Aboveground biomass distribution within trees and stands in thinned and fertilized Douglas-fir

Abstract

Nine years after thinning (removal of 2/3 of the basal area) and fertilization (at 448 kg N ha−1, applied as urea), 34-year-old Douglas-fir trees (Pseudotsugamenziesii (Mirb.) Franco) were destructively sampled. The dry weights of seven aboveground components were determined and regression equations from dbh were developed. Differences among treatments were shown for all biomass components and the proportions of the total biomass allocated to the various components. Specifically, thinning decreased the proportion of biomass allotted to wood, bark, and dead branches, while increasing the proportions in foliage and live branches; fertilization increased the proportion of biomass in branches, but had negligible effects on the proportions of other components.