UKTC Archive

Re: Tree hazard potential assessment study Highway and street tree needs and effects

Subject: Re: Tree hazard potential assessment study Highway and street tree needs and effects
From: Wayne Tyson
Date: Oct 10 2019 23:48:24
Cassian, my study has found that nearly all failures are a result of
*several* factors. If drought results in enough loss of fine roots, for
example, the resistance to lateral tension will be lowered. Many fail to
understand that the coefficient of friction in the root/soil matrix is
largely dependent upon the finer roots, whereas the larger roots provide
strength and support. Of course, any damage to the larger roots will cause
the loss of the finer root matrix connected to it. The most important
question is "What did the drought actually *do* to the tree that supposedly
brought about (or was a factor in) its failure?

I would be interested in any references to research on the differences in
friction coefficient in dry, moist, and wet soils, as well as fine, coarse,
and rocky soils--another area where presumption often rules in the absence
of evidence. "The absence of evidence is not evidence of absence" is one of
the great gremlins in research.

Of course, *context is everything*. If, for example, *all* of the trees
fail, that lends credence to the supposition that, for example, drought or
wind was at fault. If only a few trees fail, that is "reasonable" evidence
that more than one factor might be at play, meaning that more evidence is
needed. This does not mean, however, that the remaining trees are
completely free of such influences; they might fail in the next drought or
wind. GRAVITY RULES!

Wayne

PS: As to branch failures, I remember (decades ago) reading some Australian
research about internal cross-checking in eucalyptus heartwood, leading to
"summer branch drop" and weakness in timber. Can anyone provide links or
references to this phenomenon. I have noted eucalypt branch failures that
were rather cleanly broken, rather than a more jagged split as is common in
branch failures of many other species (of course, there are multiple
possible factors involved in branch failures).

On Thu, Oct 10, 2019 at 3:51 PM Cassian Humphreys <
consultingarboriculturist@xxxxxx.com> wrote:

Small luck there (glory press), looks like the house took the impact well.

Did the failure occur after a prolonged drought. In Australia l see many
more such failures occur after extended dry periods...?


On Fri, 4 Oct. 2019, 12:32 am Wayne Tyson, <wt750mv@xxxxxx.com> wrote:

I would like to hear from as many tree professionals as possible
regarding
how proximity of a highway or other public or private paving in areas
where
failure of the tree could be due, in part, to substandard root
development
and/or root system damage caused by the construction of improvements that
affect tree health and related risk.

I am only concerned with the tree's welfare; I am not concerned with
laws,
rules, and other conventions that are not based on solid, preferably
scientific, evidence.

I am finding that such proximity is often a factor in tree health and
failures.

Thanks in advance to all respondents.

Wayne



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The UKTC is supported by Bosky Trees arboricultural consultancy
http://www.boskytrees.co.uk/