Background photo - Junipers in the gardens of Le Corbusier's celebrated "L'Unite" building, Marseille, France 2008
August 2012 - Brittle or ductile failure?
August 2012 - Brittle or ductile?
While doing some windblown forestry work near Dunoon we were asked to get this monster on the ground for the client. It is just about recognisable as having been a large sycamore which someone pruned back to a pole possibly in the hope that it would sprout again. The tree succumbed among other things to Armillaria mellea, a very aggressive fungal pathogen. Had that been the only problem (after the problem of having all its branches removed), the tree would almost certainly have died. But that fungus causes white rot which, to cut a long story short, leaves the cellulose intact and removes much of the lignin, resulting in a ductile fracture, like breaking a matchstick between the fingers.
When we cut a wedge out of the base and winched the pole over, instead it snapped like a breadstick, what is known as a brittle fracture normally asssociated with brown rot.
It appears that this tree had predominantly a third type of rot known as soft rot which decays cellulose but doesn't dramatically reduce the tree strength until the very end.
Frustratingly, I don't think we'll ever know what combination of fungi got the tree in this state