Biomass distribution and crown characteristics in two Alaskan Piceamariana ecosystems

Abstract

Allometric relations for tree phytomass distribution on two black spruce (Piceamariana Mill. B.S.P.) sites in interior Alaska were developed and compared with entire unit area samples. Tree component mass equations provided R2 values ranging from a low of 0.24 to a high of 0.97, with the majority of values above 0.75. Equations were developed for foliage; live and dead cones; dead branch total, dead branch bark, dead branchwood; live branch total, live branch bark, live branchwood; bole total, bole bark, bole wood; and tree total. Regression equations were developed to predict tree height, distance from crown bottom to ground, crown width, and crown length using basal diameters. R2 values for these equations ranged from 0.89 to 0.20. Foliage comprised from 37% to 17% of the total mass for the lowland stand and 50% to 17% of the total tree mass in the upland stand for trees with a diameter class ranging from 0.32 to 7.94 cm. For these same diameter classes, the total bole mass ranged from 11% to 58% and 21% to 61% of the total mass in the lowland and upland stands, respectively. Comparisons of predicted total aboveground tree biomass, measured biomass, and an average-tree-per-diameter-class procedure showed the lowland site predictions were about 6% low and the upland site predictions were approximately 3% high. Using a second, all-tree component method of prediction, results were about 3% low for lowland sites and 4% low for upland sites. A method of prediction using an average stand diameter yielded differences ranging from 31% low for the lowland site to 45% low for the upland site.