Native forest regrowth: how old do trees need to be to make good timber?
Authors: Innes, Trevor ; Siemon, Graeme ; Armstrong, Matt
ABSTRACT: Specifiers are increasingly looking for materials with improved environmental credentials
in response to the movement in consumer sentiment toward ecological sustainability. In the case of
timber, simplistic analysis of the issues involved has tended to polarise preferences of consumers and
specifiers toward plantation material. However, argument can be made for an environmentally
sustainable sawn timber industry processing a proportion of regrowth native forest.
When considering the harvest of regrowth native forest, the processing and material properties of the
timber produced from it need to be known. Historically, it’s generally been accepted that younger trees
produce timber with inferior properties without this premise being proven. This paper describes work
undertaken to compare the processing, material and appearance properties of native forest regrowth
hardwoods of varying ages from around Australia. It was found that for regrowth Tasmanian
Messmate, the only significant differences in timber from younger logs were a decrease in the
proportion of boards reaching the highest value grade (“Select grade”) requirements, higher variability
in some properties and significant internal checking. Smaller logs of Queensland Spotted Gum
produced a lower yield of Select grade boards. There were no substantial grade differences between
timber cut from three log sizes of Western Australian Jarrah.