Bounty in the wake of HMS "Bounty" - strength determination and viable sustainability of Norfolk Island pine ('Araucaria heterophylla')

Abstract

Norfolk Island pine ('Araucaria heterophylla' - formerly known as 'A. execlsa') is native to Norfolk Island and is used there as a structural and decorative 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 structural testing has been done on Norfolk Island pine in the past, and certainly there is no evidence of in-grade testing. Previous attempts at grading were based on using small, clear specimens. This project involved testing full-size specimens of randomly selected timber that was grown and milled on Norfolk Island. The work was undertaken in accordance with AS/ NZ4063: 1992. 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 and re-jointing will substantially improve utilisation of the species. Careful selection and grading of timber will be needed for specific structural applications.