V.T.A symptoms "the chatty trees"

[RobArb]

here we go, another 6 trees like this found in an area a bit further up (plus some nice adventitious roots in a birch wound)

[Treecreeper1961]

Oh yes, nice root pics.

[davyjones]

Fantastic thread, learning much!

Spotted a similar phenomenon in a largish beech the other today to those already posted recently here.

[Tony Croft aka hamadryad]

some great examples coming in!

[treeseer]

some great examples coming in!

 

Nice to see the pics of sorbs and beech with "washboard" language. I am not hearing tissue failure or decay in these phenomena, as much as genetics.

 

"As described in the Updated Field Guide to VTA, "fiber buckling and bulgewood....the cross ribs are bulgewood after 45 degree sliding of the fibres along the shear planes."

 

It may be very explainable in individuals but seems extraordinary in a group.

What kind of stresses create this phenomena?

The beech stem I posted previously is similar. Easier to explain on a bough with the stresses of supporting it than on what seem to be fairly upright trees.

Is it something to do with local wind patterns perhaps?

Will await your interpretation with interest!"

dendro washboard.pdf

[Treecreeper1961]

The Dendro Detective was an entertaining read, not sure it shed much light on the subject though.

[treeseer]

The Dendro Detective was an entertaining read, not sure it shed much light on the subject though.

I agree; the most progress to date is finding that some explanations are more likely than others. The story took a bit of a turn to removing fill dirt, because that is what happened on the job.

 

And when genetics is the most likely explanation, that leaves little for this tree guy to expound upon!

[Treecreeper1961]

I agree; the most progress to date is finding that some explanations are more likely than others. The story took a bit of a turn to removing fill dirt, because that is what happened on the job.

 

And when genetics is the most likely explanation, that leaves little for this tree guy to expound upon!

 

It would be interesting to know the providence of the Sorbus in Rob's photos.

I don't know much about this at all and whilst the genetic theory seems plausible the only reference I have for it's occurrence suggests it is due to mechanical stress!

Intriguing.

[Treecreeper1961]

It would be interesting to know the providence of the Sorbus in Rob's photos.

I don't know much about this at all and whilst the genetic theory seems plausible the only reference I have for it's occurrence suggests it is due to mechanical stress!

Intriguing.

 

This suggests high tensile loading to me(taken from Pprune website, Professional Pilots Rumour Network)

 

 

 

The fact that the shear stress is a maximum at 45 degrees to the loading axis is shown by an equilibrium diagram of a small element of material under load. The best source of these can be found in derivations and descriptions of Mohr's Circle, such as this:

 

Mohr's Circle

 

This shows that the shear stress is a maximum when two-theta (sorry I don't know how to write Greek letters on this thing...) is 90 degrees, so theta is 45 degrees.

 

When a sample of ductile metal such as steel is pulled in a testing machine until it fails, the failure always exhibits a 45 degree 'lip'. In a rod, this failure has a 'cup and cone' appearance because the lip is circular. The 45 degree planes are where the maximum slippage has occurred between the crystals in the material, which is the mode of failure, and of course the slippage occurred along the plane of maximum shear stress. When you are examining wreckage from an aircraft accident, the bits that failed in tension are immediately obvious from these 45 degree features. They tell you the tensile loading direction too!

[Tony Croft aka hamadryad]

This suggests high tensile loading to me(taken from Pprune website, Professional Pilots Rumour Network)

 

 

 

The fact that the shear stress is a maximum at 45 degrees to the loading axis is shown by an equilibrium diagram of a small element of material under load. The best source of these can be found in derivations and descriptions of Mohr's Circle, such as this:

 

Mohr's Circle

 

This shows that the shear stress is a maximum when two-theta (sorry I don't know how to write Greek letters on this thing...) is 90 degrees, so theta is 45 degrees.

 

When a sample of ductile metal such as steel is pulled in a testing machine until it fails, the failure always exhibits a 45 degree 'lip'. In a rod, this failure has a 'cup and cone' appearance because the lip is circular. The 45 degree planes are where the maximum slippage has occurred between the crystals in the material, which is the mode of failure, and of course the slippage occurred along the plane of maximum shear stress. When you are examining wreckage from an aircraft accident, the bits that failed in tension are immediately obvious from these 45 degree features. They tell you the tensile loading direction too!

 

you should read in the face of failure and design rules after nature by Mattheck, you would enjoy them