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Pollinators

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FEDERAL HIGHWAY ADMINISTRATION
Office of Project Development and Environmental Review

Strategic Mowing Benefits Wildflowers, Pollinators, and the State's Economy

May 2015

The Texas Department of Transportation (TxDOT) wildflower program began in the 1930s with a simple but important message, “don’t mow until the wildflowers have gone to seed.” Because TxDOT vegetation managers recognized that native flower species were less costly to maintain, these plants and their associated pollinator habitat have thrived on Texas highway roadsides for decades. More than 5,000 species of wildflowers grow along Texas highways, attracting tourists nationwide to the State each spring, and bringing millions of tourist dollars to State and local economies. Without proper maintenance and care, many of these wildflowers and related tourist activities would decline. Through its wildflower program, TxDOT works to preserve and protect these wildflowers so that biodiversity, pollinator health, and tourism are secured year after year.

TxDOT maintains wildflowers on over 800,000 acres of roadside within its 1,100,000 acres right-of-way (ROW) as part of their vegetation management program. The TxDOT wildflower program is designed to reduce the cost of maintenance and labor, to create aesthetically-pleasing vegetation on highway ROW, and to establish ROW that blends into local surroundings.

Challenges

TxDOT faces challenges and complaints from farmers who believe roadside wildflowers threaten crops and ranchers who believe milkweed—the only food source for monarch caterpillars—threatens livestock. TxDOT continues to respond to concerns from the agricultural community to educate them about the agricultural benefits of wildflowers and the pollinators they support. Success in these educational efforts varies across the State.

Methods for Success

One of the keys to success of TxDOT’s wildflower program is properly timed mowing twice a year—once after the spring bloom season and once after the fall bloom season. TxDOT also mows at a sufficient height to help retain soil moisture. These mowing techniques promote both spring and fall blooms by helping seed germination to ensure the success of the next bloom season. The spring wildflower display is comprised mostly of annuals, and fall wildflowers are predominately perennial species.

To protect and preserve these natural wildflower lifecycle processes, TxDOT practices integrated vegetation management that is overseen by the Maintenance Field Support Section. The Section oversees a statewide program for herbicide operations, mowing, re-vegetation, soil erosion control, endangered species and wildlife habitat protection, pruning, and noxious weed control. To avoid herbicide effects to native vegetation, TxDOT does not use the broadcast method of herbicide application but instead uses techniques such as spot treatments to target nonnative species. As part of its vegetation management program, TxDOT purchases and sows 30,000 pounds of native grasses and wildflower seeds annually. TxDOT also harvests seeds and banks them for later use.

Each of TxDOT’s 25 districts has a vegetation manager who oversees the proper application of TxDOT vegetation management techniques, which differs by road type and function. Vegetation managers encourage biodiversity of wildflower species, particularly the use of native plants. The diverse plant species in TxDOT roadsides creates habitat corridors beneficial to many species of pollinators and other animals. Habitat corridors can help connect fragmented habitat in urban and agricultural areas.

The diverse vegetation on TxDOT roadsides supports several species of pollinators, including honeybees that are important to agricultural sustainability. Through education, adjacent land owners have also learned that there are economic benefits to allowing vegetation biodiversity on their lands. For example, some ranchers with high quality habitat have found that they are making money by allowing access to their lands to birders and other ecological enthusiasts.

One of the native plants that benefits the most from TxDOT vegetation management practices is milkweed. This is important for monarch butterflies, a species that has seen a 90% decline since 1990, largely due to a decline in milkweed. Monarch butterflies migrate north from their overwintering areas in Mexico and California at the first sign of milkweed and lay their eggs on these plants, which are the sole food source for monarch caterpillars. Although there are multiple migration corridors for the monarch, perhaps the most critical migratory path of the monarch follows the area in and around the Interstate 35 corridor, which runs north-south from Laredo, Texas at the Mexican border up to Minnesota.

Outcomes

Because of TxDOT’s overall vegetation management and maintenance practices, Texas’ wildflowers have become a major tourist attraction across the State. Many ranchers offer wildflower and wildlife viewing opportunities and communities have organized festivals, arts and crafts shows, sports events, and performing arts showcases that coincide with the spring wildflower season. TxDOT also promotes wildflower tourism; Texas Highways, published monthly by TxDOT, includes annual articles about wildflower “sightings,” local events, and biological information about various wildflower species.

From an ecological perspective, grasses and wildflowers planted and/or protected through the wildflowers program have conserved water, controlled soil erosion, and provided habitats for wildlife, including pollinators, across Texas.

Conclusions

By establishing a strong and sustainable vegetation management program that specifically addresses wildflower preservation and protection, TxDOT has increased biodiversity across the State while reducing ROW mowing and maintenance costs. TxDOTs long continuing tradition and effort in this important program sets the stage for aesthetically-pleasing highway landscapes that attract tourists (who contribute to the economy) while promoting overall ecosystem health that benefits pollinators.


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