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

[Gary Prentice]

25 minutes ago, Tommy Hutchinson said:

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.  

I'd say that less knowledgeable arbs having been using the T/r ratio in the mistaken belief that it's absolute.

 

When it was originally published Gruber (?) and others raised doubts on the statistics used to verify the hypothesis and that crown size/sail area/shelter was absent from the equation.

 

As a starting point (open or closed cylinder aside) it's something to consider - along with H/D ratio, crown exposure, crown size and density and a raft of other visual assessments, towards a determination of failure potential. It's always going to be unwise to grasp a one size fits all formula when making decisions about a living organism. 

 

I studied, in depth, almost all of the assessment methods available in collage (L6) and to be blunt, they all have faults. Even sonic tomography (sorry Steve ) only gives a picture of the interior across the plane of the test. At best I think that all we can realistically do is to make an assessment to the best of our ability using whatever/all of tools/methods/knowledge/experience that we have to hand (or that the client can afford/the tree merits)

[Tommy Hutchinson]

Just now, Gary Prentice said:

I'd say that less knowledgeable arbs having been using the T/r ratio in the mistaken belief that it's absolute.

 

When it was originally published Gruber (?) and others raised doubts on the statistics used to verify the hypothesis and that crown size/sail area/shelter was absent from the equation.

 

As a starting point (open or closed cylinder aside) it's something to consider - along with H/D ratio, crown exposure, crown size and density and a raft of other visual assessments, towards a determination of failure potential. It's always going to be unwise to grasp a one size fits all formula when making decisions about a living organism. 

 

I studied, in depth, almost all of the assessment methods available in collage (L6) and to be blunt, they all have faults. Even sonic tomography (sorry Steve ) only gives a picture of the interior across the plane of the test. At best I think that all we can realistically do is to make an assessment to the best of our ability using whatever/all of tools/methods/knowledge/experience that we have to hand (or that the client can afford/the tree merits)

Yes Gruber, and now a few others. 

 

I agree they all have limitations, some  more so than others. Especially when you start to reed extensively into the science (if any) and methodologies behind them. 

 

Arboriculture just needs to evolve a bit more, it's happening but it's slow because it's a very niche subject, but becoming more credible and known. This will hopefully mean more research funding thus progression(s). 

[Gary Prentice]

4 minutes ago, Tommy Hutchinson said:

Yes Gruber, and now a few others. 

 

I agree they all have limitations, some  more so than others. Especially when you start to reed extensively into the science (if any) and methodologies behind them. 

 

Arboriculture just needs to evolve a bit more, it's happening but it's slow because it's a very niche subject, but becoming more credible and known. This will hopefully mean more research funding thus progression(s). 

If it helps, Frank Rinn is very approachable. I contacted Rinntech for some literature for my own research and he personally sent me a raft of literature (some in German )

 

Arb has and is constantly evolving, the problem is the depth of study needed (physiology/biology/chemistry/mycology/soil sciences) to even begin to understand trees. Just food for thought, we're in 2020 and still arguing something as 'basic' as how a branch union is formed! Consider that we put a man on the moon 50+ yrs ago but with all the engineering technology available we can't, AFAIK, reproduce that branch union . Can you imagine how buildings would change with a lever arm (not cantilevered) of the same proportions that trees naturally create?

[Tommy Hutchinson]

Just now, Gary Prentice said:

If it helps, Frank Rinn is very approachable. I contacted Rinntech for some literature for my own research and he personally sent me a raft of literature (some in German )

 

Arb has and is constantly evolving, the problem is the depth of study needed (physiology/biology/chemistry/mycology/soil sciences) to even begin to understand trees. Just food for thought, we're in 2020 and still arguing something as 'basic' as how a branch union is formed! Consider that we put a man on the moon 50+ yrs ago but with all the engineering technology available we can't, AFAIK, reproduce that branch union . Can you imagine how buildings would change with a lever arm (not cantilevered) of the same proportions that trees naturally create?

Yes, Frank is interesting. I've been to a few his talks. I'd have a problem reading in German though... :-)

 

Yep, we know very little! At this moment in time I feel a lot findings within the realm of trees are making us ask more questions... However, there are some answers! 

 

Biomimicary has helped civilisation a lot and the genius of nature is a wonderful thing. But, not sure how we would construct buildings with a xylem and phloem matrix. ?

[Gary Prentice]

Google translate is your friend 

 

I've been lucky too, talking to Frank Rinn and Klaus at a number of events, the rivalry is quite amusing. When Duncan Slater wrote about Shigos branch attachment model I asked him about his thoughts. He wasn't impressed, his haughty response was "He's wrong!" 

 

A Xylem and phloem matrix! Wonderful, that would sort a buildings plumbing too