In the middle of Barcaldine in western Queensland stands a resurrected ghost gum (Corymbia aparrerinja). This reconstructed tree, Tree of Knowledge, is the spiritual birthplace of the Australian Labor Party and a symbol of the 1891 shearers’ strike.
And whilst the living tree was poisoned in 2006 with glyphosate for reasons that remain unknown, despite arborists’ efforts to save it, the tree was declared dead in October that year. Although its death was a loss felt across the region, the tree’s journey from decline to preservation and eventual reconstruction has become a remarkable example of heritage conservation and local scientific expertise.
For more than a century, the Tree of Knowledge served as a gathering point for unionists and workers. For many Australians, it was more than a tree; it was part of the nation’s identity.
The challenge was how to honour the tree and ensure future generations understood both its significance and the science behind its preservation.
Scientists from the wood protection team at the Queensland Department of Primary Industries’ state-of-the-art forestry research facility in Salisbury, Brisbane, led the effort.
In 2007, the tree was carefully dismantled at its original site, with every branch meticulously marked to allow accurate reconstruction. The branches and main trunk were then loaded onto a bed of sand and transported to Salisbury in Brisbane. There, they were installed over a large, covered, purpose-built tank fitted with an irrigation system before a preservative solution was sprayed regularly over the timber to keep it damp throughout the treatment process.
A boron-based preservative supplied by Koppers Performance Chemicals was used to impregnate the wood. The treatment, supported by regular testing, continued for more than a year to ensure full penetration.
And as the boron diffused into the timber, it provided protection against insect and termite attack. Because the reconstructed tree would be housed under cover, additional decay protection was not required.
In 2009, the preserved Tree of Knowledge returned to Barcaldine.
But simply reinstalling the trunk was not enough; it needed long-term protection from the elements. A roofed structure was built above it, and a canopy of 8000 hanging slats made from recycled spotted gum was suspended 18 metres above the ground. These slats mimic the form of the original canopy, creating the illusion of a leafy ghost gum from a distance while revealing the preserved remains up close.
And whilst the boron protects the timber from insects and termites, it is not fixed in the wood and can leach out under wet conditions. The covered installation shields the trunk from rain and direct sunlight while allowing airflow.
At night, lighting transforms the structure, making the tree’s “ghost” visible across the flat plains surrounding Barcaldine.
Whilst the full Tree of Knowledge is no longer alive, it has been preserved as a monument that has a different kind of immortality. It stands as a quiet reminder of the birth of a movement, sheltered beneath its timber canopy in the town where its story began.
