Listening for decay

[David Humphries]

Could be mighty interesting.

 

Indeed.

 

Getting a location to suit all intrested parties could be a challenge.

Perhaps some regional ones.

 

I'll try and get a candidate tree (one that's due removal) set aside for down here and will think of some dates.

Possibly mid summer.

 

We have hammer & resistograph, perhaps a member with access to a tomograph in the south east would be interested ?

 

 

 

.

[David Humphries]

There are others over here who favor a broader striking surface, in part i suspect to lessen impact per square unit of area?

 

A valid point Guy,

 

think I might 'bruise' a couple of thin & thick barked species (that are coming out) and see what, (if any)damage is evident.

 

Imagine I would have to try and effect the same force somehow?

 

 

 

 

.

[daltontrees]

Aha! That's wher a schmidt hammer Schmidt hammer - Wikipedia, the free encyclopedia would come into its own. Fitted with different caps (nylon, wood, rubber).

[Nick Harrison]

Hi David, to add my ten penneth..

 

Whilst delivering the Basic Tree Surevy Course I explain about the 'nylon mallet' as a basic sounding device to detect decay / dysfunction but suggest it should be used in a targeted manner, rather than just randomnly 'knocking around', as it could still cause injury to lightly barked trees. That said I do acknowledge that not all examples of decay / dysfucntion exhibit visual signs.

 

Not sure what the guys in the vid were trying to establish, other than obvioulsy decay of course, but was that part of a safety inspection or pre-climb...wudda liked to have seen the ladders secured too...once a H&S nurdy always...

 

 

Hi Paul,

 

it's a valid point you make above, i totally agree that it's not good practice to simply wack and bang about with a hammer needlessly. from my perspective though, the potential climber should we have decided it was safe to climb, i wanted to be as sure as i could be about the integrity of this decayed pollard union. Lying at the base of the tree (might have been out of shot?) was a big limb that had failed 2 or 3 years ago, this limb looked and sounded fine near the base, it'd simply failed at a decayed union, it had originally been sat right next to the limb i was inspecting. This probably added to my slightly over zealous hammering

 

With this in mind, coupled with my relative lack of experience in using a sounding hammer, i wanted to get as good an idea of what was going on in and around this union as possible. I think gaining the necessary experience to get a feel for how different wood types/decay sounds when using a hammer perhaps warrants a bit more excessive banging about than a more experienced practitioner. i'm aware of the potential cambial damage that can be caused (i'd obviously have been a bit gentler on a thinner barked tree), but i did feel justified in spending as long as i did in sounding a large area of the stem base.

 

Ultimately i need to feel safe if i'm going to ascend into a tree. Ideally the more i use the hammer the better my ear will get at detecting issues. hope this gets my point of view across without sounding defensive, just thought it worthwhile explaining a bit of the 'behind the scenes' thinking going on in the clip

[David Humphries]

An interesting case study that we've had going on over the last couple of days.

 

had a look at this Maple as part of risk sequencing walk over inspection yesterday.

 

Last shot is a older google image

 

.

[David Humphries]

had a look at this Maple as part of risk sequencing walk over inspection yesterday.

 

noticed this fruiting body at the base on the east (road) side of the tree.

 

I believe the bracket to be Rigidoporus ulmarius.

 

 

Historically this tree has been crown lifted and canopy reduced at various times over the last few years.

 

The tree is also subject to cavitation at height within the trunk, as I witnessed a squirell come out (previous images)

 

 

.

[David Humphries]

noticed this fruiting body at the base on the east (road) side of the tree.

 

Though it would make a good oportunity to compare sounding it with a hammer against the resistograph.

 

 

.

[David Humphries]

Though it would make a good oportunity to compare sounding it with a hammer against the resistograph.

 

my colleague & I each drew out what we imagined the decay would look like (in cross section at 150mm from the ground) after we had both used the hammer.

 

This is my (crude) attempt at mapping out the brown rot, prior to using the resistograph.

.

[David Humphries]

This is my (crude) attempt at mapping out the brown rot, prior to using the resistograph.

.

 

Here are the 4 risistograph readings starting at the fruitbody (east aspect) then at the cardinal points going anticlockwise.

 

 

.

[David Humphries]

Here are the 4 risistograph readings starting at the fruitbody (east aspect) then at the cardinal points going anticlockwise.

 

I'm interpreting these readings as showing detection of heart rot decay at between 180 - 260mm in from the edge of the trunk. (apart from the first reading which tbh, is puzzling me)

 

What i find really interesting here, is that two trees away along the line going north (red circle on map) is a stump of a maple that was felled three or four years ago due to the evident cavity & decay.

 

I didn't note any fruit body on that tree before we felled it but the brown rot perhaps indicates Rigidoporus also.

 

.