You have been warned Posted on June 11, 2015

To Kew on a perfect June day for a serious all-day session on, of all things, tree safety. The IDS organised the seminar with Tony Kirkham, the head of the arboretum, as a consequence of his horrific week in court last year when a branch fell off a cedar and killed a girl.

Accidents and Acts of God are old-fashioned concepts with little, if any, place in current law; the blame culture has to pin every misadventure on a cause, and the cause on an individual. The Royal Botanical Gardens owned the tree (a cedar of Lebanon); Tony Kirkham is responsible for all the 14,000 trees in the collection. If a tree is unsafe (the presumption if it sheds a branch) it should have been made safe. Under Health & Safety laws Tony might have had to go to jail.

His audience yesterday were people who either own or manage trees in arboreta or parks all over the country. I think they were shocked, all of them, at the risks they are running in letting anyone near their trees. Their duty of care extends to every tree and every branch, and the only way to satisfy a court is to show that you have inspected the tree in question, satisfied yourself that it is not about to break up, and kept records of your inspection. It is only the fact that Kew does have a long-term, fairly elaborate and fully documented inspection regime that saved Tony from clink.

True the family of the unfortunate girl were on the attack, hired a QC and an expert (who turned out to be not extremely so in court). We were full of questions. Does the duty to inspect apply to trees in ordinary gardens? (Yes). Does it apply to trees in woodlands or forests? (Yes). What about the notorious and mysterious phenomenon of ‘Summer Branch Drop’, when a major branch parts company with its tree without warning, for no perceptible cause? For some (or no) reason this happens most often in June, July or August. There is even a superstition that the time to stay away from trees is on July 22 and 23. Tree professionals prefer to let S.B.D stand for Sudden, rather than Summer, Branch Drop – not having a clue how it relates to a particular season.

We spent the afternoon on a practical tree-inspection tour of the arboretum, following Kew’s three-stage system: first walk (or even drive) by at 3 mph with your eyes skinned, looking for broken or split branches, splits in trunks, signs of weeping or surface fungi. This you should do as often as possible, within reason. The second stage is to come back and examine what you spotted. Carry a mallet to tap the trunk for hollow resonance and an iron rod to prod the base for soft wood. Take action as needed: cut unsafe branches straight away.

Stage three is for when you can’t tell, or decide, because the problem is hidden inside. This is when the expensive toys come out: an electronic device called a Picus Sonic Tomograph that reads the speed of sound-waves through the trunk to build up a picture of the interior. You hit a nail at intervals round the tree; the sound travels fast through sound wood, slowly through rotten wood and not at all through hollow cavities. The rule of thumb is that if one-third of the trunk is solid the tree can stand. Less than that means the chop.

Of course other factors come into it. A hazard (the possibility of something going wrong) is not the same as a risk (the chances of it doing damage). There is obviously more risk where more people congregate, by a path or a road, then in the middle of a wood. Your action can be proportional to the risk, so when a grand old specimen by a path begins to look a bit wonky Tony Kirkham’s first step is to move the path. More people walk on short grass than long, so he lets the grass grow or creates a wide circle of mulch around the trunk (which is also, of course, good for the tree). There is obviously a degree of proportionality in the precautions you must take – but the fact remains, the buck stops with you.

And you must contemplate the possibility of extreme bad luck: the Kew cedar branch not only brought down two others, but a huge chunk of wood bounced. The poor girl was six metres outside the radius of the tree.

It was a landmark case. Not long afterwards the National Trust was able to use the same defence of regular inspection and records. But it sent a shudder through the gathering. We all went home to brush up our logbooks.

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