Screening Eucalyptus bosistoana for Heartwood
By Yanjie Li and Clemens Altaner, August 2016.
Download SWP-T009 (pdf)
Some eucalypts produce timber of highest natural durability and rich colour. Only the heartwood of trees can have these properties. However, the amount and quality of heartwood in trees is highly variable. Aim of this project is to produce such high value timber sustainably in New Zealand. At the heart of the initiative is a breeding programme to establish a resource of healthy trees which form quality timber. Breeding populations of Eucalyptus bosistoana and other species have been established in New Zealand since 2009. These trees are now of an age where they start to form heartwood. The first step in ensuring a quality resource is to core these trees to obtain samples which enable the assessment of heartwood amount and heartwood properties. A motorised coring tool has been developed with Callaghan Innovation, which allows to extract quickly (~1 min) a larger (~14 mm diameter) core from these small diameter trees leaving only a small (~20 mm diameter) wound. A motorised tree corer is currently not manufactured anywhere in the world and commercialisation of the tool is currently explored.
1119 seven year old E. bosistoana trees from 2(3) sites have been cored and analysed for heartwood quantity. Generally bigger trees had more heartwood (R2 ~0.5) but there are many large trees with little heartwood. This implicates that the largest trees are not necessarily the most valuable. A site influence was also found. The site with the fastest growth did not have the most heartwood. This has implications for growth models if heartwood is the targeted product. It has also been shown that there is variation in heartwood content between the families. This indicates a potential of improving further generations by selection.
Analysis of the cores for extractive content by NIR has been commenced.
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