UKTC Archive

RE: Diameter callipers

Subject: RE: Diameter callipers
From: Jim Quaife
Date: Aug 16 2019 06:12:32
I researched the genesis of the 5837 12 x multiplier but I am not going to 
post it.  This is not me trying to be "sinister", but suffice it to say that 
there is no scientific basis for it.  The original Tree Protection Distance 
(1991) worked, but being protected by chestnut paling was vulnerable to 
'alteration' and was often ignored.  The first 5837 (1980) just mentioned 
protecting roots within the crown drip line (with a distance of two-thirds of 
the tree's height for fastigiate trees), and there is a table setting out 
minimum distances between a tree and excavation based on tree height.
Despite the lack of science, the initial development of the RPA was based on 
sound experience, and I regard it as being a sensible basis for the 
protection of roots. I was pleased that my long niggle that soil was not an 
included factor in 1991 and 2005 (it was in 1980) was at last included in 
2012.
I still maintain that the RPA is the basis for the application of 
arboricultural interpretation of the site characteristics and the 
consideration of a tree's entire root system.  I do not specify inadequate 
tree protection, but of course if arbs are not instructed to manage tree 
protection on a site . . . !
Rigid "it is the only thing that matters" application of the RPA arithmetic 
is disappointing.
My view is that if all you use is a calculator, why do you need to know 
anything about trees?
Richard Nicholson liked the term "engaged" (aka informed and thinking) 
arboriculturist - so do I.  I repeat yet again that my single word to 
describe arboriculture is 'justification'.
Jim

-----Original Message-----
From: uktc-request@xxxxxx.tree-care.info 
[mailto:uktc-request@xxxxxx.tree-care.info] On Behalf Of Paul Barton
Sent: 16 August 2019 06:30
To: UK Tree Care
Subject: Re: Diameter callipers

I’ve heard it said that the stem diameter to root volume theory is an 
extension of the ‘pipe theory’ which attempts to link stem thickness with 
foliar volume - see link.

I am not too sure where the 12 x multiplier emanated from though.

Kind regards,

Paul Barton
MSc, BSc (Hons), TechCert (ArborA) MArborA

Director | Barton Hyett Associates Ltd
Website: www.barton-hyett.co.uk
Tel: 01386 XXXXXX
Mobile: 07765 XXXXXX
Office 5E, Deer Park Business Centre, Eckington, Pershore, Worcestershire, 
WR10 3DN

Company Reg No: 7110670 Registered in England and Wales.
A copy of our GDPR Privacy Notice can be found on our website by clicking on 
this link.
On 15 Aug 2019, 22:39 +0100, Wayne Tyson <wt750mv@xxxxxx.com>, wrote:
Thank you, Bill Kowalczyk, for your summary.

Perhaps you can further enlighten me.

What was/is the basis for the "rule of thumb"?

Is the 12 x stem diameter "rule" based on the tree's dbh at maturity?

Regarding ". . . roots beyond this zone may get trammelled *without
significant negative impacts* [[Italics mine]]on the health and vitality of
retained trees," on what basis was that determined?

Cheers,
Wayne

On Thu, Aug 15, 2019 at 5:49 AM Bill Kowalczyk 
<bill@xxxxxxxxxxxxxxxxx.co.uk>
wrote:

Hi Wayne,

The oft quoted British Standard; "BS5837:2012 - Trees in relation to
design, demolition and construction” came up with a calculation for
recommended root protection areas (RPA), which works out at a radius of 12
x stem diameter (but measured at 1.5m for some peculiar reason) for most
single stemmed trees.

In practice, with most trees, this invariably comes to about the same as
measuring to the “drip-line” of the canopy edge, and accepts that roots
beyond this zone may get trammelled without significant negative impacts 
on
the health and vitality of retained trees.

It’s a bit “rule of thumb” developed by the working group who first came
up with the standard back in the early 1990’s, but it’s all we’ve got and
better than nothing.

Cheers,

Bill

On 14 Aug 2019, at 23:55, Wayne Tyson <wt750mv@xxxxxx.com> wrote:

What does dbh have to do with RPA? What are the standards and upon what
data doth they rest? Protection from what, for example? That is, in the
simplest terms, other than dbh how are RPA's determined?




--
The UK Tree Care mailing list
To unsubscribe send mailto:uktc-unsubscribe@xxxxxx.tree-care.info

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




--
The UK Tree Care mailing list
To unsubscribe send mailto:uktc-unsubscribe@xxxxxx.tree-care.info

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



-- 
The UK Tree Care mailing list
To unsubscribe send mailto:uktc-unsubscribe@xxxxxx.tree-care.info

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



-- 
The UK Tree Care mailing list
To unsubscribe send mailto:uktc-unsubscribe@xxxxxx.tree-care.info

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