The Sessile Oak

I've been an admirer of this Oak tree, located in a local park for many years, long before Arboriculture and I became acquainted. I've been monitoring the development of sporophores around the buttressing for the last five years, early on in their development identification was challenging however recently they kindly put on a growth spurt, which has aided in identification.

Now I've been itching to carry out a survey using the Picus3 for years on this tree, partly because it's so local, partly because I used to climb this Oak when I was on my journey to becoming an Arborist , all those years ago...Happily I was recently given permission and Andy Jones and myself gathered up the equipment and off we went.

One thing I have learned, it's so much easier carrying out measurements on trees with large girths with two people, those calipers can be unwieldy on full extension when on your own, not to mention keeping track of the number tags as they fly off in the wind!

Note the cable attached to the sounding hammer, I've learned to my dismay that when surveying, Bluetooth and large Oaks don't get on with one another.

Gentle, crisp taps is the name of the game if you want reliable data. We undertook two surveys, one at 30cm and one at 100cm, this was done for comparison as it was assumed decay would be more prevalent near to ground level than at 1m above.

This is the tomogram produced at 30cm, together with the positions of the fruiting bodies, calculation was checked on site and data was good.

Above we see the tomogram at 100cm, as expected we see good sound wood. The Picus3 is very good at giving us a representation of the inside of the tree. This particular tree does have targets, the green open space with public access and a road, because of this we wanted to backup this data with the use of resistance measurements, using the Resi400. We decided to take these measurements at sensor points (13) (5) (3) and (8), comparisons can then be made between the results and the tomograph.

Note the addition of the reversible puffer jacket (it was extremely cold) available from Arbortec and highly recommended!

And here are the results from the Resi400 surveys which confirm what the tomograp was indicating. The information has been passed on to the local authority responsible for the management of the tree and it'll be up to them to propose a future management plan. Hopefully the tree can be retained in some form, in an ideal world a retrenchment program would allow the tree to be enjoyed by the many people who use the park, including myself.