North of Pontardawe

A job in Pontardawe yesterday gave me the opportunity to boost a couple of tetrads (SN70H & SN70I). The sandstone crags in Coedalltacham (SN723048) held small quantities of Amphidium mougeotii and Diphyscium foliosum, but despite looking promising held little else of note in this rather dry hanging oakwood dominated by Luzula sylvactica. The most interesting event at this location was when I took off my right welly to remove a stone, then watching it roll and bounce a couple of times before dropping over a 5m cliff. With plenty Holly and Bramble in the shrub layer, it was a very prickly descent to retrieve it!

The bryoflora along the banks of the nearby stream running through more humid, largely acid oak woodland in Cwm Sion (SN729053) was much more diverse, with frequent Amphidium mougeotii and Saccogyna viticulosa  [photo below] and occasional Fissidens pusillus, Jungermannia pumila, fruiting Pseudotaxiphyllum elegans [photos below] and a small quantity of Trichostomum tenuirostre [couple of small shoots in top photo below]. Wefts of Heterocladium heteropterum were a bit confusing as cell shape (4:1 ratio) fit var. heteropterum, but size was much better for var. flaccidum - any advice welcome. Also I'd be grateful if anyone could let me know what the spiky rudimentary leaves are, which to the naked eye looked like dark reddish fuzz growing on rock, under shaded overhangs [bottom two photos below]? [identified by Sam as Tetrodontium brownianum].

 

Finally a quick stop at a bog on Cefn Gwrhyd (SN725064), which looked interesting with frequent Hypericum elodes, Menyanthes trifoliata and nine species of Sphagnum, produced records of Cladopodiella fluitans and Warnstorfia fluitans [photos below]. A Cephalozia looked interesting but I couldn't make it anything other than bicuspidata.

flood depth and duration for some bryos in a sinkhole

me again.

In my day job I am a jack of all trades, however sometimes I look at karst aquifers. I have just published an article on measuring flow into a doline / sinkhole. Anyhow I managed to scrape in some flood depth and duration data for the bryos living at the base of the sinkhole including; Gymnocolea inflata, Sphagnum denticulatum, Warnstorfia fluitans and Mnium hornum. Interestingly (or not you may tell me) is that they are all tolerant of flood depths of up to 6m for durations of 20-40% of the study period (a year). The crux of the paper was the actual hydrology however I made a call that these small ephemeral ponds are under-recorded and should be considered as wetlands? Who knows?
Maybe there is someone out there who wants to survey some upland dolines ? I hope to be supervising a MSc looking at dolines on Mynydd Llangynidr this year, so if anyone is interested, or you have students or others asking for experience, then ill be messing around up there in the very near future, im sure there will be room for one more !

Right off to a Bar-b-q, time to pack sunglasses, shorts, raincoat and umbrella.

Full paper is free to download at this link http://nora.nerc.ac.uk/513515/

Source of the Llan

... well actually, 400m downstream from it, where I managed to squeeze in a quick smash and grab session in failing light (15:45-16:15). Although the water course and its banks seemed to support a rather limited bryo-flora, there were a couple of species of interest: Warnstorfia fluitans (locally frequent on the grassy flood zone alongside the stream) and Atrichum crispum, the latter conveniently growing adjacent to A. undulatum. Like the Warnstorfia it was mostly under water following the recent rains, hence no field shots. The species has a very different look to undulatum, with the shoots being more lax and a much brighter green. The photo below shows the narrowed leaf base and broad leaf shape. The ridges on the costa are smaller than those of undulatum, which you can get an impression of through a lens (just visible in photo above - you may need to zoom in a bit), which rules out any confusion with Mnium. This was only the third Glamorgan tetrad record, but given the rather mundane habitat, it's one we might expect to see more of in upland streams.

Warnstorfia fluitans with what looks like rather large alar cells, but the habitat, habit (dense sprawling mat) and presence of rhizoids on the leaf tips (with algae entangled) all make a safe id. Note the denticulate margins rule out Drepanocladus.