QTRA vs THREATS

[PhilDye]

This is an old thread from UKTC website but I would be interested to hear from anyone who has an opinion on the merits of either methods of tree assessment.

[PaulH]

My own experience of both systems tells me that one works and the other doesn't. It's as simple as that.

Paul H.

[PhilDye]

Hi Paul,

By this I assume you mean QTRA works and THREATS doesn't. Am I right?

Cheers

Phil

[ianmonger]

I've just been looking into QTRA & THREATS myself.

I now really want to know the answer to Paul's vague hint too!  Come on Paul.  Tell us!

Does anyone else have any thoughts?

How widely accepted in QTRA?  Which approach should I choose?

Cheers,
Ian.

[DealgaO]

Guys

Look at Martin Norris's paper "Tree Risk Assessment - What Works - What Does Not - Can We tell?" Here Martin compares all of the available systems against one another, including QTRA and Threats, and he used a number of competent and qualified Arborists to assess the same 15 trees using all the systems and analysed the results. You'll find the answer to your question in there.

[masterwoodsman]

Yes and he got fifteen different replies in EVERY case!

this is because the tree is a living thing and infinatley variable as are poeple and skill/experiance levels.

Claus mattecks VTA method is flawless in my opinion, and many do not see its buety as a system, I would even go so far as to say these others are just making it worse/overcomplicated and detracting from further developing in the the VTA method.

I think claus is a legend, and his sytem and method of evaluation was new to our world, he has made a system and comincated it in a way that is avaliable to all. If you wanted to you could teach a child basic VTA. Wether your a householder with a single tree to care for, or a Mycological researching arborist there is an infinate depth and breadth to the VTA method taught by Claus and any other system is just at best,confusing the issues and at worst being created for the sole purpose of taking some of the credit for VTA

The fact remains that trees are living things and not of flesh and bone, to be able to make the calls when it is not an easy one reqiures a level of instinct and feeling for them that is ONLY gained by years of touching them and living ones life amoung them, clearing up the failures and dissecting rotten trunks.

QTRA? THREATS? Ive heard of qtra but threats? come on poeple we need to get the publics fears down not increase them, look what the movie jaws did for the great white, threats?, genius!

but this is just my opinion.

[timstrees]

Can anyone in the industry advise me which authority(s) are considered to be best practice as far as tree asset management is concerned (survey / management systems) as I am currently doing a review and would potentially like to lliase with any such authority.

[Dealga]

In reply to Master Woodman the real issue in Martin Norris' paper is not the differences between the systems, although this has a bearing, the key issue to emerge for me at any rate is that ALL systems have a reasonably to high level of subjectivity built in. The study demonstrates that each assessment by each assessor is influenced to some degree by the assessor's pre-conceptions or pre-assessment judgments. Therefore, in my opinion, it is only when someone develops a system that minimizes subjectivity at worst, or eliminates it at best, can one hope to start to get assessments that are anywhere near consistent. Is this an impossible task? At the moment I would say difficult but not impossible. The problem is that we all have to make judgments and there is a propensity among Arboriculturists, (possibly other professions as well but I can't speak for them), to cling on to what they want to believe and to distrust objective facts. This was admirably demonstrated, and continues to be, by the reaction of Arboriculturists to the results of the HortLINK 212 Project. The Science of Arboriculture is not sufficiently developed, nor is the Arboricultural Community mature enough to view the outputs of research objectively.

I remember very well when Shigo burst onto the scene and challenged the established paradigms in pruning and wound treatment. He was not immediately accepted and he took a lot of adverse criticism even to the point of a research project set up (by manufacturers of wound paints) to prove him wrong. Shigo held out and defended his position based on the results of objective research and eventually convinced the industry. Mattheck owes his almost immediate acceptance to the ground breaking work of Shigo, but even now his VTA is being challenged.

Similarly in Tree Risk Assessment, there are systems out there that have been developed over time. Some have specific applications others have more general applications but all can be used. The only 'caveat' i would offer in answer to the question, which one should I use? is this: Only use one of the systems that has been 'Peer reviewed' - that leaves you with a choice of three (i) Matheny & Clark; (ii) QTRA; and (iii) The Bartlett Tree Risk Management System. All of the others have not been 'peer reviewed' and this is a weakness. If one had to defend the use of a system in Court then a peer reviewed one would fare better.

Later

[masterwoodsman]

Good reply, and I know where your coming from, being open to new ideas and hearing out objective discussion to ones personal beliefs is a rare gift, humans like to stick to what they know.

I just want to see us all a little less divided and a little more united, but time will sort this out to a degree, as you say it is a developing field. We cant expect the public to respect our industry while were all arguing over who is right and whos wrong, which system works and which does not, we are too disjointed.

Your comment about the almost overnight acceptance of claus is a valid one, but like all truly gifted poeple he has a talent for this and a unique and objective position having come from outside of arboriculture. Whilst he may of taken much from shigos work I think it unfair to put too much emphasis on this, everyone draws from a lifes reading study and experiance, we ALL take a little of others work it is how we all develope and grow our own ideas. I am certain claus is as an origional a thinker as shigo ever was.

Eventualy most up to date latest thinking becomes obsolete, even some of shigos, and in time qtra vta and all the others were arguing over what i am sugesting is that we stick with a system that works AND is adaptable and simple enough in its constiuent parts to be broken down and made as uncomplex as possible for a ALL the levels of skills poeple may have from a simple householder to a expert witness and the V.T.A method is sublime in its ability to be simplified, and claus is a master of getting his point across in an easy to digest manner for all levels of ability.

I would be interested to read that paper by martin norris, and even more so to find out how many years PRACTICAL hands on experiance those poeple making those assesments had and just how different thier assesments where. I must admit, it is a shocking state of affairs when there is such variation in opinions of the same trees.

I have some questions, which of the three methods you mention are accepted in court? all three? and is VTA not accepted in english courts? and finaly are you saying that the 1400 quid im spending on claus's vta training is worthless?

interesting debate!

[masterwoodsman]

I have recently completed the VTA workshop with Claus, and it was an extremley worthwhile exercise, I was already confidant of my ability to asses trees but this took that to another level. Claus is an extremly entertaining individual and i can thoroughly recomend this workshop to anyone who asseses trees on a regular basis.

With regards to his "overnight acceptance" claus has been in his field for decades working away at theories and idea with his co workers, it has been his lifes work and his most recent insights into the mechanics of our business are going to change the world as we know it, your cars chassis will have an organic "bone" like look to them, and components will fail less, this is going to cause a stir. I would SERIOUSLY recomend getting behind this man, or risk being left behind.

I will however be doing the QTRA course as i think this "evaluation and quantification" aspect is important, at least enough to "add" its parts to my own assesments. Targets are targets though and a dodgy tree is a dodgy tree to coin some common language terms. At the end of the day we are a long way off from having a numbers game, this is an organic and dynamic organism, it will not conform to "statistics" its a bit like that old chestnut the average couple have 2.4 children! so according to the statistical appraoch most couples have a pair of legs and a lower torso running amock! you get my point.

We are trying to asses trees and thier likely hood of failure, damge, if we asign a numbers game and statistics we will encourage a zero tolerance approach and trees being far from perfect will be crucified as a result of "precaution to the statistical rule"