Aboveground biomass of understorey and overstorey in an age sequence of four Douglas-Fir stands.
Estimates for various components of above-ground biomass are presented for naturally regenerated stands of Pseudotsuga menziesii, 22, 30, 42 and 73 years of age, growing on the Cedar River catchment, 55 km SE of Seattle, USA. Crown development in the 73-year-old stand was thought to be comparable to that in an adjacent 42-year-old plantation in which crown development had been stable for several years. The aerial biomass of the understorey showed a decrease with age of stand which could be explained in large part by a decrease in occurrence of the dominant understorey shrub Gaultheria shallon. The relative importance of G. shallon in the understorey was shown to be inversely proportional to the foliar biomass of the overstorey.