Dead-wooding a Hungarian oak

Spent yesterday in a large old Quercus frainetto (Hungarian oak) removing dead-wood.

How does that link up with my ecological viewpoint?

Pros of dead-wooding:
- the oak was right next to and thus had part of the crown over a well-used path
- the other side of the canopy was over a lawn which is very inviting to sit on/play on in the summer
- we had no idea how long the dead-wood had been there and so was it close to failing?
- Alex Shigo - Modern Arboriculture - "dead branch removal is a health treatment because the dead wood is an energy source - cellulose, lignin, glucose - for fungi" (p.102)
- in a Botanic Gardens, where there is more of an emphasis on appearance, removing dead wood may make a tree more aesthetically pleasing

Cons of dead-wooding:
- oaks are renowned for holding onto dead wood for a long time
- dead branches will most likely fail in high winds - and the Gardens shut if winds are above 30mph
- the dead limbs provided habitat for insects, lichens, and yes even fungi (let us not forget that fungi are biodiversity too and as such should not be marginalised)
- on the point of fungi, the tree will already have compartmentalised off the dead branch (although this can of course be overcome)

In this case, despite my tendencies towards keeping trees natural and leaving deadwood for the bugs, beasties and epiphytes, perhaps we were right to remove large dead branches, given the high volume of pedestrian traffic around the tree. However, I compromised by not touching any shorter or smaller bits of dead wood (e.g. dead stubs of branches that had naturally snapped off), on the basis that these have less weight and are less of a lever, so are less likely to drop off.

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.

Pest and disease pics

Just a few photos of different tree pathogens seen in the past few weeks:

Weeping lesions on the base of a birch. Closer inspection revealed...

 ...bootlaces of Armillaria, or honey fungus. Bad news for the tree, but good news for mushroom foragers!

Beech scale insect (Cryptococcus fagisuga) on, well, a beech 

Daedaleopsis confragosa on a dysfunctional stem of a Cotoneaster shrub

Kretzschmaria deusta at the base of a Juglans regia, showing both the anamorph, vegetative phase (light grey) and teleomorph, reproductive phase (black) fruiting bodies

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Weeping lesions on the stem of a beech (Fagus sylvatica) that most likely indicate infection by a Phytophthora pathogen (ramorum? kernoviae?)