UKTC Archive

Estimating tree ages based on trunk diameter/girth

Subject: Estimating tree ages based on trunk diameter/girth
From: Paul Barton
Date: Jan 12 2022 08:55:58
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 
 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 

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 | Barton Hyett Associates Ltd | Arboricultural Experts

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