Sapwood/Heartwood Width Relationships with Tree Age in Balsam Fir

Abstract

On the basis of five response variables, the sapwood/heartwood relationships with tree age were studied in balsam fir [ Abies balsamea (L.) Mill.] trees. One hundred and one samples, from a wide range of stand densities, were collected from the university forest near Thunder Bay, Ontario. The age at breast height ranged from 4 to 85 years. The five response variables measured were the number of sapwood and heartwood rings, sapwood and heartwood width and sapwood basal area. First and second degree polynomials in tree age were fitted for the five response variables and the best fit for each, based on the significance of the regression coefficients, was selected. The number of heartwood rings expanded quite rapidly to 0.81 ring per year, at the cost of sapwood ring expansion which averaged 0.19 ring per year.