Llanelli Naturalists Newsletter - March 2000 - No 65
Leader Ian Morgan
There was a encouraging turn-out of members (both Llanelli Naturalists and Wildlife Trust) for this meeting, the main purpose of which was to examine the vegetation, both planted and semi-natural, of the Wildfowl and Wetland Trust’s grounds at Penclacwydd. For the first time, we were able to survey the new extension (variously known as the ‘Swannery’ or Millennium Wetland).
The party first examined the older, core grounds of the Centre. Innumerable spent spikes of Southern Marsh-orchid (Dactylorhiza praetermissa) were seen - the progeny of a few plants wisely introduced almost ten years ago by Barry Stewart (BS) from Machynys when the source area was thought to be threatened by development. The leader also mentioned that Dr Geoff Proffitt had seen a few Bee Orchids (Orchis apifera), believed to be natural colonists, growing amongst limestone chippings. The small population of Stone Parsley (Sison amomum), originally discovered by BS in 1991, was visited. Only a few plants were seen at SS530986 (near the boardwalk to the western hide of the main freshwater lagoon) and it seems that this plant is suffering from competition with more robust species.
The pond at SS532984 in front of the restaurant was viewed through the windows, with Great Water Dock (Rumex hydrolapathum) (introduced by BS from Pembrey Canal); Greater Pond-sedge (Carex riparia) (likewise from Parc-y-llong, near Kidwelly) and Marestail (Hippuris vulgaris) (from Machynys Ponds) noted. Also seen was the Least Duckweed (Lemna minuta), which is spreading in Carmarthenshire, and some elegant, shiny-leaved clumps of Galingale (Cyperus longus) (from Sandy Water Park, where is was originally planted). Of concern were increasing mats of New Zealand Pigmyweed (Crassula helmsii) and Parrot’s-feather (Myriophyllum aquaticum), both highly invasive and undesirable water plants. WWT staff are aware of the necessity to eradicate these last two plants.
Crassula also worryingly occurs in the pond-dipping area SS532987, where much Water-purslane (Lythrum portula) was seen. En route to this pond, the glossy leaves of (planted) Bay Willow (Salix pentandra) and the paddle-shaped, rather glaucous leaves of Purple Willow (Salix purpurea) were examined. Violet Willow (Salix daphnoides) occurs, also planted, next to the main car park. Young plants of the hybrid alder Alnus glutinosa x A. incana = A. pubescens were noted alongside a ditch (SS533986) near the pond-dipping area; the same ditch held Fringed Water-lily Nymphoides peltata.
The garden area, at c.SS532984, was examined where it was seen that plants of Cape Figwort (Phygelius x rectus ‘African Queen’) were festooned with Figwort Weevils (Cionus scrophulariae), which usually occurs on Common Figwort (Scrophularia nodosa); the small, slug-like larvae sometimes riddle the leaves with holes. Other non-native plants included Blue Sow-thistle (Cicerbita macrophylla) and early flowering Abraham, Isaac and Joseph (Trachystemon orientale); the latter a member of the comfrey family, nice in flower but later with unattractive leaves. It also grows near the railway bridge at SS533988, found by Viv and Tony Lewis.
The party then crossed over the wooden bridge into the Millennium Wetlands, 60ha of man-made open water, reedbeds and fen and planted woodland, all criss-crossed by pathways. The true Black Poplar (Populus nigra ssp. betulifolia) and the adjacent hybrid Populus x canadensis ‘Serotina’ growing at the entrance to the Centre were viewed from a distance. The leader mentioned the Balm-leaved Figwort (Scrophularia scorodonia) next to the nearby access road (SS533986) where he had previously introduced two plants from the Ffrwd population as a recorded conservation measure (not to have ‘all your eggs in one basket’!).
The new Millennium Wetlands deserve more recording time than was available during the afternoon, both to record the existing flora and other wildlife and to chronicle the vegetational evolution of this significant site. The planted trees were cursorily examined - mostly various willows and alders but with a number of true black poplars (grown from cuttings from the original male Penclacwydd tree) along the northern margin. The metallic blue-green beetle Phyllodecta vulgatissima was seen in some numbers on willows. A beautiful specimen of the larva of the Eyed Hawkmoth (Smerinthus ocellata) was examined on a young willow which it had largely defoliated (illustrated on front cover).
Brackish Water-crowfoot (Ranunculus baudotii) was growing profusely, still in flower, in some smallish south-western water bodies. However, the biggest surprise came when one of the northern ditches (lined by a hedgerow at c.SS537987) was sampled. A solitary plant of Gibbous Duckweed (Lemna gibba) was pulled out of the ditch. It was classically obese and clear-cut gibba; no others were found in spite of specific searches, though Barry Stewart had noted true gibba elsewhere at Penclacwydd several years previously. I am now dubious of my past records (1991 etc) of L. gibba from various Carmarthenshire coastal sites - they seem to be intermediate between gibba and minor in being only slightly gibbous, a state that has been recorded on the Continent.
The same ditch provided yet another surprise when many plants of Greater Duckweed (Spirodela polyrhiza) were seen, not recorded in Carmarthenshire since James Motley’s records of c.1840, presumably from a site in the Llanelli area. Greater Duckweed can be easily distinguished by the several rootlets on each duckweed frond and the purplish hue of the undersurface. It might be of interest to note that I revisited the same ditch in early October but was unable to refind any Spirodela, just mats of Common Water-starwort (Callitriche stagnalis)! I suspect that there is an ‘ebb and flow’ of these surface aquatics, perhaps reflecting changes in water chemistry, temperature and interactive competition. For example, the Ivy-leaved Duckweed (Lemna trisulca) at Machynys Ponds and related ditches has fluctuated dramatically in recent years.
Dragonflies were much in evidence during the visit. Participants stopped to admire a perched Southern Hawker (Aeshna cyanea) alongside the pathway to the pond-dipping area, whilst within the Millennium Wetland several species were noted, including: The Emperor (Anax imperator) Black-tailed Skimmer (Orthetrum cancellatum) Common Darter (Sympetrum striolatum) Broad-bodied Chaser (Libulella depressa) Common Blue Damselfly (Enallagma cyathigerum) Blue-tailed Damselfly (Ischnura elegans).
The Black-tailed Skimmer is a rather recent colonist in Carmarthenshire, preferring newer water bodies with bare banks. For those wishing to study dragonflies, the Field Guide to the Dragonflies and Damselflies of Great Britain and Ireland, by Steve Brooks, British Wildlife Publishing 1997. ISBN 09531399 05, £18.95, is recommended].
Postscript
Nigel Williams of WWT has informed me that the Millennium Wetland is already attracting good numbers of birds. Breeding figures (approx.) include 5 pairs of Little Grebe, 28 pairs of Lapwing (including other parts of the WWT grounds), c.7 - 8 Tufted Duck, 3 - 4 Pochard, 3 Shoveler (which failed) and 1 Gadwall (with 2 other pairs elsewhere at Penclacwydd).
Five species of owl have been utilising the new Millennium Wetland, including a Long-eared Owl (which have previously wintered in the Bynea - Machynys coastal strip). An Aquatic Warbler, a Bittern and a Black-necked Grebe are three rare species which have been present this winter; up to 14 Water Rails have also been recorded.
