By Amy Grotta, OSU Forestry & Natural Resources Extension – Columbia, Washington & Yamhill Counties

A bumblebee on a lavender flower. Photo credit: David Cappaert, bugwood.org.

The health of insect pollinators is an issue of increasing concern and attention.  Both managed bees (honeybees) and native bees face various threats, including diseases, chemical use, and loss of suitable habitat. While pollinators can include other insects (flies, butterflies, etc.), bees are considered some of the most important. Without healthy bee populations, many flowering crops we humans depend on would not flourish; and native ecosystems that other animals depend on would be impaired.

Because many individuals and organizations are interested in protecting and conserving bees in Oregon, the Oregon Bee Project came into being in order to be a clearinghouse of information, a facilitator of bee conservation and education initiatives. Last week the Oregon Bee Project hosted the PNW Pollinator Summit in Corvallis, a two-day conference designed to bring together researchers, Extension, non-profits, and other groups that are involved in pollinator conservation. I got to attend and was especially interested in the presentations and field trip focused on forests and forestry.

Dr. Jim Rivers, a professor in OSU’s College of Forestry, and Dr. Sara Galbraith, a post-doctoral researcher affiliated with his lab, are really at the forefront of forest pollinator research in Oregon. At the Pollinator Summit, they shared some recent research findings and ongoing projects:

It turns out that many of Oregon’s ~800 species of native bees live in forests. However, we are just beginning to learn about their populations and their roles in forest ecosystems. The goal of current research is to understand more about the role that forests play in supporting native bee populations.

A female bee in the Andrena genus digging a nesting burrow in the ground. Photo: Whitney Cranshaw, Colorado State University, bugwood.org.

One of their main messages was that recently harvested areas are especially important for native bees. Although many people might look at a clearcut and think it devoid of habitat value, the research indicates otherwise. It makes sense when you think about it – open areas such as clearcuts have an abundance of flowering plants, providing bees with a food source (pollen and nectar). Moreover, these areas also provide ideal nesting sites for bees.  Many native bees are ground nesters that create burrows in the soil. Areas with exposed mineral soil are the best nesting sites, and that exposed soil can be found along roadbeds and places where slash has been removed or burned.

Other bees nest in wood cavities, which may be found in down wood, stumps, and snags.  Then, there are those that like to hollow out pithy stems such as blackberry or elderberry stems and nest in there.

Preliminary studies suggest that the window during which native bees proliferate in recent clearcuts seems to be relatively narrow. Soon, new trees begin to dominate the vegetation, there is less sunlight, and flowering plant abundance drops off. But there are still many questions to be answered, including whether and how forest managers can adopt specific practices to protect and enhance bees. We also don’t know to what extent bees utilize older forests.

Many small woodland owners would like guidance on what they can do to manage their forests for pollinators. We’re not at the point where we can offer specific guidance yet, but that is certainly a goal. In the meantime, we can talk about broad bee-friendly guidelines, such as maintaining nesting habitat (see above) and floral resources.

And, soon we will have some research and demonstration sites! A few OSU Extension agents, myself included, are working with the Oregon Department of Forestry and the Oregon Bee Project to install bee monitoring and demonstration plots. I have several sites that I will be monitoring at the Matteson Demonstration Forest in Washington County, including two areas that were harvested last summer and the future site of a pollinator hedgerow.

Left: Christine Buhl, ODF Forest Entomologist helping to lay out a test plot to be sown with a pollinator forage seed mix at Matteson Forest, January 2019. Right: the area where a slash pile was burned has lots of exposed mineral soil which is ideal for ground nesting bees.

I’m excited to be joining the bee bandwagon. Not only do I have a new reason to get out in the field on a regular basis, but I also get to learn about collecting and identifying bees, something I knew absolutely nothing about going into this project. Fortunately, the Oregon Bee Project has fantastic resources available to help us with that, and some of their trained Oregon Bee Atlas volunteers will be helping. Stay tuned to this blog, because I’ll be sharing updates on our project over the course of the year.

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