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Chapter 9
Roadside Vegetation Management
9.4. Statewide Inventory of Invasive or Noxious Species in the ROW and Update of Databases

About a quarter of DOTs have undertaken a statewide inventory of at least one invasive species in the ROW; however, nearly a third of responding DOTs say they do not plan to implement a statewide survey in the future due to concerns about cost. The following DOT efforts stand out:

  • The Maryland State Highway Administration (MDSHA) tracks the location and quantities of certain invasive species on ROWs statewide. In particular, the agency is trying to achieve and document a 25 percent reduction in Canada thistle (Cirsium arvense) in the ROW, by 2008. Tree of heaven (Ailanthus altissima) has also been targeted.
  • Minnesota DOT (Mn/DOT) is working on a research initiative with the University of Minnesota to develop a statistically valid weed sampling system in order to determine weed extent and whether Mn/DOT is gaining or losing ground.
  • Montana (MDT) is completing a noxious weed inventory of all roadsides in 2005.
  • New York State (NYSDOT) has developed an extensive electronic inventory and with control information for the Adirondack Park Invasive Plant Program, which is then used in annual meetings with partners to evaluate and continuously improve treatment efforts, adjust plans, and ensure accountability, as necessary. Counties are increasing in sophistication as well; some NY counties are maintaining GIS data for tracking and controlling infestations of priority invasive.
  • Colorado and North Carolina DOTs have utilized GPS to map and track larger, problem sites.
  • Ohio DOT is exploring combining their endangered plant inventory program with an invasive plant inventory.
  • Washington State (WSDOT maintains area IVM plans, with treatments tracked in an associated database.

A number of states, including LADOTD, Mn/DOT, and NYSDOT, have been tracking and evaluating control of particular invasive over smaller areas (i.e., not statewide) sometimes using GPS units with sub-meter accuracy (MN). While statewide surveys have not been undertaken in Arizona, within the Maintenance division, the Arizona DOT has been utilizing the annual Level of Service surveys to map invasive species within rights of way. Maintenance staff use that information in management and work planning. Maintenance and construction staff take weed awareness training to identify invasive/noxious species and control them.


9.4.1 Inventory Approaches and Use
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State DOTs have performed inventories in a variety of ways, but by far the most common method has been inventory by local maintenance yards/districts. Temporary staff and universities have been hired, and DOT office technical staff helped in a number of cases. Alabama was the only state to have a university conduct the inventory statewide, though after attempting to perform an inventory through county weed coordinators, the Montana Department of Transportation (MDT) is working through the Montana State University (MSU) and the Agricultural College to hire temporary employees to conduct the inventory, with support from MSU staff. Washington State DOT involved counties, in that case, noxious weed boards. In almost all cases, updating of the database/GIS occurs through ongoing observation by maintenance staff.

Of those DOTs that have undertaken a survey, over two-thirds used Geographic Positioning Systems (GPS) and GIS. States using GPS to map stands of invasive species and invasive species include Iowa, Kansas, Maryland, Minnesota, New York, Oregon, Oklahoma, Missouri, New Mexico, Texas, Utah, and West Virginia; such GPS/GIS information can then be used to track treatment effectiveness. [N] Implementation of a mapping system is an element of the IRVM Plan for Mn/DOT Maintenance Area 3B. To accomplish this, CAD maps were obtained from Mn/DOT and plat books obtained from the county. The maps that were developed included established areas of noxious weed infestations, hazard trees, native seeding, and other important elements of the management plan. These maps are updated and assist in program planning, record keeping, and assessment. Paper-based map systems are widely being converted to Geographic Information Systems (GIS). NCHRP 20-5, 33-04 reported that Maryland and Utah have connected their IRVM plan to GIS and GPS. [N] Washington State (WSDOT) is utilizing ArcIMS (Information Management System) to track both species location and treatment effectiveness.

New York State DOT's Inventory Model

In addition to maintaining an electronic database of all priority invasive plant locations identified in association with Capital project development and delivery, NYSDOT strongly encourages all transportation Regions to initiate and manage an inventory of priority invasive plant species for the highway systems within their jurisdictional area. NYSDOT's directions identify four species of statewide priority to include as a starting point and common basis in any inventory. Additional consideration is recommended for region-wide priority species established through participation in Weed Management Areas, the Adirondack Park Invasive Plant Program, Watershed Management Plans or similar planning efforts. For prioritization purposes, the Regional inventories begin with the Interstate, Expressway and Parkway Systems, the primary introduction and dispersal conduits for invasive plant species. NYSDOT calls for a similar format and compatible databases for Regional inventories, with variability expected regarding the specific inventory methods and parameters included in the Regional inventory. The forms NYSDOT uses for data collection and monitoring are attached in appendix C. NYSDOT also has a sample database format available for sharing.

NYSDOT recommends establishment of a Regional Inventory Coordinator and a multi-discipline Regional Team. Although inventory information has been coordinated by the headquarters Environmental Analysis Bureau primarily through the Regional Maintenance Environmental Coordinators, design and construction staff are now collecting inventory information as well.

NYSDOT describes the following inventory methods in the agency's Environmental Procedure Manual: [N]

Sample Inventory Methods:

  1. Collect reference marker location information and complete the Inventory Data Collection Form for manual entry into GIS project; or
  2. In GPS "Mapping Mode" collect "Point" GPS coordinates from the center of the plant infestation and complete pre-programmed GPS data dictionary attribute information, or NYSDOT Inventory Data Collection Form, for each point; or
  3. In GPS "Mapping Mode" collect "Line" GPS "start" and "pause" coordinates for linear plant infestations or collect "Area or Polygon" coordinates for patches, complete pre-programmed GPS data dictionary or NYSDOT Inventory Data Collection Form thus allowing GIS to map and sum the inventory information.

Collecting information in this manner facilitates entry into a Regional Invasive Species GIS Project. Each Regional Maintenance Environmental Coordinator receives electronic copies of the NYSDOT Invasive Species Inventory database and copies of the NYSDOT Inventory Data Collection Forms attached in Appendix C of this document. This information can then be utilized during project development as a site screening tool and provided to maintenance staff for risk assessment and planning for necessary roadside maintenance activities or for implementing additional "pre-emptive" invasive species controls. As these regional databases develop, NYSDOT aims to track and monitor progress of control efforts at regional and statewide levels and contribute to larger statewide and region-wide inventory programs, e.g. Weed Management Areas, Adirondack Park Invasive Plant Program, Watershed Management Plans, etc.

Other Inventory Examples

Two other sample inventory methodologies that are currently in use in New York State are: 1. The Adirondack Park Invasive Plant Program (APIPP) Methodology ; and 2. The Nature Conservancy (TNC) Weed Information Management System (WIMS). The APIPP methodology has been implemented in portions of 12 Counties in Regions 1, 2 and 7 inside the 6.5 million acre Adirondack Park since 1999. NYSDOT's data forms are modeled closely after the APIPP forms. This inventory is conducted mutually by NYSDOT, TNC, APA and volunteers. The database is managed by the Adirondack Nature Conservancy with GIS products produced and distributed by NYSDOT. Information is collected through the use of mail-in post cards that provide the approximate location of suspected invasive plant infestations. These post cards have been distributed to NYSDOT maintenance staff and a network of volunteers. Cards are mailed to the Adirondack TNC and staff visit the site to confirm the post card information and enter the data onto a field data collection form, by reference marker (blank form attached), and then into the APIPP ACCESS database. This information is then sent to NYSDOT, entered by NYSDOT into the APIPP GIS system and species-specific location map are produced and distributed to APIPP partners and participants. The Invasive Plant Council of NYS has promoted use of The WIMS database generally adopted by TNC as their national standard.

How DOTs Are Using Collected Information

DOT roadside invasive species inventories are all used to identify and locate areas for treatment, invasion by new species, and to set priorities. DOTs also indicated that inventories are being used to:

  • Partner with other agencies in providing funding for control of specific species (CA).
  • Estimate expansion of weed presence (AL, MT), monitor treatment results and acres infested (AL, WA).
  • Guide and evaluate invasive species control efforts (CA, CO, FL, IN, MD).
  • Guide effort/budgeting to meet established goals (MD).

Just one state has determined the rate at which weeds are spreading: Alabama DOT estimated that the acreage of Cogongrass (Imperata cylindrical) is expanding at a rate of 20 percent per year within Alabama. Nevada DOT was able to estimate the accuracy of an inventory contracted out by the department, by checking it against maintenance spray logs from weed crews; the agency found the inventory was 25 percent different (75 percent accurate) by the time spraying was conducted. The agency attributed this to the accuracy of the study rather than the spread of weeds during the interim. Alabama DOT is also using their database to monitor treatment results.

Maryland SHA's inventories (each September from 2002 through 2004 for Phragmites and in December 2004 for Canada thistle, Cirsium arvense) are being used to chart current control efforts and to provide information on how much effort needs to be put into the program to meet targets.

Inventory/Mapping, Monitoring, and Analysis Resources

BLM, FS, FWS, and the Bureau of Indian Affairs (BIA) conduct inventory/mapping in coordination with county and state agencies. Other resources of inventory or mapping, monitoring, and analysis of invasive species include:

Remote sensing has played an increasingly important role in identifying large-scale weed infestations. Remote sensing provides information on the location, quantity and condition of land cover, which can be compared over time. The success of remote sensing as a monitoring tool largely depends on the instrument, the topography, size of infestation, timing, and the ability to distinguish target plants from the landscape. Three to five meter scale mapping and hyperspectral analysis is often necessary, during the flowering season, for detection of larger populations of invasive species. TxDOT has been able to identify large populations in this manner. [N]

Protection of Native and Rare Plant Communities in the ROW

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, New York, and Wisconsin are among the DOTs which have begun to preserve high quality roadside remnant native habitats, Karner blue butterfly habitat, and other sensitive habitat types. [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 (FWS), Bureau of Land Management (BLM), U.S. Forest Service (USDA-FS), Native Plant Societies, Department of Agriculture, knowledgeable individuals, and local 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 may occur.


9.4.2 Monitoring and Follow-Up
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Monitoring the numbers of a pest species killed or removed is a measure of the work being done but is not a measure of invasive species control. Success of an invasive species control project can be measured by monitoring numbers of the pest species that remain, and ultimately the condition of the ecosystem they are in. Removing an invasive alien species from an ecosystem will not automatically lead to the return of the indigenous flora and fauna. While this is often the case, removal of one alien species may simply open the way for colonization by another. Monitoring of the impact of control actions needs to be put in place, preferably starting with small-scale activities to verify the impact of control operations, and if the results are not as expected, the management plan may need to be reconsidered and adapted in light of this new knowledge.

In most cases successful eradication programs need to be accompanied by prevention measures against re-colonization by the removed species and early warning systems should be put in place to detect colonizers early. A new infestation of the successfully eradicated species can be wiped out swiftly when detected early by using the appropriate eradication method, because the knowledge of the negative impact of the invasive species and the experience in controlling the species is established and will be supported by those previously involved.


9.4.3 Information Management and Decision Support Systems in EDRR
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Effective systems of detection and response require ready access to data. For invasive species, these needs may be most efficiently served from a central system, or at least standardization of a designated system for each group of invasives. Needs that have been addressed in the National Invasive Species Council's (NISC) Invasive Species Management plan include: [N]

  • Database of existing and potential invasive species in the U.S. with current:
    • Geographic information
    • Identification details
    • Control information
  • Database of institutions and experts for identification and biology of invasive species in each taxonomic group.
  • Database of people and groups to contact in case of detection, depending on geographic location, type of invasive species, and potential threat (for use by a reporting point).

The National Invasive Species Council is charged with establishing a coordinated, up-to-date information-sharing system which emphasizes the use of the Internet for documenting, evaluating, and monitoring impacts from invasive species on the economy, the environment, and human and animal health. Although there are many sources of information concerning invasive species, incompatible database formats and other factors impede information sharing.

The Council is currently developing an information "gateway" accessible through the Council's webside- The Council plans to help develop a fully integrated Internet-based network system that will eventually support rapid and accurate discovery of data, the automatic correlation and synthesis of pertinent data from many sources, and provide a presentation of the results of data synthesis that meets the needs of users. The long-term goal is to provide accessible, accurate, referenced, up-to-date, comprehensive, and comprehensible information on invasive species that will be useful to local, State, tribal, and Federal managers, scientists, policy-makers, teachers, students, and others. To help ensure that stakeholder needs are met, the Council has formed a steering committee that includes State, tribal, Federal, and local governments, non-government organizations, the private sector, and other stakeholders. Some basic elements of this site are now in operation, and work is ongoing.

Weed Information Management System (WIMS)

The BLM developed the "WIMS" over 10 years ago and has since built upon the system in cooperation with others. BLM developed the database called "Boise-Vale" to capture inventory, monitoring, and control information for noxious and invasive weeds on BLM lands. BLM still uses the model of "Boise-Vale" but has developed a national web-based and spatial database for the BLM to which all offices will convert once it is completed. BLM's database now incorporates information about all invasive species on BLM managed lands, but its primary purpose is to collect weed data. Since the database is considered public domain, TNC has taken the database and improved its components. The database on which TNC, BLM, FWS National Refuge System, USGS National Institute of Invasive Species Science, Oregon, and the California Department of Food & Agriculture collaborated is available for free and may be used to track invasive species occurrence data, current status, and treatment information.

As currently maintained by TNC, the Weed Information Management System (WIMS) is a Microsoft Access-based relational database application that is designed to assist natural resource managers in managing their weed data. It can be used as a stand-alone database application that resides on a laptop or desktop computer, or can be used in combination with a handheld unit to collect field data. WIMS keeps track of three types of data records: weed occurrences (GPS point locations), assessments (size and status of the weed infestation to facilitate monitoring over time), and management treatments applied to those weed infestations. Data can be easily exchanged between multiple users, exported in NAWMA (North American Weed Management Association) standards, and written to shapefiles for mapping in any standard GIS program. A variety of reports can also be easily generated.

Field data collected with handheld electronic data recorders can be easily downloaded into the database. WIMS can be used on a handheld unit (either MS Windows-based Pocket PC or Trimble) with a GPS unit to capture data in the field. When using WIMS on a handheld unit with an ArcPad interface, a site manager can use background imagery and other GIS layers for mapping weeds, then upload the new data into the database automatically.

A more detailed look describing WIMS capabilities is available on-line, along with a PowerPoint presentation that demonstrates how WIMS is organized and how WIMS can be tailored to organization-specific efforts. A user manual on how to enter data in WIMS and use it is available on-line, as are WIMS Installation & Downloadable Files to run the software. [N] Reviews of hardware tools useful for those working in invasive species management are also available on-line at TNC's site, tool reviews.

Utah DOT's RoadVeg GIS system

UDOT's vegetation management professionals use ROADVEG, a geographic information system to inventory invasive plants along with other transportation-related data. UDOT staff can track the spread of invasive plant species, monitor the progress of mitigation strategies, and query and display various vegetational attributes as needed. To date, about 1,360 linear miles of Utah roadways have been field-assessed and scored. As funding becomes available, the remainder of the state's major roadways will be inventoried. Utah State University assisted in the road and county land inventory process.

PennDOT Roadside Spray Application (RoSA)

PennDOT has developed a Roadside Spray Application (RoSA) system, a web-based GIS application developed with Microsoft's .NET. RoSA assists PennDOT District Roadside Spray Specialists with collecting, storing, and reviewing herbicide spray activity along state highways. The output data from this application will serve as a status report for the districts, state, and outside agencies (e.g. Department of Agriculture, EPA). The system was developed to relieve District Roadside Specialists from having to tally results and sums and develop summary spraying reports, by hand. System users include PennDOT central office and districts, counties, and outside contractors. The system allows PennDOT's statewide roadside manager to oversee all roadside activities more effectively, including cost and production figures.

According to PennDOT's vegetation manager, "RoSA is taking the department's spray information from the file cabinet to the 21st century of GIS mapping and database reporting…The development of RoSA has been an exciting and worthwhile experience which will allow our local maintenance operations to inquiry and map spray information in minutes from their computers." Users input data on the location of the spraying, the type and amount of chemicals used, the contract and date, weather conditions, the applicator of the spray mixture, and material and resource costs. The system enables map views of new and historical spray data, and easier data collection, storage, and retrieval. Counties and districts are also using the system to reorder chemicals based on usage figures.

RoSA on the web
RoSA on the web

Caltrans GIS for Locating Appropriate Plant Species

Caltrans is developing a GIS to help employees quickly access lists of plant species for revegetation that are both ecologically appropriate for the project site and potentially useful in minimizing erosion from roadcuts and roadsides. The GIS uses hydrologic units of CALWATER at 1:24,000 as a means to link physiographic and climatalogical data together with presence or absence of selected plant species in each hydrologic unit. Plant climate classifications are being refined using elevation contours and topographic aspects derived from digital elevation models to allow assignment of different plant climates to portions of hydrologic units that exhibit steep elevational gains or considerable landform diversity. Through the overlay of other data depicting county boundaries, roads, and places, users are able to locate project sites, query the plant species climate matrix, and export data tables to spreadsheets or reports. Guidebooks that index the same plant species climate matrix through a standard route+county+mile/km georeferencing system make these data available to district personnel in an alternate format as well. [N]

Caltrans is also developing a ROW inventory system, which will include all resources in the ROW, "from stop signs to salamanders." One foot resolution aerial photography will allow prediction of species most likely to be there. Caltrans and UC-Davis plan to perform resource and land use modeling to generate a variety of useful information, from the viability of wildlife crossings to the presence of different natural communities. [N]

NYSDOT's Plant Database

NYSDOT's plant database is updated annually with occurrences mapped in GIS for four base species and additional ones in some Regions. Detailed information on more species is collected by volunteers and partners within the Adirondack Park. Sites are prioritized for management and updated manually. A field coordinator performs quality control for the system. NYSDOT is incorporating invasive species inventory with NPDES outfall mapping, herbicide recertification and application, and other ongoing departmental activities. Information collection forms for the database are included in the Appendix resources in Chapter 11.


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Continue to Section 9.5 »
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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