This letter and photos are in response to the excellent
article “75 Old Rubber Trees lost...” by Metinee Chaikuna (CM Mail
August 30). I was interested in the information about the history of the
planting of these Don Yang trees (Dipterocarpus alatus).
close to trees severs primary roots.
There has been considerable attention lately to the fate
of these trees, particularly in regard to the drainage work and root damage
that is taking place along the road at the base of these trees. Articles
have appeared in other publications, and I was asked to inspect them by
Ricky Ward, environmentalist, who is trying to facilitate the saving of
these trees through government channels.
structural root can be tunneled under instead of cut.
As an arborist (professional tree care specialist) I
would like to make a comment for the general interest of tree lovers and
custodians, regarding the last paragraph of this article: “Nowadays, the
main cause of death for yang trees are local people who like to attach
advertising signs to the trees or pour cement around them, or discard
rubbish around the trees...”.
I don’t buy that assessment. Although any wounding,
above or below ground, can open an avenue for fungal infection, I really
don’t think that attaching advertising signs is a main cause of death in
these huge trees. And of course the introduction of toxic substances
(paints, petroleum products and other chemicals) in “rubbish” dumped
within the root zone may contribute to decline, the bulk of the absorbing
roots will not be found close to the base of the trees in such large
specimens. A little rubbish or cement, while not a good thing, is probably
not a main cause of death.
I believe the main causes of death of these trees are
soil compaction and pavement throughout the root zone, root cutting and
fungal root decay.
These trees have been around a long time and many will
naturally succumb to environmental impact, decline in health and die. There
are many factors that cannot be controlled at this point. But one
preventable cause of decline, death or structural failure, is root cutting.
When tree roots are severed, not only is water and
nutrient supply cut off, but the structural support is weakened or
eliminated. When the large anchor roots of huge trees like this are cut,
disaster is being invited.
I inspected one of these giants, on the same road, that
toppled and went down through a house a few months ago. I observed extensive
fungal root decay that had advanced from old root cutting wounds. Obviously
the structural support of the tree had been undermined by mistakes made in
the past, the same mistakes that are being made today.
Donald W. Cox, certified arborist
International Society of Arboriculture
International Society of Tropical Foresters