The beef and the bees: how livestock grazing affects pollinator feeding and nesting resources over time

Stevenson, Elizabeth (2023) The beef and the bees: how livestock grazing affects pollinator feeding and nesting resources over time. Masters thesis, Northern Arizona University.

Text Stevenson_2023_beef_bees_how_livestock_grazing_affects_pollinator_feed.pdf - Published Version Download (2MB)

Abstract

Livestock grazing is one of the most ubiquitous and ecologically significant disturbances on public lands in the Western U.S., with more than 250 million acres open to grazing on U.S. Forest Service and Bureau of Land Management lands (Beschta et al., 2013; Bureau of Land Management, n.d.; United States Department of Agriculture, 2017). Although numerous studies have investigated the effects of grazing on various ecosystem elements and processes, relatively few address its impacts on pollinators. Animal pollination is critical to the majority of flowering plant reproduction (Ollerton et al., 2011) as well as crop production (Klein et al., 2007). However, insect pollinators are exhibiting declines driven by climate change, pesticide use, and disease (Lebuhn et al., 2013; Pauw & Hawkins, 2011; Potts et al., 2010), with consequences not only for biodiversity but food security as well (Bauer & Sue Wing, 2016; Bauer & Wing, 2010). Leveraging a landscape-scale baseline dataset, this study assessed the effect of low-intensity grazing on pollinators via changes to floral and nesting resources on the Kaibab Plateau in northern Arizona. In July and August of 2022 we resampled selected plots within grassland and pinyon-juniper ecosystems, in both regularly grazed pastures and areas that had not been grazed for nine or more years. Analyses examined differences in vegetation and forb communities, forb abundance and diversity, soil characteristics, and ground cover across time and grazing status. Comparing baseline to current data, we found significant grazing impacts to vegetation and forb community composition as well as increased soil compaction at grazed sites. However, these effects were inconsistent across vegetation types. In addition, forb species diversity declined consistently across time, grazing status, and vegetation type, suggesting climatic shifts and grazing may be affecting pollinator habitat independently or interactively. Climate projections predict increased interannual variability and continued drier, hotter conditions, and grazing will likely continue as a widespread public land use. Implementing adaptive management strategies and pollinator-friendly grazing practices on public lands could mitigate these continued stressors and make a significant contribution to pollinator and rangeland ecosystem conservation.

Item Type:	Thesis (Masters)
Publisher’s Statement:	© Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords:	Kaibab Plateau; Livestock grazing; Pollination; Land management; Forest ecology;
Subjects:	H Social Sciences > HD Industries. Land use. Labor
NAU Depositing Author Academic Status:	Student
Department/Unit:	Graduate College > Theses and Dissertations College of the Environment, Forestry, and Natural Sciences > School of Earth Sciences and Environmental Sustainability
Date Deposited:	20 Oct 2025 17:16
Last Modified:	20 Oct 2025 17:16
URI:	https://openknowledge.nau.edu/id/eprint/6215

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