Guest blog: Quinag’s trees get ready for spring
From aspen to wych elm... Local naturalist Ian Evans takes a close look at some of Quinag's native trees
Woodland as such is now sparse on Quinag. However, Torr a’Ghamhna and the catchment of the Allt a’Ghamhna on the northern flanks of the hill do support a good selection of the trees native to Assynt. At this time of year they are just stirring into new life and provide a reminder that spring is on its way. Each species has stories to tell, often of other forms of life dependent on them.
Most abundant is downy birch, the only large birch found in the north-west, with upright branches and trunks that are darkened at the base, but not rugged and fissured as in silver birch. From a distance, the twiggy canopy is a unique shade of reddish purple throughout the winter, and when the fresh green leaves break, they are seen to be rounded and evenly toothed. Occasional trees are host to the odd twiggy growths known as witches’ brooms, which in sheltered places can grow to over a metre in diameter. They are often described as being fungal in origin, but no-one is certain what causes them.
Scattered through the birch woodland, but also ascending much higher up the hill, as solitary trees on crags, is rowan. This member of the rose family is known for its conspicuous flat-topped clusters of white flowers and autumn crops of red berries, which provide food for thrushes and other birds. The crop on just one relatively small local tree was estimated at 44,800 berries, with a weight of 16kg. Rowan twigs provide a suitable substrate for a variety of pale grey beard and other fruticose lichens of the genera Usnea and Ramalina, with a host of other crustose and foliose species on the trunks.
Almost always found clinging to steep crags, because of its susceptibility to browsing by deer, is our one local member of the poplar family, aspen. A fine selection of mature trees, with smooth olive trunks, may be seen from the road running through the gorge of the Allt a’Ghamna. They are almost the last trees to break into leaf, often not until early June. However, those in different places both expand and lose their leaves at different times, reminding us that aspens exist as separate male or female clones, which may be the progeny, by sucker growth, of individuals long since gone. Their occurrence on isolated crags is something of a mystery, since although their fluffy fruits are wind-dispersed, nowadays they rarely flower. If you ever see flowers on aspen let us know.
Also located in the gorge of the Allt a’Ghamhna is the largest stand of hazel on Quinag, although there are a few examples on the south side of the hill and elsewhere. This multi-stemmed tree is easily picked out early in the year by the yellow stamens of its hanging male catkins. The female flowers, with red stigmas just peeping out of tiny buds, take more finding, but they are, of course, the source of the nuts which are gathered by small mammals such as wood mice and bank voles. The presence of hazels is usually a sign of deeper, fertile soils, often derived from glacial deposits. They regenerate themselves not only by seed but also by producing new shoots at the base of the often ancient stools. However, these are very susceptible to browsing by sheep or deer, which is why healthy trees are usually found in boulder scree or on crags inaccessible to large herbivores.
Holly is another tree of crags and gorges since, although bearing prickly leaves, young twigs are heavily browsed, as a struggling veteran close to the road on the north side of Skiag testifies. Like aspen and willows, it exists as separate male and female trees, with distinctive flowers, so producing the well-known red berries is a chancy business. Holly leaves last on the trees for several years, and when they fall they are skeletonised by two specific cup fungi, which appear as tiny black dots, where their fruiting bodies have punctured the tough shiny cuticle.
Probably the least common of the larger trees on Quinag is wych elm, being virtually confined to the gorge of the Allt a’Ghamhna, with one large tree on Creag an Spardain, to the east. Its fat buds will soon be bursting with globular clusters of dark red flowers, which appear before the leaves, and soon turn into the winged fruits. The leaves, when they appear, are lop-sided and very rough in texture. In places these leaves bear conspicuous club-shaped galls of the aphid Tetraneura ulmi or the light-green inflated leaf rolls of another aphid Eriosoma ulmi, a reminder that trees support extensive invertebrate faunas.
Scattered around the wetter parts of the lowland landscape of Quinag are three species of willow. Commonest are low, much-branched bushes of eared willow, less so the taller straight-twigged small trees of grey willow, and very occasionally, potentially even taller trees of goat willow. Their leaves help to distinguish them, those of eared willow being the smallest, woolly-hairy and crinkly in outline, grey willow shiny above and softly hairy below, and goat willow the largest, at up to 10cm long. All exist as either male or female trees. It is the yellow-flowered male catkins that are the traditional ‘pussy willow’, but the female ones which produce the fluffy fruits a little later in the year.
Quinag also boasts two diminutive willows, trees in all respects other than their size. Creeping willow sprawls through lowland heathland around Torgawn, its leaves distinctively silky-hairy below. In stony places high on the hill is found the tiny dwarf willow, rarely over 3cm tall, with almost circular finely-toothed leaves and reddish flower buds. Both bear bright red berry-like sawfly galls, creeping willow that of Eupontania collactanea and dwarf willow that of E. herbaceae.
And it would be remiss not to mention in this context, one of the specialities of our area in the North West Highlands, the prostrate form of our only native gymnosperm this far north, juniper. This is found hugging the ground high on Quinag, wherever it has managed to escape the disastrous fires which have swept this landscape in times past. Although allied to conifers, it does, of course produce blue-black berries, traditionally used to flavour gin.
There are conspicuous, though now ailing, Scots pines, on islets in Loch Assynt, but they are thought to have been planted, probably in the 19th century. The nearest living native examples of this conifer are further south, although the remains of ones that briefly flourished during the Bronze Age are found in local peat deposits.
Ian Evans is a former professional naturalist who retired to Assynt with his late wife Pat in 1991 and is currently BSBI Recorder for West Sutherland; see www.assyntwildlife.org.uk for more on the area.
Picture: Downy birch in winter colours by Ian Evans