Short-term responses of aspen to fire and mechanical treatments in interior Alaska

Fire suppression and limited timber markets presently hinder maintenance of the early successional broad-leaved forest for wildlife habitat near settlements in interior Alaska. During 1999-2003, we evaluated the efficacy of prescribed burning, felling, and shearblading (with and without debris removal) to regenerate quaking aspen (Populus tremuloides). Treatments were conducted largely during the dormant period for aspen: prescribed burns in mid-May and mechanical treatments in late August through early April. Prescribed burns on loess hills produced 40,900-233,000 stems/ho by the second growing season. Low relative humidity, slope of more than 100, southerly aspect, and juxtaposition to open areas produced fire behavior adequate to ensure top killing and vigorous sprouting response. Felling by chainsaw on loess hills produced 34,800-89,800 stems/ho, whereas dozer shearblading on glacial outwash (loam over gravel) produced 74,200-209,200 stems/ha (cleared portions and windrows combined) and a sandy loam floodplain produced 31,400-64,800 stems/ha. Pushing debris into windrows or scraping thick moss allowed wormer soils and produced greater sprouting on cleared sites relative to sections where debris or moss remained. Mechanical treatments were 25-75% of current prescribed fire costs, but debris accumulation may hinder access by browsing species and attract terrestrial predators of gallinaceous birds.