Heartwood

Pholiota squarrosa

...found on a walnut species (Juglans ailanthifolia).

After looking up Pholiota squarrosa in Weber & Mattheck's highly-recommended Manual of Wood Decays in Trees, it appears this fungus is a simultaneous white rotter. I've been trying to get my head around rot types for a while now, and as far as I understand simultaneous white rot attacks both the lignin in the wood (which gives the wood stiffness, especially radially) and the cellulose and hemicelluloses (which give the wood bending strength, as well as strength under compression from the weight above). So, the degradation of cellulose first makes the wood brittle, and then degradation of lignin softens the wood and removes strength.

So as (if?) the decay progresses in this walnut, it could suffer a brittle fracture in strong winds (with the loss of cellulose), then become at risk of ductile fracture as the lignin is decayed. Plus, there were clumps of fruiting bodies on both the north-west and the south-east to the trunk, which I think can be interpreted as showing decay could be fairly advanced and is not limited to just one side of the tree.

Does anyone who  might be reading this know if I'm interpreting this along the right tracks?

The woods around Loch Leven

Earlier in the year a friend and I went for a wander around Loch Leven, near Kinross. I was looking back over the photos today and it reminded me of how refreshing some of the woodland was. Walking from the RSPB reserve (Vane Farm) anti-clockwise around the loch, we passed veteran oak trees into a more closely-packed birch-dominated woodland with wet areas of willow and alder, and some Scots pine (presumably an old plantation?) thrown in.

There was a lovely sense of untidyness prevailing here - log piles, standing and fallen deadwood everywhere, and natural-feeling paths. The veteran oaks were stag-headed, had hollow cavities and were generally scruffy looking - and all the better for it. Tinder fungus (Fomes fomentarius) and birch polypore (Piptoporus betulinus) were everywhere, with birch trees in various stages of collapse because of them, and all the trees and logs were covered in a variety of mosses and lichens.

The only curiosity was a distinct lack of young trees and an understorey. Could this be from deer or sheep grazing? Certainly the fences could have done with some TLC. Or could it be that this woodland is in fact a neglected plantation, thus accounting for some of the lack of the variety of tree ages? Perhaps the pine plantation spread further throughout the woods, and the birch is a secondary woodland arising from the felling of part of it? It would be interesting to go back now the growing season is well under way and try to make sense of what the flower communities are telling us about the woodland's history.

Phototropism

Trees are living natural sculptures... who wants nice neat leaders with single straight stems when you can have trees like these?

A birch at the RSPB reserve at Loch Leven

An oak amidst spruce at Dean Country Park,
Kilmarnock

A lime at Newhailes estate near Edinburgh

Spalted birch

By pure chance I sawed up an old rotting ring of birch trunk to put it through the chipper at work. Inside on the freshly-cut surfaces was a beautiful spalting pattern - I've seen it on beech before, and even have a lovely spalted-beech bowl turned by my partner's papa, but never seen it on birch before. There was honey fungus bootlaces all over it, but perhaps other fungi have been attacking it too? Either way, the battle between fungus (fungi?) and tree have been beautifully documented, with the tree laying down its defence system by biochemically altering the wood, and the fungus eventually overcoming it and forcing the tree to draw new battleground lines. OK, a slightly anthropological view, but that's roughly what has happened. 

Veteran sweet chestnuts

The Ancient Tree Hunt is a collaboration between the Woodland Trust and the Ancient Tree Forum which aims to map all the 'ancient, notable and veteran' trees in the UK... a big undertaking but an interesting one, not least because people are getting out and thinking about all the big, old, lovely and/or important and culturally significant trees they know.

http://www.ancient-tree-hunt.org.uk/ 

I've recorded trees before, whilst working as a seasonal ranger. And after spending a rainy Sunday at the Royal Botanic Gardens Edinburgh, collecting data for tree surveys for college work, I added two of the biggest sweet chestnuts there to the database.

One is by the pond, with nesting birds in holes and a great stag-headed quality to most of the larger branches. 

The other, perhaps more noticeable, is the big old tree standing on the corner of the rock garden - right alongside a well-travelled path from the East Gate down to the south. This one lost one of three large limbs during recent storms, and has a huge wound that looks great - it tells a story and gives an indication of the tree's life history. I hope that at least some people stop and think twice about this tree - about how it is a living being far older than any person in the world, about what it has 'seen' in its life and about what it means to preserve trees like these.

Coronet cuts

I did my first coronet cuts (more 'natural-looking' cuts that simulate a tear or snap on a branch) on a southern beech (Nothofagus) at work this week. It was hidden away in a small copse-like part of the garden, so my boss asked me to reduce about four 'large' dead limbs (to reduce the weight and prevent them falling on a fence below) but leave a couple of feet for habitat.
I've never been shown how to do it, but I've seen photos and heard descriptions, so thought I'd give it a go at ending the 'stubs' with coronet cuts. Here's some of the results:

They're probably not as good as guys who've been doing them a while, and I know they're only a small branches, but for me a step in the right direction - this kind of work is part of what I'd like to do. And it was good to be doing them in a Botanic Garden, somewhere where I never thought they'd want "untidy" looking coronet-cuts... luckily this tree was hidden away enough to get away with it.

Apple trees and lichens

Been at a Scottish Orchards event today (http://www.scottishorchards.com/)... it made me think of these pictures and the countless others that I took of the old apple trees (and the lichens on them) in an old orchard where I used to work.

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?