Despite these difficulties, in some cases we have been able to obtain quite precise dating even with chestnut trees with a trunk circumference greater than 7 meters. To achieve these positive results we had to find suitable trees, as well as use treeclimbing techniques and special means to carry out the sampling.
With chestnut trees of medium size, that is to say with circumferences up to 4-5 meters, it is sometimes possible to obtain precise dates using the normal techniques of extracting a wooden carrot with a Pressler gimlet, and then proceeding with the counting of annual growth rings.
The following three images show some examples of medium-sized chestnut trees for which we have been able to specify the age.
On the mountains of Malmera, in the territory of Bellinzona, using a special chainsaw equipped with a one meter long blade, we were able to pick up 3 segments representing the entire radius of the trunk at an average height of 5 meters from the ground. These samples were carried out on a monumental chestnut without damaging its vitality in any way, working in the upper part of the trunk, now dry and debarked for some time, immediately below a topping surface dating back to 1996.
After rough sanding and finishing with a very fine-grained abrasive belt, a shiny and glassy surface was obtained on which the veins and growth rings are clearly visible.
For each of the two sections thus prepared, the thickness of the annual growth rings was measured with a special device, obtaining dendrochronological curves of 496 years that could be synchronized with each other, but not absolutely datable (floating tree-ring sequences).
To obtain an absolute dating of these long sequences, we made some targeted samples, with a normal Pressler’s gimlet, in lower areas of the trunk, where the bark still appears alive.
In at least one case we have managed to obtain an annular sequence at the base of the trunk with a secure anchorage to the present. The synchronization between this annular curve extended up to the year 2002 and the two curves of almost 5 centuries resulting from the segmented sections has been successfully carried out using software that allows the graphical and statistical comparison between the segments.
The proposed synchronization, graphically illustrated in the following figure, makes use of a clear statistical consensus and allows a reliable dating of the long curves between 1496 and 1991 AD.
The investigations carried out on the monumental chestnut of Marena have therefore led us to a result of great importance: for the first time we can estimate the age of an individual of this size with remarkable precision.