Wildflowers along a highway

Managing Roadsides For Pollinators

Excerpted from: Roadsides and Pollinators

Roads have the potential to fragment habitat, separating plants and animals from one another, as well as to destroy habitat and increase invasive plant species, pollution, and erosion. New roads, especially those through natural areas, can have adverse effects on the wildlife around them.

However, roadside vegetation can help to mitigate some of the negative impacts of roads. The management of vegetation along existing roads can increase habitat diversity and provide connectivity to habitat fragments in agricultural and urban landscapes.

Roadsides provide pollinators with food, breeding, nesting opportunities, as well as connectivity to other habitat. Pollinator diversity can be high in roadsides, with bee and butterfly communities that include both common and rare species.

Why Manage Roadsides for Bees and Butterflies?

  Roadsides in the U.S. cover more that 10 million acres of land.

  Managing roadsides for bees and butterflies will create highquality habitat for wildlie of all types.

  Pollinator habitat along roadsides supports the pollination needs of adjacent farms and natural areas.

Pollinators are critical to our food supply as well as to the health of ecosystems. Wild pollinators such as the monarch butterfly and a number of bumble bee species are in decline, and beekeepers in the U.S. have reported significant losses of managed honey bee colonies.

Pollinator declines are attributed to loss of habitat, pesticide exposure, diseases, parasites, and effects of introduced species. Roadsides can benefit pollinators by providing foraging habitat, places to breed, nest, and overwinter, and may act as corridors, linking patches of fragmented habitat.

Roadsides managed with pollinators in mind can achieve multiple goals of stabilizing roadsides, reducing storm water pollution, supporting wildlife, and building public exposure and appreciation for the local landscape.

Pollinator Decline

Roadsides are among the few remaining places to find lead plant and other prairie species

The number of honey bee colonies has been in decline over the past half-century because of disease, parasites, lack of floral resources, insecticides, and other factors. Since 2006, beekeepers have experienced record high annual hive losses of 29% or more. Less is known about the status of most of Wisconsin's pollinators, the data does exist suggests that numerous species are experiencing declines similar to or more severe than the declines seen in honey bees.

Monarch butterflies in North America are vulnerable to extinction — Monarch butterfly populations have dropped by 90% east of the Rocky Mountains. Three factors appear most important to explain the decline of eastern Monarchs: loss of milkweed breeding habitat due to increased use of herbicides on genetically modified herbicide-resistant cropland and land conversion, logging at overwintering sites, and an increase in extreme weather events

  Loss of milkweed breeding habitat due to increased use of herbicides.
  Logging at overwintering sites.
  An increase in extreme weather events.

Other butterfly species have also seen significant declines. Of the 800 butterfly species in the U.S., 17% are at risk of extinction. Twenty-six species of butterflies are listed as threatened or endangered under the Federal Endangered Species Act

Roadsides and Pollinator Conservation

Wildflowers along a highway

Concerns about pollinator decline and its repercussions have led to increased efforts to reduce threats to pollinators. Managing existing habitat for pollinators and restoring additional habitat has been demonstrated to increase pollinator abundance and diversity. Roadsides are a conservation opportunity to increase pollinator habitat.

Pollinator Food Sources

Flowering plants in roadsides are important sources of nectar and pollen for pollinators that reside within the roadside habitat as well as those that use the roadside as a partial habitat and reproduce or overwinter elsewhere. Roadsides have the potential to provide resources needed for all life stages: host plants, nectar plants, and overwintering habitat for butterflies.

Roadsides can also provide food for managed honey bees. Honey bee colonies require diverse sources of pollen and nectar, and a lack of forage is frequently cited as a primary contributing factor to declines in honey bee health

Shelter and Nesting Sites

Roadsides can also provide shelter, sites for nesting or egg-laying, or overwintering habitat. Bees provide for their young by constructing nests in which their offspring develop. Many ground-nesting bees prefer to nest in sunny, bare patches of soil. Such patches can be found around the bases of native bunch grasses such as little bluestem that tend to grow in dense bundles, leaving small areas of bare ground exposed between plants.

Roadside vegetation can also provide habitat for tunnel-nesting bees, which nest in hollow or pithy stems or other small cavities. Bumble bees require a small, insulated cavity, such as underneath grass clumps or under the thatch of bunch grasses.

Landscape Corridors

Landscape connectivity is important for the populations of many species, but due to urbanization, agricultural intensification, and other human activities, habitat is becoming increasingly fragmented. Roadsides extend across a variety of landscapes, often contain greater plant diversity than adjacent lands, and are generally excluded from further development and major disturbances. In developed landscapes, such as intensively managed agricultural lands, roadsides may provide areas of refuge for pollinators in an otherwise inhospitable environment. The linear shape and connectivity of roadsides may help pollinators move through the landscape, either for daily foraging or for dispersal to larger habitat patches

Roadside Management For Native Plants

The primary goals of roadside management by the Wisconsin Department of Transportation (WI-DOT) are motorist safety, noxious weed prevention and soil stabilization. In recent years WI-DOT have also incorporated in a few projects the incorporation of native grasses and wildflowers into rights-of-way to achieve this objective.

Integrated roadside vegatation management can combine the planting of native vegetation with site-appropriate strategies to achieve cost-effective and more environmentally sustainable management of roadsides. As an alternative to intensive mowing and blanket pesticide spraying of roadsides, vegetative management offers significant advantages.

  Native grasses and flowers that are best adapted to local conditions and are able to tolerate drought or heat.

  An established diverse plant community provides the most stable cover for reducing soil erosion and keeping out seed.

  Native plants offer improved weed and soil erosion control, reducing the need to mow or to spray herbicides, which also reduces the costs.

  Native plants are less likely to encroach on land bordering rights-of-way, a common complaint about non-natives.

  Native plant communities will reduce runoff in the spring and act a snow fences in the winter, trapping and preventing slow from blowing across roads.

  Native plantings are aesthetically pleasing.

  Native plantings may offer education opportunities, as they demonstrate how the wilder landscape once looked.

  Native plant communities support more native wildlife than non-native plant communities.

Traffic and Wildlife

For the WI-DOT, the biggest concern about native plants which are much taller, is that it will increase the number of accidents involving deer. Although there are no specific studies on this concern, other research indicates that the presence of tall vegetation does NOT increase the number of deer-related collisions.

Because deer preferentially eat tender new growth of vegetation, allow native plants to grow without frequent mowing should encourage fewer deer to browse along roadsides.

Balancing The Costs and Benefits

Native grass and wildflower seed does cost more per acre than the typically-used non-native grass seed. One way to reduce this cost is to harvest sees from established stands of grasses or wildflowers. Limited amounts of seed can be harvested by hand or sometimes through the use of farming equipment. An advantage of harvesting see locally is that the local ecotypes are particularly well-suited to the area.

Roadsides planted with native grasses and forbs should, after establishment, have less erosion as well as a reduced need for mowing and for spraying herbicides.

Reduced storm water flow and reduced blowing snow due to native plantings may reduce costs.

Further Reading:

 Beavers — Nature's Hydrologist, Part 2
 Garter Snakes — The Gardener's Friend
 Wisconsin Native Salamanders
 Goundhog or Woochuck: All The Facts
 Voles, Both The Good and The Bad

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