St David's Commons

Middle Pond on Dowrog Common

Thanks to Sarah Beynon at the Bug Farm, I've just started some work surveying commons and some associated land near St David's. Only two days in, but already some surprises.....

I'll confess I wasn't expecting much from Dowrog Common, as under-grazing has left much of it as a sea of rank heath and moor-grass pasture. Pleasing then to find Cladopodiella francisci by a cattle path near the northern fenceline, and some Ephemerum crassinervium ssp. sessile on the stone track to Trefadog. Both are Nationally Scarce - the latter is proving to be almost predictable in the right damp habitats in the county, but the former is only known from single locations on Carn Ingli and Mynydd Preseli.

The star find on Dowrog was a good population of Micromitrium tenerum on the dried-up bed of an ancient clay pit, 'Centre Pond', on the north side of the road. 'Turfs' of this tiny moss, complete with ripening capsules, dominate the silty-clay centre, and smaller patches are interspersed with Juncus bulbosus around this. It is absent from the Scirpus fluitans dominated fringe.  The only associated bryophyte is a small amount of Pseudephemerum nitidum. This represents the only extant Welsh population of this red-listed moss, the two tiny patches recorded at Wyndrush Pastures SSSI a couple of years ago having proved to be a transient occurrence from a long-buried spore bank. The several square metres occupied here may perhaps represent the strongest UK population. There are plenty of other ponds on Dowrog, but all appear to either be overly-trampled clay, or too strongly vegetated. It will be important to maintain the right grazing levels here, and to resist over-deepening or other works. Australian Swamp Stonecrop Crassula helmsii is now rife on parts of the nearby St David's Airfield Heaths, so poses a real threat here too. 

Millimetre Moss - Micromitrium tenerum

Over on the Airfield Heaths, I had no luck refinding the Drepanocladus sendtneri in the small fen-hollow on Waun Llandruidion, although the associates originally noted by Sam Bosanquet (Calliergon giganteum, Scorpidium scorpioides and Scorpidium cossonii) are still present under the Carex lasiocarpa. A small patch of open clay below a gorse bush on an old causeway around Waun Llechell held a tiny patch of Cephaloziella integerrima, which represents a third Welsh site for this rare liverwort, only recently found new to Pembs on the Castlemartin range. The biggest surprise, however, came from the edge of the limestone chip path a few metres away. Growing with Aloina aloides and common ruderal species such as Barbula unguiculata, Pseudocrossidium hornschuchianum and Bryum ruderale I collected four shoots of a non-fruiting Ephemerum. Under the microscope, the broad leaves, strong costa, prominent 'shoulders' and some cells in divergent lines all point to Ephemerum cohaerens. This would represent the first Welsh record (and an atypical habitat), so will shortly go to the referee for confirmation (subsequently confirmed by Sharon Pilkington)

Ephemerum cf. cohaerens and location

Lastly, I had a crawl about on the Bug Farm heathland creation project area that I designed and 'built' last winter. Pleasing to see plenty of open, damp clay as well as heather and gorse germinating well from the mowings from the adjoining Waun Fachelich. Ephemerum crassinervium ssp. sessile and Acaulon muticum were good early results here, amongst the abundant Trichodon cylindricus, Tortula truncata, Pseudephemerum nitidum and other pioneer species.

Heathland Creation field at the Bug Farm