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Investigation Of within-tree and between-site Resin Canal Variation in Radiata Pine

Jun Li YANG, Geoff DOWNES, Fiona CHEN, Dave COWN. Investigation Of within-tree and between-site Resin Canal Variation in Radiata Pine. Overview. Radiata pine is a softwood with resin canals. Resin blemishes cause significant Losses in some products. Factors affecting presence include:

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Investigation Of within-tree and between-site Resin Canal Variation in Radiata Pine

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  1. Jun Li YANG, Geoff DOWNES, Fiona CHEN, Dave COWN Investigation Of within-tree and between-site Resin Canal Variation in Radiata Pine

  2. Overview • Radiata pine is a softwood with resin canals. • Resin blemishes cause significant • Losses in some products. • Factors affecting presence include: • Climate • Insects, diseases • Silviculture • Genetics

  3. Objectives • To understand within-tree resin canal variation • To understand regional resin canal variation and site effects • To investigate relationships between resin canals, external resin bleeding of standing trees and blemishes in wood samples

  4. Introduction • Resin characteristics occur naturally in softwoods • Resin defects can cause significant losses in appearance grade products and are a problem in value-added processing of radiata pine • Within- and between-tree variation in resin canal occurrence is poorly documented • Site factors and links to stem resin bleeding and to internal blemishes are unknown

  5. Materials and methods Software was developed to assist resin canal quantification: • Capture measurements on scanned images of smooth transverse surfaces • Count resin canal numbers • Measure and record resin canal location within samples • Measure and record growth ring width • Measure resin canal sizes

  6. Method Development Developed on 25mm wide samples Determine if the small transverse surface represented by SilviScan samples (2mm wide radial strips) is adequate for describing resin canal occurrence within individual trees 25mm wide radial strip

  7. Materials & Analyses Used new method to asses resin canals on samples from a regional trial • 150, 2 mm wide SilviScan samples (15 sites, 10 strips per site) • Polish the transverse surface • Quantified resin canal occurrence in each sample (frequency at 15 sites, resin canal size at 9 sites) Data analysis (ANOVA) – effect of site on resin canal frequency and size Compared with assessments of stem resin bleeding and resin blemishes from discs

  8. Count Resin Canals 2 mm wide strips

  9. Measure Resin Canal Sizes 2 mm wide strips

  10. Resin Canal Radial Frequency (Single site) • Non area-weighted data • Decrease from pith to cambium • Vary between trees and between sites • Within-tree (between-ring) variation is much greater than between-tree variation • Positively related to ring width

  11. Resin Canal Size (Single site) • Increase from pith to cambium • Vary between trees and between sites • Within-tree (between-ring) variation is much greater than between-tree variation • Inversely related to ring width

  12. Mean area-weighted resin canal frequency per m2 Significant differences between sites 80% difference between two extreme sites Resin Canal Frequency Across Sites (15)

  13. Significant differences between sites 30% difference between two extreme sites Resin Canal Sizes Across Sites (9)

  14. Resin Canal Frequency v.s. Resin Blemishes • Area-weighted resin canal count (count / m2) • Moderate relationship between resin canal frequency and resin blemishes (r2 = 0.54) • Sites with very low resin canal count have low levels of blemishes • Sites with high resin canal count are among highly-blemished sites

  15. Conclusions 1 – Sampling • A 2mm radial strip gives similar resin canal information (number and location of resin canals) to a 20-25mm wide radial strip in 90% of cases • To detect annual changes in resin canal frequency, strips from 5-7 trees are required. • To investigate site differences, at least 6 trees (one strip per tree) are needed per site

  16. Conclusions 2 – Site Effect • Resin canal frequency is positively associated with site temperature (r = 0.7) and inversely associated with site elevation (r = -0.6) • Warmer and/or lower elevation sites tend to produce more resin canals • Temperature appears to have a greater effect than site elevation • Rainfall, soil fertility (C/N ratio) and latitude did not affect resin canal frequency

  17. Conclusions 3 - Resin Canal Relationships • Resin canal frequency is not related to resin canal size, based on site means • Positive relationship between resin canal frequency and ring width • Inverse relationship between resin canal size and ring width • Significant between-site differences in resin canal count and size

  18. Conclusions 4 – Relationships with Other Resinous Features • Resin canal frequency is moderately associated with resin blemishes (r2 = 54%), based on site means • Resin canal count is weakly linked to external resin bleeding score, resin pockets and resinous patches

  19. Acknowledgements This study was partly funded by the Wood Quality Initiative (WQI).

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