Roberta Parish

Age structure and growth of the tree-seedling bank in subalpine spruce-fir forests of south-central British Columbia.

Abstract We examined the dynamics of the tree-seedling bank in old-growth, subalpine Picea engelmannii—Abies lasiocarpa forests in south-central British Columbia by collecting all individuals <1.3 m tall within belt transects at two sites (n = ca. 500 per site) and determining their height, basal diameter and age. Seedlings were up to 149 y old. Regressions showed that spruce 1-m tall averaged 65-y old and fir 92-y old. Age structures indicated that recruitment into the seedling bank was variable with time, but that individuals of both species occurred in almost all 5-y age classes. Regressions of height and diameter vs. age had high predictability and showed that spruce grew more rapidly than fir. Allometric (height/diameter) relationships differed significantly between species; spruce had a much greater height/diameter ratio than fir. Seedlings accumulate gradually and persist for long periods in the seedling bank, thus forming a large pool of individuals that can potentially respond to opening of the canopy.

Effects of neighbours on crown length of Abies lasiocarpa and Picea engelmannii in two old-growth stands in British Columbia.

Crown length is a key aspect of vertical structure in multi-aged, multistrata, mixed-species forests. Crown length, defined as the distance from the tree top to the lowest live branch whorl, was de...

Assessing the wood quality of interior spruce (Picea glauca × P. engelmannii): variation in strength, relative density, microfibril angle, and fiber length

Abstract A dynamic interrelationship exists among wood density and fiber traits (tracheid length and microfibril angel, MFA) and the ultimate wood strength properties. Moreover, many of the basic fundamental wood attributes are heavily influenced by crown size and architecture. In an attempt to examine this interplay, we thoroughly characterized 60 interior spruce (Picea glauca × P. engelmannii) trees sampled in three age classes from four sites in central British Columbia. Breast height discs were taken, and relative wood density was measured along two radii. Tracheid length was assessed on isolated 5 years increments from pith to bark at breast height for each tree, as was MFA. Segmented regression was used to identify the “juvenile to mature wood” transition point, which revealed transition ages of 9.4 and 15.1 years for wood density and MFA, respectively, while fiber length continued to elongate until near 60 years of age. The flexural properties, modulus of elasticity (MoE) and modulus of rupture (MoR), were also quantified in the 60 individuals and found to be best predicted by VFV, a measure of tree vigor, and not the basic wood attributes. These findings imply that long crowns carrying large amounts of foliage, VFV, negatively impact wood strength in interior spruce.