Llanelli Naturalists Newsletter - March 1985
Dr. Nigel Stringer and Dr. R.H. Davies
During the last twelve months since the initiation of the “South Dyfed Bryophyte group” numerous different types of habitats have been visited for recording purposes. Many of these areas however prove to be more interesting for purposes other than the presence of unusual mosses or liverworts. One of these areas proved to be (dare I say it) in another vice county!, - so armed with wellies, books, packed lunches and maps (to wrap the sandwiches since we always get lost) we set off early one day, joined the M4 in Hendy, drove east, crossed the Loughor and immediately came to a halt. We had arrived. Our first journey out of Dyfed had taken us 140 yards into West Glamorgan to the ruins of the church of Llandeilo Talybont.
This church can be seen from the motorway and is conspicuous by the absence of roofing tiles. Historically this is one of our most important local ancient monuments. The site dates back to the 12th century and is one of the oldest in the Swansea and Brecon Diocese. The church was completely closed ten years ago after which vandals broke in, removed all the roofing tiles and actually dug up graves inside the church in an attempt to discover buried jewellery, not bothering then to re-bury exposed bones. Last autumn the state of the church was brought to the attention of various public bodies and in December experts from the Royal Commission for Ancient Monuments began to study the inside walls of the church. They then discovered evidence of decorative paintings dating back to the Middle Ages hidden under layers of limewash, paint and plaster. Unfortunately, because re-roofing the church and general repair will cost over £6,000 the interior wall paintings will have to be taken to St. Fagans Museum for renovation and eventual display. It seems such a shame that an attraction like this will be lost from an area which is clutching at straws in an attempt to attract tourists to the locality and surrounding districts. These paintings are well worth seeing and the church is worth a visit if you are bored one day, but don’t go visiting during high tide because the whole church is surrounded by water! The churchyard is sheltered by elm trees which have succumbed to Dutch Elm disease caused by the fungus Ceratocystis ulmae and are now being colonised by Pleurotus cornucopiae which has large ochraceous brackets produced in clumps. The main reason for our visit however was to record the bryophyte flora of the church and boundary walls. Because the site is so old we thought that perhaps some unusual bryophytes may have occurred in this area out in general the bryophyte community was similar to most stone walls found in gardens and around town.
This community is very specialised and the growth forms of mosses fauna in such habitats all show some adaptation towards water retention in such an exposed environment. Most, however, tend to form very tight compact cushions which makes them look like hemispherical green objects dotted all over the wall. Such a moss is Orthotrichum anomalum but others such as Barbula species go a stage further and conserve even more moisture by twisting their leaves around the stem thus reducing the surface area of tissue for evaporation. Water loss can also be reduced by lowering the temperature of the organism and I’m sure it comes as no surprise to learn that mosses have this ability, a primitive group though they are. Many of the wall top mosses have a silvery appearance which is due to the tips of the leaves being drawn out into hyaline hair points. This sort of silvery appearance is also shown by higher plants growing in high altitude/dry environments whore increased hairyness of the leaves tends to reflect the suns rays thus reducing the temperature of the leaves and reducing evaporation. This effect is known as the albedo effect as is ideally shown by mosses of the Grimmia family which form silver cushions on all wall substrates.
A fourth method of adaption is shown by the most abundant of the mosses found a on the church wall. This moss has the horrible name of Camptothecium sericeum but forms a beautiful green carpet flushed with yellow and gold on the young tightly compacted leaves. The moss forms a prostrate carpet on stone and adheres so closely that it is impossible to pull off. This helps water retention by again reducing the surface area available for evaporation - a method shown by higher plants growing in xerophytic conditions such as sand dunes where some of the compositae form rosettes of leaves which lie as close as possible to the sand surface thus reducing evaporation of water from the ventral leaf surface.
Very few mosses actually grow on walls and are a fairly easy group to get to grips with, We found twelve species in the churchyard, two of which, Grimmia maritima and Ulota phyllanthera, only grow near the coast. In an attempt to get people interested in mosses we have included a key to the identification of bryophytes occurring on walls at the end of the report - (Please find faults and let us knew if the key doesn’t work so that we can modify it). To be included in the next (June) Newsletter – IKM
As we were out and about in another county we continued on to Gowerton where we met up with Mrs. Margaret Morgan who is actually the sole member of the Gowerton Naturalist Society! The area we went to survey comprised a re-colonised coal tip and two marshy fields, the latter area owned by Alcoa Ltd. and leased to a local farmer. The former site lies on land used for tipping coal spoil waste around 80 years ago and now consists of a well developed stand of Birch (as one would expect) and scattered clumps of Oak. The undercover vegetation is very sparse consisting of a shrub layer of hazel, willow, holly and quite a few Alder Buckthorns. This last plant is a very important member of the community for it happens to be one of only two food plants for the local Brimstone butterfly. Although the ground flora was sparse consisting of honeysuckle, ivy, bramble, grasses end ferns there was a well developed litter layer which, because of the rapidly draining substrate had built up a good humus layer in the soil and hence a good mushroom flora, As expected the Birch Polypore was everywhere but the main find of the day was that of species of Amanita. These included Amanita rubescens, Amanita muscrari, Amanita citrina, Amanita pantherina and Amanita fulva. Another unusual mushroom we found was the hedgehog Fungus which has spines underneath the cap instead of gills and is incidentally edible. Lots of Russula were present but we wore unable to confirm the presence of Boletus piperatus (which tastes like two kilos of “Victory V’s”!) because Dick refused to eat a portion of the mushroom - his excuse being that the last mushroom I gave him to taste made him a little ill (probably because it was Russula emetica).
The moss flora was very sparse indeed and consisted mainly of Polytrichum, Diplophyllum and Eurhynchium species, all acid and shade-tolerant species.
The wood in fact is one of only a few left in Gowerton and explains why Mrs. Morgan has attempted to conserve the area via a Tree Preservation Order.
The task itself seems straightforward hut has taken her months of battling with councils, landowners and even visits to local Member of Parliament. Hopefully the area will be saved from future development which is more than can be said for the adjoining marshland. It is ironic that this area was thought to be safe because of the involvement of other Naturalists Trusts but during the first week of December the tenant farmer cleared 30 acres of bordering woodland and scrub with a mechanical digger which totally destroyed 2,000 trees. If this isn’t bad enough there is another planned clearance and drainage of another 50 acres. Needless to say the whole area new looks like something out of a World War I battlefield.
It seems that our day hadn’t been too successful. We seem to have a kind of “Midas touch” - Irish style - for wherever we go ends in disaster as regards conservation. For example our best bryophyte slack in Cefn Sidan is under 4” of tarmac, a 100 acre woodland of ash and beech in Ferryside has been stripped (top soil and all!), 30 acres of mature Oak wood has been felled in Glynhir and finally the Carmel woodlands are due for development.
As stated earlier we have been bryophyte recording for exactly one year and found it to be a time consuming occupation since confirmatory identification of some species can only be done microscopically. We did obtain the latest record cards of 10 x 10 km squares for Dyfed but soon found out that they were outdated and our original records of 9 first, 14 second and 13 third county occurrences for species were soon reduced en updating with more recently available records. We are still in pursuit of the actual numbers of mosses and liverworts present in vice county 44 but the totals are in the region of 333 mosses and 120 liverworts. Habitats visited during the year were very varied, ranging from dry (walls, dunes) to wet (bogs, moor-land, streams) and through a whole range of degrees of acidity to alkaline areas. As one would expect, as with higher plants, the areas of highest diversity or numbers of species were found in the wooded areas of the carboniferous limestone and other calcareous outcrops.
One such area was in Cwm Clydach near Mynydd-y-Garreg which comprised a mature wooded valley with gorge and river at the bottom, passing through to grazed grassland. Dominant ground flora bryophytes of the woodland were Eurhynchium striatum, Rhytidiadelphus triquetrus, (indicators of basic soils), Fissidens bryoides and Hookeria lucens (indicators of shaded areas).
Colonisation of the rocky areas of the gorge was sparse and consisted mainly of Thamnium alopecurum, Eissidens species and the liverwort Conocephalum conicum. All together, 37 species were recorded from the woodland and gorge and 12 from the open grassland which was dominated by the two calcicole species Pseudoscleropodium purum and Ctenidium molluscum. When one considers that Cwm Clydach may have the potential as an S.S.S.I., imagine our delight and surprise when we visited the Pant-y-llyn/Garn area near Carmel where we recorded nearly a 100 species of bryo¬phytes from the wood, lake and quarry. Some of these species were first county records but the most beautiful of all the species we found was Neckera crispa which is confined to damp limestone shaded areas (of which there is little in Carmarthenshire). The growth form of this moss is very characteristic because the branches grow out away from the rock face and their ends tend to curl very much like the outgrowths of mycella on the cap of the lawyers wig mushroom (Coprinus comatus). The area is also very important for its higher plant communities and it seems a shame that areas such as these will not be with us for very much longer considering the planned exploitation of the site for quarrying purposes.
Two other areas worthy of mention which we visited last year both occur in the Carreg Cennen area. The first was a “fen-carr” type of habitat which was perhaps more important for its higher plant community rather than its bryophyte flora although Acrocladium giganteum, a second county record, was found here. The area was dominated by a canopy layer of Willow and Alder and a ground flora of Viola palus¬tris and Caltha palustris in the wooded areas and Sparganium?, Equisetum, Hydrocotyle and Lotus in the open. Overlapping both areas were random clumps of the sedge Carex paniculata which totally co-dominated both areas. The size of these sedge clumps were enormous; some were up to 2 foot wide and 4 foot high and when we saw them locked very impressive amongst a yellow carpet of Caltha palustris flowers. Their size may have been related to base-rich ground conditions since the bryophyte Climacium dendroides, a calcicole, was evident. The clumps seemed to be quite old and an outstanding feature shown by them was their colonisation by the fern Dryopteris dilatata.
This fern actively grows amongst the crown or the tussock and as you can imagine gives the whole association a characteristic palm tree like appearance. Although the area was base-rich we also noted Sphagnum squarrosum in the wetter parts. Sphagnum is normally associated with acid and very wet conditions and such areas occur in the east, above Carreg Cennen castle. It is here that areas of blanket bog are found due to the high rainfall. They are called “blanket” bogs because they cover the ground like a blanket, occurring mainly in the uplands, in areas of high rainfall, and because there is a balance between precipitation and evaporation, even sloping ground is in permanently wet condition with a result that blanket beg can develop over limestone and on 250 slopes.
Polytrichum commune can develop in basic flushes on mountains but the dominant mosses of blank-bogs are Sphagnum papillosum, Sphagnum subnitens and a reddish species Sphagnum rubellum are the commonest found which may intermingle with higher plants such as cotton grass and heather where degradation of the bog has occurred due to over-grazing, burning or pollution.
The other type of bog found in this area may be of the “raised” bog type. This type of bog is usually formed on top of what used to be a lake, but due to its infill, growth eventually on its surface is totally dominated by Sphagnum species to such an extent that a dome of vegetation is formed on the original lake. The dome may become so high that it is cut off from the ground water table and becomes totally dependant on rainfall for moisture and nutrients. The Sphagnum’s peculiar morphology and physiology is ideally adapted for this environment because the living and dead cells act together like a huge sponge and absorb all this moisture. Around the raised area is a moat-like structure called a lagg and receives enriched water from rock and soil of the surrounding area and generally supports a band of differing vegetation.
The raised portion of the bog develops, different areas depending on the different growth rates of the moss species and as a consequence areas of hummocks and hollows develop with their associated species. The hummocks are mainly composed of Sphagnum papillosum, Sphagnum subnitens and Sphagnum recurvum whilst the pools are dominated by Sphagnum cuspidatum. As the hummocks grow out they tend to fill up the hollows and conversely as the centre of the hummock breaks down it becomes a pool or hollow and thus an interchange of species occurs all over the raised bog areas. Raised bogs are rather rare and two of the most important in Britain are Cors Fochno (Borth) and Tregaron Bog in Cardiganshire. The area in the uplands around Carreg Cennen may well be the site of a small raised bog so we hope to return in the spring to confirm its presence.
During 1985 it is intended to continue bryophyte recording in the county but concentrating mainly on the distribution of calcicole species, and with refer¬ence to shade and water regimes.
