Hi,
I went to a TEP seminar about Tree Statics and one of the presenters, a
German chap, gave a talk on the new German standard for tree support. My
memory is a bit vague but I seem to remember that he suggested that there
were three reasons for bracing:
1. to 'catch' a branch if it broke and prevent it from causing harm;
2. to allow branch movement but prevent it moving beyond its breaking
point; and
3. To prevent movement, for instance when a crack had formed below an
acute union and it was desired to allow new sapwood to grow over it. Also
to prevent movement when a defect was so serious that movement would be
detrimental for whatever reason.
I recently inspected a huge churchyard beech with large structural branches
overhanging a road. The large branches had been braced over thirty years
ago with steel cables and through bolts. At that time the PCC were
recommended to either fell the tree or brace it. The brace is still good
and saved the tree from felling; whether it actually needed it or not. I've
recommended that no further work should be done at this time except
re-inspecting it every two years.
Regards
Luke Steer BSc.(Hons). Dip.Arb.(RFS). F.Arbor.A. MICFor.
Chartered Arboriculturist
Treescapes Consultancy Ltd.
Melbourne
17 Millans Park
Ambleside
Cumbria
LA22 9AG
015394 34698 (Office)
07734 113964 (Mobile)
luke.steer@xxxxxxxxxxxxxxxxxxxxxx.co.uk
-----Original Message-----
From: Complete Tree Services [mailto:arbor@xxxxxxxxxx.co.uk]
Sent: 29 July 2009 16:55
To: UK Tree Care
Subject: RE:
Surely the purpose of bracing is not to support the limb/stem if it fails
but to restrict movement so as to reduce the likelihood of failure.
Obviously there needs to be movement for the limb/stem to develop reactive
growth and fulfil its dynamic dampening functions. That's where the Cobra
type systems are good as they are more flexible that steel cable.
The second photo shows what is in effect two trees hence the lack of
reactive growth around the area where they are touching as distinct from the
potentially weak union in the first that shows signs of reactive growth.
Although beech have a reputation for not withstanding heavy pruning a
combination of bracing and a combined thinning and reduction of say up to
15% could do a lot to reduce the likelihood of failure with minimal
detrimental impact on the tree's health and aesthetics in the case of the
tree in photo one.
Tree 2 in photo 2 I would just treat that as two leaning trees very close
together. Again if it was felt necessary to carry out some mitigation works
a minimal thin/reduce say up to 10%.
A combined Thin/reduce is where you take out the longer growth in the
foliage clusters to achieve the specified % reduction in density.
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