I was very sad to hear the news that the ‘Separation Tree’, a River Red Gum (Eucalyptus camaldulensis) in the Royal Botanic Garden, Melbourne, is slowly dying due to it being ring barked with a gash 1 metre wide (circumference 3.8 metres) in 2010 and again in 2013 by some rotten vandals. I don’t care what their politics or whatever their problem was, it was a terrible thing to hurt the tree.
It was a majestic old tree standing 24 metres (80ft) high, overlooking the Yarra River and silently observing life as it passed by. It was about 400 years old and was called the Separation Tree because it was chosen as the spot in 15th November 1850 where people gathered to hear the good news and celebrate the political separation of Victoria from NSW with fireworks, processions, games and the beaut all-important Australian tradition of having three public holidays.
For those who aren’t quite sure how ring barking affects trees, here is an explanation:
Just under the bark is the vascular cambium and it is responsible for laying down the trees new cells which increases the width of the girth. If it is damaged, then the tree cannot function properly which means the water and nutrients can’t travel up the xylem from the roots to the leaves and the soluble organic material made in the leaves during photosynthesis such as sugars and carbohydrates can’t travel down phloem to the roots. Trees don’t show injury immediately like people do. It may take many years to notice there is a problem and by the time you have realised that, it is too late to fix it.
The staff at the Botanic Gardens did all they possibly could and more to try and save it. They consulted the best arborists in Australia because repairing such delicate tissues takes a lot of skill, knowledge and luck; so together they worked on a management plan which was working until it was attacked again.
It was inspected by the garden staff daily, weekly and monthly, and once a year an arborist climbed it for a closer inspection. They also took photographs regularly of the canopy, so they could compare them with previous ones to detect if there was any change for the better or worse. They had also banded it to keep the ol’ possums out of the canopy and soil moisture monitoring equipment had been installed below the tree’s canopy to inform the RBG staff of the variances in the levels. This information was able to tell them if the tree was taking up moisture and whether it needed to be irrigated.
As part of the consultative process one of RGB’s propagators, Dermot Molloy, was consulted. He suggested several grafting procedures that could help improve the trees chances of surviving. The two trailing grafting techniques were:
1. Bridge grafting
2. Approach grafting
Bridge grafting is a technique often used by arborists to repair damage. A bridge graft is where a section of scion (healthy plant material) is attached above and below the wound. A small ‘V’ shape cut is put into the bark and the same is done to the scion material, making sure they both match up and fit together. The scion is nailed in place and grafting mastic tap or wax is used to seal the wound and prevent it from drying out. The area is then covered with some hessian to protect it. It is misted daily to keep it moist.
The second technique is approach grafting that involves planting saplings of the Separation tree at the base of the trunk and attaching the grafts above and below the wound. The sapling continues to grow and when the graft forms, the unwanted parts of the sapling are cut off. The graft allows the tree to carry out its physiological functions.
Things were looking good for the Separation Tree until it was ring barked again in 2013.
Over the years seed has been collected and there is another magnificent younger Eucalyptus camaldulensis planted by Sir Dallas Brooks 15th November, 1951 to commemorate a century of self government, and also another planted in 2001 by Governor John Landy commemorating 150 years, but it isn’t quite the same (although genetically it is).
Vale our River Red Gum (Eucalyptus camaldulensis) in the Botanic Gardens Melbourne. We will miss you.