Wednesday, 17 January 2018
Days in the Black Mountains 3 - Grwyne Fawr
Day 3 was a day for walking rather than mossing, thanks to a blanket of snow covering the Black Mountains. As the Grwyne Fawr valley had been visited by the BBS in 1999, it seemed a good place for a walk and some poking around, without the need for complete listing. I failed to relocate the majority of the BBS's best finds, such as Campylostelium saxicola and Scapania subalpina, but there were a few nice surprises.
Flushes above the track held abundant Philonotis calcarea and Palustriella, but plenty of searching failed to produce any Amblyodon (recorded once in the easternmost Blacks); likewise searching the flushed track and stream edges didn't reveal any Haplomitrium (again). Pseudocrossidium hornschuchianum at 530m altitude was a surprise, as was some Orthotrichum stramineum on a concrete post. A rock shelf in the river held Schistidium platyphyllum, and I was astonished to spot a colony of Riccia beyrichiana on adjacent thin soil (Tom Blockeel noted this scarce species further down the valley in 1999).
On the way back from the mountains I stopped to record in two fragmentary VC35 tetrads - getting >50 species in both SO22M and SO22R. Porella arboris-vitae was the highlight in the former square, and Fissidens celticus was a surprise find on an anonymous bank in the latter. I also stopped at Coed-dias Bridge to check on the Grimmia decipiens colony that was found there by the BBS in 1999. Only a single cushion remains, at this sole VC35 locus, and copious algal gunk on the bridge parapet suggests that nutrient enrichment and/or increased shade may have caused a decline.