Reaction wood

[waz77]

Im writing a fdscArb entrance paper on Tree Defence Systems and Structures. Think i've got most of it covered but can't decide if the formation of reactive wood would be classed as a defence mechanism. Im thinking if it was in response to a tree being uprooted rather than just phototropism it may be classed as a defence mechanism? What ya reckon?

[treeseer]

Depends on the definition; reacting to what? The US definition has to do with responding to movement, but some negatively assume it's reacting to decay or another 'defect'.

[MATTMOSS]

Like a lot of things in arboriculture I suspect there is no right or wrong answer, it depends how you perceive it.

 

My personal thoughts are that although it may not be a primary defence against decay specifically , it is a defence against failure through decay.

 

If that makes sense?

 

The more I think about it, I think I could argue it either way.

 

my head hurts.

 

[waz77]

Mine too.

I'm not meaning reactive wood as in new growth around a wound, but reactive wood in the sense of a leaning tree correcting itself. I've already covered codit.

Hope this makes more sense.

[Paul Cleaver]

I would say it was a defence mechanism - on a leaning tree if no reaction wood - tree fails at roots.

[waz77]

http://arbtalk.co.uk/forum/tree-health-care/64699-compressive-tension-reaction-wood.html Found an interesting thread on the subject here. I suppose the fact that the extra wood is put down in response to wind loading would make it a defence structure? I hope so cos I'm 350 words short and can't think of anything else to say on the other subject matters:pcguru:

[Jarhead]

I would say so. If without it the tree is likely to fail, surely the extra wood is a defence against that failure.

 

If in doubt, send the lecturer an email!

[daltontrees]

http://arbtalk.co.uk/forum/tree-health-care/64699-compressive-tension-reaction-wood.html Found an interesting thread on the subject here. I suppose the fact that the extra wood is put down in response to wind loading would make it a defence structure? I hope so cos I'm 350 words short and can't think of anything else to say on the other subject matters:pcguru:

 

I did the subject to death in the aforementioned thread. Basically reactive wood is a made-up term, the true term is reaction wood. All wood is reactive. Not all wood is a reaction to something. If a tree is slowly tilting as the soil it is growing in is sliding slowly down the hill, and the tree puts on extra and adapted wood on the tension or compression side, that's reaction wood. Ity is reacting to something other thna the normal forces associated with getting bigger and standing up to nedemic weather and wind conditions. If it puts on extra wood around a decaying wound that strengthens the zone as a reaction to its weakening because of the decay, that's a reaction. Opinions differ on teh definition, but you will get nowhere trying to understand the phenomenon if you call it reactive wood. It's reaction wood, it's a reaction to something, according to the accepted rules of grammar and syntax.

 

I woudl add as a reminder to the earlier other thread that reaction wood has specia characteristics, it is not just extra wood, which could more generally be called adaptive growth wood.

[woodyguy]

Not sure if I understand you Jules. The problem with that definition is that it describes reaction wood only as a defence against something unusual eg sliding down hill. In reality any tree branch coming out from the trunk will have unequal growth rings in response to gravity. So although it can be a defence, it is also a normal reaction to normal things like gravity ie how the tree grows everytime.

[daltontrees]

Not sure if I understand you Jules. The problem with that definition is that it describes reaction wood only as a defence against something unusual eg sliding down hill. In reality any tree branch coming out from the trunk will have unequal growth rings in response to gravity. So although it can be a defence, it is also a normal reaction to normal things like gravity ie how the tree grows everytime.

 

I'm not sure if I understand what you don't unbderstand. You seem to have covered it quite well there. But the concept of 'defence' is a bit anthropomorphic, trees don't think, they react in a relatively simple physiological way. Hence my re-assertion that trees are self-optimising structures, and that describing 'any tree branch coming out from the trunk will have unequal growth rings in response to gravity' as anything other than normal and implicit in the definition of trees is a nonsense.

 

So I suppose I think that the defintion of reaction wood is that it is the wood of special characteristics that reflect the tree's reaction to abnormal circumstances that differ from a tree's progressive and norma self-optimisation.