More Treasure in the Bracken and some Blorenge Delights

I haven’t posted for a while as I have hardly been out of the home or the office, but this week I managed to get out to the Blorenge near Abergavenny, where I found myself in an area of bracken-infested Vaccinium heath with frequent scattered boulders.  Remembering my visit to Craig y Cilau about this time last year when I found Tritomaria exsecta in similar bracken-infested and rocky habitat, I jokingly set myself the challenge of finding some T. exsecta on the Blorenge.  Amazingly, the first small rock I looked at (centre of pic) had a nice patch of Tritomaria and there were patches on other rocks nearby.  

Afterwards I checked the spores and they turned out to be nice and smooth – Sam comfirmed that it is the first record of T. exsecta for Monmouthshire since 1956.   It would be worth searching out boulders in bracken in other areas just in case the habitat turns out to be 'a fairly predictable locus' for the species.

I didn’t see many other bryos of great interest on the rocks, although there were some nice patches of Barbilophozia attenuata here and there. 

Whilst at the site I thought I would pay my respect to the large population of Andreaea rothii subsp. falcata on gritstone pavement next to the Foxhunter carpark, which I first saw about 21 years ago.  In places a small amount of water seeps from surrounding vegetation and across the rocks and in damp runnels there were a few patches of Bryum alpinum. 

  Sam informs me that this species still qualifies as a county rarity with only 5 records and that it was recorded at this very spot in 2017.  Whilst trying (and failing) to take a reasonable photo of the Bryum (I think my camera is finally starting to wear out after 17 or 18 years of use!) I noticed a dark patch of lichen out of the corner of my eye and sure enough when I took a closer look it turned out to be Umbilicaria deusta.   

The Blorenge has had some serious moorland fires in the past – the worst I recall was about 20 years ago, when the majority of the hill was burned, with pockets of peat smoking and reigniting for weeks afterwards.   About 10 years ago, just as the heathland vegetation had recovered, there was another extensive fire.  I recall visiting the area just south of the transmitter a year afterwards and was quite impressed by how large areas of bare peat had been quickly colonised by Marchantia ruderalis and also Polytrichum longisetum (pic is from back then and I expect that is longisetum in the centre).  

Today the vegetation has again recovered well, with extensive areas of heather and patches of Vaccinium vitis-idea here and there.  A close look, shows that there are still frequent bryophyte-dominated patches between the clumps of heather, but now instead of Marchantia, these are mainly dominated by Campylopus introflexus, with little bare peat.     From where I was standing I could see about 100m away some more patches of damp looking vegetation-free gritstone pavement, so I thought I would take a look to see if there was more U. deusta.   I didn’t find any of this lichen but there was a lot of Lasallia pustulata (an associate of U .deusta at most of the sites I have seen it).

There were also frequent patches of Stereocaulon – which on closer inspection turned out to be mainly S. dactylophyllum, which I haven’t seen for years.  

Also on the damp rocks was abundant Rhizocarpon lecanorinum – it also occurs more rarely on scattered boulders on the Blorenge, but perhaps these damper rocks is its preferred habitat as I have seen it in some abundance in similar habitat at Ogof Fynnon Ddu in the upper Swansea valley, also growing alongside Lasallia.   

Some blocks screes on the Blorenge support very nice bryophyte communities and some of the more exposed screes and scattered blocks that have escaped burning also have some very nice lichen communities.   Umbilicaria torrefacta is one of the more interesting lichens present – I have mainly seen it on the hill north of the transmitter, which has been less affected by fires, but it also occurs in small quantity on a handful of boulders immediately south of the transmitter and during my visit I spotted a few small patches on a couple of rocks resting on top of the gritstone pavement where the Stereocaulon was frequent. 

 Many of the scattered rocks through the heathy areas are, 10 to 20 years on, still bleached by fire damage - there is some re-colonisation, but it is slow and I doubt if I will live long enough to see species like U. torrefacta re-colonising.  The pic shows small colonies of what look like Rhizocarpon geographicum and probably represents getting on for 10 years of growth.

On returning to the car park I took a quick look at a colony of Lycopodium clavatum that Sam and I bumped in to about 20 years ago – it occupies a south-facing bank on an old spoil heap and must have really suffered during last years hot weather, so it was good to see the colony had survived and is looking relatively healthy.