Cyclophytic effects on wood structure in Pinus radiata D. Don. I. Densitometry and grain angle

Abstract

Wood structural characteristics were compared in 11-year-old Pinusradiata trees from hedge- and tree-form donors (H and T) to examine the effects of apical ageing (cyclophysis) on wood formation. Although the differences were small, T plants tended to produce wood with narrower growth rings and lower density in the first two rings. T plants showed a greater contrast between density at the end of one growth ring and the beginning of the next. The lower mean growth ring density in T plants was mainly due to a lower earlywood density with little difference in latewood density or latewood percentage. Although differences in density from early- to late-wood were greater in T plants, there was no difference between H and T plants in within-ring density variation. This was due to greater fluctuations in density across growth rings of H plants, perhaps because these plants were less buffered against the environment. Differences in wood structure between H and T plants were not the same for all clones, as shown by significant interactions in the analyses of variance. These different responses may have resulted from differences in the effectiveness of hedging in slowing apical maturation, or from differences in rates of maturation.