HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Larch heartwood is appreciated for its good mechanical properties, its colour and its texture, and it is often used outdoors because of its natural durability (decay resistance). In this study the colour of larch heartwood was studied in relation to extractives and decay resistance, with the aim to estimate durability of larch heartwood from its colour. On a total of 293 trees colour in the CIE L*a*b* space (L* lightness, a* red/green axis, b* yellow/blue axis), extractives content (acetone and hot-water extractives, amount of phenolics) and the brown-rot decay resistance were determined. For calculating the relative decay resistance (x), mass loss after inoculation for 16 weeks with two fungi [Coniophora puteana (Schum.ex.Fr.) Karst., Poria placenta (Fr.) Cke, European standard EN 113] of larch heartwood samples was compared to Scots pine (Pinus sylvestris L) sapwood reference samples (EN 350-1). Different species [Japanese larch (Larix kaempferi Lamb.), Hybrid larch (Larix deciduax L. kaempferi) and European larch (L. decidua Mill.)], provenances and age classes (38-year, >150-year) were included. Japanese larch heartwood turned out to be significantly more reddish (higher a*-values) compared to the European larch provenances. Reddishness of the hybrids was intermediate. The red hue (+a*) was strongly correlated with the amount of phenols (r=0.84) and decay resistance (r=0.63) and therefore suitable for prediction of both parameters. The results suggest that colour measurements of larch heartwood could be of benefit in tree breeding programs and for an optimised utilization of larch timber.
To maximize utilization of our forest resources, detailed knowledge of wood property variation and the impacts this has on end-product performance is required at multiple scales (within and among trees, regionally). As many wood properties are difficult and time-consuming to measure our knowledge regarding their variation is often inadequate as is our understanding of their responses to genetic and silvicultural manipulation. The emergence of many non-destructive evaluation (NDE) methodologies offers the potential to greatly enhance our understanding of the forest resource; however, it is critical to recognize that any technique has its limitations and it is important to select the appropriate technique for a given application. In this review, we will discuss the following technologies for assessing wood properties both in the field: acoustics, Pilodyn, Resistograph and Rigidimeter and the lab: computer tomography (CT) scanning, DiscBot, near infrared (NIR) spectroscopy, radial sample acoustics and SilviScan. We will discuss these techniques, explore their utilization, and list applications that best suit each methodology. As an end goal, NDE technologies will help researchers worldwide characterize wood properties, develop accurate models for prediction, and utilize field equipment that can validate the predictions. The continued advancement of NDE technologies will also allow researchers to better understand the impact on wood properties on product performance.
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
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