Observations on Average Trunk Diameters of Eucalyptus cunninghamii (Myrtaceae) in Relation to Elemental Concentrations of their Substrates

David Coleby, Rae Druitt


The rare Eucalyptus cunninghamii Sweet (Myrtaceae), the Cliff Mallee Ash, inhabits a geological niche associated with claystones, most often the Wentworth Falls Claystone Member of the Narrabeen Group. We show that some gross morphological attributes of E cunninghamii vary widely and that they are determined by elemental composition of its claystone substrate. We examined eight widely separated specimens and their substrates in the upper Blue Mountains of New South Wales and found that concentrations of thirteen elements in those substrates varied widely, mostly following a linear pattern. We also found that average trunk diameter of each specimen correlated strongly with most of the elemental concentrations in its substrate, and that average trunk diameter was therefore a good guide to the nutrient status of its substrate. Concentrations of potassium and phosphorus both varied by an order of magnitude.

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