April 2016

Chairman’s Comments

We welcome Mrs Sue Bossom from Penybontfawr, Nr Oswestry as a new member.

The release last month of findings at the Bartlett Tree Research Laboratory (U. of Reading) that ash trees

grown in soil which had been enriched with charcoal were resistant to ash dieback (the NEW scientific

name for chalara dieback is not very catchy)- was the most intriguing news for tree enthusiasts for many

years. It follows the discovery that the most fertile natural growing mediums of all are found in the

Amazon rainforest where charcoal has been incorporated into the soil. The accepted theory is that the

native peoples discovered something fifteen hundred years ago that western agriculturalists never did, but

there is also the possibility that much of the charcoal was produced naturally in forest fires- although

charcoal is wood burnt in the absence of oxygen, in intense heat the amount of available oxygen is

significantly reduced resulting in the natural formation of charcoal.

When one thinks about it, it all seems quite logical. Trees consist mainly of carbon and charcoal is

virtually pure carbon so the plant roots are in an environment which is much more benign- there has been

so much attention in recent years to the degredation of soils under conventional farming practices of high

inputs of chemicals and artificial fertilisers. On the strength of the Amazonian discovery, charcoal was

incorporated into several acres of grassland here and the compost used in the nursery contains high-grade

charcoal fines.

A very progressive farming group have arranged to visit the farm on 27th April. Numbers are not definite

at present but if any members of STT would like to attend then I’ll try to make a few places available

(there is an STT visit anyway in July). It will doubtless be a pretty intense (-ive) discussion on the future

of silvopastoral agroforestry – Moccas Park is an ancient example of this- and farming in general and, in

this case at least, without the benefit of EU or government subsidy whatsoever. There are too few of us, as

a matter of independence and self-respect, who manage so to do.

Hope to see many of you at Moccas; we all but stand on the shoulders of giants and Moccas is a giant of a

managed landscape.

Peter Aspin

Our last talk: “How can a tree live for 5000 years?” by Dr Peter Thomas of Keele University (Tues 8th March)

Trees are long-lived and the slower a tree grows, the longer it lives. Peter showed us slides of the Marton Oak near

Congleton, large and hollow and at least 1000 years old, the Astbury Yew of 2000 years and the Fortingall Yew,

recognised to be at least 3000 years old, possibly up to 5000 years. Although the latter tree was only made up of the

remains of the outer part of the tree spreading around a circumference of 17 metres, these 'pieces of tree' were all

found to be genetically identical, hence the same tree. However, the tree species that appears to contain the oldest

trees in the world is the Bristlecone Pine (Pinus longaeva), found in Nevada, USA. Its oldest specimens have been

proven to be over 5000 years old. The oldest has been dated by the Rocky Mountain Tree Ring Research Lab at

5,066 years. (See www. rmtrr.org/oldlist.htm)

So how is it that some trees can live to this grand old age ? I suppose we humans could live to an impressively ripe

old age if we were not prone to catching diseases and we could fend off all ills and ailments. And so it is with trees.

Peter took us through the ways by which trees manage to survive by defending themselves against predators, insect

pests, fungal pathogens and the myriad of attacks they face to reduce their life chances. He showed us how, although

leaves may come and go and the heartwood rot away, the woody skeleton of the tree can survive the longest. Thus,

although a tree may be hollow in old age, it may still be healthy with many hundreds of years of its life left.

Peter took us through the different types of defences inherent in trees. Using a fascinating series of powerpoint

slides, we were able to look at a tree's external defences, how it defended its wood and its internal defensive 'walls'.

Prickles, spines and thorns on leaves or branches would prevent attacks by mammal predators. Time and again,

Peter told us that trees don't waste energy. They would only produce these deterrents on the susceptible parts of the

trees. So holly leaves higher up the tree would be prickle-free as predating animals would not be able to reach this

high. Hairs on young leaves make the leaves less palatable. They are also the softest and most nutritious leaves and

have less lignin in them. Thickened leaf margins, again such as on holly, will prevent caterpillars eating the leaves.

In some cases, animals are used by the tree to 'see off' less friendly wildlife. On acacias, ants will defend their tree

from competition by other insects. Some trees, such as Viburnum tinus, have 'pockets' on their leaves (called

'domatia'), in which live small animals. These will often be predators on aphids and some will eat fungal spores.

Another form of external defence is that of chemicals. Peter told us of the great diversity available to trees: caffeine,

tannins, curare, strychnine, taxol. These prevent animals preying on the tree. For example, curare taken in by

animals will slow down or even stop its heart. Each chemical has its own assistance that it can give to its tree.

Again, Peter repeated the important maxim that trees just do not waste energy. About 15% of the annual energy

production of an oak tree goes towards the production of tannins. The tree needs this valuable energy so it will only

make tannins when and where they are needed and so will produce them in earnest only when attacked (signalling to

other parts of the same tree and others using iasmates).. Another example he gave us was that of the aspen. Grown

on poor soils, aspens produce more tannins but on nitrogen-rich soils, less tannins are required. On poor soils it is

cheaper to defend the existing leaves using tannins; on richer soils it is cheaper to replace them if eaten. So the tree

is monitoring what is going on around it.

An example that Peter gave us in support of the last statement was that appropriate to trees living in a typical forest

where the herbivory is high. In such an environment, 7.8% of the annual growth of the trees is eaten. Outside these

environments, being under less severe attack, the trees do not need to waste their energies in producing the

mechanics and substances for their defence.

Defending its wood is also of great importance if a tree is going to be long-lived. When trees seal themselves around

a wound with resins or gums this is usually a short-term method of warding off attacks by fungal pathogens or

insects while the tree grows new callus tussue over the wound. The wound never disappears, as a cut on the human

body eventually does after healing, it is merely covered over. The tree uses resins, gums and latex to do this

depending on the species. Resins are common in conifers and some hardwood deciduous species. They are oil-

based, whereas gums are composed mostly of polysaccharides in deciduous hardwoods. Latex is a milky mixture of

resins, gums, oils and proteins. We are more aware of it in the Rubber Tree (Hevea brasiliensis) and the Chickle (or

Chewing-Gum) Tree (Manilkera zapota).

The notion of 'internal defensive walls' is relatively new, coming from the work of Alex Shigo in New England.

Damage within a tree is confined by 'walls' grown by the tree. Within this 'barrier zone' any damage is contained and

is less likely to spread. In the centre of a tree, where rot has started, this rot can be held at bay by the barrier walls

and restricted from spreading into the living tissue beneath the bark. Hence, the tree may become hollow but, as all

the living tissue is still intact, its growth will not be impaired. Peter asked us if we thought hollowness would

weaken the tree. He referred us to the work of Claus Mattheck, a German physiologist turned tree botanist who uses

his knowledge of physics to interpret occurrences within trees. Mattheck has made a particularly fascinating

discovery which requires a little maths to explain. Please bear with me..... Take a hollow tree. Measure the radius of

its trunk (r). Now, if possible, measure the thickness of the outer part of the tree from the hollow inside to the outer

edge of the bark (t). The expression t/r (thickness divided by radius) will gave an important fraction (or decimal if

you've done the division on a calculator). If this faction is less than one third (0.33), the stem is likely to break. Over

one third, and even though the tree is hollow, you have a safe tree. It is more likely that strong winds will be able to

'snap' the trunk of a solid tree than if the tree is hollow. Hollowness can give greater flexing of the trunk to enable

the tree to resist strong winds. And this is where Peter led up to his pièce de résistance – during the gales of October

1987 (and Peter showed us Michael Fish's famous weather forecast and the events which followed on movie film),

15 million trees were blown over. The hollow trees still stood !

This was an exceptionally interesting talk illustrated with superb slides to back up everything Peter told us about.

Those members who couldn't make it for this particular event really missed something special. The talk generated a

number of questions which Peter ably answered not being deterred by a single one. We thank him immensely for

coming from Keele on this evening specially to talk to us.

John Tuer

N.B. I have written about Peter's talk in some detail for this Newsletter as a number of members present asked me if

I would. They felt that there was so much to take in that they would welcome some of the detail being written down

for them to go through again. I hope I have not been too long-winded ! I must add that I have shown Peter what I

have written and he has been good enough to check it for me and suggest just a few changes. Thank you Peter. J.T.

Editor’s note. Neither John nor I know what iasmates are; you will be informed as soon as we do!

Our next month's event: Saturday, 9th April.

A visit to the tree of the Moccas Estate in Herefordshire (Not to Ashwoods as previously stated. Peter has

already told you about the change of visit.)

Please allow me to whet your appetite for this visit..... I have taken the following from “The Diary of the Reverend

Francis Kilvert. Volume III 1874-1879”. This entry is for Saturday, 22nd April 1876 (Almost 140 years ago to the

week !)

“We came tumbling and plunging down the steep hillside of Moccas Park, slipping, tearing and sliding through oak

and birch and fallow wood of which there seemed to be underfoot an accumulation of several feet, the gathering

ruin and decay probably of centuries. As we came down the lower slopes of the wooded hillside into the glades of

the park the herds of deer were moving under the brown oaks and the brilliant green hawthorns and we came upon

the tallest largest stateliest ash I ever saw and what seemed at first in the dusk to be a great ruined grey tower, but

which proved to be the vast ruin of the king oak of Moccas Park, hollow and broken but still alive and vigorous in

parts and actually pushing out new shoots and branches. That tree may be 2000 years old. It measured roughly 33

feet round by arm stretching.

I fear those grey old men of Moccas, those grey, gnarled, low-browed, knock-kneed, bowed, bent, huge, strange,

long-armed, deformed, hunchbacked misshapen oak men that stand waiting and watching century after century

biding God's time with both feet in the grave and yet tiring down and seeing out generation after generation, with

such tales to tell, as when they whisper them to each other in the midsummer nights, make the silver birches weep

and the poplars and aspens shiver and the long ears of the hares and rabbits stand on end. No human hand set those

oaks. They are 'the trees which the Lord hath planted'. They look as if they had been at the beginning and making of

the world, and they will probably see its end.”

Our member, Tony Hackett, has already visited Moccas and he tells me that it's as if those old oaks are watching

you. “Their eyes are following you wherever you go,” he says, “and there are dozens of them.” Tony will lead us

around the paths of this estate to see these magnificent ancient trees.

This is a private estate, not open to the public. The only people usually allowed a visit are those following up some

research into these trees. We are privileged in being allowed to visit and being allowed to have a permit for this. In

recognition of this, we do have to abide by certain conditions. For example, we must follow the “Country Code”, we

are only allowed to take photographs for our own, not commercial, use, and we must each individually sign in and

out so that the owners know exactly who is in the Park at any one time. These are small requirements against being

allowed in to see these wonderful trees and I hope members will join us at what is unlikely to be a visit we can

easily repeat.

We shall meet on Saturday, 9th April at 2.00pm in the car park opposite the main gate to the Moccas deer park. Let

me explain how you get there:-

Take the A49 south out of Shrewsbury and go to Ludlow and on to Leominster. When you reach the roundabout on

the outskirts of Leominster where the by-pass starts, don't go onto the by-pass but go straight ahead. Now continue

on this main town road. It will turn left, then right (with a barometer shop on the corner), then turn left again, and

bring you to traffic lights. Take the road right here (the A44) probably signed to Brecon. After about 6 miles, the

A44 turns right at a junction. You must take the road left, the A4112. After another 6 miles or so, you will cross the

A480. Continue on the A4112 to a T-junction where the A4112 turns left. In less than a mile, the road meets the

A438 at a T-junction. Go left onto the section of the A438, signposted Hereford. Now, in just under 3 miles, look for

a right hand turn to Bredwardine. Once in Bredwardine, you will reach a T-junction with the B4352 crossing your

from right to left. Turn left. Moccass is just down this road in 2-3 miles. Look for the Park Lodge on your left and

enter here to reach the car park. We must assemble here to sign in at the lodge. For those of you with SatNavs, the

postcode of Moccas Court is HR2 9LH. Or Grid Reference SO358435.

This drive has taken you through most beautiful Herefordshire countryside. It is well worth the drive from

Shropshire even though it is longer than many of our visits. Entry will be at no cost as your committee will be

making a donation to the local Moccas church instead.

John Tuer

Tree Planting

Two planting sessions in March ? I was down on my knees asking for your help and you responded in such good

numbers. My huge thanks. We planted 500 hedgerow trees at The Hurst in about 2 hours. They are so grateful to us

for doing this and have made a contribution towards canes and rabbit guards. This hedge is alongside an old

mediaeval trackway which was almost lost in the landscape, the hedge now giving this old track more prominence. I

am writing this just before our second planting. More about that in the next Newsletter.

But we do have another planting for the AONB on Thursday 9th April. I shall be going to this. If anyone wishes

to join me, you will be more than welcome. Just let me know and I can give you details (01952 727642). Sorry that

all our plantings this season have been at the end of the season. This has been something out of my control. But,

believe me, I am truly grateful to all of you who have joined me.