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3BACKGROUND AND ROLE OF TRANSPORTATION IN SPREAD AND CONTROL OF INVASIVE SPECIES The battle against invasive species and their impacts on the aesthetic and natural environments is requiring increasing time and resources from state departments of transportation (DOTs), other agencies, businesses, and individuals. Organ- isms that have been moved from their native habitat to a new location are typically referred to as ânon-native,â ânon- indigenous,â âexotic,â or âalienâ to the new environment. A small percentage of non-native organisms cause serious problems in their new environments and are collectively known as invasive species or âinvasives.â Most food crops and domesticated animals in the United States are non-natives, but not invasive. Many other non-native species are simply benign. However, invasive species and their costs to society are increasing at an alarming rate, stimulated by the rapid global expansion of trade, transport, and travel. In some cases, having arrived over many years, invasive species can require a long-term commitment to control. The means and routes by which invasive species are imported and introduced into new environments are called âpathways.â Some invasive species arrive as hitchhikers on commodities such as nursery stock. Others are stowaways in transport equipment or packing materials (1). Transportation corridors provide opportunities for the movement of invasive species through the landscape. Highways cross geologic bar- riers that previously prevented the spread of species, serving as avenues to transport invasive plants and animals, as well as cars and people. The transport of weed seeds by vehicles and the spread of invasive species caused by substandard vegetation or revegetation are particularly well documented (2). An Australian study found that approximately half of all cars studied were carrying seeds (3). Consequently, trans- portation corridors are a factor in the spread of invasives and the loss of natural habitat, the top two drivers of declining biodiversity. Where transportation corridors intersect waterways, these effects can rapidly spread to additional areas. Invasive plant or animal species can move on vehicles and in the loads they carry. Invasive plants can be moved from site to site during roadside maintenance operations. Weed seed can be inad- vertently introduced into a corridor during construction on equipment and through the use of mulch, imported soil, water, or gravel and sod. Some invasive plant species may be deliberately planted as part of erosion control, landscape, and wildflower projects. Although DOTs contend with and try to make headway against insects and other fauna, including fire ants and West Nile Virus, invasive plant challenges within vegetation control absorb most of the DOTsâ attention, time, and resources. Veg- etation management affects public health, our economies (especially agricultural), and natural environments. Top vege- tation management issues for DOTs in terms of investment are: â¢ Managing vegetation along the road edge, in drainage ditches, and other unpaved areas. â¢ Managing vegetation around safety devices and signs. â¢ Managing erosion on slopes. â¢ Maintaining highway plantings and desired vegetation (and avoiding or reducing undesirable vegetation such as invasive species). â¢ Managing vegetation in paved areas, such as pavement cracks. â¢ Maintaining shoulder backing integrity. â¢ Maintaining environmental quality, including reducing invasive species and promoting native communities. The scoping, planning, design, construction, operation, and maintenance of highways, facilities, and transportation corridors all play a key role in the management, or lack thereof, of invasive species. Over the last decade, and espe- cially in the last few years, considerations for the spread and control of priority invasive species have been incorporated into the activities of many DOTs on an ad hoc basis. Some regional initiatives have incorporated a systematic regimen to set management priorities, and identify, inventory, and control priority invasive plant species. Currently, DOTs are beginning to develop policies, procedures, and practices to consider and address, to the extent practicable, the impacts of invasive species in all aspects of scoping, planning, design, construction, operation, and maintenance for all projects and activities. The environmental stewardship commitments of state DOTs and Executive Order (E.O.) 13112, which directs all federal agencies to address invasive species concerns and refrain from actions likely to increase invasive species prob- lems, have prompted transportation agencies to extend their work in controlling invasive species. The threats posed by CHAPTER ONE INTRODUCTION
invasives and declining state budgets have made a synthesis of efficient and effective practices more urgent than ever before. SCOPE AND OBJECTIVES This synthesis focuses on the state of the practice of DOTs in managing invasive species and what has been learned by uni- versity researchers and managers of linear corridors, includ- ing the utility industry. In particular, this synthesis explores the extent to which DOTs are: â¢ Identifying actions that may affect the status of invasive species, â¢ Preventing the introduction of invasive species, â¢ Tracking status and locations of invasive species in a timely and ongoing manner, â¢ Controlling populations of invasive species, â¢ Restoring invaded habitats, and â¢ Conducting research and incorporating and sharing lessons learned. METHODOLOGY This synthesis was undertaken in cooperation with DOT roadside environmental managers, maintenance managers, environmental specialists, ecologists, agronomists, natural resources managers, and landscape architects across the country. Knowledge was gleaned from university utility inte- grated pest/vegetation management researchers as well. The synthesis reviews and summarizes the state of invasive species control practice, synthesizing and presenting further resources. Central to the research effort was a survey of DOTs from the 50 states, the District of Columbia, and Puerto Rico. Responses were received from 40 states, a 75% response rate. Contributions were also received from the 4 U.S. Forest Service. A list of respondents is provided in Appendix B. ORGANIZATION This introductory chapter presents the background of the problem, scope and objectives, and organization. Chapter two reviews the issue and definitions, federal and state policies and priorities, and state and regional methods for tackling invasive species control. Chapter three reviews prevention, early detection, and rapid response approaches; identifies aspects of operations and risks, statewide inventories, and information management; and provides a greater level of detail on planning for invasive species, including connecting inventories to plans and developing Integrated (Roadside) Vegetation Management (IRVM) plans. Chapter four details roadside invasive species control mechanisms, reviewing physical, chemical, biological, and cultural controls. The prevalence of DOT use of these methods, as discovered in the survey, is also included in this section, along with links to many DOT and other guides and resources for implementing the control methods discussed. Chapter five reviews DOTsâ organizational approaches, staffing, training, and partnerships for invasive species control. Obstacles, lessons learned, pub- lic outreach, and streamlining approaches are discussed as well. Chapter six includes the estimated benefits of invasive species control, gaps, and opportunity areas for greater effec- tiveness in invasive species control and conclusions. The following appendices are provided to assist DOTs in locating assistance on-line and among their peers. The survey distrib- uted to state DOTs (Appendix A); a list of responding agen- cies (Appendix B); sample New York State DOT invasive species inventory forms (Appendix C); an overview of com- mon IRVM or Integrated Vegetation Management (IVM) steps including costâbenefit information regarding invasive species control (Appendix D); and state DOT research related to invasive species control (Appendix E). A glossary of rele- vant terms is also provided.