Date of Award
Spring 2026
Rights
Access is available to all users
Document Type
Thesis
Degree Name
Master of Science (MS) in Biology
Department
Biology
First Advisor
Dr. Justin Bastow
Second Advisor
Dr. Rebecca Brown
Third Advisor
Dr. Stacy Warren
Abstract
Prairie ecosystems in eastern Washington have been severely degraded due to agricultural intensification, urbanization, and habitat fragmentation, leaving less than 0.1% of native prairie intact. As a result, these ecosystems have become some of the most endangered in the United States. One group of essential pollinators is the bees, which facilitate plant reproduction and contribute to the long-term persistence of restored plant communities. However, despite the presence of at least 257 native bee species in the region, the impacts of habitat fragmentation and restoration on pollinator activity and plant-pollinator networks remain poorly understood. For this study, we worked across Eastern Washington in restored and remnant sites with native prairie plant communities. We selected native forb species to document pollen limitation. Three treatments were conducted for each species: ambient pollination, pollinator exclusion, and hand pollination. None of the species showed signs of pollen limitation, but three of the four species were found to significantly reduce their reproductive output when pollinator visitation was prevented. The findings indicated that pollen may not be a limiting factor in reproduction, but insect-mediated pollination is important for prairie species to reproduce and establish new populations. Bee community analysis tests were done using bee bowl trapping across three treatment groups natural, degraded, and restoration sites. Across all sites Halictidae was a dominant family, however the EWU restoration site and degraded sites support a more generalist disturbance tolerant Apidae community, while our natural sites were supporting higher stem nesting Megachilidae species. These findings suggest further understanding of disturbance on bee community composition.
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Recommended Citation
Torres, Alejandro, "Are There Enough Bees? Assessing Pollen Limitation in Native Eastern Washington Prairie Forbs" (2026). EWU Masters Thesis Collection. 1011.
https://dc.ewu.edu/theses/1011
