Friday, 22 March 2013

The tree doctor

Over the winter we have been carrying out our tree safety inspections, we need to check that trees in high public areas are safe and will not fall or drop limbs on any one. Occasionally some trees may look ok but have signs that all is not well and then we have to call in the tree doctor with his high tech piece of kit called the PICUS which is latin for woodpecker.
The picus works by ultra sound, sending sound waves through the trunk of the tree, then depending on the speed it travels through the wood, it can tell if the wood is healthy or has decay in it.

He starts by hammering some nails just a short way into the tree, these are at regular intervals around the circumference of the tree, he then attaches sensors which are connected to each other by cable and then to a computer. When it is all set up he then goes round and taps each nail three times, hence the name woodpecker, the reading is then recorded into the computer.

As he goes round the tree tapping the nails the computer records the measurements and starts to draw an outline of the tree.

When he has been around the tree and all measurements have been recorded we get a picture like the one above, the darker areas indicate sound wood and the blue and red area indicate rot. So looking from the outside the tree looks fine but the Picus shows that there is decay developing within the tree and we need to do some remedial action. In the case of this tree we did a slight crown reduction to reduce the weight and sail of the crown. The Picus machine is a very useful piece of kit but very expensive at about £5000 but if it helps to protect our visitors it's well worth it.


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