Measuring stiffness using acoustic tool for Scots pine breeding selection

Abstract

Stiffness (modulus of elasticity, MOE) of conifer trees is the most important trait for structural wood products. Finding a fast, reliable and non-destructive way to measure MOE is a priority for screening large progeny trials in tree breeding programmes. For Scots pine, time-of-flight (TOF) velocity measured on standing trees accounted for 47% of the variation to the benchmark SilviScan-based clearwood MOE (MOE_s), under the assumption of constant wood density. If wood density was included, 59% of the variation was accounted for. The TOF stiffness measurements on standing trees were, however, more related to the clearwood MOE_s in the outerwood, and the prediction was the most reliable at breast height compared to the stem base and the top section. Microfibril angle (MFA) had higher correlation with acoustic velocity (VEL) of standing trees than wood density, and among the early, transition and latewood density, the latewood density had the highest correlation with stiffness measurements on standing trees. VEL measured at breast height in combination with wood density was the most reliable predictor of MOE of standing trees for selection and breeding in Scots pine.

Keywords:

• non-destructive evaluation
• modulus of elasticity (MOE)
• acoustic velocity
• Pinus sylvestris

Acknowledgements

We acknowledge the assistance in field sampling from Henrik Hallingbäck, David Hall and Zhiqiang Chen and sample preparation by Valentina Floran and Ann Sehlstedt. The SilviScan measurements at Innventia were performed by Åke Hansson, Thomas Grahn and Lars Olsson, who also made the identification of annual rings and calculations connected to them.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The project was funded by grants from Kempestiftelserna and Föreningen Skogsträdsförädling foundations. Institutional support from Swedish University of Agriculture Sciences and in-kind support from Skogforsk and Innventia are greatly acknowledged.