Native Plantings On Illinois' Highways By WILLIAM T. SUNLEY, Engineer of Local Roads and Streets Credits to: Charles H. Gouveia, PLA Roadside Maintenance Manager

In pre-settlement times, nearly twenty-two million acres of what was to be the State of Illinois were covered by native prairie and savanna vegetation. However, by 1950, less than one percent remained in scattered small parcels throughout the State.

During the 1950s the State of Illinois began construction of the Interstate Highway System which, when completed 30 years later, would increase the size of Illinois' roadsides to approximately 139,000 acres. As a part of Interstate Highway construction, extensive landscaping was done on the right-of-way. Typical of highway landscaping styles of the time, the right-of-way was designed as a parkway setting with naturalistic plantings and fully mowed expanses of turf. Native trees and shrubs were included as part of the interstate highway landscape to the extent that they were available. Native grasses, however, were not a part of the highway planting programs through the 1960s when the bulk of the interstate system in Illinois were constructed.

One of the early uses of native grasses for landscaping purposes was a landscape element, a seeded substitute for expensive shrub massing in an interchange. In 1969, a mixture of Little Bluestem, with scattered Pin Oak trees, was seeded in the south interchange of 1-57 and 64 near Mt. Vernon. At that time, little information was available on mass planting techniques for native grasses, and sources of seed were limited.

In 1974, the Department of Transportation's Peoria District used a tree spade to transplant some salvaged native prairie to the Mackinaw Dells Rest Area on 1-74 near Goodfield in Woodford County. As a part of that project, department staff also planted some native grass and wildflower seed, hand collected from a prairie remnant on highway right-of-way. Also in 1974, they cooperated with a local Peoria group on a wild-flower seeding project using purchased seed that foreshadowed Operation Wildflower efforts, discussed later in this article.

In the Chicago area, experimentation was being done by the Schaumburg District office in cooperation with Iverson's Perennial Gardens on planting of wildflower plants and flower bulbs with a seedling tree planter. This was developed as a technique to more rapidly establish flowering herbaceous plants on highway projects.

Another means for the establishment of native vegetation on the highway right-of-way is Operation Wildflower. This program is conducted in cooperation with the Garden Clubs of Illinois, Inc., and their local affiliate garden clubs. Operation Wildflower consists of a cooperative effort between the clubs and the Department to establish flowering plants on the right-of-way. Usually, the local Garden Club supplies or purchases the plant material and the Department arranges its planting at an agreed upon roadside location. In some cases, the local Garden Clubs help with the planting, or agree to provide post planting care to the plants.

The Department also has begun utilizing native plants on a variety of restoration projects dealing with vegetation types other than prairie or woodlands. The most common of these projects involve wetland mitigation installations that utilize aquatic plants and seeding mixes for wet or partially wet areas. The Department has constructed a few projects that involve restoration

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or establishment of woodland or savanna communities with native plants typical to each. Supply of plant material for these specialized plantings is limited at present. however, the contractors doing this work for the Department have thus far been able to locate commercial sources to supply the majority of the required plants.

The newest native grass and wildflower establishment program is Corridors for Tomorrow, initiated in 1993. This program is funded through the Department's portion of the Federal Intermodal Surface Transportation Efficiency Act as an enhancement project. The goal is to establish wildflower and grass plantings at interchanges, rest areas and State entrances where sufficient room exists, and other reconstruction is not scheduled. In this program, landscape contractors handle planting and obtain their materials from commercial suppliers. The specifications for planting methods and varieties are prepared by the Department's nine District Landscape Architects, and vary according to the area of the State in which they are planted. Hydro-seeding and drilling have been employed in both bare ground seeding and in interseeding of existing turf areas. In some projects, both seeding and plant plugs are utilized in order to obtain faster establishment of the permanent species, and annual flowering plants are usually included to provide some color the first season. New signs with color graphics depicting wildflowers, prairie plants, wetlands or seedling trees, have been developed to assist the traveling public in recognizing the planted areas. •

June 1995 / Illinois Municipal Review / Page 25