South Pacific Gold - Sustainable Utilisation of a Native Timber on a Small and Remote South Pacific Island

Abstract

Norfolk Island pine ('Araucaria heterophylla' - formerly known as 'A. excelsa' or 'A. robusta') is native to Norfolk Island and is used on the Island as a structural and decorative joinery timber. Improved utilisation can be made of the timber once its structural properties are known. This paper reports on unique in-grade structural testing of the timber. No significant full-size structural testing has been previously undertaken on 'Araucaria heterophylla'. Previous attempts at grading were based on using small, clear specimens. The project involved testing full-size specimens of randomly selected timber that was grown and milled on Norfolk Island and shipped to Australia for testing. Testing of specimens included bending, shear, tensile and compressive strength tests in order to determine specific structural attributes of the timber. The work was undertaken in Rockhampton and Sydney, Australia in accordance with 'AS/NZ4063-1993: Timber grading evaluation strength and stiffness'. Preliminary results indicated higher shear and compressive strengths but lower bending and tensile strengths and modulus of elasticity than expected. The timber is weakest in tension. The presence of knots has a significant effect on strength. Knot reduction through improved silvicultural techniques and/or knot excision/re-jointing will substantially improve utilisation of the species. Careful selection and grading of timber will be needed for specific structural applications. Alternatives for enhancing the value of timber in applications beyond normal building applications are examined and discussed. Future research options are also examined and suggested.