Highway corridors crisscross the nation. The rights-of-way (ROW) that border the highway pavement total over 12 million acres of land neighboring parkland, farmland, natural areas, etc. ROW management affects adjacent lands. Invasive plants do not respect political boundaries or fencelines. Care for these acres is complicated by many uses: 1. recovery zone for errant vehicles, 2. utility lines, 3. snow storage/living snowfence, 4. open space, 5. wetland mitigation, 6. wildlife habitat/corridors, 7. esthetic greenways, 8.signage, and 9. refuge of biodiversity.
The roadside is a highly disturbed landscape, beginning with the highway's original construction. It continues to be disturbed with upgrades, mowing, spraying, snowplowing, grading/blading, dredging, signage, utility and fiber optic lines, and errant vehicles. How do plants react to these disturbances? Wherever bare soil results, nature's tendency is to repair itself. The first plants to occupy those bare spots are survivors that tolerate full sun, droughty and low-nutrient soils. These pioneers can be native or nonnative; depending on the soils and adjacent propagules. They are more likely to be invasive nonnatives if the soil seed bank has a history of disturbance or the adjacent land has been disturbed. Consequently, invasive nonnatives or weedy species are a continuing problem in roadside management. We have a responsibility to control and eradicate these invasive plants in the landscape. Prevention and control is also a legal obligation in 38 State Weed Laws. Respecting the plant species listed by adjacent States is being a good neighbor. Those lists warn you about aggressive plants known to exist nearby. Weeds move easily through disturbed highway corridors.
In the name of safety, improved visibility and obstacle-free roadsides, roadside vegetation managers favor grasslands. Until recently, those grasslands were commonly defined by available agricultural, nonnative grasses. Those grasses are bred to be predictable and establish easily. The establishment of regional native grasses has been studied and can also fill that practical and predictable niche in roadside vegetation. The science of native grass establishment, or revegetation, has evolved to the point where they can be planted almost as easily. Once established, the native grasses save maintenance dollars over time, provide a self-reliant and hardy plant community, improve wildlife habitat, and protect the local character and natural heritage of a site.
Because grasslands meet our practical and safety needs, local native grasslands can serve as models for roadside management. More than half of the United States was once covered naturally by grasslands: Palouse, prairies, Great Basin, meadows, glades, savannahs, balds, pine barrens, and others. In forested States, holding back the encroaching forest or natural succession results in a manageable grassland.
1930's - The Front Yard Approach: Roadside development was a new but natural goal following early road construction. To add to the pleasure and safety of driving, landscaping, rest areas, and so on were desirable. In his book, Roadsides, the Front Yard of the Nation, Jesse M. Bennett said "what is really desired, however, is attractive and useful roadsides which can be obtained by preserving or creating a natural or an approach to a natural condition in keeping with the adjacent or surrounding country. And the significant thing about this is that to follow a natural development is outright economy in road maintenance." Unfortunately it was the title of his book, not Bennett's words that became unofficial policy for many years.
1950's - The Agricultural Approach: It was logical to use available farm methods and equipment to manage weeds and appearance through mowing. With the advent of agricultural chemicals, spraying was added to mowing as a management tool. That mow-spray method continued to enhance a front yard look. The highway agencies by this time had surmised that the "look" was what the public wanted and expected.
In 1965, the transportation appropriations act added the highway beautification requirement. Motivating this requirement was the Johnson Administration's support of conserving our nation's "natural beauty". By the time the requirement was implemented into roadside use, conservation translated to landscaping, which ironically sometimes displaced our
1970's - An Ecological Approach: The energy crunch of the early 70's brought a halt to this labor-intensive, fossil-fuel eating, maintenance approach. Yes, economic constraints led to ecological solutions in many States. Vegetation managers were forced to mow less and spot spray; both of which had positive consequences which included: increased wildlife habitat, enhanced natural beauty, minimized herbicide use, reduced maintenance dollars....and the public did not complain.
In 1987, thanks to the vision and influence of Mrs. Lyndon Johnson, a key amendment was added to the transportation appropriations bill by Senator Lloyd Bentson. It required that 1/4 of 1% of the landscape budget on a federally-funded project be used for the establishment of native wildflowers. Without a definition of "native wildflower" the amendment was interpreted in a range of ways from hand-planted daffodils, to naturalized garden seed mixes of oxeye, chicory, Queen Anne's lace, Dame's rocket and more. Some States seeded hand-collected local seed or commercially-grown native ecotypes. The results ranged from crowd-pleasing gardens to inexperienced and unsuccessful plantings. The public applauded and patiently watched.
1990's - The Rise of IRVM (Integrated Roadside Vegetation Management): Because safety will always be the number one priority for transportation decision-makers, most States carried on business as usual. But the fiscal constraints of the 90's tightened. Once more, States sought solutions that cost less in time and dollars. Iowa's idea of integrated roadside vegetation management (IRVM) caught on. IRVM simply meant using the most cost-effective and ecologically-sound method of management on a site by site basis. IRVM included the planting of native wildflowers and native grasses as a solution. Another method, reducing mowing, for example, also fit IRVM and. Mowing only the first 8 feet of the roadside, plus mowing where visibility is critical was enough. Many Midwest States reduced mowing on rural highways and made the policy law. Only urban roadsides remained neatly trimmed, retaining that historical front yard look. Letters from the traveling public supported this economic/ecological approach.
2000's - A Conservation Approach: As we begin this century, we find that working with nature, or Bennett's 1930's ideas, are becoming the policy of the land. A combination of factors supports this approach. 1. The high cost of invasive plants is creating new private and public sector partnerships. 2. The knowledge that roadsides decisions affect adjacent lands means a need for better planning. 3. The continued need to reduce maintenance costs, makes a conservation approach economically important. 4. Our national loss of diversity, requires preservation of what we still have. Yes, a conservation approach is likely to be the accepted roadside approach by highway users and DOT management far into the future.
In the 80's Bill Haywood developed the following information in Black Hawk County, Iowa. The ecological science and common sense he brought to vegetation management fits the needs of roadsides. Here are his three ecological principles:
1. Nature does not allow bare soils to exist.
2. Bare soils are revegetated by successions of plant groups until a most-fit community of plants develops.
3. Disturbance of the vegetative cover reverses the succession of revegetation back to the bare soil starting point, and therefore allows more invasion.
Pressure to do more with less by maintenance departments everywhere led to the acceptance of such ecological principles. Key to success was preventive maintenance or avoiding impacts that disturbed plant associations in the first place. Another ecological factor was the differences among locations, including soils, aspect, moisture, context, etc. Thus it was thought that the successful solutions would be matched to each site. Deciding how to use the right tools in the right place at the right time became the goal.
Applying these ecological principles to the roadside became known as Integrated Roadside Vegetation Management (IRVM). IRVM is credited to the principles of Bill Haywood. In 1986 he said, "Success with IRVM demands a change in the philosophy guiding the management of roadside vegetation from one of weed eradication to weed prevention." This practical insight has led us to mapping vegetation, statewide planning, and new maintenance/construction practices.
Former First Lady, Lady Bird Johnson brought attention to highway corridors in what has been called the Highway Beautification Act of 1965. In her quest to save natural beauty, our natural heritage which she loved since a child, her influence created funding to screen junkyards and control billboards. However, she was most excited about the three cents of each dollar spent being used for acquisition and maintenance of natural areas adjacent to the highway. These "beauty spots" are our scenic overlooks, rest areas, and State entrances that underscore each State's regional beauty.
In the 1987 highway bill, her influence was once again felt. The Surface Transportation and Uniform Relocation Assistance Act included a requirement for the planting of native wildflowers. The natural beauty of her childhood was worth saving or restoring for future generations. Many restorations of native plants on roadsides have occurred. But the greatest threat to both preserved and restored sites, is the spread of non-native invasive plants. A decade later, Lady Bird watched as we began the war on weeds. Those invasive plants threatened the natural heritage she long had valued.
Today, we recognize her efforts and insights into our natural heritage. The importance of conservation is greater than ever. We can no longer talk about the preservation of native plants without considering the weeds that threaten them. Invasive plants are said to be the second biggest cause of extinction next to habitat loss. We can no longer address one problem at a time, but instead we must take a larger ecological view, recognizing that everything is connected. We cannot target one weed without analyzing the entire roadside. The endangered plant and animal survivors found there, as well as the threatened remnant plant communities must be protected. Yes, the roadside environment is connected to the entire environment and we have a responsibility to the future to sustain it to the best of our capabilitiesÉ.and as the First Lady said, leave it "looking as good if not better than we found it."
Why now? We have not accomplished Lady Bird's vision for conservation of our country's natural beauty, yet. If we do not come through soon, our conservation opportunity will be buried by the spread of invasive plants.
So why not now?
Table of Contents | Previous | Next
This page last modified on August 4, 2004