Beaver herbivory of willow under two flow regimes: A comparative study on the Green and Yampa Rivers
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Authors: S. W. Breck, K. R. Wilson, and D. C. Andersen
Date: 2003
Journal: Western North American Naturalist
Volume: 63
Number: 4
Pages: 463-471
Summary of Methods: Willow (Salix sp.) growth and use by beavers (Castor canadensis) was examined and compared on a site on the Yampa River (a free-flowing river) and a site on the Green River (downstream of a dam, where river flow was regulated) in Colorado and Utah. Willow abundance, distribution, percent of willows cut, and biomass removal were measured at both sites.
Article Summary / Main Points: The total area of willow patches on both rivers was similar. There were more willows along the highly accessible islands in the regulated-flow river unlike the free-flowing river where the majority of willows are found along the less accessible stream sides. Beavers cut and removed more willow biomass on the regulated river than the free-flowing river possibly due to easier access to willows, slightly higher beaver density on the regulated river, and the reduced amounts of cottonwoods on the free-flowing river. Regulating river flow creates a somewhat braided stream channel compared to sinuous free-flowing rivers. The changes in the stream channel provide for willow establishment to occur along beaver accessible sites potentially leading to a potentially unsustainable increase in willow consumption.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: 34B Warm Central Desertic Basins and Plateaus 47 Wasatch and Uinta Mountains
Agrovoc Control Words: Riparian zones Willow Beavers
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: castor canadensis, beaver, foraging behavior, regulated flows, sandbar willow, salix exigua
Annotation: These findings may not be consistent along all rivers as channel type is the result of many factors including elevation, parent material, and upstream disturbance.
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