Canadian Forest Service Publications
Assessment of white spruce and jack pine stem curvature from a Nelder spacing experiment. 2013. Belley, D.; Beaudoin, M.; Duchesne, I.; Vallerand, S.; Tong, Q.J.; Swift, D.E. Wood Fiber Sci. 45:237-249.
Issued by: Laurentian Forestry Centre
Catalog ID: 34952
Availability: PDF (request by e-mail)
This study presents a method for calculating stem curvature for trees with multiple deviations. Generally, tree curvature is assessed using the maximum deflection method. It consists of measuring the farthest point from a straight line drawn between the large and small ends of a stem. It works fairly well for a single deviation but gives poorer results for stems with several deviations. The stems used for developing this method were harvested from a 32-yr-old Nelder spacing experiment established near Woodstock, New Brunswick, Canada. A total of 96 trees were selected for this study from the white spruce (Picea glauca [Moench] Voss) and jack pine (Pinus banksiana Lamb.) that were planted on the same Nelder circle. This particular plantation design offered a gradient of initial spacings ranging from 640 to 12,000 stems/ha. Results of analysis revealed that initial spacing had an impact on tree curvature. Stem curvature increased with wider initial spacing. However, this influence varied between species and differed according to the method used to calculate curvature. The vector length calculation method showed that stem curvature in jack pine was more pronounced and more often encountered at lower densities than in white spruce. It was also observed that tree shape was influenced by the cardinal points with white spruce growing more in westerly and southerly directions.
Plain Language Summary
A tree's stem curvature is an important factor that determines its quality and has an effect on its value. This paper presents the results of a study concerning the effect of plantation density on stem curvature in white spruce and jack pine.
In this study, two methods for measuring curvature were compared. The first is based on the measurement of maximum stem deformation (standard method) and the second on a detailed measurement of all deformations. The outer shape of the trees was measured using a laser scanner, and deformations were calculated using those two methods.
The results show that with the standard method, planting density does not have a significant effect on deformation in either of these two species. However, using the more detailed and therefore more precise method, a significant effect was noted in jack pine. When density is lower than 1,600 stems per hectare, more trunk deformation is seen in jack pine. No difference was noted in white spruce, regardless of the method used. The outer shape of jack pine stems is therefore more strongly affected by stand density than that of white spruce.