From eucalypt survival to Wollemi Pine decline

The Charles Sturt University (CSU) botanist who discovered the secret bushfire survival skills of the eucalypt has turned his attention to a suspected 'design flaw' in the endangered Wollemi Pine.

While investigating the buds that form shoots at the base of the Pine, botanist Dr Geoff Burrows has noticed that the tree sheds whole branches rather than individual leaves like almost all other plants.

He found a remarkable reduction in the number of water conducting cells at the base of each branch. Externally the branch base looks quite normal but hidden beneath the bark is the constriction in the water conducting tube. While the constriction makes it easy for the Pine to shed branches it probably creates difficulties in supplying all the leaves with water, thereby causing problems in dry periods.

"It's very early days in my investigations but I suspect this 'design flaw' in today's environment could be associated with the decline of the Wollemi Pine," said Dr Burrows.

The Wollemi Pine was discovered by a NSW National Parks and Wildlife officer in a canyon in the Blue Mountains in 1994. Only a few trees in a small area have been found although the fossil record indicates the species was once widespread and abundant. Dr Burrows is working with scientists at the Mount Annan Botanic Garden on the Wollemi pine.

In 2002, Dr Burrows reported that eucalypts have developed a remarkably different system of post-fire regeneration to trees from the northern hemisphere.

The botanist uncovered that the lumps on the bark of a eucalypt are not buds as previously thought but are connected to bud-forming tissue, that runs across the bark and even into the outer wood. The depth of the bud-forming tissue ensures the eucalypt can lose 2cm of bark in a fire and still be able to resprout.

"The study provides the first evidence for why eucalypts can produce shoots after various fire intensities and various depths of bark death," Dr Burrows said.

Item provided courtesy of Charles Sturt University