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Influence of topographic,geomorphic, and hydrologic variables on beaver dam height and persistence in the intermountain western United States |
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| Authors: | Konrad C Hafen Joseph M Wheaton Brett B Roper Philip Bailey Nicolaas Bouwes |
| Institution: | 1. Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, UT, 84322-5210 USA;2. Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, UT, 84322-5210 USA
National Stream Aquatic Ecology Center, U.S. Forest Service, 860 North 1200 East, Logan, UT, 84321 USA;3. Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, UT, 84322-5210 USA North Arrow Research, Inc., Vancouver, British Columbia, Canada;4. Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, UT, 84322-5210 USA Anabranch Solutions, LLC, P.O. Box 579, Newton, UT, 84327 USA Eco Logical Research, Inc., P.O. Box 706, Providence, UT, 84332 USA |
| Abstract: | Stream ecosystems can be dramatically altered by dam-building activities of North American beaver (Castor canadensis). The extent to which beavers’ ecosystem engineering alters riverscapes is driven by the density, longevity, and size (i.e. height and length) of the dams constructed. In comparison to the relative ubiquity of beaver dams on the landscape, there is a scarcity of data describing dam heights. We collected data describing dam height and dam condition (i.e. damaged or intact) of 500 beaver dams via rapid field survey, differentiating between primary and secondary dams and associating each dam with a beaver dam complex. With these data, we examined the influence of beaver dam type (primary/secondary), drainage area, streamflow, stream power, valley bottom width, and HUC12 watershed on beaver dam height with linear regression and the probability that a beaver dam was damaged with logistic regression. On average, primary dams were 0.46 m taller than secondary dams; 15% of observed dams were primary and 85% secondary. Dam type accounted for 21% of dam height variation (p <0.0001). Slope (p = 0.0107), discharge (p = 0.0029), and drainage area (p = 0.0399) also affected dam height, but each accounted for less than 3% of dam height variation. The average number of dams in a dam complex was 6.1 (SD ± 4.5) and ranged from 1 to 21. The watershed a beaver dam was located in accounted for the most variability (17.8%) in the probability that a beaver dam was damaged, which was greater than the variability explained by any multiple logistic regression model. These results indicate that temporally dynamic variables are important influencers of dam longevity and that beaver dam ecology is a primary factor influencing beaver dam height. © 2020 John Wiley & Sons, Ltd. |
| Keywords: | beaver beaver dams spatial analysis ecogeomorphology stream restoration |