Annual Ring Formation and Wood Properties of Slash Pine (Pinus elliottii) Grown in Southern Kyushu, Japan

Abstract

Early in the 1950s, slash pine (Pinus elliottii) was introduced into Japan as an exotic species for plantation. Growth characteristics of slash pine planted in Japan were studied and it was reported that slash pine had superior growth rate and resistance to diseases as compared to domestic pine species. However, few studies examined the characteristics of annual ring formation and the variations of wood properties of slash pine grown in Japan. In this study, we examined annual ring formation and wood properties of 46-year-old slash pine grown in southern Kyushu, Japan. Based on obtained results, we evaluated the usability of slash pine as an exotic species for plantation in Japan. In slash pine, cell division during latewood formation was more active than in sugi (Cryptomeria japonica) and hinoki (Chamaecyparis obtusa). Furthermore, it was assumed that the characteristics of annual ring formation produced higher basic density in spite of superior growth rate. Basic density and mechanical properties in bending of slash pine grown in southern Kyushu were the same as those of slash pine grown in North America. In slash pine with faster growth rate, it was shown from the radial variation of microfibril angle of the S2 layer in the cell wall of latewood tracheids and latewood tracheid length that the transition from juvenile to mature wood occurred at an earlier ring number and there was less variation in mature wood. From the obtained results, it was assumed that slash pine plantations could produce wood with superior mechanical properties more efficiently than sugi plantations in Japan, because of the faster growth rate and few negative effects of the faster growth rate on wood properties. © 2011, The Japan Wood Research Society. All rights reserved.