Litter Fall and Nutrient Cycling in the Forest Floor of Birch and Aspen Stands in Interior Alaska

Abstract

During a 4-year period the biomass and mass of selected chemical elements were measured in litter fall from young, intermediate, and mature age classes of quaking aspen and paper birch in interior Alaska.Average annual deposition of biomass and mass of Mg, Fe, and Mn were consistently greater in birch than in aspen stands of similar age. Mass of Ca was consistently greater in aspen stands (range 4.02 to 4.80 g m⁻²) than in birch stands (3.18 to 3.45 g m⁻²) regardless of age class. Trends in mass of chemical elements returned to the forest floor in litter fall were generally reflected in the average percentage composition of the organic matter.Turnover time for forest-floor biomass was about the same for both the 50- and 120-year age classes of birch (16.7 years) and of aspen (12.7 years to 13.0 years). For both species Fe had the maximum turnover time in the forest floor (167 to 280 years), with K (6.9 years to 9.7 years) and Zn (5.5 years to 11.6 years) having minimum times.Linear correlations between biomass and mass of selected nutrient elements in litter fall provide an efficient means of conducting short- and long-term assessments of differences in nutrient content of litter within and between forest vegetation types.