The relation of volumetric shrinkage to specific gravity of wood

Abstract

In this paper we studied on the volumetric shrinkage of wood in relation to the specific gravity. Sample trees used were from the artificial forest of 8 tree species planted at Nopporo district in Holdmidel. Test specimens containing 5 annual rings were cut from pith to bark in 4 direction from disks at 2 meter interval in stem. Following results were obtained;
(1) The order of magnitude of mean volumetric shrinkage in each tree species did not coincide with the order of their mean specific gravity.
(2) On the relation between the volumetric shrinkage (α_v%) and the specific gravity (Rg/cm³), according to the increase of R, in the beginning the ratio of increment of α_v, increased (or remained constantly or decreased on some species) and at a magnitude of R obtained almost constant and then at the next limit of R decreased. The range of this characteristic R and the ratio α_v/R was different by tree kind.
(3) The values of these tendencies were likely to be variable by the growth condition as the dominant or inferior tree, the sap- or heart-wood, and the part of stem above the ground etc.