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.

My final stop for the day was another site which has been 'done' regularly in the past: Coed-y-Cerrig NNR.  I actively avoided the NNR in the past, focussing my efforts on other parts of the tetrad, but it is now 20 years since Martha Newton's survey and 'Bosanquet's Rule' is that "well-recorded sites will always produce the most exciting new finds".  Sure enough, star find of the day came from a sandstone block ca. 60m from the carpark: three loose cushions of Grimmia hartmanii (new for VC35) growing alongside Plagiomnium cuspidatum.  The frequency of Porella arboris-vitae was nice too, although this species is well-known from Coed-y-Cerrig.

1 comment:

  1. The Grimmia decipiens tuft I saw almost 20 years ago was about fist-sized, be amazing if yours was the same tuft, albeit much reduced - a wonder it grows there at all in such a damp shaded spot. Well done with the Grimmia hartmanii - i'll keep an eye open for more if I visit again.