Clachtoll Peat Track: a suite of evergreens

March 28th 2020

Clachtoll Peat Track: a suite of evergreens

We have been snatching days out this winter between a series of storms, named or un-named.  Another such day was on 13th February 2020, when we walked to the end of the Clachtoll Peat track and beyond (NC0427-0728).  We parked off the road and set off eastwards along the grassy track.  The sun came out at times, but puddles on the track were still iced over (photo 1).  First stop, for a hot drink, was on the stones of a ruin, probably a fank, overlooking the small lochan at Airigh Bheag, where one of very few birds encountered all day, a wren, was calling in tall heather on the far side of the valley.

Ivy-covered crag

As we turned the corner the imposing face of Creag nan Cruineachd (NC065278) came into view (photo 2).  At its southern end, a wedge of darker rock is clothed in a magnificent spread of ivy Hedera helix, which we went over to inspect (photo 3).  This is essentially a plant of crags in Assynt, rather than trees, since it is relished by browsers.  Its several trunks, some 10+cm in diameter, emerge from a crevice between two different kinds of rock (photo 4) and the root system must be very extensive to support so much ‘top hamper’. It is difficult to estimate the age of such a veteran climber, but probably well over a century.

The darker rock is part of a mafic dyke shown on the geological map, and it was typically producing some kind of calcareous deposit, rather like tufa, which is oddly inimical to growth of either lichens or bryophytes (photo 5).

On a grassy shelf below the crag, Gwen spotted the wet remains of a pellet, probably that of a tawny owl (photo 6), which was gathered up and later yielded the skulls of two field voles, standard fare, and the tiny lower jaws of a pygmy shrew (photo 7), the latter just 9.5mm long.  There was also a fox scat nearby.

To our north, after we returned to the track and continued past the crag and up the hill, was the extensive grassy sheiling of Clais nan Cruineachd (photo 8), with its old boundary dykes and a sheep fank at its eastern corner.  The track then levels out alongside two very striking ridges of pock-marked rock seamed with fissures (photo 9), which are part of the linear outcrop of an ultra-mafic dyke cutting through the local Lewisian gneiss (NC070281).

Juniper galore

This is where we noticed our first juniper, lying flat to the surface of the outcrop (photo 10).  Assynt junipers all belong to the prostrate sub-species Juniperus communis nana, which is a feature of dwarf-shrub heaths in western Scotland, with outliers in the Lake District, north Wales and the west of Ireland.  The other, upright, sub-species, Juniperus communis communis, with a profile like a shuttlecock, is mostly found south-east of the Great Glen in Scotland.  Along the north coast of Sutherland, it begins to appear in Strath Naver, by the mouth of which, at Invernaver, there is a large population of a puzzling intermediate form.

Prostrate juniper is particularly susceptible to burning and grazing and was probably once much more widespread.  It has become restricted in Assynt, and elsewhere in West Sutherland, to areas which widespread burning in the past (and present) has not reached, such as crags, and islands and peninsulas in lochs.  Inspection of this first patch revealed numerous unripe berries (photo 11), the pointed bud galls caused by the midge Oligotrophus panteli (photo 12) and black spots on the leaves formed by the fruiting bodies or apothecia of the ascomycete fungus Lophodermium juniperinum.

Leaving the end of the peat track we then made our way eastwards across very broken ground that is probably the product of peat cutting, to pick up the exit burn from the first of three un-named lochans (NC075280).  Here the prostrate juniper became more and more frequent, with mature individuals with thick writhing trunks on outcrops (photo 13) and seedlings of all ages in the wet heath.

An outcrop at the eastern end of the lochan was a good place for lunch (photo 14).  Around the rocks at our feet the juniper was intermixed with leathery-leaved plants of bearberry Arctostaphylos uva-ursi, another evergreen shrub that is very susceptible to burning (photo 15).

The lochan was obviously quite shallow, since it contained a thin bed of last year’s stems of common reed Phragmites australis (photo 16).  It was completely frozen over, and some of the reed stems bore buttons of ice where water levels had changed (photo 17).  Around its edges some peripheral branches of juniper were actually under the ice, something we have never before seen (photo 18).

Great fen sedge

After lunch, our attention was caught by a boggy lochan some 200m to the north-east (NC077281).  There was, again, a thin bed of common reeds, but amongst them two areas of a more substantial evergreen emergent aquatic (photo 19).  These proved, on closer inspection, to be beds of great fen sedge Cladium mariscus, whose leaves are armoured with razor-like rows of teeth, presumably to discourage grazing.  Great fen sedge was recorded in the Flora of Assynt (2002) from just 11 tetrads in the parish, and is described as  ‘Sparsely distributed in, or adjacent to, a few of the more base-rich lochs, where it makes good stands in sheltered bays’.  It was featured in an article on Loch Uidh na Geadaig posted on 16th December 2018.

I had no recollection of visiting this lochan, and found indeed that it had been recorded solo by Pat on 12th July 1996, when I was on my way cross-country to Cnoc Daimh, further to the east.  My notes for that day record that I skirted the substantial Loch an Aon Aite (loch of the country of the juniper); this whole area, north to Loch Poll Dhaidh (NC0729), is home to the largest population of prostrate juniper in West Sutherland.

After which, comparative, excitement, we made our way back along crags draped with yet more juniper (photo 20), to the end of the Clachtoll peat track and back along it, in the sun, to the car.

 

Ian Evans and Gwen Richards

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