daltontrees

Something to while away a couple of idle minutes, I created it for kids while pondering just how many tree names have only 3 letters in them.

There's only one issue here, and that is how much of the roots and soil need to remain undisturbed to ensure the ongoing vitality of the trees. RPA is just a first guess, and a relatively easy way out. If the simple RPA method is not appropriate, for whatever reason, it's up to you to satisfy the Council that any encroachment into the rooting area (not the RPA) will not damage the survival of any of the trees. The centre line or skew I expect is an irrelevance. Forget the RPA cop-out and try and justify a linear extent of root protection. That's my view anyway.

I'm going to breenge in to this debate a bit late. According to the RFS Norway Spruce "Timber is pale cream; often called ‘whitewood’ with no colour difference between heartwood and sapwood, and only a subtle difference between the pale spring wood and darker summer wood in each annual ring." The discolouration in the pictures must have additional explanations. The wide variation in ring widths suggests a chequered history for this particular tree. possibly having suffered and recovered from significant crown damage and/or partial windthrow (with root crown damage) a few years back. Can the OP confirm whether the rest of the tree was normal, i.e. excurrent single leader no big past breakages?

I use a smal maillon, just fits over the spliced end if rope, makes it through the big ring and not through the small one. Indestructible and the rest of teh time can be used for other purposes or kept securely on your gear loop.

Chill out everybody, we're just kicking some numbers about to see wherther Wagener and Mattheck are consistent. Wouldn't buy a used tree from either of them, as it happens, But |I think it is interesting to see that both their formulae result in the same thing, namely at t/R greater than 0.35 they both say strngth isn't compromised. As ever, anyone using a lower t/R ratio to justify tree removal without any other reasons is a twit or a fraudster.

Well you did ask. Unfortunately the scan is upside down again. Can't seem to fix it. First and second page fairly self explanatory, interestingly Wagener and Mattheck arrive at the same result (see end of second page) about the critical value for strength loss. Third page is attempt at the calculus. I tried derivation can't be done so I tried antiderivative by integration, basically every time you integrate you add unknown constants and by second antiderivative you are sunk. Would like to see th actual hosepipe kinking or shell buckling equatiion, because that's what is missing and what cannot possibly be derived by calculus. img017.pdf

Thanks for the Bond article, looks good for a mid-morning tea-break read. I certainly am hoping to be able to reach a firm personal view on t/r ratios that I can bring to bear on my professional judgements, and this is all helpful. It is a principle I have had a pre-view on until now but the answer is becoming clearer ad clearer. Poor Gary, bet he wishes he'd never asked.... But the best forms of education are the ones where you are not credited for getting the right answer but for showing that you understand why it's right, and its limitations.

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.