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ARS Home » Pacific West Area » Logan, Utah » Forage and Range Research » Research » Publications at this Location » Publication #334427
Title: Short-term regeneration dynamics of Wyoming big sagebrush at two sites in northern Utah

Author
item GERMAIN, SARA - Utah State University
item MANN, REBECCA - Utah State University
item Monaco, Thomas
item VEBLEN, KARI - Utah State University

Submitted to: Western North American Naturalist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2017
Publication Date: 1/1/2018
Citation: Germain, S.J., Mann, R.K., Monaco, T.A., Veblen, K.E. 2018. Short-term regeneration dynamics of Wyoming big sagebrush at two sites in northern Utah. Western North American Naturalist. 78:7-16.

Interpretive Summary: The herbicide tebuthiuron has been used historically to control cover of Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis - complete taxonomic designation), a widespread shrub across the western United States, with the intent of increasing herbaceous plant cover. Although the tebuthiuron is known to reduce mature shrub cover, limited information exists regarding its effect on early life stages of sagebrush. We measured sagebrush seeding emergence from seed rain traps and seed bank samples in plots treated with tebuthiuron at a relatively low application rate (2.8 kg - ha-1) and untreated control plots in northeastern Utah. We also examined densities of dead sagebrush and three size classes (small, medium, large) of live sagebrush in treated vs. control plots, one and two years post-tebuthiuron treatment. Results indicate that tebuthiuron reduced sagebrush seedling emergence from seed rain, but not the seed bank. We also found that tebuthiuron reduced densities of large sagebrush plants but increased medium sagebrush plants, likely due to competitive release of small shrubs following mortality of the large shrubs. These results suggest that low rates of tebuthiuron do not reduce small sagebrush recruitment, but do alter its demography by increasing structural and life stage heterogeneity.

Technical Abstract: The herbicide tebuthiuron has been used historically to control cover of Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis - complete taxonomic designation), a widespread shrub across the western United States, with the intent of increasing herbaceous plant cover. Although the tebuthiuron is known to reduce mature shrub cover, limited information exists regarding its effect on early life stages of sagebrush. We measured sagebrush seeding emergence from seed rain traps and seed bank samples in plots treated with tebuthiuron at a relatively low application rate (2.8 kg - ha-1) and untreated control plots in northeastern Utah. We also examined densities of dead sagebrush and three size classes (small, medium, large) of live sagebrush in treated vs. control plots, one and two years post-tebuthiuron treatment. Results indicate that tebuthiuron reduced sagebrush seedling emergence from seed rain, but not the seed bank. We also found that tebuthiuron reduced densities of large sagebrush plants but increased medium sagebrush plants, likely due to competitive release of small shrubs following mortality of the large shrubs. These results suggest that low rates of tebuthiuron do not reduce small sagebrush recruitment, but do alter its demography by increasing structural and life stage heterogeneity.