Grizzly bears and forestry II. Distribution of grizzly bear foods in clearcuts of west-central Alberta, Canada

摘要

We assessed the occurrence and fruit production of 13 grizzly bear foods in west-central Alberta, Canada. to better understand use of clearcuts by grizzly bears. Comparisons were made between clearcuts and upland forest stands, while specific models describing food or fruit occurrence within clearcuts were developed from canopy, clearcut age, scarification, and terrain-related variables using logistic regression. Ants, Equisetum spp., Hedysarum spp., Taraxacum officinale, Trifolium spp., and Vaccinium myrtilloides occurred with greater frequency in clearcuts, while V. caespitosum, V. membranaceum, and V. vitis-idaea were more likely to occur in upland forests. No differences were evident for Arctostaphylos uva-ursi, Heracleum lanatum, Shepherdia canadensis, and ungulate pellets, an indicator of ungulate abundance. Mechanical scarification negatively impacted the occurrence of A. uva-ursi, Hedysarum spp., and S. canadensis, while weaker effects were apparent for ants and ungulate pellets. In contrast, the occurrence of Taraxacum officinale and Trifolium spp. were greater in scarified clearcuts. Age of clearcut or canopy cover was well correlated with the occurrence of most foods. For some species, however, terrain-derived variables predicted occurrence best. Fit and model classification accuracy using independent data proved good for most species.