UKTC Archive

Re: Estimating tree ages based on trunk diameter/girth

Subject: Re: Estimating tree ages based on trunk diameter/girth
From: Bill Anderson
Date: Jan 12 2022 12:58:50
I don't use it often Phillip, but I did age an elderly Beech tree using it
last year. Someone mentioned it in a row about a TPO application so I was
obliged to. It did give an age (135 IIRC) that was exactly the same as the
house that was next to it, which made a lot of sense....

Bill.

On Wed, 12 Jan 2022 at 12:36, Jerry Ross <trees@xxxxxxxxxx.co.uk> wrote:

Very frequently - Notwithstanding  Jon's, and Tim's, dismissal of it!
It may be unreliable but it's all that's readily available to give some
weight when some weight is required over and above the results of simple
beard-stroking.
(Also, with all those figures and equations, it'll be bound to impress
Counsellors, planning inspectors and magistrates)

And as I wrote previously, you can omit all the calculations by using
the bristoltrees.space webpage




On 12/01/2022 12:22, elsteadbysea@xxxxxxxxxxx.com wrote:
Has anyone used this document from the FC?

https://www.forestresearch.gov.uk/documents/6765/FCIN012.pdf

Phillip


-----Original Message-----
From:uktc-request@xxxxxx.tree-care.info  <
uktc-request@xxxxxx.tree-care.info>  On Behalf Of Tim Moya
Sent: 12 January 2022 12:16
To: UK Tree Care<uktc@xxxxxx.tree-care.info>
Subject: RE: Estimating tree ages based on trunk diameter/girth

Yes - What Grumpy said
Tim Moya

-----Original Message-----
From:uktc-request@xxxxxx.tree-care.info  <
uktc-request@xxxxxx.tree-care.info>  On Behalf
Ofgrumpy@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.co.uk
Sent: 12 January 2022 11:50
To: UK Tree Care<uktc@xxxxxx.tree-care.info>
Subject: RE: Estimating tree ages based on trunk diameter/girth

Paul

You already have a reference to "Mitchell". No doubt someone will point
out "White" shortly. Neither were mensurationists or statisticians,
although clearly both collected loads of data. I frankly am appalled by
what I read and hear about tree age and diameter.

I realise most of us need a good old beard to stroke (sorry, ladies)
when we are asked how old a tree is. We stroke our beard (I don't have one)
to impress on our listeners how much thinking we are doing and how much
experience we are recollecting when we examine the size of a tree and come
up with a number. Ooooo this one must be at least 200 years old, I say.
Gasps of adulation arrive and we all go off happy, respectful of this
ancient tree. It's frankly nonsense:

Trees vary considerably in their diameter growth. Partially determined
by species, partly determined by site, partly determined by density. The
latter simply acknowledges that competition from nearby vegetation and
trees alters growth rates - closely growing trees will fatten less quickly
than free growing trees. Yes obvious in a spacing trial in early years, but
less obvious with widely grown trees when they are large.

The situation was acknowledged in Forestry Commission Bulletin No 1
dated 1919 Collection of Data as to the Rate of Growth of Timber.

We all know that weather and climate alter growth, so attempting to have
a figure for all species in all conditions is well.......an average. It's
of very little use in determining age of individual stands, and in
particular individual trees. If someone were to bring this into a court
room, I would have a field day.

Yes, it would be nice to have a simple solution to a complex problem.
The solution is to kick councils up the backside and say 50 year old, or
even 20 year old Area orders are unworkable......and if you want to
prosecute people for tree works to marginally aged trees you may have a
problem. I realise you have a practical problem in front of you, but there
is no easy answer. You are better off trying to find old aerial photos from
the second world war (or more recent if that is the age of the TPO)

Before someone does mention "White" look at his FC Information Note
dated 1998. Table 1a sort of acknowledges the significant variation in
growth rates possible. But without some sight of the data on which this
table is based or any analysis arising from it you could get seriously
misled. All of the figures are averages. Thus expectation that growth might
be greater on a "good" site than on an "average" site doesn't help much.
Poorly growing trees on a good site are likely to grow less than fast
growing trees on an average site. Using these to estimate the age of trees
using these averages is as good as stroking my beard......

A good source of tree growth data? The only source is Forest Research
but clearly their data is almost entirely for plantations & forest species.
I doubt they have much data on widely spaced trees and even less on open
grown trees. I wonder whether they hold Mitchell's and White's data and
whether it was approved for professional use (i.e. anecdotal data doesn't
stand up to much scrutiny), or just binned?. Zero data on the wider range
of trees used in arboriculture? I approached them a little while ago to see
if they have any data on yew growth. Zero was the reply. You can find a
synopsis, but no growth data in a paper in the RFS QJF in early 2021 or
late 2020. I am afraid I don't have the specific reference to hand but I
think it contains "Permanent Sample Plots" in the title. Richard Baden came
back to me with a very long email & you could explore what data they have,
but Richard's remit may be limited to the plots:

Richard Baden         (email using @forestresearch.gov.uk)
Assistant Sample Plot Officer
Forest Mensuration, Modelling and Forecasting Forest Research Alice Holt
Lodge Farnham  GU10 4LH

They may have a dusty cabinet of growth data that no-one has looked at
for a while. That's always the impression I get when I go to Alice Holt.

Jon


-----Original Message-----
From:uktc-request@xxxxxx.tree-care.info  <
uktc-request@xxxxxx.tree-care.info>  On Behalf Of Paul Barton
Sent: 12 January 2022 08:56
To: UK Tree Care<uktc@xxxxxx.tree-care.info>
Subject: Estimating tree ages based on trunk diameter/girth

Dear collective,

I wonder if you can help me?  I am looking for a simple method to
estimate tree ages as part of a preliminary review of some area TPOs - i.e.
to assess whether trees that are present now were most likely present (or
not) on the year the area TPO was served.

I have come across various apps that claim to give an age based on trunk
girth but after a brief test they seem to overestimate age (based on my
experience only) as I suspect they are based on forestry plantation trees
which tend to be more slender over time than open grown trees.

I came across this document from Newport council (
https://www.newport.gov.uk/documents/Leisure-and-Tourism/Countryside/Measuring-Trees.pdf)
which suggests that tree growth rates could be split out in to slow,
moderate and fast - each with a corresponding ‘average’ annual girth
increase.  These are given as:

• Slow - 1.88 cm per year
• Average - 2.5 cm per year
• Fast - 3.13 cm per year

Using such values would allow me to classify species by growth rate
category and therefore have a ready reckoner to estimate tree ages based on
their girth.  It can never be claimed to be very accurate but for the
purpose of quickly assessing hundreds of trees a repeatable documented
method would be useful.

BUT I don’t know if the above growth rate values are based on good data,
ideally in the UK.

Finally to the point (congratulations if you lasted this long)…can
anyone point me to a reliable source of UK tree growth rate data so that I
could verify or amend the above suggested rates of growth?

Kind regards,

Paul Barton

www.barton-hyett.co.uk  | Barton Hyett Associates Ltd | Arboricultural
Experts





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To unsubscribe send mailto:uktc-unsubscribe@xxxxxx.tree-care.info

The UKTC forum is supported by Bosky Trees arboricultural consultancy and
Stockholm Tree Pits
https://www.stockholmtreepits.co.uk