Marvellous Merthyr Mawr

Prior to undertaking a search of the scraped slack habitats at this beautiful NNR, Sam's NRW colleagues, Duncan Ludlow and Emma Brown kindly showed me one of the known Petalophyllum ralfsii colonies at Merthyr Mawr yesterday, plus we also visited the spot where George made his nocturnal observation a week or two back. Given the very dry conditions at these locations, I was pleasantly surprised by how large and verdant the Petalophyllum plants were.

We also looked at one of this year's Portland Moth locations, where George recently discovered Riccia cavernosa and we estimated there must have been a few thousand small rosettes developing. As far as I'm aware this is a new species for the reserve. The largest specimens we could find are depicted below, but most were much smaller. Given the right conditions, there could be quite a display here. Duncan informed me that this area has been subjected to some scrub clearance work and its use as a bridleway stopped, so the occurrence of the moth and the liverwort highlights at least two significant benefits of the work and controls implemented here. I've marked the extent of the Riccia colony on the photo below.

Unfortunately there was no Petallophyllum or Riccia to be found in the two scraped areas I examined, though the larger slack is at a very early stage of colonisation and was well populated with non-fruiting Bryum species. In addition to frequent dichotomum and argenteum and occasional gemmiferum, there were patches of putative dyffrynense (photo below), which may be worth sending off to David Holyoak? At least two other Bryum leaf forms were present, so a site well worth revisiting as succession takes place...

...PS. does anyone know what causes these rings in the wet sand? I'm guessing it's fungal, but I never collected any to look under the miscroscope.

 

Pendine MOD

I spent a full day on the Pendine dunes today, thanks to an Unaccompanied Pass organised for me.  The primary aim was to survey as many track edges and other areas for Petalophyllum as possible to inform future works by the MOD: something I started in ad hoc accompanied sessions on 4+ days over the last 5 years, but always struggled with because of a combination of a) some ranges always being off limits during the week and b) the difficulty of surveying when accompanied by somebody looking totally bored.

My target species was extremely elusive: it has gone from the far eastern Range where David Holyoak found it in 2002 and from most of the C9 Test Track, and was absent from various suitable-looking patches elsewhere.  The easternmost site has now developed really nice calcareous vegetation, with abundant Pleurochaete (new to Carms), locally frequent Didymodon acutus (2nd vc colony), frequent Encalypta streptocarpa & Ditrichum gracile etc, but liverworts were absent and I assume succession has knocked out Petalwort in the last 13 years.  The next patch I checked had been touted by David Holyoak as ideal habitat in 2002, but it still held no Petalwort, although two tiny patches of Abietinella abietina (3km E of the other extant Carms colony) were pleasing.  I'm sure the vegetation has developed a lot, as David would never have missed the great abundance of Pleurochaete at the first site, nor I suspect the Abietinella, Didymodon acutus here and at C9 etc.

I finally found Petalophyllum along the C9 track, but in far smaller quantity than in 2002, again because of succession: in this case blown sand burying the area alongside the track that previously held the liverwort.  The only remaining patches were a) on the sandy edges of a concrete pad (crap iPod photo below, as I didn't take a camera) and b) on the edge of the road along the test track.

Wall to wall sun, 15+ Wheatear, 3+ Willow Warbler and a flyover Tree Pipit were bonuses, as were 2 Swallow over St Clears on my way home.