Abstract:
This study was to investigate effects of growth rate
and cambial age on properties of wood from two increasingly
used hardwood species, red alder (Alnus rubra Bong.) and
Oregon white oak (Quercus garryana Dougl.), for better
understanding factors affecting wood quality in hardwoods.
Thirty 7-year-old trees grown at widely varying rates were
sampled from a red alder plantation to determine the effect
of growth rate on anatomical, physical, and bending
properties. Six 40-year-old red alder trees and six Oregon
white oak trees older than 50 years were sampled from pith
to bark at two heights to study the radial variation in
anatomical characteristics and specific gravity (SG).
The growth rate of 7-year-old red alder trees had no
effect on fiber and vessel proportions, SG, modulus of
elasticity (MOE), and modulus of rupture (MOR). Fiber
length, vessel diameter, and ray proportion increased
slightly while fiber wall thickness and axial parenchyma
decreased slightly with growth rate. Findings indicate that increasing growth rate of red alder through
silvicultural practices does not negatively affect wood and
fiber quality.
Variations among 40-year-old red alder trees were
significant for SG and vessel diameter but not for other
anatomical properties. The differences between two heights
and between the lower and upper sides were not significant
for any measured properties. Fiber length, vessel
diameter, and fiber and vessel proportions varied greatly
from pith to bark at both heights. Ray proportion and SG
remained unchanged across the radius at both heights. SG
was better correlated with MOE and MOR than any single or
several anatomical characteristics combined.
In Oregon white oak, there was significant variation
in fiber length, vessel diameter, and fiber and vessel
proportions from pith to bark. The demarcation age between
the core and outer wood was around 10 to 26 years,
depending on characteristic. SG decreased linearly from
pith to bark at both heights. Ray proportion showed little
change across the radius. Outer wood revealed stronger
relationships between anatomical characteristics, SG, MOE
and MOR than did core wood. SG was not a good estimator of
bending properties.
