Hardness of Reaction Wood from Sumatran Pine and Agathis Woods = Hardness of Reaction Wood from Sumatran Pine and Agathis Woods

다국어 초록 (Multilingual Abstract)

This study aimed to evaluate and compare the hardness and fracture morphology of compression wood (CW), lateral wood (LW), and opposite wood (OW) in Sumatran pine (Pinus merkusii ) and Agathis (Agathis loranthifolia). The hardness of the cross, radial, and tangential sections was examined by Brinell’s method according to the Korean standard, and the fracture surface was observed by scanning electron microscopy. In all sections, CW from both species showed the highest hardness, and there was no significant difference between LW and OW. On the cross-section, intercellular failure along rays occurred only in CW and LW. CW and LW showed shortening of the tracheid with a smooth cell wall surface, while OW showed a fractured cell wall with a brittle surface. On the radial and tangential sections, the tracheids from CW, LW, and OW buckled to the tangential direction. The fracture area of LW and OW was more severe and deeper than that of CW. CW showed buckling tracheids with helical cavities on the longitudinal wall, whereas the tracheids of LW and OW were buckled with horizontal stress lines. In conclusion, the CW from both species had the highest hardness value for all sample surfaces. Furthermore, CW showed distinct fracture morphology compared to LW and OW, whereas LW and OW showed mostly similar characteristics.