Brownfield slack surprise

On my way out to Witford yesterday it was spitting and looking very threatening, so I decided to make a pit stop in an area of the old BP works where I'd previously recorded the vascular plants several years back and have been meaning to return to check for bryos. The substrate is pure furnace slag that floods in the winter and consequently supports rather nice dune slack vegetation with elements of the NVC communities SD13-SD14.

The main bryos in the winter-wet areas were Drepanocladus aduncus and Hymenostylium recurvirostrum var. recurvirostrum, with locally frequent Calliergonella cuspidata, D. polygamus, Didymodon tophaceus, Cratoneuron filicinum, Bryum pseudotriquetrum & Fissidens adianthoides. I didn't have long, but in the area I walked over, I estimated the Hymenostylium colony extended to at least 1500m² (centred at SS74069208) being frequent throughout. There are similar areas in this part of the site I didn't look at, so the colony could be even bigger. Hymenostylium is not something I was expecting in this situation, but I read in the atlas that it grows at mine sites in Cornwall, so perhaps isn't too much out of context. Unfortunately, there's an inevitability this area will be redeveloped at some point, such is the nature of brown field land. [I'm pretty busy at present, but I'll add some microscope pics and better macro shots when I get a chance]

In the evening, on the way back through the site, I rechecked the general area where I saw the Tortella inclinata last month and discovered it also forms an extensive colony, being locally dominant in an area at least 40m x 4m. The main part of the colony is on tarmac, where it grows as mono-specific stands (actually discernable on the Google aerials SS73189138). Here the colony appears to be spreading over the tarmac from the edges, presumably extending by trapping wind-blown sand and gritty slag. Off the tarmac, in adjacent areas of coarser gravelly slag, the species grows as clumps in a more diverse mosaic of short dune vegetation.

Other tarmac colonists with burgeoning populations thriving on these abandoned roads, noted whilst driving across the site yesterday, included Drepanocladus aduncus (photo 1 below) and Didymodon ferrugineus (photo 3 below). The Drepanocladus hosted a fungus, which I have a specimen of - I don't know if Charles is able to point me in the right direction, if so I'll try and key it out?

Margam sidings

Also known as 'Kenfig marshalling yards', this area is now a stunning brown-field slack full of  goodies.

The 'railway fen' always seems to provide something new each time I visit and a small patch of Pseudocalliergon lycopodioides at SS7913483514 provided the highlight of yesterday's visit. Whilst Calliergonella cuspidata was largely dominant, there's also a lot of Drepanocladus polygamus and D. aduncus in the flooded areas along with a wide range of interesting vascular plants and charophytes; those noted yesterday included Chara virgata, Equisetum variegatum (a), Pyrola rotundifolia subsp. maritima (lf), Cladium mariscus (o-lf) Juncus acutus (lf), J. subnodulosus (la), and Scirpoides holoschoenus. Not too shabby for an area of abandoned industrial land!

L: P. lycopodioides, R: Location shown by plastic box

 L: Equisetum variegatum, R: Scirpoides holoschoenus

L: Chara virgata, R: Cladium mariscus

Leaves of P. lycopodioides, D. aduncus & D polygamus

The drier gravelly sidings also provided a little interest with some nice carpets of Amblystegium serpens var. salinum growing alongside species such as Rhynchostegium megapolitanum, Bryoerythrophyllum recurvirostrum and rather oddly Neckera complanata on open flat ground. A 'golden road' of Schistidium crasspilum was a fine spectacle as the sun started to break through.

 L: Neckera complanata, R: Location shown by knife

 L: Schistidium crassipilum, R: Amblystegium serpens var. salinum

My route

Kenfig slacks

The slacks at Kenfig are remarkably dry for the time of year, in fact chatting to Dave Carrington, he said he couldn't remember conditions being so dry during January in all his time at the reserve. I joined him while he checked a few dip-wells which showed the water level was still 50-60cm below the surface. Despite the low water levels, there has clearly been enough humidity in the slacks to allow the pleurocarps to flourish and there were some lovely patches of well-grown Pseudocalliergon lycopodioides (above, top 3 and below, top 2 photos) and Drepanocladus sendtneri  (above, 4th and below 3rd photo) amongst the sea of Calliergonella cuspidata.

Under the adjacent scrub I was surprised to find Mnium stellare was locally frequent on several steep dune banks.

Humid dune slack at Kenfig NNR

dune slack vegetation supporting Drepanocladus sendtneri, overtopped by Salix repens and Carex nigra tussocks

The small slack south of the bird hide floods quite deep (~80cm) during the winter, although yesterday it was bone dry. The composition and structure of higher and lower plants in this slack is very different to that found in the scraped slacks across the reserve, in fact I have been surprised by the range of vegetation variation there is between slacks at Kenfig. Interestingly, the most abundant bryophyte species in the western half of the slack I was looking at yesterday (in compartment 4a) was Fontinalis antipyretica (four photos below). In places it replaced Calliergonella cuspidata as the dominant underscrub species, forming thick wefts beneath Salix repens scrub, as-well-as carpeting areas of open ground and growing as pendant drapes off the lower limbs and trunks of Salix cinerea. I can see Sam noted similar growths in nearby slacks too, but it's the first time that I have encountered it as a major component of slack vegetation.

 

More significant vegetation in the slack included some good patches of Drepanocladus sendtneri (at SS79628103 - top photo - and SS79568102), which are to be safeguarded from proposals to rejuvenate parts of the slack. A robust form of D. aduncus was also frequent in the slack and some some material seemed indeterminate to my eye, even after examining it under the microscope.

D. sendtneri

Miscellaneous observations of less the familiar taxa included Puccinia cancellata on Juncus acutus and Tuberolachnus salignus (Large Grey Willow Aphid) noted crawling around the lower limbs of Salix cinerea.

The other Kenfig Drepanocladus species

Following on from the recent post of D. sendtneri at Kenfig, here are a couple of pics of the two commoner Drepanocladus species found there, both of which appear fairly frequently in the slack scrapes. Note the strongly falcate dry-ground form of aduncus is particularly prevalent, at least at this time of year.

D. polygamus

D. aduncus

Kenfig NNR scraped slacks

The deep scrape in the south-west of compartment 3

The above scrape is deeper than most slacks in the south of the reserve and the muddy, rather than usual sandy substrate is exposed much later than most adjacent slacks. The dry crusty margin visible in the photo mostly comprises dried up charophytes (Tolypella glomerata identifiable, but others too far gone), but various bryophytes are admixed, the most notable of which is Drepanocladus sendtneri (photos below - voucher retained if required for checking). After spending much time pondering over my specimen, it was relief to find Sam had already recorded the species at this location in December 2011, presumably in much wetter conditions than those shown above.

On the inward (i.e. deeper) edge of the Tolypella crust, in the south-west sector of the scrape, was an abundance of 'baby' (<1mm) Riccia cavernosa plants growing along with young Bryum sp. There were many thousands of plants, this was in contrast to recent observations in some other scrapes on the reserve which supported mature plants, but in much smaller numbers.

Elsewhere vascular plant interest included a reasonably good number of Liparis in Hedgehog Slack in compartment 1, though none in scraped areas. One scrape in this slack did have the miniscule Chaffweed Centunculus minimus and Dave Carrington took me on a quick visit to Sker to see the Field Gentians Gentianella campestris. Good numbers of the Nationally Scarce scarab Onthophagus nuchicornis were among the beetles found in fresh cow pats there too. Kenfig really is such a great place.