Phenotypic Correlations among Growth and Selected Wood Properties in White Spruce (Picea glauca (Moench) Voss) †

Alain Cloutier,Cyriac S. Mvolo,Jean Beaulieu,Martin-Claude Yemele,Maurice Defo,Ahmed Koubaa

doi:10.3390/f10070589

Abstract

We examined phenotypic relationships among radial growth-related, physical (i.e., related to wood density), and anatomical (i.e., related to tracheid dimensions) wood properties in white spruce (Picea glauca (Moench) Voss), in order to determine the strength and significance of their correlations. Additionally, principal component analysis (PCA) was used to establish if all of the properties must be measured and to determine the key properties that can be used as proxies for the other variables. Radial growth-related and physical properties were measured with an X-ray densitometer, while anatomical properties were measured with a Fiber Quality Analyzer. Fifteen wood properties (tracheid length (TL) and diameter (TD), earlywood tracheid length (ETL) and diameter (ETD), latewood tracheid length (LTL) and diameter (LTD), ring width (RW), ring area (RA), earlywood width (EWW), latewood width (LWW), latewood proportion (LWP), ring density (RD), intra-ring density variation, earlywood density (EWD), and latewood density (LWD)) were assessed. Relationships were evaluated at intra-ring and inter-ring levels in the juvenile wood (JW) and mature wood (MW) zones. Except for a few cases when mature tracheid diameter (TD) was involved, all intra-ring anatomical properties were highly and significantly correlated. Radial growth properties were correlated, with stronger relationships in MW compared to JW. Physical properties were often positively and significantly correlated in both JW and MW. A higher earlywood density coupled with a lower latewood density favored wood uniformity, i.e., the homogeneity of ring density within a growth ring. Managing plantations to suppress trees growth during JW formation, and enhancing radial growth when MW formation starts will favor overall wood quality. In order, RW-EWW-RA, TL-ETL-LTL, and RD-EWD-LWP are the three clusters that appeared in the three wood zones, the whole pith-to-bark radial section, the juvenile wood zone, and the mature wood zone.

Highlights

White spruce (Picea glauca (Moench) Voss) is widely distributed across North America
In order to improve our understanding of how wood properties are correlated at the intra-ring and inter-ring levels, and whether these correlations may be used for prediction models, this study addressed the following objectives: (1) Establish phenotypic correlations between earlywood and latewood among the selected wood properties, (2) establish phenotypic correlations between juvenile wood and mature wood among the selected wood properties, (3) group wood properties and select key properties that can be used as proxies for the other variables in the group, and (4) describe radial variations of selected wood properties in white spruce
All radial growth-related properties decreased steadily from the 5th to the 30th growth ring, and showed a leveling tendency toward the bark (Figure 1a), but the decrease was sharper for earlywood width (EWW) compared to latewood width (LWW)

Summary

Introduction

White spruce (Picea glauca (Moench) Voss) is widely distributed across North America. A few studies have investigated correlations among the growth rate and wood quality of white spruce, and only for a small number of wood properties (all acronyms used in this text are listed in Table 1) at the ring level [9,15,16,17]. These studies pointed out the need for more carefully planned management if the improvement of many end-use properties was envisioned [9,16]. Correlations among the radial growth rate and physical (i.e., related to wood density) and anatomical (i.e., related to tracheid dimensions) properties of white spruce remain to be clarified

Methods

Results

Discussion

Conclusion