Intra-Ring Variations and Interrelationships for Selected Wood Anatomical and Physical Properties of Thuja Occidentalis L.

Besma Bouslimi,Yves Bergeron,Ahmed Koubaa

doi:10.3390/f10040339

Abstract

Intra-ring variation in wood density and tracheid anatomical properties and wood property interrelationships were investigated in Thuja occidentalis L. Samples were taken from three stands in Abitibi–Témiscamingue, Quebec, Canada. The structure of T. occidentalis wood is simple, homogeneous and uniform, which is desirable for wooden structures that require wood uniformity. From early- to latewood, cell and lumen diameter decreased, while cell wall thickness increased. These changes led to an increase of the cell wall proportion. Wood ring density and width interrelationships were weaker in mature wood compared to juvenile wood. Earlywood density is the more important in determining mature wood density than latewood density and proportion. Earlywood density explains 92% and 89% of the variation in juvenile and mature wood density, respectively. The negative relationship between ring density and width, although significant, was low and tends to weaken with increasing tree age, thus providing the opportunity for silvicultural practices to improve both growth and wood density. Ring width was positively and strongly correlated to early- and latewood width, but negatively correlated to tracheid length and latewood proportion. Accordingly, increases in ring width produce smaller tracheids and wider earlywood without a corresponding increase in latewood. Practical implications of the results are discussed.

Highlights

Thuja occidentalis L., one of only two-arborvitae species native to North America, is distributed over a vast territory extending from the Gulf of St
The latewood zone was narrow with thick cell walls (Figure 2a–c, Table 1) and was slightly denser than the earlywood zone (Figure 1a)
This study revealed a negative relationship between the ring width and ring density components of T. occidentalis (Table 4)

Summary

Introduction

Thuja occidentalis L., one of only two-arborvitae species native to North America, is distributed over a vast territory extending from the Gulf of St. Lawrence in the east to southeastern Manitoba in the west and from southern James Bay in the north to the Lake States in the south [1] The timber of this species has a natural durability that enhances its utility in wooden structures exposed to constant moisture [2]. The average service life of an untreated T. occidentalis heartwood post is 27 years, compared to just five years for an untreated black spruce post [3]. Products such as shakes, shingles, fence posts and mulch made from T. occidentalis have considerable potential market value [4]. This work is an extension of a series of studies on wood quality variation in T. occidentalis [6,7,8]

Objectives

Methods

Results

Conclusion