Saturday, December 31, 2016

How old is a scar tree?

Aboriginal Scar trees are a diminishing archaeological resource. Those still in existence are generally more than 150 years old in Victoria. Continuing Aboriginal traditions of course, mean that culturally scarred or carved trees may still be created in traditional ways, but the record of the past, the trees that existed prior to the impact or invaders on the indigenous population, is rapidly being lost.  There are a few mechanism's for this - both natural and human-induced. Land clearing, timber cutting,  and increased burning were all brought about by the invaders, and probably accounts for the vast majority of scarred trees being removed. These impacts are continuing, either because of lack of knowledge about where the trees are or why they are worth keeping, or intentional damage by vandalism, illicit clearing, or racism-inspired acts.

But there are also natural forces at work reducing the stock of surviving scarred trees. Scars are lost both because trees die, or because the continue to live. Despite some Eucalypts being very long lived,  many are senescent in a couple of hundred years. In 400-500 years, it might be assumed that natures elements - of disease, decay, storm damage, natural fire, insect and animal damage, and just old age, will result in trees dying. Even dead a scar tree can stay in the landscape for another hundred years of more, but it will not last forever. Even the cases where tree surgery and preservation techniques are used to extend its life, the scar will still be lost. The stump in the Fitzroy Gardens is a case in point - gradually looking height and volume and sinking into the ground, despite various treatments.

In instances where the tree continues to live and is healthy, in most cases, the bark around the scar will continue to grow, gradually thickening and growing out and into the void where the earlier bark had been removed. Eventually, the two sides of the overgrowth bark will meet together and combine, leaving only a faint vertical line and some additional creasing in the bark around it to signify where the scar had been.

Here is a scar tree supposedly saved when it was relocated from Stanwell to Rockhampton Cultural Centre in Queensland.

How long does this process take? Probably not that long. A good measure is the scar tree cut on 17 November 1824, not by an aborigine, but by William Hovell, now 192 years old. In that time the scar has almost entirely sealed over, and the heartwood of the tree in which the inscription was cut, has rotted away completely. Another few decades and if the tree stays healthy, there will be only the faintest trace of where the scar once was.
So why does this matter? In another 100 years it is likely that the only scar trees left will be those in museum's or heavily restored and conserved. Natural forces will ultimately take all the rest. It is therefore imperative that some consideration is given to what is done in the mean time. Yesterday's The Age article  shows an example of well preserved scar trees at Boort, that the local Aboriginal community consider a major part of their culture and heritage. They are, however, preserved in their present dead state,because the lake was artificially flooded as part of an irrigation scheme, which killed the trees and prevented further overgrowth of bark. As they were also in a protected piece of public land, and there was no demand for their timber until, sitting as it is in permanent water, it became commercially valueless, they did not get cut down or burnt.

At least a program to identify and record them, and monitor their condition (not just the Boort trees, but all the surviving scar trees in the country) would at least let us know what we are going to lose.

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