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Tallgrass Prairie Center

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Frequently Asked Questions

Header image is a road with a truck on it and in the foreground there is grass and purple and white flowers.

Frequently Asked Questions

If you have any questions not answered here, please contact Roadside Program Manager Kristine Nemec at kristine.nemec@uni.edu or 319-273-2813.

 

Safety

How do tall prairie plants in the roadside impact driver vision and safety?

When it comes to integrated roadside vegetation management, safety is always the first priority. To make sure drivers have an unobstructed view, tall prairie vegetation should not be planted in the clear zone, or the area of the roadside closest to the pavement.

Studies indicate that drivers are drowsier when roadside scenery is monotonous. Roadsides with many different types of plants may result in increased driver alertness and reduced crash rates, although more research is needed regarding these outcomes. The seed mixes provided by Iowa Roadside Management contain 20–38 plant species, creating a vibrant and varied roadside. The tall prairie vegetation may also provide a softer landing and slowing effect for vehicles that go off the road.

How do reduced mowing and native plants in the roadside impact roadway hazards like deer? 

Because deer prefer to eat young, green grasses that have been freshly mowed, reduced mowing can reduce the appeal of roadside vegetation. However, studies in Florida and North Dakota have found that reduced mowing had no effect on deer-vehicle and other wildlife-vehicle collisions. The factors affecting deer-vehicle collisions are complex. But in Midwestern areas with a lot of agriculture, variations in traffic volume and the abundance of deer may be better predictors of deer-vehicle collisions than landscape composition, although there also appear to be a lot of deer near wooded areas. 

Additionally, reduced mowing reduces the likelihood of debris being unintentionally flung from mowers into the road and traffic. 

Erosion

How do prairie plants in the roadside help reduce erosion? 

Warm-season grasses that are included in roadside prairie seed mixes include big bluestem, Indiangrass, and switchgrass. These grasses and some wildflowers have dense roots that are 6–9 feet deep. These dense roots make them especially suitable for reducing soil erosion, in comparison to shallow-rooted cool-season grasses such as tall fescue, with roots that are 2–3 feet deep. Research on prairie strips planted within farmland has found prairie grasses to be effective in reducing erosion.

Since it takes prairie plants three years to mature won't a lot of erosion on steep roadside slopes occur in the meantime?

The prairie seed mixes include some species that establish quicker than other prairie plants, like Canada wildrye and black-eyed Susan. You can also avoid increased erosion while the other native grasses and wildflowers become established by using the following procedures:

  • Use proper seeding depth when planting.
  • Control weeds with herbicides and mowing during the first year.
  • Plant quickly establishing cover or nurse crops such as rye, oats, and winter wheat with the seed mix. 
  • Hydroseed with mulch

See the “Erosion” section of our Integrated Roadside Vegetation Management Technical Manual for more information about erosion and roadside vegetation.

Landowners and Residents

Will native plants spread from the roadside into adjacent farmland?

Researchers with Iowa State University’s Science-Based Trials of Rowcrops Integrated with Prairie Strips (STRIPS) have found that prairie plants do not spread well into tilled or conventionally sprayed farmland. STRIPS has planted strips of prairie directly within cropland for farmers who are interested in soil conservation, improved water quality, and habitat.

Do prairie plants plug tile lines?

Video taken by Iowa State University’s STRIPS and the Tallgrass Prairie Center of different farms has shown that prairie roots rarely infiltrate tile lines and do not cause obstructions. Tiles in low-lying areas may become plugged by reed canarygrass, an aggressive plant that is never included in prairie seed mixes.

How do prairie plants in the roadside improve water quality?

With their dense roots, prairie plants act like a sponge to effectively filter and remove pollutants, according to Iowa State University Extension and Outreach. The dense roots also make prairie plants more effective competitors against weeds than cool-season grasses such as fescue and smooth brome. Fewer weeds mean fewer herbicides need to be used for weed control. For more information about prairie roots, visit the Tallgrass Prairie Center’s Prairie Roots Project

How does planting prairie plants in roadsides help bees and butterflies? Aren't they just killed by vehicles anyway?

Native prairie roadside grasses and wildflowers provide important sources of food and shelter for bees and butterflies. Studies suggest that in roadsides with less frequent mowing and more types of prairie plants butterflies are less likely to cross the road and be killed, possibly because they don't have to cross the road to search for more habitat. Research also suggests the relative proportion of the local pollinator population killed by vehicles is relatively small and there is a net benefit to having habitat available in the roadside. Collisions may increase during fall migration for monarch butterflies and in areas with high traffic counts. For more information, see the Xerces Society's website on pollinators and roadsides and Monarch Joint Venture's frequently asked questions about monarchs and roadsides.

Does my county have a roadside manager? How do I learn more about encouraging them to start a roadside program and hire a roadside manager?

Check this map to see if your county has a roadside manager. If the engineer is listed as the main roadside vegetation contact for your county, the county likely doesn't have a separate roadside manager on staff. Contact Kristine Nemec at the UNI Tallgrass Prairie Center (kristine.nemec@uni.edu, 319-273-2813) or Tara Van Waus at the Iowa DOT (tara.vanwaus@iowadot.us, 515-239-1768) to learn more about how other counties have started a program or resources we can provide. 

Government

How does reduced mowing impact staff safety?

Road department personnel who spend less time mowing steep slopes will have fewer opportunities for accidents. 

How does reduced mowing save money?

For over a decade, more state departments of transportation have implemented conservation mowing to save money and establish pollinator habitat. Counties and cities can also experience savings from reduced mowing. 

Mowing is needed to keep the vegetation short in some areas of the roadside to maintain good sight lines, such as the part closest to the pavement, intersections, and driveways. However, in areas of the roadside further from the road, frequent mowing for safety purposes is unnecessary. 

There are up-front costs associated with replacing cool-season grasses such as Kentucky bluegrass, fescue, or smooth brome with prairie vegetation. The first year of planting the prairie will be more expensive than just mowing the existing grasses. However, once the prairie plants establish, they do not need to be mowed as often as cool-season grasses, which saves money in the long run on fuel, equipment, and labor.

This handout from Good Neighbor Iowa uses mowing research results from the City of Cedar Falls to demonstrate cost savings over five years from replacing one acre of turf with prairie. Although the handout is not specific to roadsides and the exact costs may vary by county or city, it demonstrates the resources needed to establish prairie and how reduced mowing can save money over time. 

Unlike the example in the handout, counties and cities with an integrated roadside vegetation management plan need to provide the labor, mulch, and equipment to plant prairie in the roadside. However, they can receive roadside prairie seed for free (a value of $220–375 per acre) from the Tallgrass Prairie Center and apply for grants from the Living Roadway Trust Fund to cover some of the equipment costs associated with their integrated roadside vegetation management plans. 

How does having a roadside manager help a county or city be more efficient and manage safe and healthy roadsides?

A roadside manager provides leadership and efficient use of government resources by:

  • being the go-to person who is familiar with a county or city's roadside vegetation—using their knowledge, they proactively prioritize planting and management of native vegetation, mowing, and control of weeds and brush in cost-effective and environmentally friendly ways 
  • saving money with strategic mowing and herbicide use
  • saving money by obtaining free native prairie seed from the Tallgrass Prairie Center and grants from the Living Roadway Trust Fund to help cover the costs of roadside management equipment and vegetation
  • providing insight for residents who have questions about their own conservation and land management projects, such as where to buy supplies 
  • managing weeds and prairie plantings during windows of opportunity when weather conditions are ideal for better long-term results—especially on small roadside projects, contractors might not have the flexibility to show up on-demand when conditions are right for managing a given weed
  • participating in two annual meetings and an online message board where members of the roadside manager community learn from each other and other experts about best management practices