Influence of age on sandalwood (Santalum spicatum) oil content within different wood grades from five plantations in Western Australia

Summary

Sixty-four sandalwood (Santalum spicatum) trees aged 8–26 y were harvested from five separate plantations during 2007 to determine wood yields and quality (percentage heartwood; oil and a-santalol concentrations) at different ages. Each plantation was located in the 400–600 mm mean annual rainfall zone in south-western Western Australia. The whole trees, including the roots, were extracted from the ground, de-barked and the wood divided into five separate commercial wood grades: butt, roots, 1st grade, 2nd grade and 3rd grade.

Mean percentage heartwood and oil concentration in the wood increased significantly with sandalwood age. However, mean a-santalol concentration in the oil was less age-related, but was generally high in the trees aged 26 y. Both oil and α-santalol concentrations were relatively high in the butt, roots and 1 st-grade wood from trees aged 26 y, and only in the butt of trees aged 14 y. Wood of all grades from trees aged 8–11 y was of low value. These results indicate that to obtain a large proportion of high-grade wood from sandalwood plantations the stand age may have to be at least 25 y.

A power relationship equation was developed to predict the total commercial weight of wood within a sandalwood tree knowing stem diameter over bark at 150 mm above the ground. Within each tree, the greatest amount (33–46% of the total weight) of commercial wood was classed as 1 st grade, and each of the other four grades contained 10–23% of the total.

Keywords:

• plantations
• yield
• age
• models
• grading
• heartwood
• wood extracts
• oils
• a-santalol
• Santalum spicatum