EFFECT OF GROWTH-RATE ON THE ANATOMY, SPECIFIC-GRAVITY, AND BENDING PROPERTIES OF WOOD FROM 7-YEAR-OLD RED ALDER (ALNUS-RUBRA)

Understanding the association between growth rate and wood properties is of practical importance to maximizing and sustaining wood and fiber production. Anatomical characteristics, specific gravity, and bending properties were determined at breast height for thirty 7-year-old tre es with varying growth rates, from a red alder (Alnus rubra Bong.) pla ntation. Wood was sampled from the growth ring with a cambial age of 5 years. Growth varied from 2.0 to 9.3 mm/year (ring width), or 264 to 3350 mm(2)/year (ring area). We analyzed the relationship between grow th rate, in terms of both annual ring width and area, and each wood pr operty. Because both measures of growth rate yielded the same qualitat ive results, we only used ring width in our analyses. Regression analy sis showed that growth rate had no effect on specific gravity, the mod ulus of elasticity in bending, the modulus of rupture in bending, fibe r diameter, or the proportion of growth ring that was fiber or vessel. Fiber length, vessel diameter, and ray proportion, however, were posi tively correlated with growth rate. Fiber-wall thickness and axial par enchyma proportion decreased slightly with growth rate. The results in dicate that the growth rate of A. rubra trees can be increased through silvicultural practices with few negative effects on wood and fiber q uality, at least in the juvenile wood zone of the stem.