Modelling wood density and modulus of elasticity in white spruce plantations in Eastern Québec

Abstract

Forest managers have to take into account multiple objectives such as stand yield, wood quality attributes, ecological constraints and social considerations when making their decisions. The objective of the present study is to build (i) a dynamicmodulus of elasticity (MOEdyₙ) model and (ii) a core wood density (WDcₒᵣₑ) model for white spruce plantations in theBas-Saint-Laurent Region (Quebec, Canada) to quantify their inter- and intra-stand variations in order for managers tobetter weigh their different options. Using data obtained from 54 sample plots in 31 white spruce plantations from Eastern Quebec, the MOEdyₙ of 143 trees and the WDcₒᵣₑ of 162 trees were analysed. Dendrometric and stand variables wereused to build a MOEdyₙ linear mixed-effect model and a WD multiple linear regression model. The MOEdyₙ model explained 66.8% of the total variation, 1.1% of which originated from inter-stand variations. MOEdyₙ was proportionalto diameter at breast height (DBH) and non-linearly decreased with tree growth rate. The WDcₒᵣₑ model explained 16.0%of the total variation. The intra-stand variations were represented by a negative relationship between WDcₒᵣₑ and growthrate. Inter-stand variations were accounted for by site index and altitude. The performance of the MOEdyₙ model was satisfactory and in accordance with the literature. However, the WDcₒᵣₑ model was below standard, mainly as a consequenceof unaccounted intra-individual variations. Nonetheless, raw simulations using these models suggest that white sprucewood from plantations may benefit from intensive forest management.