Decay dectection equipment

[Topcat]

Bought one of the first Arborsonics. Probably used it a dozen times. It works but only confirms what I knew in the first place. If I ever think "should I use it or get a different test done" it means the tree in question is usually in a high target area. By that time I have already done my VTA and found enough for the tree to come down.

 

Once others know you have put money and time into such gadgets they do tend to believe you are taking a more proffessional approach and your reports have a lot more more credit.

 

The trouble is that in this day of liability claims, would you call a tree safe using anything in the market, when a fellow arborist states a tree to be unsafe?

 

I won a planning appeal some years back and the inspector based his decision on the folowing.He could see the faults in the tree once pointed out,but he could not see any measurement of stability. All the points on stability and health were based on theory whilst faults were based on fact. The tree would have to be felled to prove the theory whilst faults could easily be seen.If there was an element of doubt that this target tree could fail , it should be removed.

 

It will always be easier to prove unsafe over safe when it comes down to liability. Thats why there is the 3 D's in TPO regs. I've never come across a TO that will get an injunction to stop a tree been felled once a damning report goes in and can we really blame them?

 

I think there is a place for decay detection but it needs to be 100% proven.At the moment I can see operators making wrong calls (on unsafe trees) and ending up in court. It's far to easy for the manufacture to claim that the operator miss read the data etc and walk away.

 

Saying all of this the thermal imaging is starting to look good and may be something that I would invest in

[Amelanchier]

You not wrong.

 

The rub is that we can never (should never?) say that a tree is safe. But the look on Joe publics face when you say that is one of fear. Sometimes I explain the nature of risk and sometimes I simply say, "It wouldn't worry me to live/sit/hold a wedding/meet the queen under it."

 

I don't think you'd end up on the wrong side of the court for making a reasonable judgement on a tree that failed - its negligence that would be your downfall.

[Topcat]

Tony...The trouble is, it is the man in the wig that decides what was negligence. You could have tested the tree with every gadget known to man. He can still trun around and say,was in not your years of experience that led you to do these tests in the first place. Should you not have gone with your first thought? after all Mr arborist working for the prosecution stated in his report that this tree was unsafe without these tests and unfortunately he was proved right in this instance.

[Bundle 2]

"I think there is a place for decay detection but it needs to be 100% proven.At the moment I can see operators making wrong calls (on unsafe trees) and ending up in court. It's far to easy for the manufacture to claim that the operator miss read the data etc and walk away." QUOTE.

 

Really....If this statement is meant to be an interpretation of the reality...please give some (numerous) examples. I dont believe this is anything more than a biased opinion frankly.....It is not a view point I can condone and offers nothing constuctive to the debate .....Conservative tree care for the ignorant !

 

" I've never come across a TO that will get an injunction to stop a tree been felled once a damning report goes in and can we really blame them? "

No , frequently the other way round...

 

 

" You could have tested the tree with every gadget known to man "

 

 

Amazing and yet still you are not prepared to stand by the science?

 

 

"- its negligence that would be your downfall. " quote Tony.

 

Yes, I would have to say this is right. I take the view that unnecessary loss of trees is a form of negligence....poor arboricultural standard .

[Marcus B-T]

I couldn't agree more. When we started to look at the way thermal imaging might be used we started off by trying to fit our findings to existing models of how tree morphology and decay relate to a failure. We quickly found two things.

 

Firstly, while we have a moderate understanding of the resopnses of trees to changes in stresses imposed by the environment, we don't have a good understanding of the stress limits at which the response of the tree is inadequte to resist the stresses imposed (the point at which a failure occurs).

 

Secondly we found that the models that were being used to describe morphological strength were very complex.

 

As a result there was either gross approximations of the structural dimensions in the tree or labourious and detailed descripitive processes that had to be followed.

 

The equipment being used to collate the information required was being shoehorned into these methodologies when in fact the methodologies were not suitable for the equipment available, and the equipment available was not suitable to give the information required for the models.

 

The alternaive methodology would have been to use the equipment as part of the 'experience' gathering process but this takes time because you are required to gather and collate details on thousands of trees to understand the realtionship between results from measurements and structural abnormailities you believe to be present and which experience tells you presents a risk.

 

This was the approach we used with thermal imaging. We wanted to know how changes in wood functionality related to changes in structure. By gathering information on a large number of trees you can understand how position and intensity of a loss of functionality relates to how a tree becomes structuraly unstable.

 

Once you understand the process of instability you can examine how applied forces might compromise stability and cause a failure. Then you can look to the structure of the tree and the environment to establish if the forces applied are sufficient to cause a failure. This is what we do with experience but the problem is without the whole picture you either spend a lifetime trying to understand what the limits are or being highly over cautious.

 

What's needed (and what we are creating) is a system where the trees can tell us what the limits are. If a 'feature' is wide spread and common but there are no failures associated with it then it is statistically well within limits of failure. If it is a feature that is uncommon but is highly linked to failure, then statistcally it is well outside of limits of failure and thse few you find are likely to fail. You could use a failure data base and in deed we do use failure information to validate our findings but if you relied on this alone it you take you years and years and years.

 

In my work I talk to a great many people and I am always interested in their experiences and opinions. Often I get conflicting opinions on certain features. In one part of the country a feature is percieved as a problem in another it is deemed to not be a problem. Is one wrong and the other right? Is it down to experience? Or is it that there is a regional difference that determines that it is safe in one part and not in the other? These clues are important to us to develop hypotheses. Our job is to test them and find out.

[Topcat]

Bundle..Quote ".....It is not a view point I can condone and offers nothing constuctive to the debate .....Conservative tree care for the ignorant !"

 

Well until the science is proven i am happy to stay conservative and ignorant. As to adding to the debate,I tought we were debating the pro's and con's.

 

Whilst we would all love a fool proof system I'm afraid that,like some one else said " a couple of mins with the tree officer and and hammer" will still continue. Tree officers do know how easy it is to miss read findings and given what Marcus says you can see why it easy to make mistakes.

 

"The equipment being used to collate the information required was being shoehorned into these methodologies when in fact the methodologies were not suitable for the equipment available, and the equipment available was not suitable to give the information required for the models."

 

The thermal imaging is expensive but if it works? in the meantime I will continue to use my arbsonic as a back up only and if one or two borderline trees come down a few years early at least I will be able to sleep at night.

[Bundle 2]

"Well until the science is proven i am happy to stay ...."

It is science that informs us of the physiology of trees and which plays such a pivotal part in the management decisions ( allegedly) ......

"Tree officers do know how easy it is to miss read findings...."

This is still science but open to interpretation.....(and misinterpretation by default...)

What, suddenly its not 100%....? There are no guarantees. A healthy tree may fail.

 

" a couple of mins with the tree officer and and hammer" will still continue" quote

This is not "GOOD" science.....you are losing sight of the arguments. If you cant see science from "over cautious ".... how can you tell pro from con.....hence it offers nothing to the debate 'cos you killed it.....

 

.At the moment I can see operators making wrong calls (on unsafe trees) and ending up in court. "

This is a gross generalisation....

Edited January 12, 2009 by Bundle 2

[Topcat]

"At the moment I can see operators making wrong calls (on unsafe trees) and ending up in court. "

This is a gross generalisation"

 

No,it's my opinion and it's based on my own use of the arborsonic,I also said "I Can see" not I have seen. By the way it seems to be backed up by some of the previous posters,Mr bullman included.(people making wrong calls that is)

 

I thought the debate was about what machines were in the market and are they any good.I gave my opinion of the one I have and use. It would also seem that some of the thinking behind decay detection has not in the past been to hot(Marcus post).

 

It seems to me (and just my opinion)that this side of the industry needs to do some catching up. It's all there in the books,Body langauge of trees, Principles of tree hazard assessment and of course Shigo and CODIT and now we need a machine that can see all and put it on paper. The science of failure in wood is well covered it's just the science of getting a good machine to capture it that is lacking.Perhaps thermal imaging is the one.

 

Just out of interest,What do you use?

[Yorkshireman]

okay I've seen the thermal imaging up close so first benefits are its completely non invasive data gathering is relatively quick in field, that coupled with the precision & accuracy % levels of the data collected & the subsequent findings that the system Marcus and Co' have developed using thermal imaging is impressive to say the least.

 

No one system is fool proof & I would never condone the use of any system by a person who cannot also take into consideration a multitude of information, incuding the history of the trees on site, location, genus, specie, Vta .. hazard evaluation etc etc

 

Thermal imaging isn’t the panacea to all ills though it is by far the best I’ve seen , once an anomaly has been identified it then leads to further investigation..

A picus or resitagraph wont highlight a sub root flare flaw along a graft line but thermal imaging did . the vta showed very little other than small leaf size nothing else diddly squat, but the camera & subsequent report showed the abnormal effects within the root base & flare of a group of trees lining a busy highway. an increment bore then confimed it 'cavitys'..

So without the camera would the bore have found it ?

had it even been done !

now if that isnt the sought of proof folks need then i Dont know what is

 

on top of that there are at least 3 counts of why not to take down a tree that doesn’t need it.

 

1 loss of amenity, 2 cost implication 3, return work potential once its gone its gone .......

 

is it right to look too advance the science of our profession ?

Imo Yes

Mature / veteran trees take a long time to get there & yes there has been a lot of none existent or poor tree management..

is that justification to start the saws straight away , well ultimately that’s for the client to decide as with all its Cost v retention values & replacement costs

 

We know that NO Tree can ever be absolutely safe.. though what we can say is, that based on experience / statistics & evidence gathered on individual specimens and compared with a known control group that the evidence points to & therefore the likelyhood is ......... we therefore recommend A.B.C !!!!

Edited January 12, 2009 by Yorkshireman

[Topcat]

Yorkshireman..Seems that thermal imaging worked. If the vta showed very little,why was that tree picked for testing or just the one for the demo? and was it retained.

 

If the tree was found to be dangerous, then that is the ideal result. But likewise does it make you feel you have to go around all the other trees that show similar signs during the VTA? and test them? and if you did'nt would you be negligent if a neighbouring tree failed in the near future?

Edited January 12, 2009 by Topcat