Radial and Vertical Distribution of Dissoluble Total Carbohydrate Content in the Beech (Fagus sylvatica L.): Relationships with Red Heartwood Formation

Red heartwood forms in most old beech stands, which reduces the commercial value of the wood considerably. Many of the chemical and biochemical processes involved in red heartwood formation are known, but research has been limited to a single level of the stem (usually at breast height). The present study investigated the radial and vertical distribution of dissoluble carbohydrates at different height levels within a red heartwood (17 levels) and a non-red heartwood (12 levels) beech stem. The radial changes of the concentrations differ notably in beech with or without red heartwood. An increase in the transition zone is not a mandatory condition for red heartwood formation, but a decrease in concentration always occurs after the transition zone. Intense sugar metabolism at the color boundary contributes to the surplus energy required in red heartwood formation and the in situ synthesis of polyphenolic compounds.