Oak. Every Tree Tells a Story.

The Many Species of Coed Y Brenin

The Many Species of Coed Y Brenin

Oak. Every Tree Tells a Story.

[I have split this piece into two halves as it came out rather picture heavy (every picture tells a story). The second half will follow almost immediately]

above: Penrhos in 1987 with two large, open grown oaks in the centre. The one behind the barn showing the classic dense, hemispherical crown. The one in front is already slightly more open. Both feature in later pictures below.

On the seminal Advanced Permaculture Design Course I attended at Ragman's Lane Farm in 1990 (or was it 1991?) led by Bill Mollison, co-originator of Permaculture Design, Bill spoke of how life evolves in flow. To be more precise, life evolves in the flow of energy and nutrients and each species preserves records of those flows in their various forms.

Trees present good examples of this and we can read their individual histories through studying their unique forms. From seed they grow under the influence of gravity, reaching towards light, conform to predominant winds, respond to increases or decreases in the availability of water and nutrients, adapt to damage and so on.

As well as the shape of the tree providing a record of its experiences in flow, the tree rings within can show with accuracy the variations of growth each year and through both simple measurement and precise, scientific analysis can inform us of their age, variation in growth each year, temperature changes, the presence of isotopes, amount of rainfall and the like.

In such a way, the older oak in Coed Y Brenin preserve a record that extends back before the coming of the plantation, informs us of their adaptation to being surrounded by conifers and in some cases, their responses to increases in light following clear felling around them.

Oak is prevalent in the Britain as two species, quercus robur, English or pedunculate oak (because the acorns grow on stalks or 'peduncules') and quercus petraea, Welsh or sessile oak (the acorns have no stalks), though the species hybridise readily. The branches of the Welsh oak are often more twisted and bent than the English oak and was favoured by shipbuilders particularly for use as knees, a wooden support brace with its angular bend designed to fasten ship parts together. Many thousands of these were required to build the British navy of the Napoleonic era.

An open grown oak will respond to the availability of light by producing wide spreading branches all round and upward and can result in a crown of an almost perfect hemisphere with the leaves concentrated at the very tips of the branches. When we first arrived here at Penrhos, our largest oak had such a form and once fenced off from livestock, its lower branches extended almost to the ground. Dipping under these branches you entered a shaded, protected dome with excellent acoustics, making it an ideal place to teach; its no wonder that historical and legendary teachers and prophets would often address their gatherings from under trees.

As the oak ages and the branches continue to grow outward and upward, the lower branches have to become longer and longer to stay in the light and a point is reached where they will be shaded out by branches above or they make break. On our oak, lower branches were about 18 inches (45cms) in diameter at the trunk and got to about 40 feet in length (12 metres) before this occurred.

above: the oak behind the barn in 1999. Some of the lower branches have been shaded out and died back- you can see a cut on the left where I have removed a “widow maker”. Some of the lower branches have probably been removed in the past to leave a clean trunk up to about 10 feet (3 metres). Note the widely radiating branches and the dense shade produced by the tight, closed canopy of leaves.

A word about these branches. At one time our temporary bedroom was close to the trunk of this oak. We'd used double glazed sliding door panels on their sides at the end and on both sides of the narrow room, just big enough to squeeze a bed into the end. The panoramic view out was roofed by the radiating lower branches of our oak and early one morning we awoke to a major storm with extremely strong winds. We opened the curtains and sat back in bed to watch, thinking that if the oak comes down on us, we probably won't know about it!

The leafy ends of each branch described circles which increased in diameter with the strength of the wind. This movement was transferred down the forty foot length of each branch, reducing as it reached the trunk and throughout the storm the trunk did not move visibly. The branches themselves however writhed like snakes! How can a foot thick piece of wood be so flexible? There is no way that anything made by humans could possible mimic the almost unbelievable strength of these limbs. This flexibility in strong winds leads to a common occurrance on oak, that of splitting of the branches. Anyone who has used an axe to split oak logs for firewood will know how easy it can be and in the past, when an oak was felled or windblown, the butts were often split into stakes, the heartwood lasting up to eighty years in the ground.

above: the oak in 2010.as the main branches continue to lengthen, the spaces between them at the crown increase, allowing more light to pass through, striking the branches and trunk below and also the floor.

Also, as the tree ages, the perfect crown begins to break up into individual clusters of leaves, very like a perfect cauliflower crown left to grow on - the individual florets separate out with spaces around them. In the tree, this allows more light to penetrate through the crown and strike the branches below which triggers dormant buds and leaf and twig growth. So an ageing oak will have many more twigs and leaves growing on its branches and trunk, sometimes forming a lower crown. As ageing progresses, the upper parts of individual branches will begin to die giving a 'stag's head' appearance to the tree.

above: the second oak from the first picture, this one taken today, 2024. The crown has opened, light has hit the branches and trunk below, triggering dormant buds to grow. The die back of some of the branches begins the “stag’s head” appearance.

So that's roughly the story of the development of the form of an open grown oak. To go on to the oak of Coed Y Brenin, some background is needed. Using old, large scale ordnance survey maps from the late 1800's, (6 inches to one mile or 1:10,560 and even 24 inches to one mile or 1:2640), which show every wall and almost every tree, it is possible to begin to imagine what the landscape of Mynydd Penrhos and beyond might have looked like in the time of the tyddynwyr (the smallholders) before the plantation replaced them. The ruins of their dwellings, often originally no more than hovels, can be found along with the fallen walls which they laboured long to build to enclose their few, small fields.

above: Ordnance Survey map from 1880 at a scale of 1:2640 showing two of the tyddynnod (smallholders dwellings) on Mynydd Penrhos, walls, footpaths (no roads yet at this time), a few cleared fields surrounded by rough grazing with areas of fridd, woodland, a marsh (peat bog) and several field clearance cairns in or on the edges of the fields, surmounted by trees.

The landscape at the time, before the coming of the plantation, would have been quite varied, ranging from the neatly walled, small fields, through areas of bog, steep slopes, probably wooded with hazel or more diversely as ffridd (you can find more information about fridd on my web site, here) as well as areas of managed coppice for fuel wood and hurdles and of course, hedges of mixed native species which were laid, including oak.

One of the simplest forms of land improvement which required only labour (only..), was the clearance of stones from land and the creation of fields through the building of walls. This was often included in the tenancy agreement as a requirement for so many hours a week, The work was usually carried out by the wife and children of the tyddynwr. The stones were piled in heaps and their number and size here on Mynydd Penrhos gives some indication of the rough, boulder strewn landscape the tyddynwyr began with.

The numerous field clearance cairns would have been quite obvious as mounds in the landscape and it was often on these that oaks became established, as marked on the old maps. The maps also depict individual, open grown trees in some places, hence growing at first in full light with low, wide spreading branches. However, when the plantation was begun, little thought was given to them and conifers were planted almost up to their trunks¹.

above: 1988. A field clearance cairn with oaks struggling in dense shade from Sitka and Norway spruce planted in 1967. The spreading branches tell us that previously they grew in the open with plenty of light. The size of the stone pile indicates the amount of effort that went into creating the fields in the first place².

In the 1980's, much of the plantation was unmanaged and in a prolonged, dense, thicket stage, almost impenetrable. Where there were old walls or hedges, there was a very thin strip of sky above where the branches of the conifers on either side hadn't quite met. Using the old maps, I was able to follow these old wall and hedge lines and found the hedge remnants of dead and dying oak and hazel struggling in the dense shade, reaching up ever higher towards the narrowing strip of light.

Following the old wall lines and finding in the midst of a dense stand of conifers, a field clearance cairn surmounted by a ring of oaks with the feel of a grove, was an eerie experience. It was plain to see from their forms a similar story had unfolded as the conifers grew up around them and cast more and more shade. The lower branches of the oaks were shaded out and died and they grew taller and taller, racing for the diminishing light. Not all of them survived.

above: the same cairn in 2023. Unusually, the stands of conifers have been thinned, allowing more light in, too late for some of the oak. Note how the lower branches have died during the lengthy time of shade and the oaks have had to grow tall and thin to reach for the light.

The second half of this piece on the Oak of Coed Y Brenin will follow almost immediately but feel free to comment on this half here if you like.

1. A good friend of mine took me into a young plantation once, many years ago, managed by a private forestry company and showed me a huge open grown oak with wide spreading branches that had been ring-barked, killed deliberately by the forestry company, with the regular rows of conifers continuing between the dead branches right up to the trunk.

2. When I first started finding these cairns in the forest I thought at first, with great excitement, that they might be pre-historic burial mounds. However, after reading more about it and talking with people who knew more than me, (thank you Andrew), it became clear that they were in fact what are known as field clearance cairns with some rectangular ones with the long side facing the sun, being peat drying mounds.

However, I still think that if I was back there in the past and about to begin clearing a piece of land of boulders, rocks and stones to make a field, I would have to make a decision as to where to dump all the stuff. Obviously convenience would be a major factor (the early tyddynwyr would probably have been too poor to keep a horse or pony, so stones would have to be moved by hand) but if there was already a pile of stones, say a prehistoric burial mound, then I may well have decided to just add to that existing pile. Who knows, without having a look?