QUANTIFICATION OF HEARTWOOD VOLUMES IN CO NIFERS WITH OBLIGATORY HEARTWOOD FORMATION

The determination of the heartwood portion in trees is often the subje ct of biological research. So far the most frequent methodical startin g point was generally limited to the measuring of cross sections in di fferent stem heights. The aim of the present study was to determine as accurately as possible the volume of heartwood in the stem by means o f a small number of disks. In the course of our investigation the rota tion volumes of stem and heartwood curves of young Douglas-fir trees w ere calculated and compared by means of higher grade polynomes as well as spline-functions. The presented mathematical formulation proved as specially suited to conifers with obligatory coloured heartwood, beca use these species have certain symmetric properties of heartwood forma tion in contrast to the trees with optional heartwood formation. most of the harvesting activities in Douglas-fir stands in Germany concern young plantations. Therefore, the knowledge about the heartwood propor tion as a result of silvicultural treatments and of harvesting strateg ies could promote the market of this problematic small-sized Douglas-f ir grade.