Quarry at Loch na Bruthaich: unexpected biodiversity

June 2nd 2019

Beside the coast road at the western end of Loch na Bruthaich, Clashnessie (NC069316) there is an area of hard-standing much used by camper vans and others (photo 1). It is the levelled base of an old quarry, presumably excavated when the road was built in the 19thcentury. Earth and rocks have been tipped there in the past, but they have now vegetated over.

David and Avril Haines stopped there on 1st May 2019 to photograph the attractive male catkins of eared willow Salix aurita, which were very striking this spring. These catkins are a favourite with early pollinating insects, such as the white-tailed bumblebee Bombus lucorums.l. (photo 2)

They then noticed some pale stems on a bank, bearing what looked like miniature cones; these were the fertile stems of field horsetail Equisetum arvense (photos 3 and 4).  The cones are exquisite when seen close-up, with whorls of hexagonal spore-bearing structures hanging from stalks on their upper surfaces (photo 5).  Field horsetail is the only one of seven species of horsetail found in Assynt which has separate fertile and sterile stems. The fertile stems appear first; they lack chlorophyll and are very short-lived, dying off after they have shed their spores.

David went on to photograph the flowers of wild strawberry Fragaria vesca and heath woodrush Luzula multiflora, species that both have local lookalikes.  Wild strawberry has its petals closer together than the similar but rarer barren strawberry Potentilla sterilis and its leaves also have a longer terminal tooth, as shown (photo 6).  The feathery stigmas of heath woodrush (photo 7) are on shorter styles than in field woodrush Luzula campestris, but the anthers, which appear later, are on relatively longer filaments; telling them apart requires close inspection with a hand lens.

He also captured a picture of the colourful caterpillar of the drinker moth (photo 8), which feeds on grasses; the adult emerges and flies in July and August.

When we were looking at his photographs the following day, I suggested that a further visit to the quarry to list the plant-life might be productive. Unfortunately I was out of Assynt for some time in early May, so we didn’t get around to this until 25th.  My prediction was born out, since in an hour and a half that morning, despite gentle rain, we managed to log some 88 species from approximately 200 sq.m. of the roadside and quarry proper. We added a further six from the bank above the loch on the other side of the road.

The list includes plants from a wide variety of habitats, including roadside, wet ditch, disturbed ground, grassland and dry heathland. There is a basic flush dominated by the grey tussocks of black-bog rush Schoenus nigricans, with lesser club-moss Selaginella selaginoides and common butterwort Pinguicula vulgaris.  Also present are a number of species typical of woodland elsewhere, such as bluebell Hyacinthoides non-scriptus, primrose Primula vulgaris and yellow pimpernel Lysimachia nemorum (photo 9).

Good finds were a few plants of two species of open ground.  Changing forget-me-not Myosotis discolor (photo 10) is a tiny plant of damp areas, with flowers that start creamy-white and change to blue as they mature. Pyramidal bugle Ajuga pyramidalis (photo 11) prefers drier south-facing slopes, often on gritty soils.  Virtually restricted in the British Isles to the northern and western Highlands, it is probably more widespread in Assynt than anywhere else, but still takes some finding.

Animal life noted on this second visit included two frogs, the caterpillar of a garden tiger moth (photo 12), a cocoon of a northern eggar moth, and shells of white-lipped hedge snail Ceapae nemoralis and garden snail Cornu aspersum. Birds included stonechat and linnet on the site, with a pair of vocal common sandpipers on the nearby lochside.

My notebooks inform me that on a previous visit, on 8th September 2007, I collected black ants from under a stone, later identified by Murdo Macdonald as the widespread species Formica lemani, and a jumping spider Euophrys frontalis, which is scarce in northern Scotland; I also noted the grass woodlouse Philoscia muscorum.

We shall visit the quarry again later in the year to add to the plant list, but have hardly started on the smaller animal life.  So, what is, at first sight, just a somewhat untidy piece of roadside engineering, proves to be a small haven for plant and animal life, well spotted by David and Avril.

Ian M. Evans

All photographs by David Haines

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