The VTA Method, lets talk

[Tony Croft aka hamadryad]

I am starting this thread because here and elswhere I see poeple debating principals of the VTA method, also many comments regarding the validity of the method, some even stating that Claus hasnt enough proof to back his theories, that he flies by the seat of his pants etc etc etc.

 

I am a BIG fan of claus, he is a natural born includer, a decent man and the best teacher ive ever had, his books and influence have completley changed my perceptions and direction with regards to trees.

 

So can anyone and everyone who has an opinion, good bad or indifferent please come chat a while as I would really like to understand what the issues are, what is not understood, the docs that strive to squash the validity of the VTA method etc etc etc, maybe even learn more myself, its all good and Im always in action for a reaction as my friend shamas used to say:thumbup:

 

TR ratios have been an issue for time, and it seems slenderness ratios are also now up for debate, so lets start here, anyone going to kick this off?

[BatiArb]

I am starting this thread because here and elswhere I see poeple debating principals of the VTA method, also many comments regarding the validity of the method, some even stating that Claus hasnt enough proof to back his theories, that he flies by the seat of his pants etc etc etc.

 

 

TR ratios have been an issue for time, and it seems slenderness ratios are also now up for debate, so lets start here, anyone going to kick this off?

 

No problem with simple visual tree assessment (VTA) based on an arborists view of the tree through the reading of morphological symptoms within the tree's reactive growth form.

 

It is the TR ratio and 70/30 cut off that has always been the matter of debate for me. Although I also think many of the issue are due to miss use of the criteria, without consideration for the trees structural form.

 

Claus is always at pains to stress that the 30% sound wood boundary is for mature maiden (un-reduced) full grown trees. It is not relevant to trees that have started to retrench or have been reduced by pruning or storm damage.

 

The 30% rule cannot be used in all tree populations either. If it were to be broadly accepted in Australia then most of the mature Eucalyptus trees would be felled.

 

The TR ratio is totally irrelevant for ancient trees where they have retrenched and are re-establishing a new crown form on a hollow trunk.

 

Claus only really deals with structurally sound wood and does not go into the relevance of physiologically functional tissue verses dead but solid wood.

 

He is great at keeping things Stupsy Simple, but sometimes his efforts to make things easy and understandable mean that the reader is encourage to find black and white answers to very grey questions........

[slasherscot]

a slight side topic, but dont u find hollow trees stand much better in a storm than solid trees, most blow over trees tend to be solid trunked trees.

[Tony Croft aka hamadryad]

a slight side topic, but dont u find hollow trees stand much better in a storm than solid trees, most blow over trees tend to be solid trunked trees.

 

I would suggest a lot of that is down to the fact there simply isnt that many hollow trees, in the urban context they would have been long felled and in the woodland scenario they would have long ago died as they retrenched and became out competed. growing down works in an open woodlan pasture situation, but not in the competative world of the forest.

 

Over simplification:001_smile:

[Tony Croft aka hamadryad]

No problem with simple visual tree assessment (VTA) based on an arborists view of the tree through the reading of morphological symptoms within the tree's reactive growth form.

 

It is the TR ratio and 70/30 cut off that has always been the matter of debate for me. Although I also think many of the issue are due to miss use of the criteria, without consideration for the trees structural form.

 

Claus is always at pains to stress that the 30% sound wood boundary is for mature maiden (un-reduced) full grown trees. It is not relevant to trees that have started to retrench or have been reduced by pruning or storm damage.

 

The 30% rule cannot be used in all tree populations either. If it were to be broadly accepted in Australia then most of the mature Eucalyptus trees would be felled.

 

The TR ratio is totally irrelevant for ancient trees where they have retrenched and are re-establishing a new crown form on a hollow trunk.

 

Claus only really deals with structurally sound wood and does not go into the relevance of physiologically functional tissue verses dead but solid wood.

 

He is great at keeping things Stupsy Simple, but sometimes his efforts to make things easy and understandable mean that the reader is encourage to find black and white answers to very grey questions........

 

 

 

yes I agree, a lot of the problems we all face are down to interpretations, and I suppose claus does allow for it, this both benificial and cause of some issues.

 

maybe this is why the big shots are always going on about finding an EXACT method, one that is quantifiable and definate?

 

oh yes..... thats right, it isnt achievable!

 

Isnt the flexability of VTA taking this into acount?

[sean freeman]

He is great at keeping things Stupsy Simple, but sometimes his efforts to make things easy and understandable mean that the reader is encourage to find black and white answers to very grey questions........

 

Very well put Andrew.

 

Personally I have absolutely no problem with the way Claus presents VTA, in fact I have spent not insubstantial amounts of money to benefit from those very presentations.

 

I am very uneasy with the way in which "golden rules" have emerged out of some of his work, and some of the problems identified in the data by those who assisted with his research, and by others reviewing his research.

 

Simply because there is disagreement on aspects of interpretation and presentation does not mean that fundemental flaws exist, it does mean that those who want to apply broad sweeping statements in the application of pure mathematical formulae really should be aware of the criticism that exists, as well as the adulation.

barcelona_2005.pdf

Risk%20Bond%20%20over%20r%20debunk[1].pdf

how_hollow_a_tree.pdf

[scotspine1]

His latest stuff about tensile triangles in nature - people have known about this for thousands of years, its just nature....he seems to think he's discovered the secret of life itself.

 

The dome of Florence cathedral was designed over 600 years ago, you could fit his tensile triangle model to the dome, but the men who designed it already knew this as they also looked at nature for inspiration. Think of the boughs of the Viking longboats or Roman ships, designs that are 1000s of years old.

 

 

He also reckons that the species of the tree plays no part when assessing it's structural strength as all trees are essentially made from lignin and cellulose. Anyone whose worked with trees for any decent length of time knows this is at the very least questionable. Sycamore - Acer pseudoplatanus is far more brittle and will shear more easily compared with a Sitka - Picea sitchensis. So how can the principles of VTA apply to both species equally?

 

 

 

 

 

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Edited July 15, 2010 by scotspine1

[Tony Croft aka hamadryad]

Very well put Andrew.

 

Personally I have absolutely no problem with the way Claus presents VTA, in fact I have spent not insubstantial amounts of money to benefit from those very presentations.

 

I am very uneasy with the way in which "golden rules" have emerged out of some of his work, and some of the problems identified in the data by those who assisted with his research, and by others reviewing his research.

 

Simply because there is disagreement on aspects of interpretation and presentation does not mean that fundemental flaws exist, it does mean that those who want to apply broad sweeping statements in the application of pure mathematical formulae really should be aware of the criticism that exists, as well as the adulation.

 

ive never been one to say that ideas and theories should not be questioned or argued over, that is a healthy thing. Your right people should be aware of the critisicms as well as the great stuff. thats one of my main reasons for starting this thread, to see and hear from anyone who has more knowledge than I on the whole conflict issues.

 

Personaly i cant as yet comment on some of the Statics stuff, and have yet to find a paper that is out there about slensderness ratio conflicts, but by the time this threads reached a significant length I will be a lot more able to understand the whys and what fors of all the arguments.

 

my main reason being to broaden my own knowledge and learning, the other to decide wether they have any grounds, or are just trying to feed on the glory:sneaky2:

 

I sometimes wonder why people go out of thier way to find a means of debunking claus!

 

I guess it makes you feel like your on his level when you try?

 

As for the tensile triangles, shear squares and force cones, can anyone seriously say that until Claus presented them to us in his format that we would have could have thought this way?

 

The man is trying VERY very hard to educate us and make our lives easier, as he said we are not just engineers we are tree engineers, a very tricky profession indeed!

 

Wether we agree or disagreewith his, style or method he has changed the way we look at trees, and produced some of the best books ive read to date, and in a language i understand, and those bits i dont i am working on! never was keen on math or physics, but this subject is kinda making me want to learn.

 

Ive had the good fortune to chat with Claus a few times now, and some people say he is all ego, but I have never once found him to be less than modest about his work he bends over backwards to help you and is the greatest teacher youll ever meet.

 

He hasnt a jot of concern over the arguments, cant even be bothered to argue anymore, like he said, let the market decide.

 

I know where my money is going, but I would be foolish to not learn about all the arguments and methods out there that would/could potentialy give me a les biassed and broader view of tree mechanics.

 

i would love to know where this wood is that contained so many hollow trees as to provide such conclusive contradictory results to the TR thing!

 

and if that wood did exist was the loss of veteran/habitat REALLY justifiable?

[slack ma girdle]

Wow this is like big talk, on Mitchel and Web......

:thumbup:

[sean freeman]

To me the issues are fairly simple when it comes to what problems have been identified with the research presented to support the t/R ratio 'rule'.

 

I have also spoken to Claus and found him quite personable and friendly, I don't place him nor anyone else on a pedestal...not because I want nor need to feel their equal, I try and evaluate what it is they are saying based on my understanding....if there are significant problems in my mind with some of their arguements I try and engage with them to clear up what might be at the heart of that.

 

Claus Mattheck, like David Lonsdale, Alex Shigo and a few others have undoubtable altered the way we perceive and conceive of trees. I would also suggest that Colin Tudge has done the same, anyone who has read "The Secret life of Trees" will never think about trees in quite the same way.

 

The problems for t/R are laid out in those papers I attached previously...you don't need to have an intimate knowledge of Statics to understand why providing all the data collected is quite important when making a claim of statistical significance between only two variables.

 

Claus himself in 2006 showed that the relationship for t/R was statiscally random...in other words no single t/R value exists that predicts stem failure. This is presented quite clearly in Jerry Bonds paper. Unfortunately there are a great many consulting Arbs providing advice (for a fee) applying the t/R ratio as if it were a golden rule....this is not Claus's fault, but it is simptomatic (IMO) of what happens when you try to reduce complex relationships down very simple formulae.

 

From my perspective much of the criticism of the supporting evidence for tR or some of the other areas of Claus Mattheck's research of don't lead me to devalue VTA or its underlying principles....it does make me suitably dubious about anyone that lays claims to have magic numbers in relation to tree strength or tree "safety".