Reaction wood

[kevinjohnsonmbe]

Jomoco, I am pleased to have anyone pitching in. Sometimes I noticve that hundreds of people have read this thread since a couple of days ago yet only a few (mainly from USA?) bother to comment.

 

 

As 1 one of silent observers, following with great interest!

 

Speaking for myself, it's not that I can't be bothered to comment, more appropriate would be, I don't have the depth of knowledge to make a worthwhile contribution!

 

Great thread nonetheless and part of the journey!

[treeseer]

I don't have the depth of knowledge to make a worthwhile contribution!

 

How can you be sure unless you try?

 

Re depth, I'm in the shallow end of the pool much of the time, but I try to keep swimming.

[David Humphries]

Re depth, I'm in the shallow end of the pool much of the time, but I try to keep swimming.

 

Pass me the arm floats when your finished with them, please Guy

 

 

 

 

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[Gary Prentice]

How can you be sure unless you try?

 

Re depth, I'm in the shallow end of the pool much of the time, but I try to keep swimming.

 

Pass me the arm floats when your finished with them, please Guy

 

 

 

 

.

 

Think I'm drowning - not waving

[daltontrees]

I have just been through Bowen v National Trust, Micklewright v Surrey, Atcins v Scott for relevant references to the terminology. Only the first has any, but boy does it use adaptive growth in spades. So much so that in the written judgement it has to be abbreviated to AG it is used so many times. But in a nutshell it is described by the juidge as a 'phenomenon', not as a kind of wood. I'll rejig my notes for the useful bits there and that btggaz quoted from Shigo. And hopefully it wil all materialise as a plain english unambiguous authoritative set of definitions in Wikipedia.

 

It's a start anyway. I have a daunted sense that we are really only in the paddling pool messing about with the definitions.

[fagus]

Re Wikipedia. A minor point as your addition is good.

I prefer changes to modified. I think modified is overused; to me it implies some thought whereas the cells are only reacting, e.g lengthening, shortening, to the stresses put upon them be it gravity, wind, fungal attack

I find at times Shigo humanises tree growth giving it a thought process.. Might just be the use of language used describing wood but it gave me the wrong impression at times.

[treeseer]

AG stands for Attorney General here, which seems to fit Jules' encounters of that acronym in case law...was it used in a "you should've known there was trouble" kind of way in those cases?

it also fits that RW was Shigo's term, as he was a forestry researcher, granted with some keen arboricultural insights.

 

What I'd tend to call AG (which results in RW) pic here on the lapsed willow pollard, the rib with inner bark showing. Then the apparent decay in--or on?-- the sinus (shriveled buttress? rotting rib?) of the Aesculus--if the ribs on either side start growing rapidly, would that be called AG/RW?

 

 

Pass me the arm floats when your finished with them, please Guy

 

.

 

OK, here they are, but mind the left one as I've had to patch it twice. I noticed it was leaking badly when I started going round in circles.

Edited April 20, 2014 by treeseer

[daltontrees]

Re Wikipedia. A minor point as your addition is good.

I prefer changes to modified. I think modified is overused; to me it implies some thought whereas the cells are only reacting, e.g lengthening, shortening, to the stresses put upon them be it gravity, wind, fungal attack

I find at times Shigo humanises tree growth giving it a thought process.. Might just be the use of language used describing wood but it gave me the wrong impression at times.

 

Point taken. The words 'to generate' impliesd thought too, so maybe the words 'modified to create' shoudd be replaced by 'different, resulting in".

 

Shigo's not half as bad as Mattheck and Breloer for dippy anthropomorphisms. I like to stick to the observable and let others have their version of the metaphysical.

[daltontrees]

Here's the core of what the case said about AG.

 

"Examination has revealed that where it joined the main stem of the tree there was a depression or cup on the upper surface and at either side of that point of the branch there was the phenomenon of adaptive growth (“AG”) in the form of what Mr Forbes-Laird calls adaptive growth flares, and which some others call “bulges” or “ears”. These, it is agreed, would have been visible from the ground, and are very much at the heart of this action. In simplified terms AG is a biomechanical response by the tree to load stress on a branch, or to gravitational forces causing deflection of the branch, or as a “repair” response, for example, to some internal damage to the cambial cells on the outer surface of the wood of the branch. This autonomic response causes the normal annual growth ring process, programmed into every tree, to become exaggerated in thickness in order to reinforce or add strength to the branch at this point. In other words it is autonomic response by a tree to a stressed branch.

 

"All agree that inspection of trees for safety purposes is carried out from ground level – a system called visual tree assessment or VTA, first defined by Professor Mattheck. It is based on inspection from ground level and does not require any aerial examination. The depressed area I have described above would not have been visible from the ground. The claimant’s expert estimates that the AG flares had been in place for 5-10 years. At some later stage a crack or fissure had developed in the central upper surface of the join as a primary failure due to stress and this had led to oxidation and water ingress into the wood of the branch at this point. This too would have been impossible to see from the ground. Once this crack process started it is said that a secondary failure leading to the shearing from the branch of the stem was inevitable.

 

"At the heart of the claimants’ case is the proposition that the mere presence of the AG at this point was a warning sign of a possible failure and meant that further investigation of the join was indicated. The defendant’s case is that AG is a frequently found feature on many if not most mature beeches of the age of this tree."

 

The case is worth a read as it has all the drama and suspense of a Detective Dendro story...

[treeseer]

This puts it rather well: "In simplified terms AG is a biomechanical response by the tree to load stress on a branch, or to gravitational forces causing deflection of the branch, OR as a “repair” response, for example, to some internal damage to the cambial cells on the outer surface of the wood of the branch."

 

I like the way they list these causes in order of frequency, the worst possibility listed last, not as the first assumption that defect-centric assessors sieze upon. But the climber in me cringes at this assumption:

"All agree that inspection of trees for safety purposes is carried out from ground level..." as for any inspection of a significant tree my assumption is i'm going up, at least to scaffold attachments.

 

One case in the US was a hickory with 'ears' that had been cabled (too low) decades prior, and failed onto a car. I lost track of it after deposition, but it seemed the owner was not going to be held liable due to technicalities, despite all the obvious conditions.

 

Funny you should mention the Detective--the June episode has been 6 months in review, a more complex case that centers on reading AG, in which Codit and his chinese buddy Clai Ming Hai do an aerial assessment.

 

re assigning purpose to non-sentient organisms, to be precise this is 'teleology'. I first got familiar with it when I had a thesis proposal shot down because of it, and crawled back up the tree with my tail between my legs. Now my eye's sharpened to it, and like you guys I'm surprised and bothered to see teleological wording used in academia. However I'm not so sure that 'generate' is necessarily so, though 'modify' does carry a stronger whiff of purposefulness.