The buttressed blue marble tree: Wood and growth characteristics of Elaeocarpus angustifolius (Elaeocarpaceae)

Abstract

Elaeocarpus angustifolius, a forest tree native to Australia, was introduced into the Hawaiian Islands and is now naturalized locally. The main purpose of this study was to test the hypothesis that a radial increase in wood specific gravity was present in trunk wood of these trees, which grow quite large (diameter at breast height = 200 cm) and have massive buttress systems. Information on buttress height and number and specific gravity of the outer trunk wood (sampled at breast height), as well as anatomical characteristics pertaining to conduction (vessel diameter and density), was obtained from a range of different-sized trees. Both buttress height and number increase with increasing tree diameter. Wood specific gravity has a median value of 0·49 and increases more than 50 % over the range of tree diameters studied. Vessel diameter increases over two-fold and vessel frequency decreases with increasing tree diameter, although very large trees (diameters > 70 cm) exhibit more variability. Trees have buttresses spaced evenly around the circumference (maximum of 15-20) and exhibit no difference in wood specific gravity on the leeward and windward sides in spite of their location in the trade wind belt. Radial increases in specific gravity of the type documented here may be important in evaluating the carbon present in forest stores.