. The Canadian field-naturalist. 192 The Canadian Field-Naturalist Vol. 90. Table i—Species composition of forest stand with tree damage, Abitibi County, Quebec, 1970 Relative frequency (9c) of all trees Figure 1. Base of mature spruce tree with bark damage, west of Duparquet. Quebec. 23 June 1970. My first thought was of vandaHsm by humans, but the extent of damage that emerged made this explan- ation highly improbable. Black bears (Ursus ameri- canus) are known to cause damage to conifers on a scale comparable to that found (cf. Poelker, R. J. and H. D. Hartwell. 1973. Black bear of Washingt
. The Canadian field-naturalist. 192 The Canadian Field-Naturalist Vol. 90. Table i—Species composition of forest stand with tree damage, Abitibi County, Quebec, 1970 Relative frequency (9c) of all trees Figure 1. Base of mature spruce tree with bark damage, west of Duparquet. Quebec. 23 June 1970. My first thought was of vandaHsm by humans, but the extent of damage that emerged made this explan- ation highly improbable. Black bears (Ursus ameri- canus) are known to cause damage to conifers on a scale comparable to that found (cf. Poelker, R. J. and H. D. Hartwell. 1973. Black bear of Washington. Washington State Game Department, Biological Bulletin 14. 180 pp.). But photographs in that publication and others by Bob Hatcher (of Centre de recherches forestieres des Laurentides, Quebec, Que- bec) show a different pattern to that found, with the tree trunks usually completely stripped of bark for 1 to 2 m above the base, and with the cambium layer under the bark sometimes chewed or clawed. Reports of bear damage to conifers may be widespread as a result of continued activity over an extended period. The damage I found apparently had occurred entirely within the 10 days since my last visit to the plot. While bear damage might be thus concentrated, at the time of a major sap flow, for example, I believe that the evidence available points to a violent wind storm as a ^ i cm dbh' ^ cm dbh Balsam fir 64 48 Black spruce 19 21 Paper birch 5 \ 12 \ Balsam poplar Trembling aspen 5 j 2 1 ) 17 6 [ 8 ( Others 5 1 5 1 ' = diameter height. more plausible explanation. It seems possible that the bark of the large spruces burst when the trees were bent or twisted by a sudden squall, as a fat man might burst his suspenders by bending over too abruptly. Only the largest trees (diameter > 25 cm) were damaged, and these taller veterans would have been most exposed to the full force of a squall. Additional evidence for damage by a wind storm included a few large tr
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