Two projects are introduced which took place between 1986 and 1991 at the Forstliche Versuchs- und Forschungsanstalt Baden-Württemberg/Germany, dealing with coloured heartwood of beech.
The first project primarily answered the question, whether properties of beech trees showing high degrees of defoliation differ from those with low defoliation, considering increment as well as physical, mechanical and anatomical wood properties. As some of the selected trees revealed intensive coloured heartwood, the goals were enhanced to this item. The main results were the following: Increment of the trees with high degrees of defoliation showed a significant dropdown since 1980, in comparison to those with low degrees. The technological wood properties – density, pressure strength, bending strength and modulus of elasticity – of trees with high degrees of defoliation did not differ from those of trees with low defoliation, even after different storage periods in the form of sawn timber or round timber. During the anatomical analysis, yellowish and structured substances were found in lurnina of tracheids at the borderline of coloured heartwood.
For the second project, a classification for coloured heartwood of beech was developed. By use of this classification, the occurrence of coloured heartwood in correlation to DBH and average stand age was analyzed. DBH was found to be more significant for representing the occurrence of coloured heartwood than average stand age. Coloured heartwood appeared most intensively on the first 10 meters of tree length, but was less prominent at the stump end. Furthermore, theoretical net proceeds of timber, considering exclusively coloured heartwood grading restrictions, were calculated. Maximum proceeds were found within the DBH-class 60For the second project, a classification for coloured heartwood of beech was developed. By use of this classification, the occurrence of coloured heartwood in correlation to DBH and average stand age was analyzed. DBH was found to be more significant for representing the occurrence of coloured heartwood than average stand age. Coloured heartwood appeared most intensively on the first 10 meters of tree length, but was less prominent at the stump end. Furthermore, theoretical net proceeds of timber, considering exclusively coloured heartwood grading restrictions, were calculated. Maximum proceeds were found within the DBH-class 60-69 cm. The increasing proceeds for increasing dimensions balance decreasing proceeds for decreasing quality grading caused by increasing occurrence of coloured heartwood. Finally, a classification of analog soils was developed to explore soil-specific concentrations of the occurrence of coloured heartwood. Within the Buntsandstein-group analog tree diameters were found when compared with the top-increment Feinlehm/Lehm-group, but also less occurrence of coloured heartwood. Accordingly, the sites of the Buntsandstein-group yielded the maximum theoretical proceeds.