any ideas?

[Ben90]

The position of the pith as it appears in the picture in the first post. ( Pith...google it:001_smile: )

The growth rings continue to form but with an "eccentric' centre....This tells us something of the forces that the tree was under at the time this wood was "laid down" as we arbs are so keen on saying!! ( which put another way means "formed" )

 

Interesting. Is it also true that if that image were a hunk of conifer, the tension/compression sections would be on opposite sides? I remember being taught that under pressure, conifers build 'triceps' and broadleaves build 'biceps' of extra wood to deal with it, making it appear as though the heartwood is offset.

[Bundle 2]

Interesting. Is it also true that if that image were a hunk of conifer, the tension/compression sections would be on opposite sides? I remember being taught that under pressure, conifers build 'triceps' and broadleaves build 'biceps' of extra wood to deal with it, making it appear as though the heartwood is offset.

 

Extra "brownie"points to anyone who can explain why Ben is right AND wrong..

[arbclimber]

Because it would be on the other side, but he has it the wrong way round?

[Bundle 2]

To be fair, the explanation given to Ben is illustrative of forces but it serves only to confuse the image you need to have of the way wood "appears" as a result of forces ( and so loading )

It is true that broadleaves and conifers have significantly different wood anatomy. One of the distinctions that are made between them is the reaction wood characteristics.

Ben, conifers will attempt to "prop" against a lean for example. They effectively "push" against the force acting on it.

Broadleaves are the opposite as was stated. Tension side of wood is what gives the broadleaf its strength. It is in this way that the broadleaves resist the forces acting on it..by "pulling"

Now if you consider say,an elastic tube,like, a bicycle inner tube for example. Pull on this to stretch it out and it appears to become narrower, thinner; of smaller dimensions. You get the picture.

So it is with the appearance of wood layed down by conifers and broadleaves alike. The conifer will show a "comparative" increase in growth ring dimension cos it literally lays more, reinforced if you will, wood, against the forces.Because the broadleaf lays down wood that is modified also to increase its effectiveness against the forces present, the tension side also appears to show narrower growth rings ( the result of a modified structure to do with microfibrils and pectin and S1,S2 &S3...sorry:001_smile: ) The tree is experiencing forces applied from the same direction...(conifer and broadleaf alike ) They also appear to be formed with an eccentric geometry that mirrors each other.

This is despite the fact that as species, they have evolved to deal with stresses to do with loading and self optimisation in different ways...

Hope this helps.

I highly recommend Claus Mattheck's illustrated works..In particular "Tree Mechanics" It is not the heavy tome you are probably expecting but a " comic strip" style handbook.

(isbn 3-923704-40-2 )

[Ben90]

Love it. Thanks Bundle!