Creating Pollinator Habitat Along Roadsides

Winslow Way, Bainbridge Island, WA / image: Alexandra Hay

Below, you’ll find a re-post from Entomology Today of “Study Finds Bees Can Have Their Wildflowers and Almonds, Too” by Josh Lancette—a timely subject, with Pollinator Week later this month and an ASLA Online Learning webinar on the topic, Creating Pollinator Habitat Along Roadsides, coming up on June 14 hosted by the Transportation PPN.

The post discusses the use of wildflower planting strips adjacent to almond orchards in California. While at first blush it might appear that this practice has little to do with transportation, keep in mind that millions of miles of rural roadways are adjacent or proximate to agricultural fields. Furthermore, Section 130 of the Surface Transportation and Uniform Relocation Assistance Act of 1987 (STURAA) added a requirement that native wildflower seeds or seedlings or both be planted as part of any landscaping project undertaken on the federal-aid highway system. This requirement is mandatory and applies only to federal funded landscaping projects. One quarter to one percent of funds used for landscaping projects must be used to plant native wildflowers.

Other federal initiatives promoting the use of native wildflower plantings exist. USDA’s Natural Resources Conservation Service (NRCS) defines a field border as a “strip of permanent vegetation established at the edge or around the perimeter of an agricultural field.” The practice is used, among other things, to provide pollinator habitat and to manage agricultural pest populations. Field borders assist with agricultural pest management by providing habitat to beneficial organisms or as a place for agricultural pests to congregate. When field borders are designed for pollinator habitat, they have been shown to facilitate pollination services to agricultural crops. A properly designed field border provides nectar and pollen sources for pollinators when the target crops are not in bloom. This practice is currently being used in Michigan, where “flowering plant strips” increase crop productivity through the support of beneficial insects and pollinators.

Landscape architects engaged in planting roadside vegetation must be thoughtful. Selecting plant material so the crops are not harmed (e.g. plum pox virus, which attacks stone crops) but are benefited should be an integral part of the planting program.

Resources

1998 Revised Guidance for the Native Wildflower Planting Requirement, FHWA Environmental Review Toolkit: Roadside Use of Native Plants

Michigan Researchers Use Flowering Plant Strips to Support Beneficial Insects and Increase Crop Productivity, North Central Sustainable Agriculture Research and Education

Establishing Wildflower Pollinator Habitats in Agricultural Farmland to Provide Multiple Ecosystem Services, Frontiers in Plant Science

Wildflowers Benefit Agricultural Operations, Ecosystems, USDA Natural Resources Conservation Service

Wildflower plantings enhance the abundance of natural enemies and their services in adjacent blueberry fields, Biological Control

Conservation Practice Standard: Field Border, Code 386, USDA Natural Resources Conservation Service

image: Alexandra Hay

Study Finds Bees Can Have Their Wildflowers and Almonds, Too

Originally published April 4, 2017, on the Entomology Today blog. Copyright 2017, Entomological Society of America, Annapolis, Maryland. Republished with permission.

New research published this week in the journal Environmental Entomology shows that planting wildflowers next to almond orchards does not cause fewer honey bees to visit the orchard. This finding is important because it shows wildflower plantings can help keep bee populations healthy while also not harming almond crops.

“Establishing flowering field-edge plantings has gained popularity as a strategy to mitigate the threats that bee pollinators face in intensively managed agricultural landscapes,” says Ola Lundin, Ph.D., one of the researchers and an author on the paper. “The basic idea is simple: to provide more flowers for bees. Flower plantings can potentially affect pollinator visitation rates in neighboring crops both positively by supporting pollinator populations and attracting them to crops or negatively by distracting them from crops. Growers and practitioners are often understandably concerned that alternative forage blooming concurrently with the focal crop might compete for pollinators and negatively affect crop yield.”

While the concern that wildflowers would pull valuable pollination services away from almond crops is understandable, the study suggests that almond growers can put this particular concern aside. While honey bees (Apis mellifera) did visit the wildflowers, it didn’t detract from the number of bees visiting the almonds. But how can this be?

“We suggest two explanations as to why the wildflowers and almond might not compete for honey bee visits,” says Lundin. “One is that wildflower plantings might increase bee foraging activity overall—crop and non-crop visitation combined—such that visitation to non-crop plants in the borders increases when wildflower plantings are added without affecting crop visitation. The second explanation is that the loss of foragers from the crop to the wildflower plantings might be negligible because the crop resource is large relative to the non-crop resource.”

Planting wildflowers next to almond orchards might also be good for the bees.

“The high honey bee visitation rates to the flower plantings suggest benefits of wildflower plantings for honey bees,” said Lundin. “Such benefits may include the ability to support or increase bee population sizes before and after almond bloom and increased resistance to harmful effects of pesticides and pathogens through a more diverse diet.”

Interestingly, wild bees were rarely found visiting the almond orchard, regardless of whether wildflowers were planted or not, a finding that Lundin said indicated “a limited potential for augmenting crop pollination using wild bees in the highly simplified agricultural landscape where we performed the study.”

by Josh Lancette, manager of publications at the Entomological Society of America

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