Comparison of annual ring density profiles in hardwoods and softwoods by X-ray densitometry

X-ray densitometry was used to study annual-ring density of 15 softwood and 21 hardwood tree species growing on the University of British Columbia campus. Intraring density profiles and some pith-to-bark density trends are presented. Radiographs of transverse wood sections gave the best results in most cases, but radial sections of some ring-porous hardwoods provided superior data. A fixed-density earlywood–latewood boundary criterion is satisfactory for the softwoods studied but less appropriate for most hardwoods. The softwoods vary more than hardwoods in intraring density contrast.