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Roadside Use of Native Plants

Restoring Grassland Ecosystems — An Opportunity to Save the Pieces

Reed F. Noss, Conservation Biology Institute

As a rule, ecologists and conservationists detest roads. Roads fragment wild habitats; create noise, air, and water pollution; increase landslides and erosion, filling rivers with silt; serve as invasion routes for exotic weeds, pests, and diseases; create barriers to the movement of animals; kill millions of animals that are struck by vehicles; and provide access to wildlife poachers. Generally speaking, the fewer roads, the better.

But most roads are here to stay. Is there anything we can do to make them less troublesome? Can roads ever provide benefits to the environment? I am almost surprised to hear myself answering "yes." In an increasing number of regions, roadsides provide some of the only seminatural habitat left. Everything else has been committed to the plow or turned to asphalt and concrete. In Australia, for example, roadside remnants of forest provide breeding habitat and movement corridors for many species of wildlife that have been extirpated from the intensively used Wheatbelt landscape. Similarly, in much of the American Corn Belt, roadsides, railroad rights-of-way, old cemetery edges, and other marginal habitats that escaped the plow provide the best places to find native prairie plants. Birders know that some uncommon birds, such as loggerhead shrikes, are usually encountered along roads.

In North America, some of the most highly imperiled native habitats are prairies and other grasslands. Actively restoring these grasslands is one of the few things people can do to compensate, in small part, for the destruction that has occurred over the last couple centuries. Roadsides offer excellent opportunities for restoring some components of the prairie ecosystem. In Iowa, for example, 600,000 acres of roadside habitat provide more area than all the state, county, and city parks combined. Because Iowa was a prairie state and has lost some 98% of its native habitat, managing roadsides for native prairie makes abundant sense. These plants are well adapted to roadside conditions, require little maintenance (for example, periodic burning usually suffices), and beautify the landscape. By planting them, we help maintain the gene pools of prairie plants and some of the small animals associated with them. Together, the Iowa Department of Transportation and the Roadside Management Program at the University of Northern Iowa are doing great things to restore roadside prairies. But alas, a roadside prairie is not a complete ecosystem. Such plantings will not help us bring back the buffalo and other animals that need large areas of grassland.

Another way that the effects of roads can be mitigated is to provide corridors for animals that need to cross under (or, in some cases, over) them. "Toad tunnels," for example, have been used for decades in Europe and, recently, in parts of the U.S. to allow frogs, toads, and salamanders to cross roads (during their breeding migrations) without getting squashed. Wider crossings (underpasses) have been used successfully to allow deer and other large mammals to cross highways in many regions. In South Florida, underpasses constructed on Interstate 75 to mitigate fragmentation of Florida panther habitat and prevent roadkills have allowed panthers and dozens of other kinds of animals to cross safely. In these cases, roadside fences help funnel animals into the crossings. In situations where no underpasses are constructed, wide roadside clearings help animals and drivers see and avoid each other. As is the case in Australia, wide swaths of natural habitat adjacent and parallel to roads may help animals and plants disperse across human-dominated landscapes.

I do not believe that roadside enhancement projects will ever completely compensate for the ecological damage done by a road. When the choice is no road, a road with its edges restored to native vegetation, or a road with non-native vegetation, the best choice is no road. But for roads already in existence, the best option is to mitigate the damage by restoring the roadsides. Indeed, the advantages of restoring roadsides to native habitat are accompanied by few, if any, disadvantages. As natural habitats become fewer, smaller, and more isolated everywhere, native roadsides provide a vestige of what once was, living space and movement routes for many native creatures, and a reminder of our responsibility to hang on to whatever we can in an increasingly impoverished world.

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Questions and feedback should be directed to Deirdre Remley (deirdre.remley@dot.gov, 202-366-0524).

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