July 2011 - Castle Howard oak
I recently got to go to the spectacular Castle Howard in Yorkshire, an enormous residence open to the public which has extensive grounds. Right outside the entrance to the visitor centre stand several very large oak trees (Quercus robur) like this one.
It is at least 5 metres (16 feet) around and must be a coulle of hundred years old. Although the picture makes it look quite compact, a closer look showed that limbs at least 1.5 metres (5 feet) around have been taken off the sides and top, suggesting that the tree was originally 3 times this size.
The second picture was what intrigued me. It shows that a square of bark had been cut out, a hole about 100mm (4") had been drilled into the centre of the trunk in a slight upward slope and a lenght of grey PVC guttering inserted. There also seems to be the remains of a black tar or bitumen paint around the hole. The hole is slowly starting to close over.
My guess is that the hole was made to drain water from the rotting centre of the tree, this used to be common practice. Nowadays it is known not to be a good idea because it simply gives bacteria and fungi more air and drier conditions to work in, and lets in more infection. JM