Uniseriate ray characteristics for wood identification and quality indices of six Korean oak species

Radial variation in uniseriate ray characteristics of six Korean oak species was observed to provide information for wood identification and quality evaluation. Radial variations in uniseriate ray characteristics, such as ray height, number, and spacing, were observed at five growth ring intervals from the pith to near the bark using optical microscopy. The transition point between the juvenile and mature wood was evaluated using a segmented regression model. All species showed a comparable trend in uniseriate ray number and spacing, gradually decreasing from the pith to near the bark. Transition zones for the six Korean oak species ranged from 21 to 39 years of growth. The highest uniseriate ray heights and spacings were observed in Quercus aliena. Quercus dentata exhibited the highest number of uniseriate rays. Across all species, uniseriate ray number and spacing were higher in juveniles than in mature wood. A negative correlation was observed between the uniseriate ray number and spacing and the uniseriate ray height. The strongest positive correlation was observed between uniseriate ray number and ray spacing. The most reliable parameters for estimating the demarcation point were uniseriate ray number and spacing. The ray characteristics may be used to identify the six Korean oak species.