Investigation of wood properties that influence the final moisture content of air-dried sugi (Cryptomeria japonica) using principal component regression analysis

Abstract

Sugi (Cryptomeria japonica D. Don) lumber is known to have a large variability in final moisture content (MCf) and is difficult to dry. This study investigated the variability in MCf of sugi in relation to wood properties. The wood property variables included initial moisture content (MCi), basic density (BD), annual ring orientation (ARO), annual ring width (ARW), heartwood ratio (HR) and CIE L * color (L *). Sugi samples were cut from flat-sawn lumbers and air-dried; a principal component regression (PCR) model for predicting MCf was developed with the wood property variables. The wood properties that contributed to the prediction of MCf were evaluated by PCR analysis. Significant positive regression coefficients of the PCR model were observed in the MCi, BD, ARO and HR, whereas negative ones in the L *. There were no significant regression coefficients in the ARW. These results suggest that the MCi, BD, ARO and HR had a positive influence, the L * had a negative influence, and the ARW had little influence on the MCf of air-dried sugi wood. This finding is in line with the general view on the drying characteristics in relation to these wood properties.