Investigating the out-of-roundness and pith-off-centre in stems of three broadleaved species in Hyrcanian forests

Abstract

The out-of-roundness and pith-off-centre of Alnus subcordata, Acer velutinum and Quercus castaneifolia growing in Hyrcanian forests of Iran were investigated. Stem disks were cut from the breast height and stump height of felled trees in diameter classes of 20 cm to 90 cm. Results indicated that the pith eccentricity for Acer velutinum was significantly greater than that of Alnus subcordata and Quercus castaneifolia (P < 0.01). The pith-off-centre significantly increased with increasing stem diameter from 20 cm to 50 cm, while no significant difference were observed for pith-off-centre index from diameter class of 55 cm to 90 cm. The out-of-roundness in stems of Acer velutinum and Alnus subcordata was significantly greater than that of Quercus castaneifolia (P < 0.01). Moreover, out-of-roundness significantly decreased with increasing stem diameters from 20 cm to 45 cm except for 35 cm. There were no significant differences among diameter classes from 60 cm to 85 cm with respect to out-of-roundness. For all the species, the out-of-roundness and pith-off-centre at stump height were greater than those at breast height.