Burnham Beeches – old trees, wood decay and sun

A huge thanks to Burnham Beeches yesterday for hosting some of us for the day and showing us around the site. Below are some of the stand-outs from the day, which I am certain you will all appreciate!

The importance of functional units

As we can see in the below few images of a particularly striking beech pollard, very little of the structure of the tree needs to remain for the tree to persist as a living and functional organism. In this example, only one unit of vascularity supports a very small crown, though the beech is generally without significant fault. It could, potentially, persist in this state for many decades! Certainly, the two natural ‘props’ that support the crowd through a sort of tripod could, in their eventual failure, be the demise of this tree; assuming the functional unit cannot itself adequately support the crown. Depending on the rate of decay of this two ‘props’, this last vascular strip might (if decay is slow) – or might not (if the ‘props’ fail sporadically) – be able to lay down the necessary wood fibres for such mechanical support.

Reduction work on lapsed pollards

There comes a point where one has to make a decision – for what reason is a lapsed pollard being managed? If it is to be managed for the provision of habitat then the major failure of the structure might not be an adverse occurrence (to a degree!), though if the intent is to retain the pollards for as long a period as is at all feasible then it might be necessary to undertake quite extensive reduction work, in order to reduce the mechanical loading upon the old pollard head. As can be seen from the below beech, heavy reduction work has taken place and the crown architecture / good number of ripe buds that remain below the pruning points will hopefully ensure that this lower crown will function very effectively. Of course, where lapsed pollards don’t have this lower growth then a heavy reduction might not even be possible, though where such low growth exists then it does provide for more effective means of management, with regards to reduction work of the crown.

Submerged deadwood for reptiles

A terrapin uses a large section of a mostly-sunken stem for sunbathing, in the centre of a large pond. Indeed, this section of deadwood is an effective tool for the terrapin, which allows it to be exposed to direct sunlight and isolated from potentially aggressive mammals (that includes humans – seriously). Improving the texture and heterogeneity of this aquatic habitat with deadwood is evidently important, therefore!

Artificial propping

As some of the old beech pollards are quite literally falling apart, safeguarding their structures against such cataclysmic failure is necessary, if their presence in the landscape is to be retained. For some, this involved reduction work, whilst for others it involves installing props to support either the enture tree or large / heavy parts of its structure. In the below two cases, we can see how props have been installed to stop the trees falling over completely.

Wood-decay fungi

As you’d very much expect from a place such as this, wood-decay fungi are found in relative abundance. Beneath, the best examples are shown – this includes less common fungi, which we also came across during the trip; or less common associations, as you’ll see for one particular set of photos!

Fomitopsis pinicola (red-banded polypore)

Along the stem of a beech, this single bracket of a very infrequently found (in the UK, anyway) wood-decay fungus, the red-banded polypore, resides. Adjacent to a colony of Bjerkandera adusta and above extensive swathes of Kretzschmaria deusta, exactly to what degree this fungus has secured the wood substrate is unknown, though the good thing is that it has produced a fruiting body and in sporulating!

Heterobasidion annosum (fomes root rot)

A common fungus but probably not one you see every day on hawthorn! Hidden beneath a branch ridden with Fuscoporia ferra (syn: Phellinus ferreus) and some leaves, a series of fruiting bodies were tucked away comfortably. Fungi love to throw curve-balls!

Ganoderma pfeifferi (bees-wax polypore)

Sadly, the host beech had recently failed, due to the decay caused by this fungus. With respect to the rot induced, the failure was seemingly a brittle one and thus the failure can be attributed to a significant loss of cellulose. The cross-section of the failed region also yielded some glorious ‘rosing’ patterns, which is something that has been seen in other cases of failure as caused by this particular fungus.

Fomes fomentarius (hoof fungus)

Found on both birch and oak, this species isn’t notably abundant in the south of England, where the pathogens Ganoderma australe / resinaceum / pfeifferi (in order of commonality) tend to be better suited. In the two instances shown below, fallen deadwood has provided the resource, which aligns with its colonisation strategy – that of awaiting stress / entire vascular dysfunction of an area or whole tree, before launching wide-scale colonisation activities.

Daedalea quercina (Oak mazegill)

Found quite frequently on dysfunctional wood of oak, this instance has provided the best sight yet of this species. As you can see, an oak monolith is utterly littered with fruiting bodies, which is genuinely a spectacular sight!

That’s all for today, folks!

Fungi everywhere on a single declining beech pollard, New Forest (UK)

I was forunate to be able to spend some time in the New Forest yesterday, having driven back from Somerset after picking up a microscope (more on that, in due time). When last down there, which was during mid-summer, I spent a few hours sojourning around the Bolderwood / Knightwood Oak ornamental drive, with specific focus upon the myriad of mature and veteran beech pollards that dressed the roadside. One beech, even then, alluded to fungal parasitism, given its dire vigour and evident crown retrenchment (perhaps associated with ground compaction, given its close proximity to a car park and the Knightwood Oak). Therefore, I paid a visit to this beech, with the hope of finding some fungi – and I wasn’t disappointed!

I’ll actually be honest and say this beech is testament to the ability for the species to provide for many wood-decay fungal species. I really don’t think I have ever seen a tree more covered in fruiting bodies of many species than this one, and we’ll run through the suspected species below. First, we’ll look at the tree as a whole, however, and from the first image I don’t think there’s any debate over its poor condition. Granted, with the impending demise of a tree, weak fungal parasites and saprotrophs can enter, and this alludes to the cyclical aspect of energy transfer. In time, this beech will be the food for other plants and trees, though for now it’s fungal food.

I wonder how many more years this beech has before its snatched from the throes of life! Probably not many.

The arrows relate to the various fungal species found. Working clockwise from the tip of the centre, I spotted what I suspect are Hohenbuehelia atrocoerulia, Chondrostereum purpureum, Mensularia nodulosa (confirmed), Exidia plana and Bjerkandera adusta.

Here, behind a limb adorned brilliantly with one of the ex-Inonotus species, sit some fresh oysters (Hohenbuehelia atrocoerulea). Evidently, they are free from frost damage, suggesting they are probably only a few days old.

There’s also a younger set emerging just behind this cluster in the foreground!

Looking down the main stem, here we can observe how Chondrostereum purpureum and Mensularia nodulosa are inter-mingling. On the whole, it appears the Chondrostereum is more limited in its amassed substrate, if the presence of fruiting bodies are anything to go by – the ex-Inonotus species is abundant on the trunk and further up into some of the limbs.

In this image we can identify how the two species really do run right up to their respective thresholds.

For good measure, these are older sporophores of Chondrostereum purpureum. In their juvenile days, they’d have been far more attractive.

Further round the trunk, we enter the sole territory of the Mensularia nodulosa.

Angling upwards, the slotted nature of the tube layers becomes very evident.

Down on one of the buttresses, this witches’ butter (Exidia plana) gets comfy amongst mosses. Note that it’s more likely to be this species of Exidia, as Exidia glandulosa is more often found on oak. To discern between the two however, you’d need to inspect some spores under the microscope.

Looking more closely one can appreciate (I guess…?) why it’s called witches’ butter.

And up on another limb, we have what is probably Bjerkandera adusta.

It seems to be ejoying the decay column from the pruning wound and general dysfunction.

There’s also some gilled sporophores in this one, which could potentially be Panellus stipticus, though they were too sparse and too small to see properly.

Massive limb failure of a mature oak pollard

Around a month ago, after a very long period of sustained hot and impossibly dry weather, I became alerted to the quite incredible failure of a single bole from a lapsed oak pollard. As can be seen in the images below, the failure I saw once I arrived at the site left me slightly speechless, though given the absurdly dry and hot weather over the weeks prior it was one that was not entirely unexpected.

According to residents who lived nearby, the failure occurred at around 19:00 in the evening, after a very warm and still morning and afternoon. The sound, it is alleged, was akin to (I quote) “a mass of scaffold collapsing”. Given the sheer size and weight of the bole, which is in itself larger than many trees, that isn’t all too farfetched of a description. Having heard lorries tear off moderately-sized ash limbs, which generates a sound almost like a gunshot, it’s not a sound one forgets quickly.

Certainly, the timing of the failure piques interest. It can be proposed that this failure was potentially in alignment with the phenomenon known as ‘summer branch drop’, as there had not been any other means of mechanical loading on this tree whatsoever in quite some weeks (ignoring the odd slight breeze). The failed area also showed no sign of rot. On the opposite side of the tree, on an old pruning wound, I saw a Laetiporus sulphureus fruiting body the year before, though the brown rot did not appear to have impacted upon this area whatsoever. Quite simply, it was as if the limb just slipped out of its socket.

Not the view you want to see every time you go and look at some lovely parkland trees…

From the side, we can appreciate just how major this faulure was.

A ‘clean’ tear, with the limb having completed severed all vascular contact with the trunk.

Standing underneath the bole, we can also observe a huge buttress root that may – to a degree – suggest just how much inherent mechanical loading the low trunk was being placed under.

Walking further around the southern side of the tree, perhaps the pronounced buttress root is worthy of even more recognition.

A closer view of the ‘socket’.

And from the other side of the tree, looking south into the park.