Interesting Biomechanics

[David Humphries]

The problem I have always had in trying to understand it is that where vessels cross, something has to give. The way that trees cope with this at side limb unions or even at the inside of forks is as far as I know not well understood. Braiding presents a fascinating theoretical and actual dilemma for the tree to manage the crossing of vessels and the additional of annual incrementsi. My hunch is that if it has any self-optimising outcome it is the avoidance of unnecessary bulk in the interbraid areas rathe than additional strength in the braids.

 

Jules, are you familiar with Duncan Slaters work on unions and biomechanics?

 

http://www.myerscough.ac.uk/downloads/pdfs/Subjects/Arboriculture%20-%20NYTOG/NWTOG11/Slater%20-%20The%20Failure%20of%20Forks.pdf

 

Although this presentation is specifically about forks and failures it is a worthy read to at least see where Duncan has taken Alex Shigo's work on and researched the anotomy of union wood fibres further.

 

 

 

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[treeseer]

Is it just me or does that third photo look like the broken toe of a gigantic raptor?

 

It's just you.

 

Jules, how can one tell the difference between reaction wood and 'growth abnormality'? How can this be demonstrated?

 

btw, 'Dundee' in the attached is Cassian; I put him in there to honor his cataloguing of this phenomenon. Also, Dr. Frank Telewski was kind enough to review it. Boy, did I get schooled!

 

In his words, all wood is reaction wood. And he should know!

 

A unified hypothesis of mechanoperception in plants

Detective Dendro and the Wondrous Washboard (2).doc

[daltontrees]

Jules, are you familiar with Duncan Slaters work on unions and biomechanics?

 

http://www.myerscough.ac.uk/downloads/pdfs/Subjects/Arboriculture%20-%20NYTOG/NWTOG11/Slater%20-%20The%20Failure%20of%20Forks.pdf

 

Although this presentation is specifically about forks and failures it is a worthy read to at least see where Duncan has taken Alex Shigo's work on and researched the anotomy of union wood fibres further.

 

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Nice to have someone reply on this. Yes, I was thinking specifically about Slater and Harbinson 'Towards a new model of branch attachment' (AJ, 2010) when i said 'where vessels cross, something has to give'. I suppose I should have been more precise and said 'something has to be compromised or some special adaptation has to take place to allow ongoing biomechanical angd physiological integrity', but then everyone would have run away screaming.

 

The generality of the dilemma stands. though. When wood overlaps, it can't just put on an outer ring every year.

Edited October 18, 2013 by daltontrees

[daltontrees]

It's just you.

 

Jules, how can one tell the difference between reaction wood and 'growth abnormality'? How can this be demonstrated?

 

btw, 'Dundee' in the attached is Cassian; I put him in there to honor his cataloguing of this phenomenon. Also, Dr. Frank Telewski was kind enough to review it. Boy, did I get schooled!

 

In his words, all wood is reaction wood. And he should know!

 

A unified hypothesis of mechanoperception in plants

 

Gosh, two replies!! Give me a few minutes, hours, days or years to get back to you on this.

[daltontrees]

It's just you.

 

Jules, how can one tell the difference between reaction wood and 'growth abnormality'? How can this be demonstrated?

 

btw, 'Dundee' in the attached is Cassian; I put him in there to honor his cataloguing of this phenomenon. Also, Dr. Frank Telewski was kind enough to review it. Boy, did I get schooled!

 

In his words, all wood is reaction wood. And he should know!

 

A unified hypothesis of mechanoperception in plants

 

I ejoyed the article on rippling. The article on mechanoperception was heavy going. since it lacks a conclusion and isn't entirel in point to my notion about braiding, I'm going to pass on it for now.

 

It is of course possible to see all wood as reaction wood insofar as every cell of new wood is tuned to its stress situation at the time of its growth and maturation. But that's not what I mean by reaction wood. Here's the definition of reaction wood from the International Association of Wood Anatomists -

“wood with distinctive anatomical and physical characteristics, formed typically in parts of leaning or crooked stems and in branches, that tends to restore the original position of the branch or stem when it has been disturbed; also known as tension wood (in deciduous trees) and compression wood (in conifers)”. When I saidf growth abnormality I meant some sort of genetic abberation or pathogen-induced malformation. Like we see with Taphrina deformans, for example, which on Birch can be responsible for some weird and wonderful shapes and lumps. And Birch is known for its braided wood (sic). I won't therefore take up your challenge to demonstrate the difference since I suspect you had a different definition of growth abnormality in mind such as atypical distribution of wood.

 

So wheeling back round with maximum economy of effort, I stand by my precautionary approach to braided wood since intuitively there is no particular suggestion that it is there to compensate for any biomechanical weakness in a way that normal wood would, or even that it is additional wood or is of different character to wood in the rest of the same tree.

 

If I ever get to inject and dissect a suitable tree, I may also get round to taking a few samples of wood from different zones and put them through the microtome and then under the microscope for a comparison of cell size, length, shape and cellulose content.

[treeseer]

...If I ever get to inject and dissect a suitable tree, I may also get round to taking a few samples of wood from different zones and put them through the microtome and then under the microscope for a comparison of cell size, length, shape and cellulose content.

 

That would be interesting!

 

I'm still not comfy with aberration, abnormality, deformation etc. used as descriptors on an intuitive basis. But that's just me.

[daltontrees]

I feel the same way about the term 'reaction wood'. But maybe that's just ME.

[treeseer]

Fair enough then; these are minor issues, within broad agreement on arboriculture.

[Goaty]

Pohutakawa(Metrosideros excelsa) aerial root into trunk graft.

[David Humphries]

nice example

 

 

 

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