daltontrees

Narrowed it down quickly with a series of lucky guesses about morphology.

See most recent post by me, the t/R 0.3 observations useful but their theory to support it falls apart before ones very eyes.

Well, quite. all he is saying is that buckling is a function of hollowing, with some vague allusion to a second derivative. Which is all I said in a different way about the cubed function. I fear some calculus will be needed to illustrate why the cubed function curve is not as steep as the curve on p.103. I am obliged to you for bringing this to my atention. The M&B stuff in the book is scientifically and mathematically flawed, by the end of p.39 they have dug a hole for themselves and throw a few shovelfuls of dirt on at p.40 to complete the burial. There is nothing wrong as I see it wth the evidence for a t/R ratio 0.3 for widespread failiure but I do not accept the arguments for the physics or mechanics that they put forward to explain it, because they don't. Their only mistake is pretending that they can.

I think that Einstein was alluding to someting morespcifically known as Okkam's razor which say that that among competing hypotheses, the one with the fewest assumptions should be tested first, a presumption in favour not of simplicity but of scietific validity. Saying that you shouldn't look for complications if your theory can be proven without them. This does nothing for the tree failure debate, we have only the fairly convincing body of evidence from Mattheck that failures increases dramatically in all species an all sizes after t/R falls below 0.3.

All quite confusing... Mattheck & Breloer in "the Body Language of Trees" (p103) plot the strength loss relative to t/R ratio according to some mysterious and undisclosed formula whch they claim is based on a hollow flexible beam. No mention of shell buckling. If you have a formula for it please put me out of my misery. The curve begins to look like what if you plot Wagener as remaining strength on the basis of d/D = 1 - t/R which I think is correct (proof available if you really want it, it stretches to 3 post-it notes, can you tell my stationery is running low?), but the celebrated sudden steepness of the curve cited by M&B around t/R 0.35 simply isn't there in the Wagener cubed function. Another hour of my life wasted this morning.

Most enjoyable, and I have never seen a follow-up before of coronet cuts looking so good. Almost sculptural.

It does seem hard to get any decent stuff about solid stems. There's plenty to be had about homogeneous rods, but I can't apply it to trees because they are very very definitely not homogeneous or isotropic. And that's just when they are in good condition! Have you come across the Wagener (1963) strength loss formula that is featured at the back of Matheny & Clark's 1994 book? When looked at alongside the usual tiresome t/R ratio debate it seems to make relatively good sense and is closer to the engineeering formula for tube structures than anything else.

I'd agree with the mulching strategy, but please remember that mulching is there to do quite a few things, like keeping soil moist beneath, slowly feeding roots with nutrients, preventing weed and grass competition and usefully avoiding the need for grass cutting or strimming with the risks of abrasion that come with them. But to get the mulching started, it could be useful to get a couple of cardboard boxes from the supermarket and open them up then lay then around the base of the tree with decent overlaps, then mulch on top. This will finish off the weed competition, kill the grass and let the mulch settle while still allowing the roots to breathe.

i SUSPECT WE ARE TALKING ABOUT SLIGHTLY DIFFERENT THINGS. sEE THE ATTACHED FOR WHAT i MEAN. Sorry about the low quality drawing, I sketched it on an envelope and then thought' that'll do'. Hopefully Adobe will let you rotate the view. In the first picture the wind force F is causing compression and tension as expected and as normal. In addition the centre of the stem is in shear as the dead weight of the tree, displaced over the centre of gravity temporarily, bears down on the compression side and pulls up on the tension side. What I meant was that a diametral crack (see second picture) could be started by this shear force. But once it causes separation of fibres, radial tension would ebb released and the crack would open for as long as the Force F remains. It would of course exacerbate the fibre buckling. If you turn the diagram suideways, it is basically like a hazard beam. img016.pdf

Sorry Tony, but I'm not sure I follow. I said and meant weakness in the purely biomecnhanical sense, and the Birch's ability to keep compensating for this by adaptive growth means that it is probably not a source of elevated risk.

Try Robinia hispida

At first glance I wold have guessed fencing wire. The tensile strength of wood is so much greater than its compressive strength that buckling occurring almost 50% of teh way around the stem seems unthinkable without an associated vertical shear, rather like a hazard beam partial failure. But on closer look at the photos, the raised ridge of wood seems to be resolving itself downwards in a slow curve on the right hand side, commensurate with shear. Birch have a life fast die young approach. I think if the tree had been hollow it would have snapped under such force. A bit of buckling is trivial, but the tree might always have this weakness.

As others have said, A.p doesn't like being pruned. The people who owned our house before us had one and pruned it lightly and it took to it very badly and only two years of fairly intensive management got it back to full strength. I cna't prove it, but I feel that a few large bold branch removals may be better than lots of small ones. The tree can then consolidate in a more compact form. I wouldn't prune in summer, this will probably restrict regrowth. I would do it in early early spring and would feed afterwards and again in the summer.

I am told that fuel in the pipes if left standing, and if it has lots of ethanol init like all supermarket petrol now has, can dessicate the rubber parts like the fuel line or the diaphragms.

Hey, you'd feel a lot worse if you didn't report it and it flattened someone.

In the case the ivy was only the second barrier to inspection, the first was that the tree was in an overgrown part of the garden and the owner was not expected to battle through brambles and nettles to get to the bottom of the tree. It seems a weak judgement in that respect. A judge could equally have said tha thte landowner knew it had last a stem, that it was next to a railway witht eh potential for multiple deaths and that she should have reacted to heightened risk by at least going to the bottom of the garden. I should explain, I posted originally to alert tree surgeons to the dangers of assumed expertise and duty to warn, but the ivy discussion here relates to the other part of the case, namely whether the owner should have called in an expert becasue she spotted or suspected something wrong with the tree.

This question seems to have been partly answered in a recent case McLellan v London Borough of Lambeth. A non-Planning committee of the Council authorised removal without internal consultation and the Court said it was wriong to do so. The Council must start again.

It may be as simple as making sure the customer knows that you are not there to assess the trees, you're there just to clarify instructions and price, as happened in the case. The more you look, even if that's not why you are there, the more it might be implied tha tthe customer relied on your arboricultural knowledge and relied on it rightly or wrongly, with or without payment. I think it puts the 'free advice' contractors in a position where they have to caveat their advice very carefully, or don't give any advice. The public knows little or nothing about teh distinction between tree surgeons and arboriculturists and they are apt to assume a tree surgeon is both. 'Surgeon' has for me always carried a pseudo-professional connotation. I'm not having a go at anyone for using the title, just be careful? Speaking of which, anyone relying on my comments or interpretation here on Arbtalk does so, as ever, at their own risk.

Good posting, Jon. It is these 2 bits that I think should be noted by tree surgeons purporting to be giving advice. There is a somewhat alarming extent to which it doesn't matter whether you don't say you're not giving professional advice, that you're only taking instructions prior to pricing and being appointed.

Someone on UKTC just flagged up a recent law case Stagecoach v Steel and Hinds, the written judgement goes into huge depth am ong other things as to whether a tree surgeon who had done work in agarden should have spotted rot on a tree and have brought it to the owners attention. The tree fell over later across the railway line and a train hit it. Damages £1/3M. It's scary because although the tree surgeon was off the hook if he had been qualified in arboriculture he might not have been in the clear. These law cases probably don't affect most tree surgeons acting purely as contractor, but there seems to be some implied professional duty to alert customers to defects in trees that you aren't even there to look at. If anyone wants me to post the transcript I can do, or maybe attempt a summary of the relevant tree surgeon bits.

COuld be Coprinus sylvaticus, explaining the lack of flecks. But the shininess suggests they are indeed Glistening Ink Cap Coprinus micaceus. Same prognosis either way. Suspiciously close to kerb. I would dig a little and see if a large root has been severed by kerbing and that it is Horse Chestnut.

It's Elm alright, don't know which one though. First guess Ulmus procera.

Tragic! A lapsed pollarded poplar by the look of it. It's days are surely numbered in the dozens.

Couple of pics of Neodiprion sertifer (European Pine Sawfly) caterpillars under the USB microscope last week.

I suspect some of the confusion here is arising from a wee misunderstanding. The latin legal maxim of a caelo usque ad centrum must be taken very literally. Draw a line vertically from the centre of the earth to the top of the sky. If you own land you own the soil and rocks beneath and the airspace and sky above. A tree that starts on one side of a boundary belongs to the owner of that land. If its roots or branches come to cross the boundary they are encroaching. But if the normal annual growth increments of the stem bring part of the stem across the boundary, that too is encroachment. In other words, it's not just branches and roots that can encroach. A tree on a boundary may appear to straddle the boundary so evenly that it may appear to be owned in common. But it is only owned in common if it originated excatly on the boundary by mutual agreement or mutual tolerance. Common ownership cannot be created by a tree, only by the actions or inactions of both parties. This is very much the exception to the normal presumption that it originated on one side or the other. The parties may have jointly chosen to plant a boundary hedge and let the trees in it grow (action). They may both have spotted a wild seeded tree on the boundary and both decided to let it grow (inaction). They are then barred from subsequently asserting in law that they have been encroached upon by its stem, roots or branches. If there is no express written or verbal agreement, this 'bar' is known in scots law as 'acquiescence'.Presumably it has another name in english law but the principle is the same. Keep it simple, because it is simple. It only gets complicated when agreements are lost say by the original agreeing parties dying or selling up and moving on. The law seems to have no equally simple answer for this situation. It would be for a fool with more money than sense or a very strong attachment to a tree to invoke the courts to decide a dispute.