The Many Species of Coed Y Brenin
Corsican Pine, pinus nigra or Black Pine
This species, a two needle pine similar to Scots pine, was introduced to Britain in the mid eighteenth century, intended for use as railway sleepers and pit props. Though not naturally durable, and considered inferior to Scots pine, it takes preservatives well and is used for general building work, telegraph poles and for processing into plywood.
It was favoured over Scots pine for forestry though, interestingly, according to the Scottish Government, Corsican pine is only really suitable as a crop in the south and eastern side of Britain where there is lower summer rainfall and higher levels of sunshine.
Interesting then that several coupes of Corsican pine were planted during the middle phase of establishing Coed Y Brenin in 1942, just to the east of us. They seemed to have grown quite well at first but by the time we arrived in the mid 1980s, some were showing signs of a problem with browning of the needles towards the top of the tree.
above: the thin stand of Corsican pine lining our eastern horizon. Thinner every year as more of the dead and dying are cut out.
Not long after that, in the early nineties the whole of the eastern hillside was clear felled, using the Forestry Commission's first harvester, a huge, 80 ton beast of a machine that had to work up and down slope, leaving tremendous wheel ruts and actually gouging out some trees like hazel that were lower down towards the roadside. I collected one, a large hazel root ball which nearly filled the back of our trusty Reliant Robin (a Supervan Mark III) and replanted it (the hazel, not the Supervan), at our place where it recovered quickly and is now a substantial tree.
Incidentally, that early harvester was at the in-between stage of the digital age and broke down regularly. A large polytunnel had to be erected over it wherever it happened to die and a specialist was flown in by helicopter to open up the boxes that contained racks of circuit boards with integrated circuits (chips) soldered to them. Wearing a mask to avoid contaminating them, they would swap boards until it started working again.
For some reason, a thin strip of Corsican pine was left, opposite our gate, running roughly north-south and its been interesting watching from our kitchen window how these 80 year old trees behave in strong winds.
The topology of the landscape has, of course, a considerable impact on the flow of air. There's a large triangular chunk of land, very roughly 20 miles on each side, with a point more or less at Dolgellau and the others at Trawsfynydd and Bala1. The Afon Union, the largest tributary of the Afon Mawddach, defines the Dolgellau-Bala side and the Afon Mawddach begins the Dolgellau-Trawsfynydd side.
This huge water catchment is generally mountainous from the Trawsfynydd-Bala side which drains into Llyn Tegid at Bala, gradually lowering towards Dolgellau. The Afon Mawddach coils down from a huge upland bog of some 9,000 acres on the highlands, picking up fast flowing tributaries along the way that carve their way through steep sided valleys and gorges with many a waterfall before the river enters its mature stage, just after Ganllwyd, in a glacially carved, U shaped valley running roughly north-east and throwing off ox bow lakes as it meanders along. It joins with the Afon Union between Dolgellau and Llanelltyd, becoming a tidal estuary running roughly due west.
above: Pistyll Cain on the Afon Cain, one of the tributaries of the Afon Mawddach, and typical in its rocky, gorge like course, deeply carved over time. The name Pistyll, rather than Rhaedr for the falls, suggests a spout of water. It also makes me wonder about the English word piss…
So the predominant westerly winds come rushing straight up the estuary until, near Dolgellau, it meets a hill and splits rushing on along both the Afon Union and the mature Afon Mawddach. Then there's the great fist of rock that is Mynydd Penrhos that channels much of the wind up the Afon Wen fault, a remarkably steep sided and straight valley. A small hanging valley captures something of that blast and steers it up our way and straight into the Corsican pine along the ridge.
We have watched these trees in the most intense gales, including a hurricane force 12 in the Irish Sea, that saw the Llŷn peninsula register gusts of over 100 miles an hour, waiting for them to snap or blow over, in vain! The tops begin to curve away from the wind and the curve works its way down the trunk as the wind speed increases, almost reaching the ground, until the 80 or so feet (25 metres) of the tree describes a beautiful curve, not unlike the curve of a bow, the angle of the bend increasing towards the crown which ends up parallel to the ground.
Pines are renowned for their flexibility; a Douglas Fir in a similar situation would simply blow over or snap. More recently though, we have observed a change and the trees have taken on a definite rocking action, backwards and forwards and seem less inclined to bend in the wind.
I mentioned that we noticed signs of a problem of some sort appearing in a few trees sometime around the end of the eighties and gradually spreading to others and worsening. It was unclear whether this was a disease or a change in conditions. We have experienced more extremes in weather in the last twenty or thirty years, including sustained wet periods, when the ground remains saturated for months at a time, to long dry spells and a defintie soil moisture deficit2. When I raised this with Forestry Commission foresters or later, Natural Resources Wales (NRW) operations managers, they had no answer and showed little interest.
As the condition of the pines worsened and began to die, NRW took action, mainly because they are close to a single track Council maintained road and contractors were employed to selective fell some of the dead or dying trees. They usually fell about three at a time and return several times a year. They are extremely skilful and really know what they're doing, cutting a decent hinge and using big wedges to drop the tree exactly where they want it. There's hardly any space for the trees to fall and its a definite art to get them down without leaving them hanging up on other trees or across the road; and these are big trees remember. Its also dangerous work as some of the trees that have died have begun to rot and large chunks break off as they fall and the chunks fall straight down.
Why this approach has been chosen, returning regularly to fell just a few dead or dying trees each time, rather than dropping the whole lot at once, which would be much easier and cheaper, is another of those small mysteries of Coed Y Brenin.
above: 80 foot/25metre Corsican pine felled and left as habitat. There are some self seeded oak doing well in here as well. The green conifers are mostly the prolific western hemlock, self seeded more or less throughout the forest and destined to take over from everything else unless phyophthora pluvialis gets it first…
The timber is just left where it falls, the trunks lying up to three deep now in some places, criss-crossed over each other. When I asked an operations manager what was going to happen to them and wasn't it a bit of a fire risk to just leave them there, (the resinous pines burn extremely well), I was told it was “for habitat”. This is a great catch-all and is similar to the Forestry Commission's “do nothing” approach, allowing for a turning of the blind eye to all sorts of stuff! The next question is obviously, habitat for what, honey fungus? And lo! There was a good outbreak of that parasitic fungi in oak felled in the same area and left there for similar reasons. Ah well. If NRW would reinstate the ticket for locals to clear dead wood, I'd have had that oak out long before it was a problem!
After the major clear felling of the northern parts of Mynydd Penrhos, Bryn Coch and Bryn Merllyn in the mid-eighties, several areas were replanted with Corsican pine but these seem to have suffered right from the start. A coupe just to the west of us was planted on what had been a bog.
above: Corsican pine planted on the edge of a bog in the mid 1980s, mostly dead or dying.
In a fairly typical example of the Forestry Commission's left hand not knowing what the right hand was doing, we were contracted to clear the bog of conifers which we duly did and a very good job we did too, it being on our own watershed3 only to then find a different gang replanting parts of it with conifers, including Corsican pine...duh!
A block of Sitka spruce planted at the lower, wetter end of the bog, so in pretty soft ground, were fairly easy for the wind to blow over. The Corsican pine was given a slightly drier patch but have really struggled. Similarly with another coupe further to the west, this time on a pretty steep hillside, so you'd think quite well drained.
above: more Corsican pine, here dying on a fair slope that might be expected to be reasonably well drained, though note the abundant mosses.
However, here, where a harvester has cleared an access route up into the stand, you can observe rushes growing in the ruts, standing water and a very dark, peaty soil. There are even some patches of sphagnum moss still surviving in amongst other mosses, suggesting that, despite the slope4 this was at one time very wet land. The name Penrhos in Mynydd Penrhos is a bit of a give away, pen being top and rhos can be moor or marshland5.
above: Corsican pine struggling to either side of rushes and standing water in the wheel ruts of the harvester tracks; Mynydd Penrhos lives up to its name.
above: a closer look under the Corsican pines shows a patch of sphagnum moss (the greener green covering the right mid and back ground) surviving on this evidently still wet, sloping site.
Both of these stands of Corsican pine are about 35 years old yet have struggled to reach 20 feet in height and some are clearly dying or have already died and been easily overtopped by self-seeded Western Hemlock. My weather records show a ten year average annual rainfall here of 2.3 metres; perhaps the Forestry Commission should have taken notice of the Scottish Government's recommendations and restricted Corsican pine to the drier south east.
Many thanks for reading. Please feel free to leave comments to help steer this ship as it merrily flies before the wind! Or not…
Bala, like some other place names in Cymru, is actually known as Y Bala, The Bala. Similarly, Y Ganllwyd, Y Bermo. Gwynedd Archaeological Trust suggest the name Y Bala probably comes from something like The Outlet, as the Dee flows out from the Llyn Tegid (Bala Lake).
A soil moisture deficit is when the soil no longer holds sufficient water for maximum growth of the plants rooted in it. In extreme cases, which are becoming common, shallow rooted plants will die. Trees, with deeper roots, able to tap into deeper water resources, will tend to survive for longer.
If you want to get a job done really well, its probably best to give the work to people who will benefit directly from the quality of the work they do. By removing conifers from stream sides and bogs, we were improving the storage capacity and the water quality of our own watershed- that’s the water we drink so obviously its in our interests to do an excellent job.
I intend to write a piece about the peat bogs of Mynydd Penrhos that were drained by the Forestry Commission prior to planting the conifers as it is quite a story in itself. I'll just mention here that I was amazed recently when pushing through a previously impassable thicket on a fairly steep slope to find sphagnum moss carpeting the ground beneath. When considering peat formation we tend to hear about blanket bogs or raised bogs but little is said about wet slopes and what can go on there.
Geiriadur Coleg Prifysgol Cymru. University College of Wales Dictionary.