Forest Cover and Snow: Implications for Deer Habitat in Southeast Alaska

Abstract

Relationships between snow depth and overstory characteristics were studied on 19 0.4-ha oldgrowth plots and 1 60-year-old 0.4-ha 2nd-growth plot near Juneau during winter, 1983-84. Mean tree diameter at breast height (dbh), number of stems/ha, percent Sitka spruce (Picea sitchensis), mean tree height, percent timber defect, basal area, and net timber volume were measured using variable plot and point-centered quarter techniques. Canopy cover was measured from photographs of the overstory taken at each snow measurement point. Snow depth in a high-volume plot (>100,000 board feet/ha) averaged 29% of that in an adjacent forest opening. Snow depth was correlated with net timber volume (r, = -0.90), tree height (r, = -0.85), basal area (r, = -0.79), percent canopy cover (r, = -0.76), percent spruce (r, = -0.66), and mean tree diameter (r, = -0.65). Old-growth plots with high net timber volume had the lowest snow depths. The low snow depths observed in high-volume, old-growth stands are attributed to the large-diameter limbs and deep crowns of older, dominant trees. J. WILDL. MANAGE. 51(1):28-33 Snow is an important component of the winter and early spring environment of Sitka blacktailed deer (Odocoileus hemionus sitkensis) in southeast Alaska. Snowfall reduces the availability of forage, increases the energetic costs of locomotion, and influences deer habitat selection and survival (Edwards 1956, Klein and Olson 1960, Parker et al. 1984). Correlations between overstory characteristics and snow depth beneath the canopy can aid wildlife managers in identification of valuable oldgrowth winter range for deer and may suggest silvicultural treatments to enhance the snowinterception qualities of even-aged, 2nd-growth stands. Our objectives were to develop relationships between snow depth and forest stand characteristics across a broad range of oldgrowth types in southeast Alaska and to compare snow depth in the open to snow depth in the forest, and in old-growth vs. 2nd-growth stands. This study was conducted in the winter of 1983-84 by the Alaska Dep. Fish and Game, as part of Fed. Aid Wildl. Restor. Proj. W-22. We thank R. W. Flynn, J. W. Matthews, and M. H. Thomas for field assistance during this project. P. B. Alaback, A. S. Harestad, D. E. McKnight, R. S. McNay, and S. R. Peterson provided helpful review comments on the manuscript.