Quantifying the Influence of Crown Size on Mechanical Wood Properties in White Spruce (Picea Glauca)

Conceptual models of wood formation suggest that trees with large crowns produce low quality wood, but few studies have explicitly examined the relationship between crown size and wood quality. In this study, I examine how crown size influences the strength and stiffness of wood, as measured by Modulus of Elasticity (MOE) and Modulus of Rupture (MOR), using 42- and 72-old year plantation white spruce (Picea glauca) from Ontario, Canada. Mechanical properties were determined from 10x10x140 mm mini-clear samples (n=657), selected from a radial gradient at three heights within the stems. Non-linear mixed-effects models showed that strength and stiffness significantly decreased with crown size, and that MOE and MOR were best predicted by cambial age and crown ratio. The results suggest that the models could be used in conjunction with remotely sensed data to identify high quality timber prior to harvest.MAS