Effect of Felling Time and Kiln-Drying on Color and Susceptibility of Wood to Mold and Fungal Stain During an Above-Ground Field Test
Keywords:
above-ground test, color, drying, felling time, fructose, glucose, mold, nitrogen, <i>Pinus sylvestris</i> L, starch, sucroseAbstract
The study shows how the content of low-molecular-weight (LMW) sugars, sugar alcohols, starch, and nitrogenous compounds in Scots pine trees in winter and spring and their subsequent redistribution during drying of timber affect color and susceptibility to fungi during above-ground exposure.
One tree from pairs of Scots pine was felled, sawn, and dried in winter, whereas the other was processed in spring. The content of soluble carbohydrates and nitrogen and also the color of timber surface were measured before and after drying. An above-ground test was carried out to show differences in susceptibility of winter- and spring-felled and dried timber to fungi.
The total content of LMW sugars was 1.59 times higher in winter than in spring. Sucrose was the most common sugar in the living tree at both sampling occasions. The content of oligosaccharides was higher in winter; in spring they were hydrolyzed to monosaccharides. The content of two sugar alcohols was negligible. Starch content rose significantly in spring. Nitrogen content in winter and spring was not significantly different.
Drying enriched the timber surface (0-3-mm zone) with LMW sugars and nitrogen, whereas the deeper zones had an almost constant content of soluble substances. The content of accumulated soluble substances in the 0-3-mm zone after drying was approximately proportional to their content in similarly located wood at the time of felling.
An important practical consequence of the redistribution of LMW sugars and nitrogen is the increased susceptibility to mold. The surfaces of winter-felled and dried timber were more susceptible to mold growth than those of spring-felled and dried timber.
The measured colors on the surfaces of winter- and spring-felled and dried pine timber were not significantly different. At the same time, distinct color differences between regions beside and within sticker marks were observed. It is concluded that the accumulation of water-soluble substances influences the surface color, but a certain difference in concentration has to be exceeded to obtain significant differences in color.
References
Boutelje, J., T. Nilsson, and S. Rasmussen. 1986. An analysis of the effects of some factors on the natural durability of pine (Pinus sylvestris L.) and spruce (Picea abies Karst.). Int. Res. Group on Wood Preservation, Document IRG/WP/1279.nCIE Publication No. 15, Supplement No. 2. 1976. Recommendations on uniform color spaces—Color difference equations—Psychometric color terms.nFellner, J. 1991. Schlägerungszeit und Holzqualität— eine Literaturübersicht. Holzforschung und Holzverwertung 43(1):25-28.nInternational Standard ISO 7724/3-1984(E). Paints and varnishes—Colorimetry. Part 3: Calculation of colour differences.nKirsten, W. J., and G. U. Hesselius. 1983. Rapid, automatic, high capacity Dumas determination of nitrogen. Microchem. J. (28):529-547.nMilton, J. S. 1992. Statistical methods in the biological and health sciences. McGraw-Hill, Inc., New York, NY. Pp. 437-439.nSteen, B., and K. Larsson. 1986. Carbohydrates in roots and rhizomes of perennial grasses. New Phytol. 104: 339-346.nTeischinger, A. 1992. Effect of different drying temperatures on selected physical wood properties. 3rd IUFRO Conference on Wood Drying, August 18-21, Vienna, Austria.nTerziev, N. 1995. Migration of low-molecular sugars and nitrogen in Pinus sylvestris L. during kiln and air drying. Holzforschung 49(6):565-574.nTerziev, N. 1997. Fungal discolouration of kiln- and air-dried Scots pine lumber in above ground testing and its assessment by digital image processing. Forest Prod. J. 47 (9):43-46.nTerziev, N., J. Bjurman, and J. B. Boutelje. 1996. Effect of planing on mould susceptibility of kiln- and air-dried Scots pine (Pinus sylvestris L.) lumber. Mat. u. Org. 30 (2):95-103.nTerziev, N., J. Boutelje, and K. Larsson. 1997. Seasonal fluctuations of low-molecular weight sugars, starch and nitrogen in sapwood of Pinus sylvestris L. Scand. J. For. Res. 12(2):216-224.nTheander, O. 1987. Conversion to phenols and enones. With special reference to humification and to colour formation in pulping and food processes. Pages 481-492 in Industrial polysaccharides. Proceedings of the conference on recent developments in industrial polysaccharides, Gordon and Breach Sci. Publ., New York, NY.nTheander, O., J. Bjurman, and J. Boutelje. 1993. Increase in the content of low-molecular carbohydrates at lumber surfaces during drying and correlations with nitrogen content, yellowing and mould growth. Wood Sci. Technol. 27(5):381-389.nUzunovic, A., J. F. Webber, and D. J. Dickinson. 1996. Comparison of blue stain fungi growing in vitro and in vivo. Int. Res. Group on Wood Preservation, Document IRG/WP 96-10149.nViitanen, H. 1996. Factors affecting the development of mould and brown rot decay in wooden material and wooden structures. Dissertation, Swedish Univ. of Agr. Sci., ISBN 91-576-5115-9. Pp. 8-20.nViitanen, H., and A-C. Ritschkoff. 1991. Mould growth in pine and spruce sapwood in relation to air humidity and temperature. Swedish Univ. of Agr. Sci., Dep. of Forest Prod., Report No. 221.nWazny, J., and K. J. Krajewski. 1984. Jahreszeitliche Änderungen der Dauerhaftigkeit von Kieferholz gegen-über holzzerstörenden Pilzen. Holz Roh- Werkst. (42): 55-58.n
Downloads
Published
Issue
Section
License
The copyright of an article published in Wood and Fiber Science is transferred to the Society of Wood Science and Technology (for U. S. Government employees: to the extent transferable), effective if and when the article is accepted for publication. This transfer grants the Society of Wood Science and Technology permission to republish all or any part of the article in any form, e.g., reprints for sale, microfiche, proceedings, etc. However, the authors reserve the following as set forth in the Copyright Law:
1. All proprietary rights other than copyright, such as patent rights.
2. The right to grant or refuse permission to third parties to republish all or part of the article or translations thereof. In the case of whole articles, such third parties must obtain Society of Wood Science and Technology written permission as well. However, the Society may grant rights with respect to Journal issues as a whole.
3. The right to use all or part of this article in future works of their own, such as lectures, press releases, reviews, text books, or reprint books.
