NORTH Queensland landholders who over the past two decades planted farm forestry plantations as nest eggs for the future will welcome the results of a State Government investigation into the value of this plantation timber.
Department of Employment, Economic Development and Innovation (DEEDI) forestry scientists have recently harvested and processed African mahogany trees from a plantation in the Burdekin.
The result of the harvest was described by DEEDI principal scientist, Dr Kevin Harding, as "pleasing", with the forestry plots registering above-average yields of marketable, high-grade timber.
"African mahogany is an established and highly sought-after timber in international markets for high-quality furniture, boat building and veneer products, and has also been used to make musical instruments," Dr Harding said.
African mahogany plantations produce an average of 338 cubic metres per hectare of commercial quality saw log over 20 years. This generates 204 cubic metres of dried sawn timber per hectare.
Current prices for milled and dried timber boards vary between US$1800 and US$2250 per cubic metre.
In the past 20 years, many landholders were encouraged to plant African mahogany plantations as part of community forestry projects.
Trees were harvested from one of the oldest plantations of African mahogany - a trial plot at the Burdekin Agricultural College.
"We took 32 trees from plantations established in 1989 and 1991 and produced veneer from 11 of these and sawn boards from the other 21 trees.
"These trees are nearing the optimum age for commercial harvest and were all pruned to two-and- a-half metres in height.
"We assessed log volume, log end split, wood colour, shrinkage and heartwood/sapwood proportions - all factors that influence grading and marketability of timber, and ultimately return to growers."
Dr Harding said the Burdekin plantations produced an above-average amount of usable timber, with only six percent of 'reject' timber, mostly due to later-age pruning of these trees than is desirable for high-quality wood production.
"Of the recovered sawn, dried and dressed volume of the Burdekin logs, 30pc could potentially be used for select grade, 43pc for medium feature grade and 22pc for high feature grades," Dr Harding said.
On average, each 3m log sawn would return between $150 to $200; however, better plantation management techniques could increase this price by up to 50pc, Dr Harding said.
He said the major limiting factor for achieving high feature grades was knots or wane in the timber, which may be traced back to plantation management.
The influence of large knots may be reduced by the implementation of initial higher stockings, timely pruning or the selection of superior genetic material that produces small branches with shallower angle.
With this in mind, researchers have also grafted the best trees from the plantations into clone banks to use for breeding so that better genetic quality material can be supplied to plantation growers.
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