Stem allometry in a North Queensland tropical rainforest

The stem allometry (tree height versus stem diameter) of four tree species found in a North Queensland rainforest was examined. These species were dicotyledonous trees, two of which were classed as early successional species and two as later successional species. No significant differences (P > 0.05) were found in the stem allometry of dicotyledonous trees of the same successional status. However, significant differences (P < 0.05) in stem allometry were found when comparing species of different successional status. Later successional species, but not early successional species, were found to be ''elastically similar'' to a theoretical buckling limit. The relationship between stability safety factors and tree height indicated chat both early and later successional species have large buckling safety margins when of low stature. At medium statures (subcanopy), early successional species display a moderate buckling safety margin while later successional species exhibited their lowest buckling safety margin. At tall statures (canopy and above), early successional species exhibited their lowest buckling safety margin while later successional species had moderate buckling safety margins. Stem allometry may be influenced by a tree's life-span, wood density, and environmental conditions in its crown region.