Native to another area

March 12, 2007

Since the construction of early roads in the 1900s, the debate over land use and aesthetics on public property has been argued in practically every jurisdiction. In Iowa, the discussion currently centers on efforts to reintroduce native vegetation to the state’s roadsides.

Since the construction of early roads in the 1900s, the debate over land use and aesthetics on public property has been argued in practically every jurisdiction. In Iowa, the discussion currently centers on efforts to reintroduce native vegetation to the state’s roadsides.

The industrial revolution brought the automobile to the prairie, leading to the Good Roads Movement. In the early 1900s, getting Iowa “out of the mud” meant increased road construction and the tilling under of even more native grasses and wildflowers. Flourishing road construction created a need for roadside management.

Today, Iowa’s public lands add up to approximately 2% of the state’s total land area. The Iowa Department of Transportation (IDOT) is responsible for managing more than 175,000 acres of this land, which is dedicated to the state’s highway right-of-way. While rights-of-way are necessary for public safety and future road construction, they also can serve as valuable habitat for plants and animals. Several programs aid IDOT in carefully enhancing and managing Iowa’s roadsides.

From early roadside development up to the 1980s, Iowa’s roadsides were primarily planted with imported species deemed aesthetically pleasing, reasonably priced and readily available.

In the 1960s, Dr. Roger Landers of Iowa State University recommended as part of his research that Iowa use native vegetation for roadside management. He concluded that native plants were best suited to the state’s soils and climate. While the research was promising, the lack of available seed inhibited any attempt to implement major change in IDOT’s planting policy.

In the 1980s, Dr. Lander’s research was re-examined, and IDOT decided to deploy pilot projects using native vegetation. As the number of projects grew, IDOT created a viable market for native seed, a market that was gradually met by private suppliers.

In 1989, the Living Roadway Trust Fund was authorized by the Iowa Legislature. The fund supports integrated roadside vegetation management programs on city, county and state rights-of-way, and public areas adjacent to traveled roadways. These funds allow for the purchase of special equipment, roadside inventories, gateway plantings, native grass and forb seed, tree and shrub plantings and research, education and awareness programs.

Plants with benefits

IDOT personnel responsible for the maintenance of state roadways (highway rights-of-way) use a number of approaches to enhance and preserve these areas. The primary objectives of roadside maintenance are motorist safety and control of noxious weeds, while at the same time allowing a habitat for wildlife and an aesthetically pleasing environment. Roadside mowing is limited to safety zones and noxious weed areas. Spot herbicide applications also are used for noxious weed and brush control. Wildflowers and native grasses are being established to provide competition for weeds, while offering travelers a more intriguing landscape.

Flowers, grasses, trees, shrubs and other woody plants are a familiar sight to most people traveling Iowa’s roadways. However, few pause to consider how the plants came to be in the right-of-way, how they are managed and the benefits they bestow. In reality, people take the plants for granted.

The native species have adapted over the centuries to Iowa soil and weather extremes. Below ground is where the benefit of native species is fully realized. The native prairie plants’ massive root systems offer many benefits that non-native species cannot. Water quality in Iowa can be improved because of increased water infiltration provided by the extensive root systems of native roadside vegetation. Hair-like root fibers of trees and other plants trap pollutants such as nitrates and phosphates that can contaminate groundwater. Storm-water runoff into Iowa’s waterways is drastically reduced as deep root systems provide a solid conduit into the soil to facilitate infiltration.

Established root systems of native roadside species bolster the stability of the roadbed and associated right-of-way. A dense cover of plants and mulch holds the soil in place, keeping sediment out of streams, lakes, storm drains and roads. The root systems also help reduce flooding, mudslides and dust storms. The decaying of dead plant parts improves the soil through the addition of organic matter.

Plant foliage improves air quality by acting as a filter, absorbing both solid and gaseous particulates. These particulates include such pollutants as carbon dioxide, chlorine and sulfur dioxide. One tree can remove 26 lb of carbon dioxide every year from the atmosphere, equaling the emissions created by 11,000 miles of automobile travel.

Landscaping alters the environment in which we live by moderating climate. Climate control is obtained by moderating the effects of the sun, wind and rain. Radiant energy from the sun is absorbed or deflected by leaves in the summer, and is only filtered by branches in the winter. Urban plants reduce urban air temperatures significantly by shading heat sinks, such as buildings and concrete, and returning humidity to the air through evaporative cooling.

Landscaping enhances busy streets and roadways. Well-placed plantings offer privacy and tranquility by screening out sources of street noise and objectionable views of traffic, as well as unwanted views from highways such as junkyards. They also reduce glare and reflection from headlights and street lighting.

Good landscaping creates community appeal. Psychologists have discovered that trees, well-landscaped grounds and places for taking walks are the most important factors considered when individuals choose a place to live. Size and distribution of trees also relate to citizens’ satisfaction with their neighborhood.

Some native insect and songbird species have once again found Iowa’s rights-of-way to be suitable habitat. Birds, butterflies, skippers and other species can be seen from border to border in areas where sightings had become rare.

The deep root systems and hardiness of the plants provide increased standibility of the native tall grasses as a natural snow fence to help reduce blowing snow, which interferes with visibility. Even in areas where the grasses do not provide a significant wind barrier, having varied vegetation breaking up through the snow’s reflective surface provides added safety for drivers.

Non-winter benefits of native vegetation can be seen in the varied colors, sizes and textures that provide visual interest. This visual stimulation helps reduce driver fatigue, sleepiness and highway hypnosis. Plants also can be used to delineate highway alignment, giving visual clues to drivers of upcoming curves or intersections.

When looking for species that are tough enough to thrive in roadside conditions, IDOT has looked at what grew there historically. It is not striving to recreate the prairie, but to use prairie plants for landscaping Iowa roadsides.

No trouble mixing in

IDOT purchases Iowa-origin seed, and there are multiple mixes for each project. The seed purchased is G0 (gee-zero), meaning the genetic source is from Iowa.

In general, using grass-only mixtures in weedy areas allows for the future use of broadleaf herbicides. Tall-grass mixtures in combination with forbs are best suited for maximum snow control. Shorter-grass mixtures are best where visibility is an issue or where visibility of wildflowers is desirable.

Minimum-maintenance mixes are used on the majority of roadsides. The intent is to use plants that can best tolerate the least amount of maintenance and still provide the needed erosion control and weed competition. Only spot mowing and targeted spraying are planned as maintenance activities.

Native grasses and wildflowers are most commonly used, with some non-natives occasionally added for faster vegetative establishment in highly erodible areas. These mixes include approximately 70% grasses and 30% wildflowers, attempting to mimic the grasses-to-forbs ratio found in the tall-grass prairie. Cover crops of annual plants are sometimes added to these mixes to reduce erosion during establishment.

Wildflower mixes are a variation of the basic, minimum-maintenance mixes. In these combinations, shorter grasses and a higher concentration of wildflowers are used to give a more showy floral display. These are used in selected areas where there is a desire to draw attention to the roadside. Communities often request these mixes to beautify their gateways.

Mowable mixes are used for areas that will receive periodic mowings. Cool-season, non-native plants, such as fescues and ryegrasses, are often used along shoulders and in medians where mowings occur three to four times each year. Where an aesthetic turf look is desired, seed mixes containing bluegrass and creeping red fescue are used because they tolerate more frequent mowing.

Special seed mixes are designed for areas such as butterfly gardens, outdoor classrooms, wetlands, woodlands or areas with unusual soil characteristics. It is important to know about the growth and habitat characteristics of many different species to identify which plants to use in these areas.

Natives are restless

Beginning in 2000, IDOT dedicated funding to reintroduce native species into existing non-native roadsides. While the seeding of native species on new construction sites in Iowa has been very well received, the process of revegetation on existing roadsides has been met with some resistance, especially on two-lane roadways where the impact is more immediate to adjacent landowners.

It’s not a pretty sight. Bright-green and flower-covered roadsides are decimated with a non-selective herbicide. The brittle brown aftermath can cause quite a stir in nearby communities. IDOT has been working diligently with local civic groups, service organizations and media to walk through the process of revegetation and assure area residents that the benefits of the program far outweigh the negatives.

Overcoming common myths and misunderstandings is essential from a public relations perspective. The most common question asked when a revegetation project is proposed is, “Why kill perfectly good existing grass?” Other concerns expressed pertain to the investment costs; the perception that revegetation projects cause weed problems that did not exist previously; and the desire to move the project to some other roadside—the “not-in-my-backyard” mentality. Traditionally, many Iowa farmers have mowed and hayed the roadsides adjacent to their property, and still have the desire to continue managing these areas for their own use and benefit.

Highway users and area residents witness first-hand the steps performed by the contractor during site preparation, seeding and plant establishment. The first phase is often the most alarming to residents. Herbicide is sprayed on existing plants until the area is void of all living vegetation.

The area is then seeded with a native grass drill with a no-till attachment. This method eliminates full preparation of the seedbed, which could open the soil to weed infestation and erosion. The seed mix will depend on the area and land use.

Results can vary depending on a variety of factors (soils, weather, contractor performance, etc.). Some projects have excellent establishment the first growing season, while others take two to three years before tangible results are seen. Continuing dialogue with community groups is key to calming negative reaction to the initial steps of this process.

Going with a wild look

Because Iowa had mowed its roadsides for many years, some travelers find the transition to natural vegetation unsettling. The wild, unkempt look of a native prairie does not appear to them to be as aesthetically pleasing. There also are those individuals who believe that flowers belong in flowerbeds, while others express their preference for the constantly changing colors and textures of the native prairie species. Keeping a mowed edge along the shoulder exhibits a certain level of maintenance and reinforces IDOT’s desire to have tall, unmowed vegetation as the desired look.

When local residents begin to understand the extensive planning and reasoning behind the return to native vegetation, most are accepting of the end product. For farmers accustomed to using the roadside vegetation for livestock, IDOT may permit periodic grazing and haying of the new native vegetation as a plant-management tool. However, they are cautioned that some native plants can cause illness to grazing or hay-fed animals, and farm equipment can only be used in the right-of-way by permit.

The borders are safe

While uninformed residents may initially believe the native species will invade adjacent property, IDOT has not seen this fear become reality in 20 years of the program. When farmers see fluffy seed blowing over the fence, it is natural for them to wonder about the expense of killing it, but normal farming practices will easily discourage any accidental invasion. This is another point where contact with local residents is critical to a successful program.

The re-establishment of noxious weeds also is a frequent concern regarding revegetation efforts. It is true that eliminating existing vegetation provides an opportunity for the seed banked in the soil to germinate and become established. This often means thistles and other undesirable plants show up where they had previously been controlled. Neighbors fear these will spread to their property. IDOT responds to many requests to control these plants to prevent infestation of fields or adjacent property.

In nature and in large, open prairie areas, fire is often a way to rejuvenate vegetation. However, the process of burning roadsides is not practical from a safety standpoint. If a change in wind direction blows smoke over the pavement and reduces visibility, the road may need to be closed to finish the burn. Fires that get out of control also can cause damage to fence posts, signs and utilities. As a result, IDOT considers the risks of burning to be far greater than the benefits. Some local landowners burn the right-of-way without permission, a practice strongly discouraged by IDOT.

During the establishment period for new vegetation, it is important that the contractor control competing weed growth. Poor contractor performance can give the public the idea that revegetation projects merely promote weed growth.

Because the market for this type of work is new, there are a limited number of qualified revegetation contractors. IDOT is always looking for additional qualified contractors. Identifying and using firms with solid performance will be a main focus area for IDOT in the coming years. The ultimate success of a project and confidence of the local residents are dependent on the work done by these companies and the ability of IDOT to manage projects uniformly throughout the state.

With nearly 20 years of experience putting Iowa roadsides back to the native plants that once waved serenely over a majority of the tallgrass prairie, IDOT will continue to work with other state and local agencies, civic groups and adjacent landowners to stress the benefits of native roadsides.

About The Author: Bramble is an information specialist at the Iowa Department of Transportation, Ames, Iowa.

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