Dissections of a eucalyptus

Since last posting about the options of studying via distance learning, I was encouraged by tutors to apply for suitable arboriculture jobs. One such job, as temporary arboriculturalist at a Botanic Gardens, actually came through, and I started early in the year.

The first month or so were spent clearing up the damage caused from January's storms, which led to around 40 trees being knocked down and another 40 needing removal at some point, just in this one garden.

One such tree that survived standing, but wouldn't have lasted much longer, was a large eucalyptus. It was multi-stemmed, having arisen from a coppice, and there was unstable included bark between the stems that began to fail in the January storms. Coupled with the tree's signs of decline the decision was made to remove it as opposed to reduce it.

We dissected the stump and saw brown rot that had broken through and been compartmentalised, and the rings were a recorded battle between tree and decay fungus. Unfortunately the fungus never fruited and so we have no idea what it was, but seeing the stump and how the decay had operated was still interesting...

1. Ring of brown rot in the heartwood compartmentalised by the tree (Shigo's Walls 2 and 4)

2. Another ring of brown rot in a different stem

3. Included bark between the two stems, showing the beginnings of decay associated with it

4. Possibly the entry point of the decay - the rotted centre of the coppice stool. Also shows "rams-horn" growth pattern where the two stools have included bark instead of joining.

1. Areas of one of the cracks formed by included bark, where decay was widespread

2. Ring of rot compartmentalised by the tree

3. An area where the decay broke through Wall 4

4. Another area of decay, entering through included bark

Also interesting to find was a lump of concrete in the centre, remnants of the old practise of filling up cavities (in this case, the centre of the coppiced stool) to prevent rot from spreading.