PARENT SESSION
Poster Session 37: Forest Ecology.

Thursday, August 5 Presentations from 5:00 PM to 6:30 PM, Exhibit Hall A 1.

Is western hemlock dwarf mistletoe a keystone resource for insects in Pacific Northwest old-growth forests?

French, Jennifer^*,1, ¹ University Of Washington, Seattle, WA, USA

ABSTRACT- Dwarf mistletoes, parasitic angiosperms that infect coniferous trees throughout the Western United States, may have keystone functions because they facilitate old-growth forest structural diversity and provide essential wildlife habitat. At the Wind River Canopy Crane Research Facility, I investigated whether western hemlock dwarf mistletoe (Arceuthobium tsugense) has keystone functions for insects within old-growth forests by providing essential pollen and nectar resources. Over the course of the dwarf mistletoe flowering season, I observed visitors to dwarf mistletoe flowers and sampled the insect community within the upper canopy. The number of floral visitors peaked at prime dwarf mistletoe flowering, suggesting that the insects are tracking the floral resource availability. These data, along with phenology data of other flowering species, indicates that western hemlock dwarf mistletoe is the sole source of nectar and pollen within old-growth forests during the late summer. These results argue for treating dwarf mistletoe as a key resource for the northern forest biological community rather than as a forest pest.

Key words: keystone species, insect, dwarf mistletoe, canopy