Gleann Ardbhair and its wildlife

July 14th 2020

Gleann Ardbhair and its wildlife

One of the more extensive areas of woodland in Assynt is scattered along its north coast, between Oldany and Unapool.  In the eastern half of this area a wooded glen stretches in a south-easterly direction for some 3km, from Loch Ardbhair to Airigh Arainn, an old sheiling north of Sail Ghorm on Quinag (NC1733-1932).  This is Gleann Ardbhair, the upper part of which we explored on 5th May 2020, when the downy birches Betula pubescens which dominate the woodland were coming into fresh green leaf.

The day started cloudy, but the clouds cleared and it warmed up later.  We started at the road bridge (photo 1) and slowly made our way upstream, zig-zagging across the watercourse and occasionally having to climb up the side of the glen to by-pass vertical crags.

Holly and Ivy

Our first stop was in a pinch with vertical crags above a pool on the north bank, draped in ivy Hedera helix (photo 2), and with solitary trees of holly Ilex aquifolium and hazel Corylus avellana, safe from browsing.  Stone bramble Rubus saxatilis was hanging from a ledge (photo 3) and the shiny fronds of hard shield-fern Polystichum aculeatum sprang from a crevice (photo 4).  A little further up, above an especially bouldery section of the watercourse (photo 5), there were two large clumps of ramsons or wild garlic Allium ursinum on the south side (photo 6).  The geological map shows an ultramafic dyke running up the glen, which may well account for the presence of these and other less common species.

Crags in the middle part of Gleann Ardbhair bore a few aspens Populus tremula, well out of reach of browsers and not yet in leaf (photo 7).  Lunch was taken high on the north bank, surrounded by clumps of primroses Primula vulgaris, which seem to have had an exceptional flowering season, perhaps held back by cold wet weather earlier in the year.  Common dog-violets Viola riviniana were also in full flower (photo 8) and the ground flora also included sanicle Sanicula europaea and wild strawberry Fragaria vesca. .

Dropping back down into the valley, we began to find further signs of base-enrichment in the water draining off the rocks, with the tiny leaves of alpine meadow-rue Thalictrum alpinum (photo 9), black bog-rush Schoenus nigricansand yellow saxifrage Saxifraga aizoides.  In these damp areas the primroses were accompanied by beech fern Phegopteris connectilis (photo 10).

Deer exclosure

About three-quarters of the way up the wooded part of the glen we reached the boundary fence of a deer-exclosure.  Several exclosures were installed a few years ago to promote natural regeneration of the Ardvar woodlands.  They have been very successful, with numerous saplings of downy birch, rowan Sorbus aucuparia and willows Salix spp. springing up.

Climbing the north bank to reach the hand gate into this exclosure, we came across a small burn with pools, from which I took a sample of the aquatic vegetation.  This was processed later and sent down to David Williamson in Leicestershire to examine for desmid algae, proving quite productive (see elsewhere).

Dropping down again to the valley floor, we came across a very obvious outcrop of the dark rock of the ultramafic dyke (photo 11), with more hard shield-fern, maidenhair spleenwort Asplenium trichomanes and wild thyme Thymus polytrichus.  However the best find of the day, in a crevice, was mountain melick Melica nutans, an uncommon and very elegant grass which is associated with such dykes (photo 12).  Nearby there was a small amount of northern bedstraw Galium boreale on the crag, another indicator of base-richness.

Sheiling

A little higher up, the valley begins to widen out into the former sheiling Airigh Arainn (kidney sheiling, from its shape; photo 13), with a high crag on the north side (photo 14).  Both the geological map and vegetation indicate that the ultramafic dyke has petered out at this point, but the crag still carries quite a varied flora, with shelves of bluebellsHyacinthoides non-scriptus just coming into flower.  There was still some base-enrichment in the valley, perhaps from high on Quinag, where the burn originates, since we found both water avens Geum rivale and globe-flower Trollius europaeus along its course (photo 15).

A long tea break was taken in warm sunshine beside the deer fence that crosses the grassy floor of the sheiling, with magnificent views of the buttress of Sail Ghorm above us (photo 16).  We then slogged along the top fence of the exclosure, out through the gate and cross country to the north, reaching the unusually quiet road quite a bit later, near the track to Rientraid, with stops to admire the views over Eddrachillis Bay.

Animal life was not plentiful during our six hours in Gleann Ardbhair, but we did see badger snuffle-holes and heard a predictable range of birds, including chaffinch, cuckoo, great tit, meadow pipit, stonechat, willow warbler andwren.  We had four brief sightings of common lizards, a frog, and small brown trout in the burn at the sheiling.  Invertebrates included peacock butterfly, drinker moth larva, emperor moth cocoon and adult brown silver-lines moth, also a heath bumblebee Bombus jonellus and a common carder bee B. pascuorum.

Altogether an excellent day out for the time of the year; quite strenuous at times, but with stunning views of the woodland, hills and coast.

 

Ian M. Evans and Gwen Richards

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