Refining log calculations on the south coast
From the Winter 2007 edition of Bush Telegraph Magazine.
A field study is underway in State forests on the New South Wales south coast to refine mathematical calculations for timber volumes from local species.
Forests NSW Batemans Bay-based resources forester, Ken Boer, explained that a tree trunk is a complex shape – flaring out at the base, going into a near cylindrical bole and progressing to a long, tapering crown.
“As the tree ages the shape changes,” Ken said. “In native forests, there is the added complexity of many different species, each with their own shape.”
To accurately measure the volume of timber in the trunk of a tree, precise measurements are needed along the length of the trunk.
“Obviously, to do this for every tree is impractical so instead mathematical equations, called taper models, are developed,” Ken said. “This allows accurate estimates to be made of individual species across the range of ages and sizes.”
The better the model, the more confidence can be placed in volume estimates used to plan future timber harvesting.
On the south coast, refinement of these models is being assisted with detailed measurements being undertaken of several hundred trees. It is part of a statewide inventory program being undertaken by Forests NSW.
“The sample trees are being felled and cut into disks at intervals along the trunk of the tree to allow precise measurements to be made under the bark,” Ken said. “This needs to be done with care and skill to ensure minimal damage is done to the trunk of the tree as it falls.”
Ken said the results of the measurements will be used in new and improved taper models that will be useful for many years, ensuring better volume predictions and assisting with the scheduling of future harvesting.
“We want to be able to predict the effect of current and future silviculture. It’s a complex process, greatly assisted by good modelling from solid local research.”
Communications, Maitland
