Productivity, Population Structure, and Subsistence Use of a White Spruce Forest in the Kennicott Valley, Alaska

Abstract

The dynamics of white spruce (Picea glauca (Moench) Voss) in a sparsely populated Alaskan valley were examined for management of subsistence firewood and houselog harvest. Site index, disturbance history, current productivity, and population age structure of white spruce were determined at 26 sites on five landform units. Human residents were interviewed to characterize local harvest patterns. Site index averaged 59 and was not significantly different among landforms. Current productivity, which ranged from 0.20 to 2.22 m 3 /ha/yr, was reduced by a 5-year old spruce beetle outbreak that killed up to 42% of the standing volume in some stands. Forests consisted of even-age stands initiated by deglaciation (20% of study area), wildfire (13%), and anthropogenic fire (26%), and mixed-age stands characterized by small gap-forming disturbances (41%). The latter stands exhibited old-growth characteristics. A demographic model based on age-structure in the old-growth stands showed that current recruitment was too low to maintain current tree density under conditions of natural mortality, and that removal of live trees by selective harvest or beetle outbreaks will diminish tree density. Current annual firewood demand of 61.5 cords/year is adequately supplied by beetle-killed spruce, but demand for live trees will rise as beetle-killed trees decay and become unusable. Small community woodlots are suggested as a sustainable alternative to selective harvest.