Background photo - Junipers in the gardens of Le Corbusier's celebrated "L'Unite" building, Marseille, France 2008
March 2012 - Forking hell
This set of photos are of a 'compression' fork in a Lime (Tilia x europa) one of several we dealt with recently for a client in the West End. Inspireds by the techniques of the late great american re-inventor of arboriculture Alex Shigo, I sawed it right down the middle to examine the structure. I have annotated the photographs. At A the stem is very definitely two independent substems, and at D it is equally definitely one stem. In between is a transition where the continuous rings of wood at the bottom of the fork become two sets of undistorted rings above (see the 3rd and 4th pictures).
From A to B there are two back-to-back skins of bark within the fork and hidden from view. This 'included bark' is the inherent weakness of tight forks in trees. From B to the wood from both substems is starting to enmesh or fuse but in this slightly dried-out (one week old) sample the continuing weakness is accentuated by a crack that has formed. By D the fusion is complete. The photo of the outside gives an idea of which surface features correspond with where the inclusions and the strutural weakness begin/end.