decay detection, weapon of choice?

[Marcus B-T]

Since I have had a rant here is some eye candy for all tree lovers

Eye Candy.pdf

[arb culture]

I sure am, HD......

 

Trying, but failing dreadfully. I ran out of fingernails to chew, so am back on 10/day.

 

 

Keep trying Andy. It took about 5 or 6 serious attempts (as well as many half hearted ones)for me to finally give up about five years ago.

 

If you keep trying you'll get there.

[Amelanchier]

However a robust system that demonstartes that actually tree x is no different to 95% of the population is a compelling argument for not carrying out the work or not felling the tree. Every time a local authority tree survey is carried out, this data is collected and could be used to give us this information, but we are not making good use of this data. In every other biological field this approach is used, why not in arboriculture?

 

Trees adapt to their enviroments and it is only the outliers that fail. Finding the outliers is relatively straight forward but you need a methodology. It still starts with VTA and always will but before work is recommeded there should be an evaluation of those attributes that are idntified.

 

This is an approach I find very interesting Marcus. How do you ensure consistency between VTA symptoms and determine the actual likelihood of failure? What are the scale of thresholds in your methodology?

 

It does seem to compliment the concept that the most important part of hazard assessment is an understanding of the 'normal' tree. Getting a proper feel for the normal distibution doesn't seem to have been done to date - I suppose the national tree failure database has a part to play in this?

[Tony Croft aka hamadryad]

When a visual analysis of trees is carried out it identifies a number of attributes that the tree has and these often relate to Mattheck's ideas of how trees respond. The problem is that they are just that, attributes and it is hard to quantify them. What often happens is that based on the identification, work is carried out on the trees in response to the identification, because there is no way of separating out which ones are more likely to fail than others. This is the logical conclusion. However a proportion of the trees will not require work because the attribute is not sufficiently developed to cause a structural problem. Thermal imaging allows you to quantify the attributes identified through visual assessment, and find out at what point they become critical. Then work is recommeded when it is needed. In some cases work can be delayed (to wait and see what happens) in some cases it is unecessary.

 

Some examples.

 

Around 15% of K. duesta infections in Beech are purely saprophytic.

 

Around 50% of M. giganteous infections are due to historical damage the tree has recovered from.

 

Most Ganoderma sp. decay causes a retrenchment of the canopy such that work is unecessary apart from dead wood removal.

 

Thermal imaging allows you to make sence of the VTA data you collect. You can detect decay with it but it almost becomes a so what? Because what it also does is identifies the boundaries to a trees structural capabilities, you cannot do this with resistograph or any othe technology because you can't get a big enough set of data to base the assumptions on. However, these other technologies do have a place and the TI tells you when and where to drill, tap or whatever.

 

The industry may have its faults but why stick our heads in the sand. We already have most of the data that we need to make very good assumptions about trees, all we need is the methodology to make sence of it.

 

All I can say is that about three years ago I went to a beech tree in Bedfordshire that was due for removal because it had M. giganteous and K. duesta at the base. I surveyed it and made some calculations based on the data sets we had, and recomended that if the height could be reduced by around 25% it should be stable since every other beech with that amount of dysfuction fell below that particular height classification. I consulted with J Forbes Laird as to the practicalities of such a reduction and he agreed that the tree could just about withstand the amount of removal if the tree required it. The tree is still hollow, the tree still has fungi, the tree is still there, the tree is healthy, and the client saved around £1500.

 

Tree work becomes more focused, and fewer trees are removed. I disagree with the statement about the majority of people not liking trees but there is a problem with confidence of prediction. This tends to lead to a mitigative approach and work is carried out just in case. This is not a criticism since I have been in this situation myself. However a robust system that demonstartes that actually tree x is no different to 95% of the population is a compelling argument for not carrying out the work or not felling the tree. Every time a local authority tree survey is carried out, this data is collected and could be used to give us this information, but we are not making good use of this data. In every other biological field this approach is used, why not in arboriculture?

 

Trees adapt to their enviroments and it is only the outliers that fail. Finding the outliers is relatively straight forward but you need a methodology. It still starts with VTA and always will but before work is recommeded there should be an evaluation of those attributes that are idntified. THREATS is very good at dealing with many of them but even JFL agrees that TI can introduce an excellent next step before work is considered. If it can save the client's money why wouldn't they go for it.

 

Firstly Marcus that case with the meripilus and Dusta sounds awsome, did you do an article on the case at all? a link possibly?

 

We still have to be careful regarding Meripilus and Ustulina on beech in particular, most of the vets I see laying down in the ancient woods fail to these two, sometimes, not all the time, but eventualy ALL trees go down and with a beech of 300-400 years which is about the longest term for a beech with a full crown it is to be expected that one of these two fungi will result in its ultimate demise, a fact we will never escape.

 

This full crown situation is what I tried to bridge in "pollard - a four letter word" but it went over most peoples heads as a drastic butchers wish to reinstate ancient forgotten methods.

 

I believe almost any tree can be retained if only in a somewhat more mechanicaly stable form as you point out with the 25% reduction in the case you mention. beech are way tougher than we give them credit for.

 

For the record I am a big fan of the TI cameras, i do think it was pushed a little too hard and in the wrong way, setting it back. I can see the simplicity of its use and application, what it can tell and show us, it is a far simpler thing than it is given credit for. Anyone with an eye for tonal differences, and tree anatomy should be able to use it without a hitch, but its hindered by us all being told how much assitance we will all need to use the system and how much training we need to buy in order to make the most of it.

 

I still think the mono images are the better, far more tonal gradiation avaliable to the viewer. what is your view on this point marcus?

[Marcus B-T]

To answer Tony's qusetion about threshold analysis, we use the accepted statistical figure of 95% of the population. So you separate out the 5% that is likely to be atypical of the population as a whole. But what you go through is a series of statistical tests till you find members of the population that fail them all and you are left with a small number of trees that require further investigation. This is exactly what people do with a VTA but they have to be (in part) subjective about it and so they don't get close to 95% and often make errors if they try to.

 

A 95% confidence figure for separation of data is well within the recorded numbers of failures every year and so there is an experimental validation of the data. It may be that over time we go to a higher level of significance say 99% but it is too early to say at the moment.

 

Failure data bases are important in terms of understanding structural weakness but unfortunately they are not quick enough to capture data to build up useful databases beyond this. You would have to wait around 80 years before you would have enough data if you only used failures. So a methodlogy that looks at both sides of the story, 'why trees fall down' and also 'why they stand up' is always going to be more robust.

 

The question about the camera pallet is an interesting one because some people are colourblind. You can use any pallet you like once the images are calibrated so it's just down to preference. We extract the temperature data and analyse it so it doesn't matter in the end but it is a way of quickly discarding insignificant trees.

 

Hope you liked the picture, it must be one of the highest 'value' trees I have seen.

[Marcus B-T]

Sorry Tony I didn't respond to the piece on consistency.

 

It is quite straight forward realy. The attribute comes about in response to the a change or inconsistency in wood properties brought about by structural, environmental or biological pressure (or any combination of these).

 

There are critcal dimensions that bring about the failures associated with the attributes. So by using a combination of defnining the dimensions through VTA and assessing the wood properties through TI, or other measure of wood properties, you get your information for a database. The consistency is ensured by the combination of the dimensions and the wood properties for each attribute. If you don't have that link then there is no consistency. What is also important is that if you have someone who cannot define the attribute then you may look at the wrong relationship. So proper training and understanding of VTA is essential.

[Tony Croft aka hamadryad]

To answer Tony's qusetion about threshold analysis, we use the accepted statistical figure of 95% of the population. So you separate out the 5% that is likely to be atypical of the population as a whole. But what you go through is a series of statistical tests till you find members of the population that fail them all and you are left with a small number of trees that require further investigation. This is exactly what people do with a VTA but they have to be (in part) subjective about it and so they don't get close to 95% and often make errors if they try to.

 

A 95% confidence figure for separation of data is well within the recorded numbers of failures every year and so there is an experimental validation of the data. It may be that over time we go to a higher level of significance say 99% but it is too early to say at the moment.

 

Failure data bases are important in terms of understanding structural weakness but unfortunately they are not quick enough to capture data to build up useful databases beyond this. You would have to wait around 80 years before you would have enough data if you only used failures. So a methodlogy that looks at both sides of the story, 'why trees fall down' and also 'why they stand up' is always going to be more robust.

 

The question about the camera pallet is an interesting one because some people are colourblind. You can use any pallet you like once the images are calibrated so it's just down to preference. We extract the temperature data and analyse it so it doesn't matter in the end but it is a way of quickly discarding insignificant trees.

 

Hope you liked the picture, it must be one of the highest 'value' trees I have seen.

 

Im not keen on "tree valuation" as a rule, the systems in place currently give wild readings making a tree that in a wood be worthless become a million pound "green gem" the valuation methods need to be developed further in my view.

 

I am looking forward to actualy having a go with the TI's and seeing for myself or rather confirming my belief in the system. I am certain with my knowledge of decay fungi i will read the images very well, but we shall see!

 

i dont do math, but images, thats my THANG!

[Arborist Sites]

Sorry Tony I didn't respond to the piece on consistency.

 

It is quite straight forward realy. The attribute comes about in response to the a change or inconsistency in wood properties brought about by structural, environmental or biological pressure (or any combination of these).

 

There are critcal dimensions that bring about the failures associated with the attributes. So by using a combination of defnining the dimensions through VTA and assessing the wood properties through TI, or other measure of wood properties, you get your information for a database. The consistency is ensured by the combination of the dimensions and the wood properties for each attribute. If you don't have that link then there is no consistency. What is also important is that if you have someone who cannot define the attribute then you may look at the wrong relationship. So proper training and understanding of VTA is essential.

 

I just like to say a quick thankyou to Marcus for answering only the questions he chooses throughout this thread and others on thermal imaging, i and others have tried to get some simple answers and it seems you cant reply without a sales plug or repeating yourself on only a few q's.

 

This slippery technique has lost all credibility with myself and probably many others, its a shame Marcus but i and others did ask some questions several times..

 

Good luck with thermal imaging in the future, however i dont think you will need it with the postive attitude towards it of many and the excellent testimony of satisfied clients like Sam Corngrass.

 

Sorry if it seems a little strong but my head is bleeding from all the banging against the wall...........

Edited February 5, 2010 by Arborist Sites

[Marcus B-T]

If you would like to put down the questions here I will be only too happy to answer them. I don't deliberately avoid questions but I do get bombarded with them some so occasionally some pass me by.

[Amelanchier]

Im not keen on "tree valuation" as a rule, the systems in place currently give wild readings making a tree that in a wood be worthless become a million pound "green gem" the valuation methods need to be developed further in my view.

 

IMO tree valuation is a vital piece ofthe Arbs arsenal. Its useful to be able to establish monetary values on environmental assets with a systematic system so that proper comparisons can be made with other non-green processes/proposals.

 

E.g.,

• Option 1 - A straight driveway is cheaper at £6000 but you need to loose the £12,000 value Oak = Net cost £18,000.
  
• Option 2 - Longer driveway avoiding Oak or No Dig solution costs £8000 but retains above Oak = Net cost £8000.
  

 

A gross simplification but you see the point. People understand money - they might argue with your valuation but with a structured system you have a defence.