- Category: Lichens
- Hits: 2186
Llanelli Naturalists Newsletter - Winter 1992/1993
If you stand in Dinefwr Deer Park. looking across the pond to the old castle and the flood plain of the Tywi, you will be looking at one of the most beautiful views in Wales. If you are a archeologist, you will soon realise that the lichen florae is also something out of the ordinary. The medieyal aspect of the view, with its rough grassland, ancient oak trees and fallow deer, are clues to the special nature of the lichen flora.
The importance of the Deer Park for lichens was recognised in 1972, and subsequent visits by lichen specialists have continued to add notable species of lichen to the list. Every tree in the Park has now been surveyed for lichens, and some of the results can be correlated with a recently introduced system of tree tagging.
The total number of species recorded on trees and wood in the Deer Park now stands at 142, of which about 50 are rare in Wales or in Britain as a whole (see table). Many of the notable species are considered to be indicators of sites with a long history of ecological continuity - in this case meaning that mature trees haye been present continuously for hundreds of years.
The Deer Park is a relic of the type of woodland management known as pasture woodland, which has the dual purpose of timber production and grazing of animals. Before man began to have a major impact on the natural vegetation of the British isles, most of the land would have been covered by forest. Studies into the probable composition of this forest (the 'wildwood' as it has been called), suggest that some examples of pasture-woodland may be among the closest approximations to the wildwood which we have left, with abundant ancient trees, dead wood, and with glades allowing light to penetrate to the ground.
Lichens found mainly in sites with a long history of ecological continuity are known as old-forest species: they are slow to colonise new habitats and may require niches found only on old trees. They are not found in coppiced woodland, even when of ancient origin, because they eannot suryive the frequent felling.
The likelihood of ancient origin and ecological continuity can be estimated using the Revised Index of Ecological Continuity (RIEC) devised by Rose (1976), where the RIEC is given by n/20 x 100, where n is the number of old-forest species from a published list of 30 species. Dinefwr scores well on this index, with an RIEC of 85. A similar, more recent index, intended to refer mainly to conservation value is the New Index of Ecological Continuity (Rose 1992), which uses a list of 70 species. Dinefwr scores 29 on this Index.
Some of the trees in the Park derive from plantings in the late 18th and early 19th centuries, but the south-west corner contains semi-natural woodland. This part of the Park is the stronghold of seyeral species which prefer shelter or shade: Lecanactis subabietina prefers the deeply shaded recesses at the base of oak trunks, coating the dry bark with a pale grey film dotted with white pin head-sized spore-producing organs called pycnidia.
Dinefwr experiences some degree of air pollution despite its rural position. Although the precise effects of each pollutant on lichens in the field are still inadequately known, acid rain appears to be an important influence at Dinefwr. as in most of Wales. Lobaria pulmonaria, usually a large and distinctive old-forest lichen, can be found on only one oak in the Park, and appears small and unhealthy. This species contains a blue-green alga (cyanobacterium) as its partner in the symbiosis, and such species are thought to be particularly sensitive to the effects of acid rain. The bark of oak is naturally rather acidic, and additional acidity from air pollution can easily make the bark unsuitable for the growth of many lichens. The potentially large lichens Sticta sylvatica and S, limbata also occur only on single oaks.
Oak is oyerwhelmingly the most important tree for lichens in the Park, but ash and sycamore are also important because of their less easily acidified bark. Beech, horse- and sweet-chestnut and lime are of little importance at Dinefwr, although beech may be a valuable lichen tree in some parts of the country.
Many of the interesting lichens are small, and need to be searched for carefully. In Gyalideopsis muscicola (see figure), a good lens is needed to see the minute dark spiny structures sprouting from a thin grey film (the thallus) coating moss on a few sheltered tree trunks. The structures shed long narrow spores from their undersides. This is a rare species in Britain.
It is scarcely practicable to search every square inch of bark, but fortunately it is often possible to spot a potentially good tree, and also potentially good areas of a single trunk. This may be by means of larger species indicating rich bark (e.g. the mosses Hypnum cupressiforme var. resupinatum and Homalothecium sericeum), or by less easily communicated features of bark colour and texture. The oak trees in the park vary considerably in their value for lichens, good trees sometimes occurring near to poor trees. The reasons for this type of variation can only be guessed at at present. Possibly there are genetic differences between the trees, or subtle environmental factors operating. Interesting lichens can sometimes be found only in a narrow zone on the trunk, where conditions of pH, or lack of competition from large mosses, make conditions particularly suitable. The dry side of the trunk that is sheltered from rain has its own specialised community of lichens able to absorb moisture from the air.
Dead wood should by now be well known as an important habitat for several groups of organisms, but it is a particularly threatened substrate in most woodland. Hard, slowly decaying wood is best for lichens. A large oak log in the Deer Park, which is still the only site for the lichen Lecidea turgidula in the whole of South- and Mid-Wales, narrowly escaped becoming firewood in the 1980's.
The Deer Park is now a National Trust property. The future of the lichen flora is dependent on a combination of management, and external factors such as pollution. Maintenance of the numbers of ancient trees and of dead wood, and maintenance of shelter and humidity without excessive shading, are of great importance. Tidying up 'dying' trees and dead wood must be resisted. The beauty of the Park is largely dependent on its 'natural' appearance, and correct management of the natural history need not conflict with the landscape interest.
Harding, P.T. & Rose, F. (1986) Pasture woodlands in Lowland Britain A review of their importance for wildlife conservation. Abbots Ripton: Institute of Terrestrial Ecology.
Rose, F. (1976) Lichenological indicators of age and environmental continuity in woodlands. In Brown, D.H., Hawksworth, D.L. & Bailey, R.H. (eds.) Lichenology; Progress and Problems.. London: Academic Press.
Rose, F. (1992) Temperate forest management: its effects on bryophyte and lichen floras and habitats. In Bates, 1. W. & Farmer, A. h1. (eds.) Bryophtes and Lichens in a Changing Environment. Oxford: Clarendon Press.
Table 1. List of some notable species recorded from Dinefwr on bark or wood, indicating species used in calculation of the RIEC and NIEC. In the RIEC, any Pyrenula spp., and in the NIEC any Chaenotheca spp., score one altogether.
- Category: Lichens
- Hits: 1734
Llanelli Naturalists Newsletter - Winter 1990/1991
R.N. Stringer & R.H. Davies
During the last twelve months an attempt has been made to contribute to the lichen records of the county. Due to the need for expensive specialist equipment (high powered microscopes) to aid identification this group of primitive plants has been sadly neglected in the past. This is reflected in the membership to the British Lichen Society which has only 14 members throughout Wales and only 2 in Dyfed. Whilst this has advantages in that the Dyfed A.G.M. can be held in a telephone kiosk at minimal cost it also means that recording proceeds at the same growth rate of many lichen species (very slowly!).
Nevertheless, the authors have contributed to the distribution records over the last year, and to date a total of over 500 species have been recorded for the county out of a British total of about 1600. Lichens are usually found in habitats which are unfavourable for the growth of higher plants but can occur in the same location as certain mosses and liverworts. Environmental conditions in these habitats tend to be extreme and hence growth rates are low and the size of the resulting thallus (the lichen body) is small which causes problems in locating the specimen, and, in its identification.
Most lichens occur on either rock 'saxicolous' or bark 'corticolous' substrates. Some species are specific to the rock type and similarly, on bark, some lichens are only associated with particular tree species or the age of the tree. Bark substrates can vary from smooth to rough and can be chemically different between trees, or from the top of one tree to tis base; consequently a variety of microhabitats occur. Also, an over-riding factor determining the distribution of lichens is the degree of aerial pollution. Lichens are extremely pollution-sensitive so their distribution patterns are governed by their proximity to industrial centres and urban areas.
Coastal locations are particularly rewarding and one site close to Llanelli has been found to contain a lichen rich flora. This is St. Ishmael's Church (SN363083) near Ferryside which is a good site because it is away from polluting influences, and, as well as containing a wide variety of 'rock types' in the form of gravestones and the church building itself, it also contains a few large trees in the vicinity.
The church is built mainly of limestone*and this is colonised by Verrucoria species (V. hochstetteri and V. sphinctrina) which are white in colour and contain minute pits on the thallus surface which contain the sporulating structures. The yellowish colonies belong to Caloplaca species which produce characteristic yellow disc-shaped sporulating structures on the thallus surface. Both Verrucaria and Caloplaca species are indicative of a limestone substate but the mortar is also colonised by a particular species (P. niderosiensis) which imparts a pink colouration to the substrate. The gravestones, most of which are marble are extensively covered with a white lumpy lichen (Ochrolecia parella) which forms large patches up to 20cm across. In previous times it was used for dyeing and may have been the source of the purple dye 'perelle'. The other white-coloured lichen thallus which contains black circular ascocarps on the surface is Lecanora atra. These well-covered gravestones contrast with the slate tombstones which are only colonised by a green lichen Lecanora muralis. Some of the tops of the gravestones and especially the ridge tiles of the church (*actually mildly calcareous Old Red Sandstone - Ed) roof are colonised by a yellow-orange, rather chunky lichen Xanthoria parietina. This requires bright sunlight and also nutrient rich substrates to succeed and its common occurrence on the roof and tops of gravestones is entirely due to bird activity. They perch on high spots and the droppings are rich in nitrogen and phosphate which are utilised by the lichen. Most of the south-facing surfaces are well covered in lichens but the north-facing and shaded areas are not so well colonised, and, only support the presence of a powdery mealy-green lichen Lepraria incana.
The trees in the churchyard are also substantially covered by lichen species. The dominant community is the Ramalina/Parmelia type which are fleshier and have more structure than those species occuring on the stone substrate. The Parmelia species (P. pereata, caperata) are those characteristic of unpolluted areas, and as a consequence a high diversity of species are present on the bark - Lecanora, Pertusaria, Xanthoria, Opegrapha and Graphis species.
Over 40 species have been recorded from the churchyard which is very good compared to other areas of Britain. Many of the species found on gravestones are used to monitor growth rates because tombstones are dated and can give invaluable information on the decline or increase in species due to atmospheric conditions. Thus churchyards are notable habitats for lichens (as well as for flowering plants) and are a very useful starting point for anybody studying lichens, either their distribution or their physiology.
- Category: Lichens
- Hits: 2762
Llanelli Naturalists Newsletter - June 1984
R.H. Davies and R.N. Stringer
In the course of our investigations into Carmarthenshire mosses and liverworts we have examined many areas. We would like to take this opportunity to describe one exceptional site. This site is not only important for its bryophytes, but had a large lichen flora-many flowering plants of interest.
Craig y Derwyddon lies north of the Carmel-Llandybie road to the west of the Village of Pantllyn (Grid Ref: SN 605165) and comprises of abandoned limestone and gritstone quarries, spoil heaps, ruined kilns, a small lake and a wet basic pasture. With such an evocative name as Craig y Derwyddon it comes as no surprise that this site has very important historical interest also.
There are two legends recorded linking the area with sleeping heroes. One makes King Arthur the hero but according to Gomer Roberts, this appears to be an early nineteenth century embroidery by Iolo Morgannwg. A more ancient tradition links the area with Owain Llawgoch, possibly the same Owen that is remembered in Llyn Llech Owen although some historians link the latter Owen with the knight of King Arthur's Court. An historical Owen existed as a fourteenth century claimant to the Principality, yet he never set foot in Wales. It is interesting to note that one of the charges of treason brought against Rhys ap Gruffydd of Dinefwr by Henry VIII was that Rhys had likened James V of Scotland to Owain Llawgoch a man who could free his people. The legend tells of an underground cave or room where the sleeping warrior and his see were sleeping in readiness to be awakened at the appointed signal and claim the throne of Britain. This cave was supposedly that of Craig y Derwyddon and the legend was reinforced by the finding of twelve skeletons in a cave in 1813 during blasting operations in the area.
Quarrying in this area ceased in the early 1850's when R.K. Person of Dinefwr erected new kilns at Cilyrychen and began quarrying Craig y Ddinas.
Since then, the rockfaces, spoil heaps and rock platforms have all been colonised and there has now developed a mixed deciduous woodland of Oak Ash and Beech with a well developed shrub layer of hazel. One of the oak trees was found to be over a hundred years old when felled by its owner and the presence of Clematis which is abundant in area was even noted by Walter Davies in as early as 1858. The site therefore is relatively old and together with the presence of sheer rockfaces and uneven stony kerries has led to the occlusion of the area for grazing purposes and this has resulted is a luxurious ground flora.
Species such as Dog's Mercury, Wood Anemone, Sweet Woodruff, Violets, Herb Robert, Primroses, and various grasses indicate its bawe rich nature and this is confirmed by the presence of the two common hard shield ferns and the Harts Tongue ones of the Rusty Back fern were also found and apparently a rare fern has also been found at this locality. Other rarities of the area include Paris quadrifolia Ghost Orchid and Scottish Primrose (the latter three species to be confirmed).
Below the quarry, skirting the main road lies a small oval lake about 100 yds long, 20 yds wide and 2 yds deep. The lake has a small outlet but because of the porosity of the underlying bedrock it dries out in summer but even so, is damp enough to suppert the growth of willows and alders.
The richness of the site has led to the investigation of the area by the Nature Conservancy Council. Dr. R. Woods surveyed the area in December, 1983, and whilst compiling a species list of bryophytes came up with a total of 56 different species. We visited the same area a fortnight after and this total has been increased to 86 species, thus emphasising the importance and diversity of habitats within the locality. Two moss species found are species previously unrecorded in Carmarthenshire and are new county records. Many of the mosses found by us in this area are unusual because they do not normally occur inland over much of Wales due to the nature of the substrate. Their normal habitats are dune slack areas characterised by having a high water table and a pH which is neutral or slightly alkaline. Species sharing such a distribution include Campylium stellatum, Campylium elodes and Trichostomum crispulum. Grassland species found in the open areas of woodland which are also recorded in similar calcareous environments such as sand dune areas (see previous newsletter) include Pseudocler(?) purum, Tortula ruraliformis, Barbula species Bryum capillare and Dicranium scoparium.
Two species Rhytidiadelphus squarrosus and Rhytidiadelphus triauetrus were also found in Cefn Sidan but they were more abundant in Pant Llyn. One of the most important finds of the area was Thuidium philibertii growing on spoil waste in association with another species of the same genus Thuidium tramariscinumo. The former is a new county record.
The dense bryophyte ground cover extended into the woodland area and the most dominant species encountered here were those of Eurhynchium and Brachythecium species, common species found in such habitats.
Bordering the woodland on the lake edge were found not only hydrophilic/aquatic such as Acrocladium cuspidatum, to Acrocladium cordifolium, Leska polycarpa and Eurhynchium riparoides but an even more important epiphytic community on the willow and alder branches. The high rainfall of the area and the presence of as sheltered lake gives rise to very humid conditions and the luxurious epiphytic flora is unlike any we have found in our bryophyte travels of the county so far. Such species as Hypnum mamillatum, Lejeunea cavifolia, and Lejeunea ulicina were found for the first time by us and these were intermingled with more commoner species such as Hypnum cupressiforme, Ulota crispa, Metzgeria species and the beautiful Frullania dilitata.
This high humidity area contrasted greatly with that of the rock faces which were open to the drying wind and as a result the numbers of species were less and the only of note found included Grimmia apocarpa, Tortula muralis Fissidens cristatus and Encalypta species. The rock faces were however colonised by a healthy lichen community (Dr. Woods recorded over 70 from the area) but where the rock was shaded Neckera species and the calcicole Cteniduim molluscum became dominant. On the seepage areas however the liverwort Pragiohila asplenioides var majus became dominant and it was amazing to find large differences in species composition over such a small change in substrate composition. This was ideally shown at the top of the quarry on a small plateau. Having high rainfall causing nutrient loss and the presence of gorse bushes has induced a high soil acidity and this is reflected in the bryophyte community. Marked calcidity species such as Polystichum, Atrichum and Diplophyllum albicans were abundant and it was near the top of the plateau where Fissidens viridulis var viridulis another county record was found.
The caves in the area were a bit of a disappointment, even though Pellia endivifolia and Conocephalum conicum grew in profusion around the entrances a thorough search failed to yield the Fairy Gold Moss (Schistostega pennata) which Richard Pryce found in a cave in Stradey Woods.
There is at present a conflict of interest as to the future of this area. The landowner Mr. Rhodes has put in an application for a leisure development incorperating 10 or more holiday caravans and a building with four living units together with a reclamation scheme for the grounds. This includes the opening up of the cave systems and perhaps the utilising the rock faces for climbing purposes.
McAlpines, the company which own the adjacent quarry claim not only that they have a lease for the land allowing development in the future but that caving and climbing in the area will prove highly dangerous in view of blasting operations in the existing quarry.
For the moment the planning application is in obeyance until Solicitors can establish the legal position. The West Wales Naturalist Trust are keen to turn this area into a reserve and the Nature Conservancy will be making a thorough survey of the area in the summer. Any help with biological recording will be gratefully appreciated in the area concerned. Please contact Mr. Rhodes the landowner (lives in caravan in field next to lake) for permission of access.
DAVIES W. Llandeilo Vawr and its neighbourhood, past and present. Llandeilo 1858.
ROBERTS G.M. Hanes Plwyf Llandybie Gwasg Coleg Prifysgol Cymru Caerdydd 1939.
- Category: Lichens
- Hits: 2039
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.