The Visual Tree Assessment One-Third Rule: Frequently Applied, but Mostly Irrelevant

[Tommy Hutchinson]

The Visual Tree Assessment One-Third Rule: Frequently Applied, but Mostly Irrelevant

 

http://download.rinntech.com/2018_Rinn_SMA_OneThirdRule.pdf

[Gary Prentice]

Like most tree related 'rules', T/r is just a starting point in an assessment and shouldn't be followed blindly. Lots of veteran trees around with small crowns and a T/r of 0.1 that have stood for decades or longer. 

[daltontrees]

Yes the article shows that  once trees stop putting on height the t/r 'rule' ceases to have relevance.

[Khriss]

I would say its once trunk has stopped putting on girth. As internal decay will eventually catch up with the cambium. K

Edited January 12, 2020 by Khriss
( long after i am gone hehe)

[Tommy Hutchinson]

Some more reading: 

 

Why t/R Ratios Are Not Very Helpful

 

https://www.validtreerisk.com/resources/Documents/Why%20tR%20Ratios%20Don't%20Help%20v1.1-2019.pdf

 

 

Edited January 13, 2020 by Tommy Hutchinson

[Tommy Hutchinson]

And some more: 

 

Overview of techniques and procedures for assessing the probability of
tree failure - David Lonsdale,

 

1 - DL tree Statics Final Version 031203.pdf

Edited January 13, 2020 by Tommy Hutchinson

[Tommy Hutchinson]

:-)

 

Tree risk assessment:a review of methods:

 

https://www.researchgate.net/profile/Peter_Sterken/publication/323757808_Tree_risk_assessment_a_review_of_methods/links/5aa94cfd458515178818bbe1/Tree-risk-assessment-a-review-of-methods.pdf

Edited January 13, 2020 by Tommy Hutchinson

[Tommy Hutchinson]

On 11/01/2020 at 10:26, Gary Prentice said:

Like most tree related 'rules', T/r is just a starting point in an assessment and shouldn't be followed blindly. Lots of veteran trees around with small crowns and a T/r of 0.1 that have stood for decades or longer. 

The only time it should be a starting point is when a tree has perfect cylindrical residual wall which is closed. And how many hollowing trees have these features?! 

 

Arborists have been using the t/R ratio for decades unbeknown to the lack of scientific credibility and its near uselessness for predicting tree failure.  

Edited January 13, 2020 by Tommy Hutchinson

[Tommy Hutchinson]

More reading:

 

Shell-wall thickness and breaking safety
of mature trees

 

http://ps.ictinternational.com/content/uploads/2014/03/Shell-Wall-Thickness-and-Breaking.pdf

[Tommy Hutchinson]

FOUNDATIONS OF TREE RISK ANALYSIS:
Use of the t/Rratio to Evaluate Trunk Failure Potential

 

https://www.urbanforestanalytics.com/sites/default/files/pdf/bond_tR.pdf