Density and size of snags, tree cavities, and spruce rust brooms in Alaska boreal forest

Abstract

To forecast the potential effects of forest management on wildlife habitat, I surveyed late-seral features in boreal forest near Fairbanks, Alaska. I sampled 75 randomly selected plots stratified among nine stand types to count and recorded physical characteristics of snags, cavity trees, and Picea spp. trees with rust brooms. Snag density differed among some stand types (range, x̄ = 10 -72/ha) and increased with mean age of stand type, whereas cavity density (2-17/ha) and broom density (3- 46/ha) showed no trend with stand age. Only 15% of 199 cavity openings were large enough (>50 cm2) and had a shape (width:height ratio, 0.5-1.5) that made them likely to be suitable for use by larger birds or arboreal mammals. The oldest and most valuable stand type for timber harvest (Picea glauca >23 cm dbh) often had trees with larger cavity openings and larger broom volumes than trees in other types. I recommend retention of rare specimens of late-seral features, considerations for feature recruitment in managed forests, and further documentation of wildlife use and associated fitness. Copyright © 2010 by the Society of American Foresters.