Compressive & tension reaction wood

[David Humphries]

Nothing new here, just going through the motions to help me continue to understand how wood grows.

Feel free to add your own comments/observations/images.

 

A basic premiss derived from various texts.......

 

Compressive wood = formation of reactive wood to gravity/wind force (made up on the underside of gymnosperm branches & trunks by the laying down of additional lignin in the woody cells to help push the weight against the implied force..

 

Tension wood = formation of reactive wood to gravity/wind force (made up on the upper side of angiosperm branches & trunks by the laying down of additional cellulose in the woody cells to help pull up the weight against the implied force.

 

 

 

 

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[David Humphries]

Having said the above, trees don't always play strictly by the 'rules'

 

Adaption to force can be seen to be applied in the opposite

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[David Humphries]

Here, the reaction wood ribs on the compressive underside of these beech branches

 

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[se7enthdevil]

how does it work when you get a rippled tree then. has the tree just been blow rippled????

 

there are a couple of beeches in cliveden house hotel grounds that look very rippled.

[David Humphries]

there are a couple of beeches in cliveden house hotel grounds that look very rippled.

 

Any shots?

 

 

 

 

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[AA Teccie (Paul)]

Hi David,

 

Similar to your Oak shot above, I think, I have seen pronounced growth striations on the underside of heavily loaded branches on broadleaves indicating reactive growth (?) which I didn't understand.

 

Regarding the general premises of 'push' n 'pull', conifers n broadleaves respectively, in terms of remembering it someone, poss. on the forum, said broadleaves have biceps, i.e. tension pull like a bicep (not mine tho ), n conifers have triceps, i.e. compression pull like a tricep (not mine either )

 

Anyway enough waffle from me, clearly I need to go back to 'arb' school.

 

Thanks as ever for your informative posts, racks up my CPD every time

 

Cheers..

Paul

[MATTMOSS]

Hi David,

 

Similar to your Oak shot above, I think, I have seen pronounced growth striations on the underside of heavily loaded branches on broadleaves indicating reactive growth (?) which I didn't understand.

 

Regarding the general premises of 'push' n 'pull', conifers n broadleaves respectively, in terms of remembering it someone, poss. on the forum, said broadleaves have biceps, i.e. tension pull like a bicep (not mine tho ), n conifers have triceps, i.e. compression pull like a tricep (not mine either )

 

Anyway enough waffle from me, clearly I need to go back to 'arb' school.

 

Thanks as ever for your informative posts, racks up my CPD every time

 

 

Cheers..

Paul

 

This is a good way to remember it!! I find these little phrases helpful.

[MATTMOSS]

It just gets a bit confusing when I keep thinking of cellulose as concrete and lignin as ligaments.

[se7enthdevil]

Any shots?

 

 

 

 

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afraid not but they are very similar to the branches in your shots ripple wise.

 

from memory they are 24"dbh+ and very straight and tall. no lean that I can remember hence why I wondered if its just the wind that can do that.

 

they are relative close forest grown. they look like a cylinder of ripple!!!

[Amelanchier]

Having said the above, trees don't always play strictly by the 'rules'.

 

I think we can draw a distinction between normal (homogenous?) wood that happens to be growing more rapidly to cope with applied forces and structurally specialised wood doing the same. It might seem like a semantic trick but just as a rock can function as a fairly serviceable hammer without being a 'hammer' - not all wood resisting compression is compression wood (and I imagine the same applies to tension wood).

 

I imagine that all trees will add wood where the cambium detects uneven forces - if they are adapted to produce specific types of wood, then they will use those. Trouble is, you need a microscope to see the difference.