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NALDC Record Details:
Is differential use of Juniperus monosperma by small ruminants driven by terpenoid concentration?
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We examined the relationship between volatile plant secondary metabolite concentrations and Juniperus monosperma herbivory by small ruminants. Two groups of animals (10 goats or 5 goats plus 4 sheep) browsed 16 paddocks (20 x 30 m) containing one-seed juniper for six days during two seasons. Juniper leaves were sampled from 311 saplings on the same day they were browsed. Saplings were categorized by size (short [< 0.5 m], medium [0.5-1.0 m] or tall [> 1.0 m]) and browsing intensity (light [<33%], moderate [33-66%] or heavy [>66%]). Juniper bark was also collected from 12 saplings during spring. Total estimated terpenoid concentrations in leaves and bark were 18.3 ± 0.3 and 8.9 ± 0.8 mg/g, respectively, and the dominant terpene in both tissues was a-pinene (11.1 ± 0.2 and 7.6 ± 0.7 mg/g, respectively). Total terpenoid concentration was greater in spring than summer (20.6 ± 0.5 vs. 16.7 ± 0.3 mg/g, respectively) and lower in short saplings than medium or tall saplings (16.5 ± 0.6 vs. 19.8 ± 0.4 and 19.5 ± 0.4 mg/g, respectively). Total concentration also differed among the three defoliation categories (16.1 ± 0.4, 18.7 ± 0.5, and 21.2 ± 0.6 mg/g for heavy, moderate, and light, respectively). The smallest subset of terpenes able to discriminate between heavy and light browsing intensity categories included eight compounds ([E]-ß-farnesene, bornyl acetate, y-eudesmol, endo-fenchyl acetate, y-cadinene, a-pinene, cis-piperitol, and cis-p-menth-2-en-1-ol). Our results suggest terpenoid concentrations in one-seed juniper are related to season, sapling size, and browsing by small ruminants.
R. E. Estell
S. A. Utsumi
A. F. Cibils
D. M. Anderson
USDA Scientist Submission
Journal of chemical ecology 2014 v.40
Journal Articles, USDA Authors, Peer-Reviewed
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
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