We developed a stereophotographic technique to estimate browse use by moose. We collected 30 whole plant specimens representing 4 different browse species and placed them in an outdoor compound on the campus of The University of Northern BC. We physically counted all branches on each plant and categorized them as recently browsed, browsed prior to the preceding winter, or unbrowsed. Then, we stereophotographed the plants against a white backdrop in ambient outdoor light. We viewed stereopair prints under a stereoviewer and classified them using the same method as was used in manual counting. We found that this stereophotographic technique tended to underestimate total browse removal, but allowed us to determine browse availability (the number of unbrowsed shoots) and percentage of plant shoots removed by browsing for all species examined. Of the 4 species we examined, we were able to most accurately determine the number of total browsed shoots through stereoscopy on Cornus stolonifera, Acer douglasii and Salix scouleriana while the percentage of newly browsed shoots was best determined on Betula papyrifera, A. douglasii and C. stolonifera. Our findings suggested that estimating browse supply with stereophotography is possible, whereas estimating browse use is more appropriate for some species, but not for others. With adjustments, the method may be useful in reducing field time and costs involved with spring browse surveys.
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1 January 2010
The Use of Stereoscopic Photography to Estimate Browse Use by Large Ungulates
Roy V. Rea,
Dexter P. Hodder,
Jullanne Trelenberg,
Tracy M. O'Brien
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Northwest Science
Vol. 84 • No. 1
May 2010
Vol. 84 • No. 1
May 2010