Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub
    Author(s): Richard E. Miller; Harry W. Anderson; Donald L. Reukema; Timothy A. Max
    Date: 2007
    Source: Res. Pap. PNW-RP-571. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 29 p
    Publication Series: Research Paper (RP)
    Station: Pacific Northwest Research Station
    PDF: Download Publication  (1.17 MB)


    Incidence and effects of tree damage by black bear (Ursus americanus altifrontalis) in a 50-year-old, coast Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) plantation are described. Bears girdled or partially girdled 35 dominant or codominant Douglas-fir trees per acre, but only in that portion of the plantation that had been interplanted at age 4 with red alder (Alnus rubra Bong). No red alder were damaged. Bears damaged Douglas-fir in this stand on at least four occasions between 1929 (planting) and 1991. Fully girdled Douglas-fir (six per acre in 1976) died within 2 to 14 years. Of the 29 per acre partially girdled trees, 17 percent died in the 16 years of observation, compared to 9 percent of nondamaged trees. Cross-sectional growth of surviving damaged trees exceeded that of matched, nondamaged trees by about 30 percent at three heights on the bole: 6 ft, 4.5 ft, and immediately above the damaged area. Death of six large Douglas-fir trees per acre reduced live stand volume of this species for about 6 years after bear damage until growth of the remaining trees compensated for the volume lost to mortality. Confirmation of the stimulating effects of bear damage on subsequent tree growth is needed at other locations.

    Publication Notes

    • Visit PNW's Publication Request Page to request a hard copy of this publication.
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    Miller, Richard E.; Anderson, Harry W.; Reukema, Donald L.; Max, Timothy A. 2007. Growth of bear-damaged trees in a mixed plantation of Douglas-fir and red alder. Res. Pap. PNW-RP-571. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 29 p


    Google Scholar


    Black bear, Ursus americanus altifrontalis, bear damage, Douglas-fir, tree growth, tree mortality.

    Related Search

    XML: View XML
Show More
Show Fewer
Jump to Top of Page