Utvärdering av betydelsen av morfologiska fiberegenskaper vid skogsträdsförädling av björk

An 11-year old birch clone test in the southwestern part of Sweden was used for a genetic evaluation of growth, external stem quality and fibre properties such as basic density, fibre length, fibre width and coarseness. Samples from 30 clones and 3 ramets per klone were used. Growth and wood properties were under high genetic control. The individual broad sense heritabilities varied between 43 % and 73 %. The genetic coefficients of variation of the wood properties were quite low (3.5 – 6.2 %). Hwever, they were of the same magnitude as for height, indicating that selection for density would be just as effective as selection for height. There was a negative and significant genetic correlation between diameter and basic density (rG=-0.53). No genetic dependences between external quality traits and wood traits, except for branch number and fibre length (the less branches, the longer fibre) were found. Even if there is a clear negative genetic correlation between density and diameter, the results reduce the fear of a decrease of dry matter production when selection is based merely upon height and diameter. On the other hand a slight reduction in wood density might have impact on wood strenght in lumber. Multiple trait selection is proposed for optimisation of growth and wood density.