Historic pine at risk of collapse


An historic Cook Island pine tree recently removed from a Wellington Point property would have been prone to “unpredictable collapse’’ within two to three years, an analysis of the tree has revealed.

A report by Redland City Council’s arboriculture technical advisor has found one section of the 45m tree was 90 per cent decayed, with only a thin section of structurally supportive sound wood remaining.

The decay, photographed below, was at a height of about 10m and extended well towards the tree’s apex.

“The presence of an active white-rot fungus was evident in all of the decayed dissections of the trunk analysed. In some samples the fungi infection was almost through to the outer bark layer,’’ the report says.

“The cavity contained rain water that had penetrated through the opening in the trunk caused by an old lightning strike. This moisture had contributed to the rapid rot of the heartwood within the columnar cavity.

“It was estimated that the fungi infection would have breached to the bark layer in some areas of the trunk within two to three years, based on the known spread-rate of this type of fungi. This would have rendered the tree extremely unstable and prone to unpredictable collapse.’’

The report says the health and visual appearance of the tree did not give an indication as to the level of deterioration inside the trunk.

“It is normal for a tree of this vintage to contain extensive decay within the heartwood and, providing sufficient sound-wood is present, the tree will remain structurally sound and visually healthy. It is the presence of the white-rot fungus that consumes and weakens sound-wood and cambium, predisposing the tree to inevitable collapse,’’ it reports.

The tree had been protected under a Vegetation Protection Order but Council voted to allow its removal after an independent arborist found it was riddled with white rot.

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A section of the pine tree with rotted heartwood removed, showing the remaining sound wood.

 

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The same section of the pine tree before the rotted core was removed. The dark area shows the extent of the fungus.