Tapering and Volume of Aspen (Populus tremula L.) in South Norway

1989

42 S.

5 Abb., 3 Tab., 28 Anh.

Unselbständiges Werk

200037843

The purpose of this project has been to develop means for evaluating the form and volume of aspen trees. The main results are presented in the Appendix and consist of four tables (Table 4 to Table 7). First, three separate tables present tree volume under bark, over bark, and bark volume percentages. Then, the taper table displays diameter under bark and accumulated volume pr. 1m section of the stem. The material consists of 409 felled, rot-free trees. Diameter and double bark tickness are measured at 1m intervals on each tree, starting from 0,5m above stump. About half of the material comes from the Agder-counties, while the rest is from Telemark, Buskerud, Hedmark, and Akershus county (Fig. 1). Linear interpolations are used to find a general expression of stem form. 11 relative diameters are selected to represent the whole tree. These are calculated at 5, 10, 15, 20, 30, ..., 90% of total tree height. Polynominal regression models are constructed to predict the diameters at the 11 relative tree heights. The models are then used to calculate diameters and accumulated volume at 1m intervals, separate volume tables and a bark volume percentage table. Tree volume is illustrated in Fig. 2, while tree shape is illustrated by examples displayed in Fig. 3. Mean tree taper is calculated to 9mm/m. Between 0,5m and 50% total tree height, the taper is only 6mm/m. On the upper half of the bole, the value is 12mm/m. The results are tested against statistical assumptions, and the form of the regression models is tested against an independent material. All tests showed that the form of the models is correct, and that predicting ability is high. The results may be used to estimate sawing yield, volume and general end-use possibilities. If it should be required to construct special control programs, base-files and related programs can be obtained from the author.