Llanelli Naturalists Newsletter - March 2003 - No 69
Andrew Stevens
A surprisingly large group of members and friends met at the farm on a beautiful sunny day - in marked contrast to the previous visit two years earlier when a handful of stalwarts battled against ever-increasing rain and wind. First stop was by a small area of woodland which contained a single Sorbus torminalis (Wild Service-tree). Richard Pryce pointed out that it is a good indicator of ancient woodland (ie a site having had continuous wooded cover for at least the previous 400 years), and one of only seven native trees recorded in Carmarthenshire.
The track opened out into a semi-improved meadow and offered a fine view over the Gwendraeth Fawr valley to the former open-cast coal site at Ffos Las, now being restored. Richard gave an informative account of the history of the working of the site and of the local geology. Waun-y-Gwiail farm itself lies on glacial boulder clay over Lower Coal Measures rocks with older Millstone Grit and Carboniferous Lime-stone outcropping higher up the escarpment at Mynydd-y-Garreg. Water rising from the many springs may thus differ considerably in pH and mineral content depending on its origin. This was clearly demonstrated as the group reached a small unimproved wet meadow where acid loving Sphagnum (bog-mosses), Dactylorhiza maculata ssp. ericetorum (Heath Spotted-orchid) and Erica tetralix (Cross-leaved Heath) grew alongside Listera ovata (Common Twayblade), typically a plant of base rich soils. Also present was an interesting selection of sedges including Carex viridula ssp. oedocarpa (Common Yellow Sedge), C. echinata (Star Sedge), C. flacca (Glaucous Sedge), C. hostiana (Tawny Sedge), C. laevigata (Smooth-stalked Sedge), C. pallescens (Pale Sedge), C. panicea (Carnation Sedge) and C. remota (Remote Sedge). Also seen were a range of insects including Pyrrhosoma nymphula (Large Red Damselfly), Coenagrion puell (Azure Damselfly), Anax imperator (Emperor Dragonfly) and Deilephila elpenor (Elephant Hawk-moth).
Following a track constructed of builders’ rubble and surfaced with waste fill from a nearby limestone quarry revealed an intriguing mix of plants. Aliens including Buddleja davidii (Butterfly Bush), Cymbalaria muralis (Ivy-leaved Toadflax) and Alchemilla mollis (a lady’s-mantle); calcicoles such as Origanum vulgare (Marjoram) and Geranium lucidum (Shining Cranesbill) and plants of disturbed ground such as Tussilago farfara (Coltsfoot) appeared alongside invaders from adjacent wood and field. Phalaris arundinacea var. picta (Variegated Reed Canary Grass), a garden escape, survived at one spot, while further along the unvariegated native grass grew on the wet track edge. Richard and Tony discussed whether a toadflax was the native Linaria vulgaris (Common Toadflax) or the introduced L. purpurea (Purple Toadflax): on flowering later in the year, it proved to be the latter.
The track skirted a pond in which was observed Ranunculus flammula (Lesser Spearwort), Potamogeton natans (Broad-leaved Pondweed), Glyceria fluitans (Floating Sweetgrass) and Lemna minor (Common Duckweed). A more detailed inspection a week or two later revealed Peplis portula (Water Purslane), and Eliogiton fluitans (Floating Clubrush), which is only the 12th site recorded in Carmarthernshire. On the opposite side of the pond was a heathy area recently cleared of encroaching scrub which supported Potentilla erecta (Tormentil), Holcus mollis (Creeping Soft-grass), Luzula multiflora (Heath Wood-rush), Polygala serpyllifolia (Heath Milkwort), Pedicularis sylvatica (Lousewort), Calluna vulgaris (Heather) and Sphagnum spp. Insects noted were Calopterix virgo (Beautiful Demoiselle), Enallagma cyathigerum (Common Blue Damselfly) and Libellula depressa (Broad-bodied Chaser).
Further on, a transition to full woodland saw Vaccinium myrtillus (Bilberry), Molinia caerulea (Purple Moor-grass), Lonicera periclymenum (Honeysuckle), and Hedera helix (Ivy), Carex laevigata and C. remota as ground cover beneath birch, all indicative of acid conditions. The group then entered the ravine of Cwm Clydach which is notified as a Site of Special Scientific Interest due of its rich, humid, Atlantic-type vegetation communities. It is cut deeply into the Farewell Rock, the upper sandstone strata of the Millstone Grit which was christened as such by miners as they knew it marked the lower limit of workable coal seams. The plants included species characteristic of more base-rich soils in contrast to the acid boulder-clay derived soils of the surrounding land, particularly at the lower levels. These included Lamiastrum galeobdolon (Yellow Archangel), Euphorbia amygdaloides (Wood Spurge), Polystichum setiferum (Soft Shield-fern), Milium effusum (Wood Millet), Luzula sylvatica (Great Wood-rush), Galium odoratum (Woodruff) and Mercurialis perennis (Dog’s Mercury) and woody species included Ulmus glabra (Wych Elm) and Euonymus europaeus (Spindle). This same rock was responsible for the dramatic stream bed where more resistant inclined strata gave rise to a series of cascades and falls. Here the high humidity, luxuriant vegetation, particularly of mosses and liverworts and overhanging trees gave it an almost sub-tropical atmosphere.
The walk was completed by an arduous haul up the opposite side of the ravine through more fertile, predominantly Acer pseudoplatanus (Sycamore), woodland returning to the starting point at the farm by car.
