2020 ESA Annual Meeting (August 3 - 6)

PS 66 Abstract - Effects of low intensity fall grazing on a plant-pollinator community in the Columbia River Gorge, WA

Rebekah L. Gaxiola and John Bishop, School of Biological Sciences, Washington State University, Vancouver, WA
Background/Question/Methods: Dalles Mountain Prairie is a former working cattle ranch now part of Columbia Hills State Park located in the Columbia River Gorge, Washington State. In 2008, Washington State University Cooperative Extension began a rehabilitation research project using low intensity, rotational fall grazing. The primary goal of the research project has been to increase biological diversity of the native plant community in the prairie, which is dominated by an introduced wheatgrass cultivar but contains a high number of valuable native plant species. In 2019, we implemented a pollinator monitoring protocol to assess the impact of the grazing treatments on pollinator communities in the prairie. We aimed to answer the question: how does grazing impact floral resource and pollinator abundance and diversity? We established focal transects in grazed and ungrazed cultivated pasture, and supplementary transects in uncultivated patches within each grazing treatment, and in nearby remnant prairie. We conducted both hand-netting surveys and bee bowl surveys to measure pollinator abundance and diversity, and quantified floral resource abundance and diversity within each transect.

Results/Conclusions: We found that pollinator abundance and diversity did not differ between the grazed and ungrazed pastures, but floral abundance and diversity was higher in the grazed pastures. This suggests grazing increases floral resources for pollinators, and that pollinators are actively searching for resources in the ungrazed pasture although there are fewer resources. Grazing as a conservation tool is still a new frontier, and understanding how plant-pollinator communities as a whole respond to this restoration technique is critical for advancing the field of ecological restoration.