After the Rhodies have 'gone'

Following the clearance of blanketing thickets of Rhododendron in parts of Cwmdulais a few years back, I have made a few casual records of what has been recolonising. The only lower plants (which currently provide the bulk of the ground cover) noted in a small sampling area during a casual Christmas Eve stroll, were (in decreasing levels of abundance) Campylopus introflexus, Cladonia chlorophaea agg., Dicranella heteromalla, Hypnum cupressiforme var. cupressiforme, Polytrichum juniperinum, Cladonia coniocraea and Dicranum scoparium. Clearly there is more diversity than this in the valley (see my previous post HERE on this subject), but to date recolonisation of cleared Rhododendron in the valley has been by a rather limited suite of species. Needless to say the Rhododendron is showing good signs of recovery!

A small, mildly basic flush at SN61730358 did provide a point of interest amongst this predominantly acid tolerant vegetation, with species noted (again in decreasing levels of abundance) including Dicranella varia, Riccardia chamedryfolia, Aneura pinguis, Cratoneuron filicinum, Didymodon fallax, Philonotis Fontana, Didymodon tophaceus, Didymodon insulanus, Pellia endiviifolia, Pohlia wahlenbergii var. wahlenbergii, Bryum pseudotriquetrum & Pseudocrossidium hornschuchianum. I'm not sure if this vegetation comprises recent colonists or was hiding beneath the Rhodendrons prior to clearance?

South Wales gets Bigger

Having recently moved to Wales I thought I’d share some of the bryophytes near my new home but it would be stretching it a bit to call it South Wales!  We now live in Goginan which is about 6 miles east of Aberystwyth in one of the many valleys that penetrate into the Cambrian Mountains from the coast.  The stream here is the Melindwr which joins the better-known Rheidol a few miles downstream.  There is much evidence of mining in the valley, the local spoil heap having good quantities of Lophozia incisa under heather but none of the real specialities of some of the lead mines in the area.  Lane banks as you start walking upstream are notable for an abundance of Diphyscium foliosum and rock outcrops often have some Rhabdoweisia crispata cushions.  Further still up the valley the sides steepen and there are extensive rock outcrops.  Both Hedwigia stellata and H. integrifolia can be found here, the latter in impressive sheets over wide areas of rock.  Judging from the comments in Jeff Bates’ excellent book, this must surely be one of the best spots for it in this part of Wales so far discovered.  Many patches are over a foot across.

 

Also on these rocks are numerous cushions of Cynodontium bruntonii.  The mamillose cells are readily apparent in section but the way the leaves get markedly longer going up the shoot is proving to be a useful indicator in the field, at least for separating it from Dicranoweisia cirrata.  No rare Grimmias as far as I can see but will keep looking.

 

The valley opens out into moorland at the top with some very old sunken trackways.  The banks of these have fine colonies of bryophytes, in some places with good patches of Anastrepta orcadensis easily picked out from surrounding Barbilophozia floerkii by the dark brown gemmae.

On the vertical peat edges of one of the tracks, where cut by vehicle tyres, are tiny patches of Cladopodiella francisci, difficult to find buried under filamentous algae and surely much overlooked in this most unglamorous of habitats.  Another under-recorded moss on these tracks is Polytrichum commune var. perigoniale.

  

 I’ve spent many hours identifying Racomitrium spp.  To start with I couldn’t find anything other than R. affine but after cutting innumerable leaf sections, R. heterostichum was finally found but only on the rocks along the ridge at the top of the valley with all material from the valley sides proving to be R. affine.  Also on rocks at the top are many small cushions of R. sudeticum, hardly resembling the other members of this group.  I'll try and put some notes together on some of these segregates, including R. obtusum I hope, but I'm still learning at the moment!

I’ve followed in Sam’s footsteps to a few other sites nearby, particularly where basic rock intrudes through the very acid shales that dominate the geology here.  Bryn Bras proved an excellent spot and I refound most of Sam’s goodies but Sphagnum skyense eluded me.  I was able to add Cephalozia pleniceps from a small bog on the moorland above the cliffs and there was Barbilophozia atlantica on a boulder by the river.  The Bwlchglas mine still has Ditrichum plumbicola but clearly much reduced from 2005 when Sam described it as being abundant in the identical spot.  A walk to Craig y Pistyll via Banc y Garn got no further than Banc y Garn as the basic outcrops and flushes there were just too tempting with sheets of Preissia quadrata pointing the way.  Not much new for the site although a large colony of Rhabdoweisia crenulata was a nice way to end the day.

More news soon.  Tom.

Rhododendron clearance pioneer bryophytes

Today I stopped to take a very quick look at an area on the valley sides of Cwmdulais (SN618035), which were cleared of dense stands of Rhododendron ponticum four years ago. Vascular plants seem very slow in recolonising and the ground was found to be largely dominated by bryophytes, with the most abundant species being Ceratodon purpureus and Polytrichum juniperinum, with frequent Atrichum undulatum, Bryum capillare, Campylopus introflexus, Cephaloziella divaricata, Dicranella heteromalla, Pogonatum aloides and Polytrichastrum formosum. No surprises, but a good indication of the pioneer bryophyte assemblage which develops following ‘Rhody’ clearance on open hillsides. For reference the adjacent vegetation on non-affected slopes is principally Bracken-dominated, though there are some signs of this slowly re-establishing in cleared areas.

Polytrichum juniperinum

Ceratodon purpureus & Dicranella heteromalla

Interestingly Yellowhammers still occupy the Rhody areas, both cleared and dense stands, and we saw 7+ nearby in Sandra's aunties garden.

More stuff from the uplands

Block scree habitat above Blaengwynfi

High above Blaengwynfi, in the Afan Valley, a forestry road straddles the border between NPT and RCT. Not far away, the Pen y Cymoedd wind farm development is transforming the landscape on a geographical scale. Some nice habitat mosaics survive (just!) at least for the time being, such as small areas of wet peatland with abundant Drosera and heathy banks with clubmosses. In a few places, sandstone block scree, the remnants of old quarry workings, provide the sort of bryophyte habitat that George has been showing us recently. Racomitrium ericoides is common on rock in places like this. As Sam tells us, we should look for and perhaps expect R.elongatum in these habitats and I have spent hours looking at likely specimens - but to no avail. Spotting R.elongatum in these places might be tricky and serendipity will probably play a big part. On our trip to the site in the photo above (SS9009/9858), we saw a smallish dark-coloured Racomitrium growing in a fairly tight, cushion on a rock. It looked pretty good for R. sudeticum in a likely habitat not far (as the crow flies) from the Craig y Llyn population, and not that far from the Afan Argoed colony. However, leaf sections clearly revealed a bistratose costa - so it's heterostichum.  All other R. heterostichum that I've seen has been the typical dark grey in colour with conspicuous hyaline points on the leaves.  I think I'm beginning to appreciate how variable this species is - and this also ties in nicely with George's recent post.

Racomitrium heterostichum

Other species on rocks here included R.aciculare and R. fasciculare, the former frequently encountered by us in habitats like this, away from any water course. The iron-rich sandstone rock typically supports crustose lichens like Porpidia macrocarpa and Lecidea lithophila but there was also a significant population of Stereocaulon dactylophyllum scattered over the scree.

Stereocaulon dactylophyllum

Hilary was struck by the large amount of fruiting Polytrichum piliferum here with attractive red seta (completely lost on me, of course!!!).

Polytrichum piliferum

Other interesting stuff included Tortella tortuosa, in the company of other calcicoles like Ctenidium  molluscum and Campyliadelphus chrysophilus, mostly confined to the calcareous edges of the road. This is a rare species in NPT (there's no limestone in the county) but is also found on a coal tip in Afan Argoed and on an old wall near Cwnllynfell.

It's not always easy to get to these upland sites and, invariably,it requires quite a bit of hiking. But since that has probably put off others doing it before you, there's always a high probability that you'll be doing some trail-blazing surveys. RCT is full of places that fit into that category.