Relationships between Sitka black-tailed deer and their habitat.

Abstract

Old-growth, western hemlock-Sitka spruce forest in southeastern Alaska is an important element of the habitat of Sitka black-tailed deer. The conversion of uneven-aged, old-growth forests to even-aged, second-growth forests has generated concern about the future carrying capacity of the habitat for deer, especially where snow accumulation is common on winter ranges. Even-aged, second-growth forests produce very little forage for black-tailed deer. Young(< 20 years), open stands produce greater amounts of forage than do old-growth stands. Snow accumulates to greater depths in openings than in forest, however, and forage becomes unavailable to deer as it is buried in snow. Habitat quality for Sitka black-tailed deer must be viewed as an energy benefit-cost relation. Energy intake decreases and energy expenditure increases as snow depth increases. Habitats differ in their canopy characteristics and in the amount and kind of forage they produce. The relative qualities of habitats shift with changing snow conditions. An understanding of these dynamic relationships between deer and their habitat is essential for developing management objectives for deer habitat. The current theory is largely qualitative and lacks the ability to yield unambiguous, quantitative predictions. Research is needed to quantify the key relationships between forest canopy and understory production and snow interception, and between the metabolic requirements of deer and the nutritional quality of available forage.