Modelling spiral grain angle variation in New Zealand-grown radiata pine

Spiral grain measurements are subject to a high degree of variation and interpretation, depending on the assessment method used. A new measurement approach was tested whereby light was directed through disc samples on a flatbed scanner and the deviation along the grain assessed by means of a template to allow the mapping of grain angle variation radially and tangentially within discs. Initial results showed that the approach was valid for green discs up to 35 mm thick and small enough to fit on an A4 scanner. Comparisons with traditional scribing and cleaving methods were favourable, indicating that the light transmission approach could allow much faster and more accurate data acquisition. The possibility of using larger discs would enhance the ability to assess spatial variation in grain angle and minimise the effects of sample reference geometry with respect to the tree axis (disc tilt and parallax). Further work may also be required to ensure that reliable spiral grain values are obtained from both sapwood and heartwood. The ultimate goal is to develop an automated system for reconstructing stem characteristics from measurements on large fresh green discs to enable the 3-dimensional mapping of individual stem variations in key wood properties and modelling the impacts of silviculture and genetics on wood products.

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Differences in intra-tree variation in spiral grain angle for radiata pine

New Zealand Journal of Forestry Science ◽

10.1186/1179-5395-43-12 ◽

2013 ◽

Vol 43 (1) ◽

pp. 12 ◽

Cited By ~ 4

Author(s):

Michael S Watt ◽

Mark O Kimberley ◽

Jonathan J Harrington ◽

Mark JC Riddell ◽

Dave J Cown ◽

...

Keyword(s):

Radiata Pine ◽

Spiral Grain ◽

Grain Angle ◽

Spiral Grain Angle

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Spiral grain in plantation trees of Piceaabies

Canadian Journal of Forest Research ◽

10.1139/x94-215 ◽

1994 ◽

Vol 24 (8) ◽

pp. 1662-1671 ◽

Cited By ~ 12

Author(s):

Frede Danborg

Keyword(s):

Standard Deviation ◽

Ring Width ◽

Specific Pattern ◽

Annual Rings ◽

Basic Pattern ◽

Angle Variation ◽

Spiral Grain ◽

Grain Angle ◽

Slow Decline ◽

Large Trees

The spiral-grain angle of Norway spruce (Piceaabies (L.) Karst.) was measured on diametrical strips from five stands 23–47 years old, on soils of high and moderate fertility, most of which had been thinned heavily. Ninety-five small, average, and large trees from each stand were sampled from which 261 discs were sawn at heights ranging from 1.3 to 12 m. The basic pattern was typical for a conifer; spirality was left-handed in the inner annual rings, peaking in ring numbers 3 to 8, followed by a slow decline towards straight grain, or even right spirality, near the bark. The between-tree variation was statistically significant in all stands, with standard deviation near 1°. A stand may exhibit a specific pattern of grain angle variation along the bole, but no variation with height in stem could be generally applied for Piceaabies. For the three stands grown on fertile soils, the larger trees exhibited larger grain angles than the smaller trees. However, a consistent positive effect of ring width was only statistically significant for one stand. A subsample of 24 stem discs including 421 annual rings measured twice on two diametrical strips at right angles (i.e., crosses) showed fairly good accordance between the two directions, with a pooled standard deviation of 0.5°. The results support earlier conducted studies with respect to complex and perplexing variations in the basic pattern of spirality typical for a conifer.

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Inheritance of spiral grain in the juvenile core of Pinus radiata

Canadian Journal of Forest Research ◽

10.1139/x06-202 ◽

2007 ◽

Vol 37 (1) ◽

pp. 116-127 ◽

Cited By ~ 12

Author(s):

Washington Gapare ◽

Adrian Hathorn ◽

Dominic Kain ◽

Colin Matheson ◽

Harry Wu

Keyword(s):

Pinus Radiata ◽

Genetic Gain ◽

Radiata Pine ◽

Correlated Response ◽

Lower Grade ◽

Tangential Plane ◽

Individual Tree ◽

Spiral Grain ◽

Grain Angle ◽

Selection For

Spiral grain is the angular arrangement of fibres in a tangential plane with reference to the pith or vertical tree axis. Spiral grain angles exceeding 5° can cause wood to twist, which may result in a considerable amount of waste and degrade. We assessed spiral grain at breast height in two related progeny tests of radiata pine (Pinus radiata D. Don) aged 8 and 9 years established at two different sites in Australia. Radial trends for grain angle at the two sites were similar. Mean spiral grain (MSG) across the two trials was 4.3° with a standard deviation of 1.5° and a range of 0.8–10°. Estimates of individual tree heritabilities on a single-site basis for individual rings and MSG suggested that spiral grain is lowly to highly inherited (h2 = 0.11 ± 0.08 to 0.66 ± 0.21 for individual rings and 0.44 ± 0.12 for MSG). Additive genotypic correlations between individual rings grain angle and MSG were generally high, above 0.71, suggesting a favourable expected correlated response of mean grain angle in the juvenile wood to selection for grain angle of individual rings. Selection to reduce spiral grain on any of rings 2–4 (at a selection intensity of 1.755, i.e., selecting the best 10% of trees) would result in a predicted correlated genetic gain in MSG of 1.0°. Our results suggest that selection could be performed in any of the individual rings 2, 3, or 4 (equivalent to ages 4–6) and still achieve at least 75% of the genetic gain possible from selection on the mean of all rings 1–5 (MSG). This suggests that there is an optimum stage (rings 2–4) in which selection for this trait should take place. Our results suggest that a reduction in spiral grain angle in the juvenile core is one strategy to reduce the amount of lower grade timber owing to twist.

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