Decay images

[Paul Melarange]

I should add that if a tree, made up of a number of semi autonomous units (I.e. a veteran or ancient tree), has a very small wind load and a large carrying capacity/stem diameter, the risk of it failing in sheer or compression is much reduced. Hence how veteran and other veteran trees can exist in this state.

[treeseer]

t/R formulae are bollocks anyway. Trees do not do arithmetic.

[Gary Prentice]

t/R formulae are bollocks anyway. Trees do not do arithmetic.

 

But they are a starting point for further considerations👍

[David Humphries]

t/R formulae are bollocks anyway. Trees do not do arithmetic.

 

But they are a starting point for further considerations👍

 

Agree with both points.

 

t/R is part of the journey (explored by others) that we should all tread to add foundation to our own real life (and dysfunction) experience.

 

 

 

 

.

[treeseer]

That foundation has crumbled too many times to put any weight on.

http://www.urbanforestanalytics.com/sites/default/files/pdf/bond_tR.pdf

 

Identifying vascular pathways and buttressing and load is a starting point provided by the tree. There may be a role for formulae but it is not primary.

 

Starting with a number (gained from wounding the tree) leads one to chase more numbers, down the rabbit hole.

 

Off with his head!

[Alinicoll]

Hi Alasadir,

 

I hope all is good with you.

 

You are quite right regarding the issue of semi autonomous units. The tree statics model is based on the wood failure in compression (wood is weakest in compression).

 

Strength loss can be calculated using section modulus (the distribution of the material) where gaps (open cavities) in the residual wall are incorporated into the calculation.

 

However, the model does not allow for sheer failure or torsional failure. It is worth noting that a lot more force is required for a wood to fail in sheer as opposed to compression. That said, the risk of sheer is increased when the residual wall is below t/R 0.1 (10%) because the stem/cylinder can separate into semi autonomous units which start moving independently of each other e.g the tension side vs the compression side.

 

I hope this makes sense?

 

Hi Paul,

 

Thanks for you reply.

 

Yes it does make sense. Another useful tool in the kit.

 

Am I correct in thinking that you need specialist training to practice statics?

[David Humphries]

Inspected this sycamore with Kretzschmaria deusta last year and advised the fell.

 

The colonisation looks to have been at a basal wound possibly created during 

the fence installation.

 

Still had a proportion of residual wall left but progressive decay and relatively high target area, plus visual Id and sounding mallet informed the final decision.

 

 

 

 

[Gary Prentice]

What was the canopy like on that David?

 

I dismantled one a few years ago, with probably 90% of the canopy dead, which had more live sapwood than that.

[David Humphries]

7 hours ago, Gary Prentice said:

What was the canopy like on that David?

 

I dismantled one a few years ago, with probably 90% of the canopy dead, which had more live sapwood than that.

I haven't got an image of the canopy condition Gary but I recall that it had full leaf cover.

[David Humphries]

 

 

No cross section on this one as it stays standing, but the decay drill readings appear to show a slightly eccentric cavity (or heavily decayed column) at the base of this cherry with Grifola frondosa fruiting on the trunk.

 

 

The first graph (below) is the reading taken above the fruitbody and shows 5cm of residual wall.

 

 

The second reading taken at the same height on the opposite side of the trunk indicates a 16cm residual wall.

 

 

I suspect there may be another fungal agent at play (possibly Ganoderma) that is causing the heart rot which can be seen in the drop off of needle resistance at 7cm and 18cm on each of the readings.

 

Gano has never fruited on this tree but I don't believe that Grifola would be causing the decay up to 60cm above ground here.

 

More likely (I feel) the Grifola is present on the old dysfunctional roots or possibly directly associated with the girdling root.

 

Some of you may recall that we undertook an airspade investigation on this cherry earlier in the year that focused on the girdler.