Encouraging pollinator activity at Scatter Creek Rest Area

National Pollinator Week a great time to check in on progress being made

By Ann Briggs

A couple years ago, we talked about our integrated vegetation management program as a way of helping pollinators and encouraging a healthier ecosystem around our state highways.

One of the projects we highlighted at that time was our work around the Scatter Creek Rest Area on I-5 north of Centralia. By limiting mowing operations, we let native plants return to form a meadow, providing habitat for native pollinators unique to that ecosystem.
Solitary bees have been one of the main pollinators we’ve observed at the Scatter Creek Rest Area.

With National Pollinator Week June 17-21, it's a good time to check in on the progress.

In September 2018, we planted 39 species of native plants in three seed mixes, with species overlap among the mixes. Our goal is to evaluate seed mixes and site preparation treatments to determine which mix will establish pollinator-friendly plant cover for use on roadsides and at construction sites.
Left: A hover fly finds a good spot to check out near the I-5 Scatter Creek Rest Area. Right: Empid flies like this have been a frequent visitor to the meadow area near the Scatter Creek Rest Area.

We had a relatively cold spring in 2019, followed by an unusual warm and dry period in April when some of these plants were beginning to germinate. As of late May, at least 10 species of plants had germinated from the seed mixes – some were not yet at a stage where we could identify the species. Within the 29 test plots, we identified 35 plants in total, including 10 native plant species from the seed mixes, which indicates there are still many seeds remaining from prior plants despite our efforts to remove them. The most common species from the seed mixes were Roemer's fescue (Festuca roemeri), giant blue-eyed Mary (Collinsia grandiflora), and lupine (Lupinus bicolor).
By limiting our mowing to encourage growth of native plans, we’re working to produce a healthier
ecosystem for pollinators at the rest area near Scatter Creek along I-5.

The majority of pollinators we observed are "generalists" visiting any flowers that are available. As one species of plant blooms out, the pollinators switch to other species that are beginning to bloom. We also observed shifts in the abundance and diversity of pollinators over time. In late May, the dominant pollinator groups were solitary bees, hover flies, and empid flies. In mid-June, dominant pollinator groups were honeybees, solitary bees, and hover flies.

This is important work that our environmental team is doing. Evaluating this and other areas will take some time but we're committed to helping encourage healthy ecosystems for pollinators as part of our roadside management program. We will continue to measure both plant and pollinator activity throughout the summer.

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