Temple Newsam's sweet chestnut

A few pictures of a beautiful, ancient sweet chestnut pollard from the Leeds City Council-owned Temple Newsam park. Whoever decided on the management of this tree made the right choices - reducing the limbs in to reduce the lever-arm stress on them, and fencing off the tree to discourage people from being near it. I doubt it will fail any time soon anyway - it's so short and squat, and so well-established that it's probably going nowhere - but by keeping people away from under it, the risk of harm is even lower. Again, another example of brilliant tree management, maintaining ancient trees for their cultural significance and the biodiversity benefits they bring.

The afterlife of a tree

Spotted this tree (or its remains) walking down from the Merrick in Galloway Forest Park.

Collapsed co-dominant stems? Or something more sudden - possibly a lightning strike?

Either way, a wonderful testament to the ability and importance of trees, even after they have died. How many epiphytes grow on this structure, how many bats, beetles and other animals call it home, and how many detritivores and fungi has it fed?

And furthermore, it is as awe-inspiring as any man-made sculpture.

Call of the wild

The Botanic Gardens I work at is an important green space in the middle of a city, so it is naturally a place where people go to connect with nature, wander amongst trees and watch birds and squirrels. However, of late I've really been missing the countryside.

Not that the Garden isn't beautiful in its own way. But it's probably a symptom of my inner countryside-lover that my favourite area is a Scottish Heath Garden, a wild corner hidden away from the main paths. Here is a place full of rowans, bird and wild cherries, alder, willows, pines; rushes, gorse, broom and heather jostle for understory space with bilberry and ferns. There's no evidence of weeding or edging, and hidden away in part of the undergrowth is the remains of a cottage (although I must admit I have a feeling this was deliberately placed there "for the feel"). I love it there - so many people walk straight past it without realising. The birds soon forget you if you sit quietly and begin to flit around, singing and squabbling. And the one remaining trace of storm damage is found in the this area - a wind-blown Pinus contorta that has been forgotten about (when I started we were due to clear it up, but that's fallen by the wayside) and remains with roots exposed and crown hidden in the growth.

As for the rest of the Gardens, its a different environment to what I'm used to. We take down a tree and spend more time tidying it up than doing the work. Every last leaf must be picked up and cleared. The lawns are protected by boards, lest a piece of wood fall on them. Deadwood on the ground is few and far between, something that may actually be reducing plant health by removing nutrients that would normally be recycled back into the plants? And this only applies to the days we are doing tree work. For an arboriculture job we seem spend the majority of our time weeding, strimming and making nice, neat lawn edges, and generally tidying borders.

Days spend pulling up geraniums and willowherb which aren't 'meant' to be there make you think. For me, it's helped me realise that whilst the Garden is an important place for science, for amenity horticulture, and as an escape for city dwellers, longer-term I'd rather be out in the countryside. I'd like to work somewhere where you can leave deadwood, coming back years later to find that discarded logs have been transformed into a home for bryophytes, lichens, invertebrates, amphibians and the odd small mammal. I don't care much for having nice neat lawn edges (I chuckled earlier this week at seeing badgers making short work of an edge that was in their way) and whilst I realise that invasive species need to be controlled, do we really need to remove every wayward plant or 'weed' (some of which are quite lovely in their own right)?

Of course, I am lucky to work here; I am learning about trees in a commercial-free environment, working on some beautiful specimen trees, and I am not for a second saying this is a bad job to have. And there is wildlife in the Garden - watching bullfinches on a lawn one morning as the sun rises, hearing woodpeckers drumming whilst you're working and seeing sparrowhawks flying with food in their talons all make you pause and reflect. But this job, for all its positives, has made me realise that longer-term I want to be using arboricultural knowledge and skills in a more "wild", countryside setting.

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

 .

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

Fungus fun

A few fungi spotted this winter:

Armillaria (honey fungus) rhizomorphs

Kretzschmaria deusta on beech

Pleurotus ostreatus (oyster mushroom) on a very ill-looking horse chestnut

Piptoporus betulinus (birch polypore) on, um, birch

A top view...

...and a bottom view of Trametes gibbosa (lumpy bracket) found on a beech stump

Ganoderma (not sure which species - resinaceum? applanatum?) - there was plenty of it on a fallen beech

and, finally:

a fungus in symbiosis with an alga, or otherwise known as a lichen. Possibly a Parmelia species?