning of response organization and arrangements.

Per research for the National Invasive Species Council (NISC) on effective EDRR programs, opportunities for substantial enhancement of passive, early detection should be exploited:

  • For each type of invasive species, explicit consideration should be given to advantages and opportunities for passive vs. active detection. Most detection of invasive species has been passive, and the approach can be cost-effective when multiple agencies, states, universities, private groups, and amateur biologists are involved.
  • Anyone who frequently goes into the field and has some knowledge of biology should be aware of the need for surveillance and enlisted to help. Publicly available, user-friendly databases support EDRR efforts. USGS's Invasive Species Research Center in Fort Collins, Colorado, working with several partners, has created a web-based early detection and rapid reporting database for use by volunteer groups trained to assist in identifying local invasive species. The database is publicly available to any agencies that wish to use the data and may help local mapping and response efforts.
  • Effective EDRR requires strong public awareness and involvement. Many agencies have public education programs that support EDRR efforts with cross training and volunteer programs. They have increased public curiosity and awareness of the environment. For example, BLM is collaborating with local Coordinated Weed Management Areas and the state of Wyoming to test the different elements of FICMNEW EDRR plan for invasive plant. The concepts of the FICMNEW EDRR plan have been integrated into all of BLM's actions with over 50 Coordinated Weed Management Areas in the western U.S.

The Invasive Plant Atlas of New England ( IPANE) developed "Invasive Alerts" is so that people can watch for additional incursions. Each alert contains information on the occurrence, when it was first observed and the potential threats from the invader. A regional map to show where these incursions are and photographs to facilitate identification are included. [N] IPANE's "Rapid Responders" database is used to establish teams of experts, once a new incursion has been reported.

On the other side of the country, the Invaders Database includes weed distribution records for five northwestern states, with maps, photos, and biological information updated regularly. Also, the Western Weed Coordinating Committee distribution maps of leafy spurge (Euphorbia esula) and yellow starthistle (Centaurea solstitialis) in the western U.S. indicate areas where early detection/rapid response may help land managers avoid widespread infestations.

Active Detection - Surveys, Data Collection, and Storage

Active detection may be most effective when targeted to sites near invasion pathways and to sensitive ecosystems. NISC compiled the following examples of successful EDRR practices among NISC cooperating agencies: [N]

  • As little may be known about certain new invasive species and the correct identification of specimens is critical, NOAA has developed a list of over 100 taxonomic experts who can identify specimens.
  • Monitoring high risk areas and knowing what is present before an invasive species arrived (baseline data) are essential to the early detection of new invasions. ANSTF members have instituted systematic monitoring programs for aquatic invasive species in San Francisco Bay, Puget Sound, the Lower Columbia River, Prince William Sound, Honolulu Harbor, Mobile Bay, Chesapeake Bay, and Massachusetts Bay. This is providing baseline surveys of aquatic organisms that occur in those systems as well as looking for new invasions.

Though DOTs more often depend on chance sightings for early detection of invasive species, experts recommend that early detection of non-indigenous species be based on a system of regular surveys to find newly established species. [N] In general, surveys for early detection are designated and targeted to answer specific questions quickly and economically, and give a "yes" or "no" answer. There are three general types of surveys to consider:

  • General surveys for large or conspicuous animals and plants may be conducted via a "looking survey." While doing other work, staff should be vigilant and continually aware of possible signs of new invaders. The public should be encouraged to report new sightings as well.
  • Site-specific surveys can be characterized as general surveys targeted at key sites, e.g. high value biodiversity areas and areas near high-risk entry points.
  • Species specific surveys. Where specific threats are identified and prioritized, species-specific surveys become possible. Frequency and timing of surveys is important. The potential range of newly arrived invaders needs to be considered along with the climate of the region. Survey methods for specific invasive plants will depend on how easy it is to recognize the target. If there are similar non-invasive and/or indigenous species present, then field guides, illustrations and training may be necessary.

Recommended practices for surveying include:

  • Recordkeeping of the species found, both native and introduced, and the action taken.
  • Collection and preservation of specimens. When local knowledge is not adequate to make an authoritative identification, material should be sent for specialist identification. Local and regional museums are a good starting point for advice on identification of invasive.
  • Storage of information in a database, in a standard format.

DOTs may want to establish and keep up-to-date a contact list for their specific state or region, including the names of both institutions and people, what types of invasive species they might be able to identify and the methods that should be used for the specimen collection. Records collected for NEPA evaluations should be collected in a standard format so that they form a baseline for further use by the DOT and/or other agencies. Information about incorporating volunteers into early detection and monitoring programs may be found on-line: The Early Detectives: How to Use Volunteers Against Invasive Species, Case Studies of Volunteer Early Detection Programs in the U.S. [N]

Effective Rapid Response

A crucial part of early detection is a contingency plan, which determines the action to be taken when an invasive species is been found. Given the diversity of potential new incursions, an initial plan is usually general in nature and notes the stakeholders and experts who need to be contacted for a more detailed action plan. Contingency plans targeted at specific high-risk species can be very efficient, with an exact schedule for what to do.

For a contingency plan to work, the needed labor and equipment must be available and accessible. Response cannot be rapid if elaborate steps are required between detection and actual attempts at containment or eradication. Thus the following recommendations were made out of a national examination rapid response approaches: [N]

  • The process for assessment and decision-making should be flexible and simple, and involve detailed agreements worked out carefully in advance. This allows partners to focus on the actual response rather than on negotiating in an atmosphere of confusion and ambiguity. Agreements may be numerous and involve many levels of a hierarchical system and multiple agencies. They specify what will be done by whom in any given situation, how leadership will be identified, how funding will be arranged, and what preparation will be undertaken. Agreements should be made at the lowest appropriate levels. [N] If flexibility in organizational structure is desired, this can be added after the preplanned organization is operating.
  • Identify an organizational structure for response in advance, but appoint individuals to positions as appropriate to the situation while organizing the response. In interagency responses, a system for assigning leaders of response organizations (Incident Commanders) should be identified through agreements made in advance. The Incident Command System should be adopted as a standard organizational model for rapid response, and considered also for long-term, interagency control projects.

Over a five year period, the Federal Interagency Committee for the Management of Noxious and Exotic Weeds (FICMNEW) developed a Conceptual Design for a National Early Detection and Rapid Response (EDRR) System for Invasive Plants, after deciding that EDRR is the most cost-effective and environmentally sound approach to addressing invasive species. The proposed National EDRR System for Invasive Plants is comprised of five elements: 1) Detection and Reporting, 2) Identification and Vouchering, 3) Rapid Assessment, 4) Planning, and 5) Rapid Response. [N] To facilitate these, the effort plans to develop/identify lists of target species, list-serves, and contacts for reporting, and develop generic (broadly applicable) rapid response protocols and action procedures for use by local, State, Tribal, and regional partners. These generic rapid response plans are to be provided on various invasive plant websites and publications. They plan to include basic protocols for detection and delimiting survey data to be collected during treatment efforts, and methods for post-treatment appraisal surveys. The initiative also plans to develop and provide technical expertise on rapid response methods and procedures, through development of a cadre of scientists and technical specialists to provide on-site and distant support on rapid response initiatives and developing, modifying, or adapting web-based, computer-assisted, decision support systems to aid land managers in identifying and developing management options and priorities for addressing new invasive plants. The effort also seeks to collaborate with State and national partners to develop, test, and implement post-response monitoring protocols and establish a mechanism for reporting post-management monitoring results and alert network if more action is needed (adaptive management feedback loop).

Areas in which scientific expertise is likely to be useful to states are: [N]

  • Identification and systematics
  • Techniques for surveillance, detection, monitoring, and related data analyses
  • Eradication/control technology
  • Biology/ecology with emphasis on risk assessments

These areas of expertise are needed in each taxonomic group or type of invasive species. NISC's research also found that the quality of detection and response activities may be enhanced by providing training and certification in detection and response. [N]

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Table of Contents
Chapter 9
Roadside Vegetation Management
9.0 Introduction
9.1 Inventory of and Management for Rare Species and Sensitive Resources in the ROW
9.2 Growing Threats Drive Expansion of DOT Invasive Species Practice
9.3 Practices for Prevention of Roadside Infestations
9.4 Statewide Inventory of Invasive or Noxious Species in the ROW and Update of Databases
9.5 Planning for Invasives Control
9.6 Roadside Vegetation Control Methods and Resources
9.7 Management of Visual Quality of the Roadside
9.8 Staffing, Training, & Partnerships
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