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Influence of thinning on wood density and branch size of young western larch

https://library.fpinnovations.ca/en/permalink/fpipub5543
Author
Sauter, U.H.
Gonzalez, J.S.
Gordon, J.R.
Schmidt, W.C.
Jaquish, B.C.
Date
March 1999
Edition
37489
Material Type
Research report
Field
Sustainable Construction
Author
Sauter, U.H.
Gonzalez, J.S.
Gordon, J.R.
Schmidt, W.C.
Jaquish, B.C.
Date
March 1999
Edition
37489
Material Type
Research report
Physical Description
21 p.
Sector
Wood Products
Field
Sustainable Construction
Research Area
Advanced Wood Materials
Subject
Treatment
Silviculture
Larix
Growth
Series Number
Technical Report No. 18
W-1544
Location
Vancouver, British Columbia
Language
English
Abstract
Western larch (Larix occidentalis Nutt.) is one of three native Larix species in North America, besides subalpine larch (Larix lyallii Parl.) and tamarack (Larix laricina (Du Roi) K. Koch). It easily reaches 50 m in total height. High wood density and strength usually characterize its wood. In British Columbia, western larch represents a minor component of the provincial timber supply. Due to extensive western larch plantations in southeastern British Columbia it promises to become an important wood species in this region. Throughout most of western larches' natural range, existing stands originated from natural regeneration following wildfires, and are often overstocked. Therefore, early reductions of stand densities by precommercial thinning became an important management tool to establish stabilized stands and to concentrate stand growth potential on fewer vigorous, well-formed trees. This process of maximizing total stand value rather than maximizing yield can be completed by later commercial thinning and artificial pruning. The intent of this study was to provide basic information on the relationship between tree spacing and the two major wood quality parameters wood density and branch size to support stand management decisions. From four 43/45-year-old western larch experimental stands in northwest Montana, 618 sample trees were chosen representing different stocking levels ranging from 270 to 6700 trees per hectare. From two pith-to-bark cores, taken at breast height for each tree, density profiles were obtained using Forintek's x-ray densitometer. Additionally, the largest branch diameters in 4 m-stem height and below in four selected plots on three sites were measured and analysed. The sample trees showed a strong relationship between width of spacing and tree height and diameter breast height. As expected, trees in the widest spaced plots grew the fastest. Despite large differences in diameter growth, no significant differences in average wood density occurred between spacings. A second moderate thinning on the best sites clearly showed that enhancing the wood density of western larch is possible. As expected the branch diameter increases nearly linearly with the width of the initial spacing in western larch stands. But for the most valuable part of the tree, the branch sizes do not exceed 20 mm even when a wide spacing as 4.6 by 4.6 m is applied. The overall high relative wood density level of about 0.52, which is the highest average wood density of the commercial softwood in North America, and a reasonable knot size confirm that western larch from managed stands remains a valuable tree species in future markets.
Larix occidentalis - Density
Larix occidentalis - Growth
Growth - Influence of silvicultural treatment
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