As the forest industry in British Columbia becomes increasingly dependent on second-growth
timber for its raw material supply, the question of wood quality becomes more relevant. Accelerated
growth in forest plantations, coupled with an earlier harvest, will lead to changes in the quality of the
timber harvested. The influence of cambial aging, initial spacing, stem taper and growth rate was
non-destructively evaluated on the wood quality characteristics of Douglas-fir (Pseudotsuga menziesii
(Mirb.) Franco var. menziesii), western hemlock (Tsuga heterophylla (Raf.) Sarg.) and western
redcedar (Thuja plicata Donn ex D. Don). The wood properties analysed included ring width,
earlywood width, latewood width, latewood proportion, earlywood relative density, latewood relative
density, whole-ring relative density, whole-ring tracheid length and microfibril angle. Juvenile wood
development was determined based on whole-ring relative density trends from pith to bark. A highly
significant cambial age effect was noted for practically each wood property considered. An identical
pattern of development, regardless of spacing or taper class, was identified for Douglas-fir via
latewood proportion and whole-ring relative density, and for western hemlock via latewood width,
earlywood relative density, latewood relative density, whole-ring tracheid length and microfibril angle.
No identical results were identified for western redcedar. An increasingly non-significant relationship
evolved over time for Douglas-fir between growth rate and whole-ring relative density. A slight, but
increasingly negative relationship unfolded for western hemlock. An increasingly stronger negative
relationship developed for western redcedar. The Kajaani FS-200 Optical Fibre Analyser was found
inadequate for measuring tracheid length variability on the basis of 12 mm increment cores. A
gradual decrease in juvenile wood ring count was commonly identified with increasing height.
Generally speaking for both Douglas-fir and western hemlock, the larger the volume of crown foliage
relative to length of branch-free stem, the lower the passage from juvenile wood to mature wood
below the base of the live crown. In the case of western redcedar, the larger the volume of crown
foliage relative to length of branch-free stem, the higher the passage. The use of a variable exponent
taper equation was explored for predicting juvenile core development.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/11069 |
| Date | 11 1900 |
| Creators | Fabris, Stéphanne |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Relation | UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/] |
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