Variation of Microfibril Angle in Plantation trees of Cunninghamia Lanceolata Determined by pit Apertures and X-Ray Diffraction

Abstract

Microfibril angle (MFA) is an important ultrastructural feature of the wood cell wall that provides insight into tree growth and wood quality. Unfortunately, it is a property whose value is sensitive to the method of measurement. The aims of this study are to clarify and compare the variation of MFA in Chinese fir [Cunninghamia lanceolata (Lamb.) Hook.] plantation trees by using the pit aperture (PA) and X-ray diffraction (XRD) methods. A decrease in the average MFA from 25° to 12° as determined by PA and from 15° to 9° as determined by XRD was shown from growth ring 2 to ring 26. When measured at various stem heights up to 5.3 m, the MFA decreased from 18° to 15° using PA and from 12° to 9° using XRD. The results show that XRD tended to measure lower MFA values both in the juvenile and mature wood than PA. The majority of within-tree variation in MFA is mainly attributed to the difference between the juvenile and mature wood.