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Log segregation for a structural lumber mill based on stand location and log position within trees

Authors: Glen Murphy
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 2021, Issue N.Z.J.For. 66(4) 2022, pp 36–42, Jan 2022
Publisher: New Zealand Institute of Forestry

Abstract: For the wood processing value chain to operate efficiently and profitably, processors need to obtain the wood raw material resource best suited to their needs. This may mean wood suppliers identifying and segregating stands and logs based on internal wood properties, as well as log external properties. A techno-economic model was developed that allowed calculation of mill-gate return-to-log (RTL) values ($/ m3) based on log external characteristics and wood density. Stem descriptions from eight stands located in four wood supply regions around New Zealand were input to the model. Data from 8,271 logs were output from the model and segregated into groups based on stand location, small end diameter (SED) classes and position up the stem where the log was cut. There were statistically significant differences in RTL due to stand location, SED and log position. For a given log SED class, RTL was shown to differ between stands and to decrease with height up the stem. These differences are due to differences in the wood density of the logs between stands and between positions in the stems. Individual log identification (log ID) may provide an opportunity for forest owners and wood processors to segregate logs based on wood property differences and to potentially share improvements in value recovery.