Spatial and temporal variation in Palouse Prairie bee communities

Authors: HAWSE, ANNA - University Of Idaho; GARDNER, JOEL - Washington State University; Griswold, Terry; COOK, STEPHEN - University Of Idaho

Submitted to: Western North American Naturalist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2025
Publication Date: 12/16/2025
Citation: Hawse, A., Gardner, J., Griswold, T.L., Cook, S.P. 2025. Spatial and temporal variation in Palouse Prairie bee communities. Western North American Naturalist. https://scholarsarchive.byu.edu/wnan/vol85/iss4/3/.

Interpretive Summary: Pollinators are necessary to keep flowering plants in natural areas. This is especially true when a region has largely been converted to agriculture. Such an area is the Palouse Prairie in the Pacific Norwest of the United States. Only a few fragments of the original prairie remain. Seven such fragments in good condition were studied to see what native bees were present there. The study occurred in back-to-back years, 2022 and 2023. Over 5000 bees were found on flowers in these fragments. How many bees were present differed by year, fragment, and time of year while the basic structure of the community of bees was similar across the two years. But almost a third of the bee species were only found in one of the seven prairie fragments. This study suggests that saving a variety of fragments is import to maintain the Palouse Prairie bee community.

Technical Abstract: Pollinators are vitally important for natural ecosystems. Without pollination, many plants have reduced reproductive success and persistence. As a result, there is interest in how pollinators, and bees in particular, function within ecosystems. Here we explore a highly fragmented native ecosystem, the Palouse Prairie, located in the Pacific Northwest of the United States, that demonstrates variability in biotic and abiotic factors. Seven fragments of good quality remnant Palouse Prairie were sampled across entire flowering seasons of two consecutive years, 2022 and 2023. Over the course of sampling, 5,791 bees were collected from inflorescences of Palouse Prairie wildflowers. The species diversity and community composition of bees, and network structure of plant-pollinator interactions were examined to describe the patterns of spatial and temporal variation present in prairie fragments. Bee diversity varied among collection years, sites, and within a sampling season. Community composition varied between collection years and within a sampling season, but not among sites. Network structure was stable between collection years but varied among sites and within a sampling season. Overall, there was variation in the Palouse Prairie bee community depending on the context of collection. Spatially, 30% of the bee species were detected in only one site. This variation has conservation implications as it suggests that conserving a variety of fragments and plant species may be important to protect the full scope of the Palouse bee community.