the objectives of this study were 1) to provide information on the above ground biomass production of young jack pine (pinus banksiana lamb.) stands, and 2) to evaluate the influence of crown foliage stand density, and age on the net current annual wood production of young jack pine trees and stands. two naturally regenerated jack pine stands, 17- and 32-years old, were selected for study near thunder bay, ontario, in each stand, one sample plot was established at each of three density levels. each sample plot consisted of 15 live jack pine trees. in all, 90 trees were felled in september 1978 and analyzed to determine the above ground distribution of biomass by foliage, cone, stem wood, stem bark, live branch wood, live branch bark, and dead branch (wood plus bark) components. total current annual wood production was determined by adding the periodic annual increment of the stem for the last three years to the mean annual increment of the live branches. stand density was determined by computing number of stems per hectare, relative spacing, and basal area. stem wood, stem bark, foliage and dead branch biomass increased with density in both stands. live branch wood, live branch bark, and cone biomass were not affected by stand density and age. total current annual wood production was closely related to the foliage dry weight supported by individual trees; stand density and age seemed to have no influence on this relationship. total current annual wood production per hectare was linearly related to foliage dry weight and stand density. it was concluded that within the range of densities sampled, the two jack pine stands do not give any indication of being over-crowded. results suggest that jack pine stands, grown for maximum fibre production, should be grown as dense as possible, at least within the range of densities sampled.