Ah yes, the Three Horsemen of The Suburban Apocalypse: Dogs, Noise and
Trees.
Some astute observations there, Julian. I doubt that bark-chewing
contributes much to limb-shedding by E Mannifera, the aptly named Brittle
Gum. I recently had to have one removed from the nature strip,
unfortunately. It was a wonderful spreading tree of great height, the
largest of its class, that had benefited from intermittent watering over a
life of some 46 years. A victim of its own vigorous growth, each year it
would shed a few branches and about every second year a large one that would
have been death to anyone beneath and a write-off for any vehicle. I had to
tell people not to park near it on days like we are having at the moment.
However this year a large branch came through a window, and a few months
later about a quarter of it thumped down in the driveway. Incidentally, if
you are in a similar position it is important for any property damage claim
that you make 'dangerous tree' representations beforehand.
The point is that none of the fallen limbs showed any disease or prior
damage, although some were naturally hollow. The brittleness is caused by
the growth habit which sees heavy, often fresh, foliage at the end of
over-long tortuous branches that twist and work in the wind. The species is
simply unsuitable for street planting, unfortunately.
Now, another experience with a lesson for serious tree-savers. Nearby there
was a contentious development now some 20-years old. The section in
question had to be rezoned to allow construction of residences, and this
threatened about 17 mature 'original' yellow-box, all in good health. The
approval allowed felling of 5, but required preservation of the remainder.
Later 3 were allowed to be removed on representations by the new residents.
However there followed a depressing series of case by case approvals for
lopping of substantial limbs which led to disease and grotesque lollipop
malformation so that complete removal was eventually authorised. The lesson
is: if you are told 'preservation of trees will be required' do not believe
it. The subsequent 'balancing of interests' will see them all gone.
Now, back to Julian's Tree in Question (TIQ). I think we are zeroing in on
the main point which is the lack of justification for lopping while there
was an active Gang-gang nest. The claimed careful decision-making process
described in the letter to Wendy is a fine example of advanced
bureaucratspeak, conveying nothing about what they actually thought about
the issue, if anything. The involvement of RSPCA was a nice touch but
should have been unnecessary. It seems incredible that hand-rearing was
really part of the plan. Not a risk-free option and a lot of trouble to go
to when they could have waited a couple of weeks.
-----Original Message-----
From: Julian Robinson
Sent: Thursday, 24 December 2009 12:01 AM
To: Canberra Birds
Subject: Trees
As mentioned, dangerous branches can be separated from dangerous
trees. The tree in question certainly had some risky branches, a
fact that had been pointed out to TAMS some time ago. For whatever
reason this advice was not acted upon until one of them fell
recently. Now after some attempts to get quantified information on
the integrity of the tree (which may or not have been completed and
may or not have supported drastic action), TAMS presumably used
advice from the consultant Ian mentioned and then elected to do what
they did i.e. remove all but the tall stump immediately. From the
point of view of the tree, it would be interesting to see any hard
evidence that was used to support more than lopping one or two
remaining risky branches. No information has been made available
publicly which is unfortunate given the feelings of some interested
parties and some (non-professional) post-felling opinions that the
tree appeared fundamentally sound (which if true would be contrary to
what Ian's expert reported).
From the point of view of the nesting Gang-gangs, I can't for the
life of me understand why it wasn't possible to leave the
felling/lopping for another couple of weeks until they fledged, with
whatever precautions may have been legally necessary in the meantime.
The decision making process in Canberra re tree safety activities is
not transparently functional despite recent publicity and discussion.
re trees having dangerous branches without being themselves a
risk... interestingly in a COG context, I only learned tonight and
maybe some others haven't picked up on this either, one of the
significant causes of trees dropping branches is the direct result of
Cockatoos. I knew galahs would chew around tree hollows but had no
idea of how active they are in other areas. There are some excellent
examples very close to the Tree In Question of some that have been
dramatically chewed by Galahs(?) around the area where branch meets
trunk i.e around the fork. This often leads to rot, failure to grow
and loss of strength to the extent that those branches eventually
fall prematurely. It has been suggested that this behaviour might
even be proactive, instinctive hollow-making behaviour since
then-fallen branches often leave a nice hollow. Arborists sometimes
go to considerable lengths in domestic environments to prevent
cockatoo access to these vulnerable areas. This preventive measure
doesn't yet seem to have made its way to government pro-activity,
even for notable trees or especially risky trees. Anyone who is
interested in this behaviour can see some great examples in the trees
around the Tree In Question - especially the tree to the right or
left of the blue marker on this map ...
<http://maps.google.com.au/maps/ms?ie=UTF8&hl=en&msa=0&ll=-35.267188,149.142
221&spn=0.002729,0.003401&t=h&z=18&msid=109598757085709980006.00047b634eeb4e
a3aa1af>
I think E Manniferas are particularly affected -- I wonder how much
of their 'brittle' characteristic is due to the fact that their bark
seems to attract the best attention of Galahs?
Julian
At 09:38 AM 23/12/2009, Peter Ormay wrote:
>The tree itself may be less likely to fall because of the reduced
>windload and the weight on it but the branches are more likely to
>fall because of the weakened tree, often an empty shell and often
>weakened branches due to termites and rot.
>Peter
>
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