Maps developed using Akima’s interpolation method were used to compare patterns of within-tree variation for Pinus taeda L. (loblolly pine) wood properties in plantation-grown trees aged 13 and 22 years. Air-dry density, microfibril angle (MFA) and modulus of elasticity (MOE) maps represented the average of 18 sampled trees in each age class. Near infrared (NIR) spectroscopy models calibrated using SilviScan provided data for the analysis. Zones of high density, low MFA and high MOE wood increased markedly in size in maps of the older trees. The proportion of wood meeting the visually graded No. 1 (11 GPa) and No. 2 (9.7 GPa) MOE design values for southern pine lumber increased from 44 to 74% and from 58 to 83% respectively demonstrating the impact of age on end-product quality. Air-dry density increased from pith to bark at all heights but lacked a significant trend vertically, while radial and longitudinal trends were observed for MFA and MOE. Changes were consistent with the asymptotic progression of properties associated with full maturity in older trees.

We examined the within-tree variation of pulp yield and lignin content for loblolly pine (Pinus taedaL.) trees aged 13 and 22 years. Radial trends in pulp yield (increase) and lignin (decrease) were consistent with what would be expected for loblolly pine as were changes in properties related to maturation. Maps, based on the average of 18 trees at each age, depicting pulp yield variation within-tree were similar to loblolly pine maps reported for microfibril angle and stiffness, while lignin maps resembled the inverse of those reported for density and related properties. Mixed-effects models for both properties were developed with the base model for pulp yield explaining 64% of the observed variation, with the inclusion of tree height improving the model slightly, whereas models for lignin content explained 44% of the variability. The models could be incorporated into growth and yield prediction systems, or procurement model systems that predict within-tree wood properties based on age and tree size.