Aboveground Biomass of Understorey and Overstorey in an Age Sequence of Four Douglas-Fir Stands

(1) Estimates for various components of aboveground biomass are presented for naturally regenerated Douglas-fir stands of 22, 30, 42 and 73 years of age. (2) Crown development in the 73-year-old stand is thought to be comparable to an adjacent 42-year-old plantation in which crown development has been stable for several years. (3) The decrease with time in understorey aboveground biomass is shown to be explained in large part by changes in the dominant understorey shrub, Gaultheria shallon. The relative importance of G. shallon in the understorey is shown to be inversely proportional to overstorey foliar biomass.