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Chapter 9
Roadside Vegetation Management
9.1. Inventory of and Management for Rare Species and Sensitive Resources in the ROW

Maintenance and construction crews are making increasing use of environmental GIS data at DOTs. DOT staff in construction and maintenance already use GIS layers depicting topography (including Digital Elevation Model, Digital Line Graph, and other topographic layers), hydrology (Streams, Lakes, Wetlands), and Geology (Bedrock Geology, Soils, Land Use, Karst Aerial Photographs). [N] Inventories of species in the ROW are now being used to support Integrated Roadside Vegetation Management (IRVM) planning as well.

A number of states are beginning to identify rare plant species in the ROW and tailor ROW management to encourage native species. California, Colorado, Delaware, Iowa, Missouri, Minnesota, and Wisconsin are among the DOTs which have begun to preserve high quality roadside remnant habitats. [N] These initiatives typically have several common elements:

  • Mapped information is combined from multiple agencies. Typically, the primary mapped data on known plant locations of rare species is obtained from the state Natural Heritage Program. Other potential contributing agencies may include the state DNR or Forest agency, U.S. Fish and Wildlife Service, Bureau of Land Management, U.S. Forest Service, Native Plant Societies, Department of Agriculture, knowledgeable individuals, and counties.
  • Upon completion of the initial data compilation phase, field surveys are conducted in some cases.
  • Special Management Areas are set up with particular management practices.
  • Maintenance forces are educated regarding the special maintenance needs of and expectations in these areas.
  • Tracking of species condition and progress, in some cases.

Caltrans Biological Management Areas

Caltrans began a plant community preservation program in 1994. Working with conservation groups, they identified more than 20 quality natural heritage remnants on highway ROW. Each Biological Management Area is signed and has its own management plan.

Colorado DOT Maintenance Specs and Training for Management of Rare Species in the ROW

Roadside resource management is an important aspect of the Colorado Department of Transportation (CDOT)'s Shortgrass Prairie Initiative, a programmatic consultation and proactive avoidance, minimization, and mitigation effort covering 36 listed and non-listed species and associated habitats that could be impacted by CDOT's maintenance and construction activities on Colorado's eastern plains over the next 20 years. As part of the agreement, the U.S. Fish and Wildlife Service (USFWS), the State Division of Wildlife, and CDOT negotiated best management practices to be employed in the right-of-way (ROW) and developed geographic information systems (GIS) and hard copy resources/maps that can be used by regional environmental and maintenance staff. Field training is being developed as well.

Management practices were recommended as follows: [N]

  • If target plant(s) are present, mowing will be avoided until late in the season (mid-September) if possible.
  • Re-seeding of disturbed areas will be with a mix of native graminoids and forbs wherever possible. Native mixes should be specified and/or approved by the CDOT landscape architect.
  • Herbicide applications will be used only if the herbicide targets monocots but not dicots. If monocot targeted herbicides are used, timing of application is not an issue.
  • Where road widening results in alteration of the hydrologic regime, efforts will be made to ensure that water flow is not interrupted.
  • Habitat destruction for species and decimation of the original seed source population will be avoided to the maximum extent practicable during construction/widening.

Right-of-way management practices are designed with multiple, and sometimes conflicting, species needs in mind, and with attention to the maintenance and enhancement of ecosystem processes. This builds upon CDOT's ongoing efforts to map patches of invasive, noxious weeds and sensitive areas in the ROW via geographic positioning systems (GPS), and selectively manage plant species to promote natives. The effort has been extended statewide and will incorporate management prescriptions and proscriptions.

North Carolina Rare Species Management

The North Carolina Department of Transportation (NCDOT) has been protecting roadside populations of rare plants since 1989, focusing on over 90 sites with federally listed species and a number of other sites with state listed species. NCDOT's initial efforts emphasized marking these rare plant populations in order to prevent them from being mowed. NCDOT signed a Memorandum of Understanding (MOU) with the NC Department of Environment and Natural Resources in 1990 that committed NCDOT to protect populations of threatened and endangered species that occur on NCDOT ROW, and a MOU with the NC Department of Agriculture in 1996, agreeing to work cooperatively on a variety of plant conservation issues, including protecting roadside populations of federal and state-listed endangered and threatened species. For simplicity, NCDOT has established some general statewide management guidelines for areas marked for rare species as noted in the Appendix.

Oregon DOT Special Management Areas for Rare Plants

In 1994, the Oregon Department of Transportation introduced a voluntary Special Management Area (SMA) program designed to protect threatened and endangered (T&E) plant species occurring on its lands, drawing on information from the Oregon Natural Heritage Program and multiple agencies, individuals, and counties. The system helps ODOT apply the appropriate levels of protection within SMAs, and enables ODOT to maintain or increase population numbers and assist long-term conservation of these resources on public lands.

SMAs have special signs and activities are restricted. SMA signs installed at the edge of buffer areas for sensitive species are coded so maintenance forces understand which activities are and are not allowed. Maintenance personnel carry a "decoder card" that allows them to decipher the code on the sign. The code provides information that tells what type of maintenance activity is allowed (such as ditch cleaning, mowing, spraying, etc.) and when it is allowed (season). ODOT also developed an educational video and implemented training that was presented to ODOT maintenance crews and sign installation was initiated.

Figure 1: ODOT Special Management Area Maintenance Sign
ODOT Special Management sign
Click for a full-sized version

Field Signing has the benefit of giving ODOT maintenance crews information on correct management requirements for each SMA, defining the field limits of the SMAs, provides a clear optical reference so inappropriate management is not applied, and establishes continuity around the state. All SMAs in the state follow the same signing format, leading to less confusion and fewer impacts.

Thus far, 40 SMAs have been established for 14 different threatened and endangered plant species in 15 ODOT Maintenance Districts. Proactive late fall mowing has benefited two Willamette Valley species. The ODOT model is being adopted by Oregon counties and WSDOT, to manage rare species. Currently the SMA program is focused almost exclusively on flora (plants), however, other disciplines such as wetlands, fisheries, and possibly archaeology may benefit from the use of Special Management Area Signage. ODOT has noted that long-term departmental commitment and a good working relationship between Environmental Services, district maintenance crews, and state and federal regulators have been essential components in the effort's success in protecting and enhancing populations of rare plants.

Oregon DOT GIS-Based Sensitive Resource Inventory

The Oregon Department of Transportation (ODOT) has developed a geographic information system (GIS)-based inventory of sensitive resources and erosion control problem areas along nearly 6,000 miles of state highway as part of its Salmon Resources and Sensitive Area Mapping Project. The primary purpose of the project is to provide accurate resource protection maps to roadway maintenance crews so that mowing, pesticide application, and other activities do not harm listed salmon species and other sensitive resources and so that streams and banks in poor condition might begin to be addressed.

The comprehensive resource inventory was developed by using color infrared digital imagery with 2-foot resolution. Other sensitive resource features were recorded from current knowledge bases and limited roadside surveying, and from modeling of interactions between multiple resources and data layers. After distance to water, stream and bank characteristics, known threatened and endangered species locations and the overall condition of the salmon and trout habitats were identified. ODOT compared the imagery to previous data collected from other sources, such as wetland information from the National Wetland Inventory and hydrographic data from the U.S. Geological Survey to update and validate these findings.

GIS maps were tied into ODOT's linear referencing system, which enables ODOT to identify the locations of sensitive natural resources features within a hundredth of a mile. [N] From this GIS resource, ODOT's Transportation Inventory and Mapping Unit and the Information Systems Branch developed a series of detailed resource maps in 0.01-mile segments, which indicate where sensitive resources are present including which side of the road. Based on the potential for environmental harm, certain restrictions were developed for each mile of highway. This information was then placed on restricted activity zone maps. These maps were designed to alert ODOT staff to specific locations of sensitive natural resource features in order to avoid inadvertently harming wildlife or wetlands when performing routine maintenance practices, such as slope maintenance, snow removal, and vegetation management. They also served to help minimize the potential for violations of the Federal Endangered Species Act and the Clean Water Act. ODOT supplied these maps to all districts, for use by biologists, planners, and maintenance managers. Laminated Restricted Activity Zone Maps for maintenance use a simple color-coding scheme of green and red to indicate, for each major class of maintenance activity (e.g., surface and shoulder work, vegetation management, snow and ice removal, etc.), whether or not that activity should be restricted along the left or right side of a given 0.01-mile segment of highway.

For approximately the same cost as field surveys, ODOT produced better quality data that was less subject to individual interpretation, and covered over a much larger analysis area - 1,000 feet from the roadway centerline, without concern for access/trespass issues. By using remote sensing techniques to collect and map data, ODOT recognized significant savings, both in cost and time. Before turning to advanced imaging technology to help implement this project, ODOT had been sending three two-person crews into the field for three and a half months to physically capture data. Once the digital imagery provided a base map to work from, the field crews were able to focus their energies on data validation instead of data capture. It also reduced the amount of time and resources needed to one two-person crew for two months, allowing for a quicker solution to the increasing problem of deteriorating wildlife habitats. Had ODOT chosen not to use digital imagery to map these sensitive areas, the results may have been significantly less accurate and outdated within a short period of time. In fact, some natural features may not have been inventoried at all as they would have been inaccessible to the field crews or too expensive to map across the entire state. The methodology developed by this project is easily adaptable for other state projects.

The library of geographic information system (GIS) data resulting from the project has given ODOT's regional staff a detailed environmental inventory of ecological resources, facilitating consideration of sensitive natural resource features when planning and designing transportation system improvements. The maps have proven to be a reliable, desktop scoping tool. The GIS system, data layers, and existing modeling routines facilitate easy updating as new information and aerial photography becomes available. ODOT is now developing an internet-based application to enable wider desktop access to the information. Because the inventory data is digital and easily transferable between agencies, ODOT can also easily share this data and streamline communication processes with the National Marine Fisheries Service, the Oregon Department of Fish and Wildlife, the USFWS, and the U.S. Army Corps of Engineers. ODOT's Resource and Restricted Activity Zone Maps were also key to negotiation of programmatic consultation for maintenance operation activities with the National Marine Fisheries Service (now NOAA Fisheries), under the federal Endangered Species Act (ESA). Specifically, ODOT received an exemption under 4(d) of the ESA allowing crews to perform routine road maintenance without having to consult with NOAA Fisheries on individual actions. ODOT is also exploring real-time geographic positioning system (GPS) connection to maintenance vehicles, as well as herbicide application spray booms to automatically activate and deactivate applicators as needed to avoid impacting sensitive resources including streams, wetlands, or rare plant populations.

Washington State Threat-Specific Rare Plant Management

During June and July of 1998 WSDOT conducted an extensive survey within 200 feet of US Highway 2 for its length of Tumwater Canyon. Biologists/botanists from WSDOT, the Washington Department of Natural Resources' Natural Heritage Program (WDNR-NHP), and the U.S. Forest Service participated. This survey disclosed the presence of three rare plants; one of which is proposed for federal listing as endangered and the others listed as state threatened and sensitive plants. An ortho photo with GPS points of rare plant locations was prepared and a GIS map, of much larger scale showing these same points, was prepared for the WSDOT Maintenance Office in Leavenworth and the Leavenworth Ranger District.

Actual/potential threats to rare plants were identified, highlighting ones over which WSDOT had control or influence. From that list, appropriate management practices were identified.

  1. Competition and shading from native trees and shrubs
  2. Competition from nonnative and/or state-listed noxious plant species
  3. Wildfire and fire suppression
  4. Activities associated with fire suppression
  5. Plant succession in the absence of fire
  6. Low seedling establishment
  7. Roadside vegetation control by applying herbicides
  8. Spreading of roadway anti-icers/deicers during winter months
  9. Mass-wasting and soil erosion on unstable slopes
  10. Motor vehicle exhaust emissions
  11. Human trampling and collecting
  12. Poor seed development
  13. Low reproductive capacity

WSDOT determined the agency had the most to contribute in minimizing threats 1, 2, 7, 8, 9, which are covered below in the next sections. [N]

Minimizing competition and shading from native trees and shrubs

Rare plants can be threatened by competition and shading from native trees and shrubs. In some instances, the removal of hazard trees can help protect rare plants. At the same time, tree removal can impact rare plants if not done correctly.

WSDOT maintenance implements the following stewardship practices to reduce undesirable shading:

  • Identify areas where trimming or removal of trees is desirable for maintenance.
  • Contact the land manager (USFS) or regulatory oversight agency and come to agreement on the best approach, meeting on-site if needed.
  • Employ identified BMPs.

Minimizing competition from non-native and/or state-listed noxious plant species

Nonnative and/or state-listed noxious plant species threaten rare plants by competition. Applying herbicides to weeds while performing roadside vegetation control can help protect rare plants. To this end, maintenance in areas with rare or endangered species involves the following stewardship practices at WSDOT:

  • Inform the land manager/regulatory agency of spraying dates. Agree on best approach. Meet on site as needed. The land manager, in this case USFS, is responsible for weed control in immediately adjacent areas.
  • Identify road segments where rare plants are absent and spraying can be conducted.
  • Utilize selective control and hand application of herbicide when near rare plants.
  • Employ BMPs for water quality, habitat, and worker protection.

Minimizing impacts to rare plants during work on ditches

To avoid adversely affecting rare plants near the highway while working on ditches, WSDOT maintenance forces employ the following stewardship practices in the vicinity of identified populations:

  • Check the known locations of all rare plants.
  • If rare plants occur within 2 m (6.6 ft) of the ditch and plant disturbance cannot be avoided, consult the land management/regulatory agency in advance. If another agency manages the area (such as the USFS), maintenance forces can identify work locations and ask the land manager to mark any individual rare plants on the day work will be done.
  • Perform the maintenance and repair in accordance with agency procedures and stewardship practices for Water Quality and Habitat Protection.
  • Remove all location markings from plants in the field.

Minimizing threats to rare plants from soil erosion on unstable slopes

To minimize rare plants being threatened by soil erosion on unstable slopes within the highway easement, WSDOT maintenance forces have committed to do the following for identified target populations:

  • Check to determine if rare plants are known to exist in the unstable area.
  • If within the area, mark all individual plants on the day work will be done.
  • If the plant disturbance cannot be avoided, consult the land manager or regulatory agency.
  • Perform the maintenance and repair in accordance with standard and agency best management practices.
  • Remove all location markings from plants in the field.

Permanent solutions to chronically unstable slopes are undertaken by WSDOT's Unstable Slope Program. In those cases, construction forces:

  • Identify the areas with chronically unstable slopes.
  • Consult with technicians from the Unstable Slope Program.
  • Check to determine if rare plants are known to exist for each of the chronically unstable areas.
  • If safety measures such as "scaling," "bolting," "netting," "trim blasting," "doweling," "fencing," and/or "rock buttressing" will be performed, consult the land manager and/or the regulatory agency for concurrence.
  • If possible to revegetate the exposed areas, confer with the land manager or regulatory agency about using local rare plants or suitable noninvasive native plants.

Minimizing threats from human intrusion, trampling, and unauthorized collection

Rare plants that are threatened by human intrusion, trampling and unauthorized collection will require a conscious effort, on the part of land managers and the DOT to watch for such action or implement a monitoring program. If it is determined that such threats occur, both agencies will confer with one another to establish a contingency plan for minimizing the threat. Actions the DOT can take may include blocking newly constructed maintenance pullouts during flowering of rare plants or other measures if parking and public access become significant issues.

Annual training sessions will be conducted to assure that rare native plants receive the attention required for their protection and sustainability. Field staff from both Design/Construction and Maintenance Divisions will receive training that includes discussion of the importance of the rare plants in their associated ecosystems, their natural history, and the roles each agency has agreed to play in the planned rare plant management strategies. Training should include a field review to point out individual rare plants, their specific locations, and advice as to what can and cannot be done to them. Such training should be conducted annually.

Identifying new locations of rare plant species

If new or additional rare plants are found, their type (common or scientific name) and specific location should be reported to DOT biologists, land management or regulatory agency biologists, and/or the state Natural Heritage Program, depending on the state DOT's process for confirmation of plant identification. If confirmed, and depending on the location, it may be recorded as a new sighting and subsequently logged via GPS into the appropriate GIS database. The relevant state or federal agencies should be notified of the find and its location.

TxDOT Rare Plant Management Partnership

One of the major public landholders in Texas, a state with less than 10 percent public land, is the Department of Transportation (TxDOT). TxDOT manages over 750,000 acres of highway right-of-way. [N] A 1989 survey of the Texas Biological Conservation Database revealed 150 occurrences of listed or category plants on or within the immediate vicinity of highway right-of-way. To assure protection for these species, a project was undertaken between 1990 and 1994 to identify listed and non-listed rare plants occurring on highway right-of-way, collaboratively develop management agreements to protect these species, and establish monitoring plans to assess the effectiveness of the management. Of the 150 potential sites identified in the Conservation Database as possibly occurring on highway right-of-way, 57 were relocated, 15 were either not found or not found to be on highway right-of-way, and 88 were still being verified as of 1995. The management effort for species in the ROW led to establishment of 26 management/ monitoring areas; monitoring/management agreements were maintained between TxDOT and the Texas Parks and Wildlife Department until the program ran out of money several years later. A total of 33 populations representing 26 species were monitored while the program was in effect, and data collected in that period indicated that about two-thirds of the species' populations increased or remained stable under the agreed upon management regimes. Decreases were usually assignable to drought, but occasional abnormal habitat disturbances such as fiber optic cable placement contributed as well. However no decreases in either population numbers or vigor were attributable to TxDOT management. TxDOT placed "No Mow" or "Wildflower Research Area" signs were placed around some rare plant populations. In a few areas reflector posts cordoned off populations, to help keep mowers out.

Wisconsin DOT Characterization of the Karner Blue Butterfly Habitat in the ROW

As part of Wisconsin's Statewide Habitat Conservation Plan (HCP) for the Karner blue butterfly, the Wisconsin Department of Transportation (WisDOT) conducted an initial inventory of high potential corridors for the presence of lupine along state highway ROW, using soil types as a simple key indicator. Management for the Karner blue butterfly also benefits a number of other state-listed species and federal species of concern, including plants, turtles, lizards, and other butterflies.

WisDOT's primary strategy for maintaining butterfly habitat is to manage ROW to provide for corridors of dispersal between larger butterfly population centers via habitat in the ROW along corridors controlled by DOT. USFWS and Wisconsin DNR see the corridors as important in creating connectivity, short-term refuge areas, and dispersal corridors. This strategy includes the following measures for areas with high potential for presence of the Karner blue butterfly (KBB), as determined by soil type: 1) selective mowing that avoids the growing season except immediately adjacent to travel lanes, 2) lupine seeding after construction projects in appropriate soils and locations, 3) removal of brush and trees during the non-growing season to assure continued lupine habitat (2-5 year basis for mowing), 4) mitigation for permanent take or removal, 5) monitoring KBB/lupine populations through annual surveys, and 6) public education WisDOT corridors meeting the following criteria were included in the agreement: 1) those within high potential range of KBB, typically upland sandy soil areas in central and northwestern Wisconsin, 2) corridors that already contain significant wild lupine populations or KBB, and 3) those close to, or connected with other KBB HCP lands that have potential for similar management.

WisDOT also implemented an internal education and training program for maintenance crews and other appropriate field personnel regarding KBB and lupine identification. Herbicide use is limited to spot applications for invasive weeds and cut stumps. WisDOT shares roadside management techniques and information with counties and towns upon request.

The overall Habitat Conservation Plan brought together 26 partners, including eight counties, the WisDNR, and WisDOT. WisDOT undertook a species and habitat conservation agreement with the state DNR, which, in turn, has a statewide HCP and Incidental Take Permit with the USFWS. The implementation agreement covers approximately 4,000 acres for 10 years.

Canadian Practices for Vegetation Preservation from Winter Maintenance

The Transportation Association of Canada makes the following suggestions for protection of sensitive plants in the ROW from winter maintenance practices: [N]

  • In urban areas protect newly planted conifers by erecting burlap screens during the winter months;
  • In urban areas consider applying anti-desiccants and anti-transpirants to the tender shoots of sensitive plants;
  • Sweep salt laden grit from turf areas as soon as possible in the spring;
  • Shield natural areas from salt spray by planting buffers of salt tolerant species; and
  • Where feasible and cost-effective consider using snow fences (living or structural) to reduce snow accumulation on roadways or to trap salt spray and prevent it from traveling far from the roadway.

Winter maintenance practices are discussed in greater detail in Chapter 8 of this Compendium.

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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
Lists: Examples | Tables | Figures
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