daltontrees

Sorry guys, |I don't seem to be able to leave this subject alone. Barring any retorts, I will try and make this my last contribution on QTRA (but not oin the subject of the quantification of tree risk). I think we all agree it is impossible to quantify tree risk with any degree of precision OR accuracy. If you accept the rough-and-ready notion that likelihood of harm equals likelihood of failure x likelihood of target present x severity of harm it is clear that none of these components can be measured, predicted, whatever, and that the multiplication of errors means that any calculation could result in a flawed probability. Notwithstanding, with a bit of observation and professional judgement a decent stab at them can (and in my opinion should) be made. If I have any point it is that a systematic attempt is better than a finger in the air and that having put a system in place and implemented it in good faith is all that the law can expect of anyone. So, in conclusion, from what I know of QTRA it sems like a decent effort at going that little bit further, but in my newly enightened view can't achieve any useful additional kudos in the courts for having discharged the tree owner's duty of care. Maybe in 100 years we will have enough statistical evidence to show that the use of QTRA has measurably saved lives, but I am inclined to think that it's precision is a distraction from it's accuracy, if any, as compared with sound tree-by-tree judgement.

Lkike I said a while ago, it is possibly an unresolvable issue without statutory intevention. Nearest we currently have is High Hedges legislation. Up here in Scotland a private memebrs Bill has been submitted for a HIgh Hedges Act and there is much baying from a few parties for the legislation to be applicable to deciduous hedges and even to solitary deciduous or evergreen trees. That would be an enormous step for society to take, great for tree surgeons, bad for trees, a great result for individuals, an expensive and loathsome result for tree owners and I think ultimately bad for civil liberties. If we all expect a right to light, we must all accept to have our right to privacy, our personal choice of garden and our right to develop a natural rapport with neighbours to be stripped from us and replaced by state-sponsored curtain-twitching. The original subject of this thread, and the situation that materialised regarding prohibitive legal costs illustrates the dilemma perfectly. The law, if forced to, would find precedent or analogy to establish a definitive judgement that would clear the whole thing up in everybody's minds, but no-one wants to take it that far as (it would seem) it is too expensive relative to how little trees matter. Perhaps they matter so little in the grand scale of things that politicians and legislature have never seen fit to give even the debate air time never mind stepping in to pen new legislation that would fill the void so that the likes of us and our exasparated clients know where they stand. If trees could talk, the ones that weren't getting the life pruned off them would no doubt be laughing at us and wondering how our species ever managed to get this far at the expense of every other species. Sorry, can't fund a light-hearted emoticon to add that expresses my oveall feeling about this.

Nice pics as ever! British Mycological Society recognises C. ligula as established in Britain, as the 'Ochre Club'

Don't they call it bark-strippers lung disease? Nasty nasty stuff. By the way the Sycamores up here have had a fabulous year. See too posting elsewhere about the lack of Tar Spot in central Scotland and elsewhere.

It'd be nice to hae enough spare cash to take them to court anyway just to see how they thought that root damage would be solved by wholesale branch removal.

Have a look at "HSE Reducing risks protecting people" you will get it on internet somewhere. Covers it very well inc the 1:10,000 threshold. Tree survey risk assessment is about protecting public at that threshold, forget industry thresholds and actual stats. But of course I have to do a risk assessment for surveying trees which in theory involves examining tree with binoculars to check it is safe enough to survey.

3 bed semidetached victorian sandstone icebox, was taking £2k a year in gas when we moved in, then we insulated attic and put in dovre 7kw stove in main room, can't now stand the heat in there with the door shut, it heats the whole hallway (cavernous) and takes chill off whole upstairs on a 15kg basket of logs a day. Gas bill including cooking and hot water down to £600 a year. We thought about a back boiler and link into central heating radiators but the cost was terrifying. We now use both systems, stove for real free heat and central heating for occasional boosts or lazy moments and for hot water.

Strange one! Did the top have a lean on it on the gob side before you cut it? Maybe gob wasn't wide enough to allow transfer of momentum into a pull on the hinge to rip the wood there, so the top split vertically instead.

I think I have been up worse and not known it was goosed until the stem was felled at the end of the job. 30% woood left is quite a lot but if the decay is off-centre it's not very safe. You ought to assume the tree is by now worse than at the last good wind blasting it stood up to. Also if the decay is on the compression side under wind loading but on the tension side for rigging down it's abiltiy to stand up to wind is no proof of it's abilty to stand up to loads from another direction. I would be thinking about the additional shock forces of rigging down that a tree doesn't normally feel. And if the tree is going to be unbalanced after one side is cleared. I'd climb it and take it down in little bits, freefalling as much stuff as possible. I wouldn't let a trainee anywhere near it. Better still, a MEWP or crane is probably justified after risk assessment. Good luck!

I have looked up P. involutus, it doesn't seem to grow directly on wood and is known for darkening conbsiderably when cut. A couple more tests and examinations are making G. junonius less likely than I thought before. Also I didn't realise this was the posh name for Rustgills which I have seen before. The lack of ring and sporeprint would be very uncharacteristic of the species, from what I have read. I have got to get me some KOH because the reaction for this species is supposedly quite conclusive. I even cooked a bit of it because I read it turns green. This one didn't. Also looked at A. tabescens, it aint that. Fungal idents just seem SOOO frustrating and inconclusive. The Oak had inexplicably lost a lot of branches recently in storms, so it is down for some close monitoring anyway. I have made a mental note to have a look at the base next early November to see if there is any further fungal fruiting action.

I have a very good reason for not having considereds Gymnopilus junonius, and that is that I have never even heard of it! I shall have a look at some books and websites, it's always nice to have an excuse to research something new.

BE cautious, verbal advice even if not paid for, may be taken by landowner as sufficient then relied upon, could come back to haunt you. But if you are also to take all necessary action then the temptation would be for you to take a very precautionary view on what actions are needed.

I would agree the ferny one is a Mimosa. Couldn't say which one though, picture is a bit fuzzy.

I would appreciate any pointers anyone has on this fungus, found yesterday on a 24m high mature Quercus robur in a wholly broadleaf wood, growing between butresses about 10cm above soil. The section of butresses seemed intact but sounded dull to the mallet. There was only this one mushroom and a much smaller one round the corner. There was a pit of water in the butresses just above and to the side of the specimen. The cut-through picture was about 12 hours after cutting, no noticeable discolouration. I have been trying to get a spore print, but nothing so far. First thought was Pleurotus but I am struggling to fit it into ostreatus, cornucopiae or dryinus.

This post has wandered off the QTRA/risk assessment theme into different territory. To me a 'client' is someone who pays me to do a specific report or give specific advice, and commissions me before the advice is received rather than rewarding me with paid work if the advice is accepted. A 'customer' is someone who pays me for doing tree work. Indeed, in all cases I make it clear that in advising a 'client' on a course of action I consider it a potential conflict of interest if I was to be the one doing the resultant tree work. I would suggest that it is almost impossible to give objective advice to a client and give a price to a customer (i.e the same person regarding the same treee) simultaneously. As a contractor I agree with ScotsPine1, but as a consultant I don't think this situation has much to do with objective risk assessment. If the client was worried about a tree and someone advised against touching it that would be unwise because whether you are there as consultant or contractor and whether you advise verbally or in writing and whther you are subsequently paid or not or do the work or not you have invited a liability on yourself inthe even tof the tree failing. It's not that hard to explain to a potential customer that a tree is objectively fine on the balance of probabilities (which is about all a risk assessment says anyway) but that if they want to err on the safe side then get the tree reduced or removed. It's their tree andf their roof over the bed they have to sleep in at night worrying when a tree might land on them. Being able retrospctively to sue a consultant for negligently signing off a tree might be no comfort on a windy night.

I get it Albedo, I think. P Trees fall over. Q It's a tree, so it is going to fall over. Yes HCR, I should have said vitality. Old habits fie hard, I always have a look to see whether twig extension this year is more or less than last year or less than noirmal for species. But I have never concluded anything from it that couldn't be worked out from unseasonal weather or some obvious defect like Armillaria. Thanks for the correction though, accuracy beats precision every the time.

That's the abridged version of the full-size NTSG doc, which is a dull dull 90 pages or so. Wisely said to me once that to know what a dodgy tree looks like you need to know what a normal one looks like. Doing lots of tree surveys gives you a chance to do that. But the most useful thing I find is to spend time looking at recent failures (before the deadwood fungi get stuck) in and to get to know for example how much included bark causes failure of compression forks, what extent of fungal hollowing precedes stem failure, how the amount of k. deusta at the surface relates to the extent of decay inside, what abnormalities of bark correspond with what kinds of failures. When you see it again on a standing tree the right alarm bells ring. I have had a look at the QTRA website now, it looks like a system that might have been cutting edge (in terms of risk assessment) once but I can't see many people taking it up for money now. If nothing else NTSG seems to have demystified the whole thing. In a dull dull way.

Ahh, oslac, just when I was going to say I concur with you and tha tthat was a comfortable juncture for patting myself on the back for not wasting a license fee for QTRA, I realised there is a serious message in this somewhere. I hate to drag in the National Tree Safety Group stuff, but NTSG does rather fancy itself as having arriveds at the definitive guidance on the matter and goes as far as to say it hopes its findings are adopted in the courts. Anyway the distinction needs to be made between the landowner, the inspector and the assessor of risk. NTSG suggests the landnowner should identify which trees, which if the fell, would harm someone. An inspection by a bod who need only have a working knowledge of trees (not necessarily and arboriculturalist) should follow and if defects are noted the risk should be quantified by an arboriculturalist and then mitigating action taken where appropriate. 3 separate acts by 3 different classes of people there. Agreed the assessor of risk should have 'appropriate knowledge and expeerience' (to quote NTSG). Teh contract I am working on requires someone like me to do all 3. With the fallback of referral of unusual cases to experts, a call for a climbing inspection or tomography etc. Hope that makes things a little clearer.

sorry, finaL comment before I put the wean to bed. I should ahve read the counter argument properly. I didn't say bad example, I said stupid. Does it put my posting in a different context if I say a 'grossly oversimplified example selected for its illustrative purposes'? When I am looking at trees I trry and look atthe whole tre. The canopy for vigour, every branch, limb, fork, every bit of the stem and as much of the roots and butresses as possible, and I stamp about a bit to see if there is anything telling under the ground. What my purpose in that is (others may take a different approach) I am looking at every possible way the tree or any bit of it can fail. And then how likely that failure is. Then I pick the most likely failure. That is a start for quantifying one part of the risk i.e likelihood of failure. And the size of treh part that can fail and the height it will fall from points to the seriousness and likelihood of harm. Then I stand there for 3 months to see how many people go past.

oh and another thing... and i am being counter-counter-argumentative here... what reason might I (or anyone) have to be biased? unless i am secretly a sales agent for QTRA.

Rob Arb, I think I pointed out the likely flaws myself, I know it's not perfect and the assessments i find myself doing on site get a lot more complicated. But I STILL say if you don't try to quantify you get nowhere. I don't want to be a case law bore but the whole thing was brought into stark relief in bowen and others v national trust, kind of backs up the benefits of having a reasonably robust basis for assessing risk. I would hate for someone to be hurt by a tree on my watch, but if one were up in front of queens counsel for negligent tree assessment resulting in deaths and one presented the defence that one thought the tree was ok because one knows about this sort of thing, QC would shred you like you had been tossed into a chipper head first. Even an expert (I mean Lonsdale standard) would get a grilling. I wouldn't hide behind risk assessments, the courts (see bowen) know treees are fickle and would recognise that by using a reasonably robust system a defendant had done all that was reasonable. I think tht that's more or less what the Occupiers Liability Act says.

Sorry I haven't been able to reply before now. I don't know what QTRA is if it is a brand of risk assessment. I do risk assessments. I am not assessing the risk of a tree failing I am assessing the risk of someone being sertiously hurt by a tree failing. If that's what QTRA does, that is basically what I am doing. Stupid example to illustrate the arithmetic ... Tree with kretzschmaria bursting forth from every crevice, and I m ean proper soft-rot-brittle-failure-likely. Upwind from a well used footpath. There's a 50:50 chance of the tree harming someone (or worse) while they ar ein the danger zone. So, probability of harm 0.5 It can be obseved that on average someone passes once a minute. They will be within the death zone for 15 seconds each. So, there is a target present 1/4 of the time, or to put it another way probability of a target being present at time of failure 0.25. Probability of tree couping over prior to next scheduled inspection 1 in 10 or 0.1. Risk 0.25 x 0.5 x 0.1 = 0.0125 or 1:80. Way way above the specified 1:10,000. That tree would be phoned in for removal within 48 hours. The arithmetic for that timescale is not much more complex. It is easy to see how things are never that simple. What about during the night? Don't trees fail usually in strong winds when there are less people using paths etc. etc.? And I am doing VTAs so there is an imperative to instruct expert examination, climbing inspection, intrusive testing etc. I am just AA Tech and PTI, also a tree surgeon, which seems to be more than enough for the client, I think I have a little knowledge to spare beyond the requirements of the contract. I should add that I am surveying great long stretches of footpaths, streets, school boundaries etc. where the target probability needs only to be estimated once. All in all, Is till say that if you can't at least try to quantify the risk and have athreshold to work to you would stand the bottom of every tree, and possibly eventually at the front of a courtroom someday, umming and ahhing in a most unseemly and unproductive manner.

Sorry that should say 'every single day for every single tree'

Wow, you guys are giving this subject a good seeing to! I amn't sure what this QTRA is, is it that sysstem devised by Forbes Laird that you have to pay for to get a license to use? This winter I am surveying around 8,000 trees for a nearby local authority. The contract specifies (words to this effect) that trees must pass the 1:10,000 risk of serious harm test or works must be specified to bring the tree within that probability. Evey single day for every single day I quantify the risk, there is no scope for pontification about the benefits or drawbacks of statistics or the question of whether a tree is Ok or not. It either passes or fails the threshold. And the more I have read your interesting and entertaining debat the more I am reassured that (i) without quantification of risk the whole business is impossible and (ii) most aspects of quantification are not that hard really. Read any survey report, if the author is worth a tosser the report will make it very clear (i.e. not just buried in the small print and disclaimers) that there is no such thing as a safe tree and that the report can only try and predict that the likelihood of harm is or is not above the threshold of acceptibility. The difficulty therefore lies often with the lack of client/public understanding with the limitations (and I don't mean cop-outs) of tree surveys and reports. That's my view anyway. It keeps me sane out on survey day after day after day.... when otherwise I would go ga ga.

Dead right. Small businesses earn money, banks literally make it out of fresh air. They are a necessary evil, I plan to continue to use them only to teh extent things can'be done any other way.