Measuring and monitoring pollinator diversity along elevation gradients in Olympic and North Cascades National Parks

Rykken, Jessica

Insect pollinators, specifically bees and syrphid flies, are critical to maintaining functioning ecosystems. Despite their ecological importance and vulnerability to threats such as climate change, many of these pollinators remain unknown in Olympic and North Cascades National Parks. To address this knowledge gap, I conducted a pollinator survey in 2014 with three main objectives: (1) to document and compare the diversity and distribution of bees and syrphid flies in selected habitats along elevation gradients in both parks; (2) to develop protocols and suggest permanent sites for continued monitoring of these pollinators; and (3) to educate park staff and visitors about pollinators and threats to their health. Between June 28th and September 17th, 2014, I and several park staff and volunteers used insect nets and bee bowls to collect pollinators at 28 sites in North Cascades and 58 sites in Olympic, ranging in elevation from sea level to more than 2,000 m. We targeted areas of high floral diversity, including trails and roadsides, subalpine meadows, and edges of waterbodies. In all, we collected 1,890 bees and 298 syrphid flies across the two parks; these comprised 89 and 57 taxa, respectively. The dominant genus of bees in both parks was Bombus, comprising 14 species overall and 45% of the bee catch. Habitats above and below tree line shared 36-43% of their combined pollinator species in both parks, and while more taxa were collected in higher elevation habitats due to more intensive sampling, extrapolated rarefaction curves suggest that taxa richness may be as high or higher below tree line if sampling efforts were equal. Several species of bees and syrphid flies were strongly associated with higher elevations. Detailed sampling protocols were developed and permanent sites were suggested for future pollinator monitoring efforts. Park visitors, volunteers, and staff learned about insect pollinators through field trips, slide presentations, and a show-and-tell microscope session in a visitor center.

Measuring and monitoring pollinator diversity along elevation gradients in Olympic and North Cascades National Parks

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