Botanic Gardens Trust, Sydney, Australia

Wollemi Pine research - determining its age

To determine their age, a scientific team cut cross-sections from a fallen tree trunk (a large mature, 35–40 metres tall trunk when it collapsed) at the first discovered site in Wollemi National Park, and sent them to the Australian National University Forestry Department for analysis.

Seasonal growth characteristics of the tree rings were examined under a scanning electron microscope. The sharpness of the latewood-earlywood boundaries, and the knowledge that winter freezing temperatures occur in the canyon, indicate that the rings are annual.

By counting the tree rings - the study of tree rings is called dendrochronology - combined with carbon dating, the best estimate for this sample is probably about 350 years old, meaning that this trunk starting growing around 1650!

However, because of the unusual branching habit of this species (called coppicing - see characteristics), we can’t determine how old the original tree was before this trunk was produced - possibly hundreds or even thousands of years since it was a seedling.

Although preliminary results have been released in a poster, there is still more to be done. By examining a number of cross-sections along the length of the trunk, and establishing the age of the trunk at a number of different heights, a model for determining the growth of a tree can be developed. This model can then be used in estimating the age of all the trunks in the site.

Researchers

Dr Cris Brack (Australian National University)

cross section of trunk
Cross section of fallen trunk of Wollemi Pine showing growth rings used to determine the age of the trunk.

Many trunks formed by coppicing
The many separate trunks formed by the unusual habit of the Wollemi Pine to self-coppice means it's only possible to determine the age of the individual trunks not the trees.

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