Sunday, 4 February 2018

Beacon Hill bryophytes

Beacon Hill, part of the Aston Rowant National Nature Reserve, was the latest destination for the bryophilic element of the Oxfordshire Botany Group (28/01/2018). Three members assembled for a bryological recording session around the chalk grassland and woods of the hill (SU7296 & SU7297), a location that has not been thoroughly surveyed for bryophytes since Ron Porley's study of Chiltern chalk grasslands in the mid-1990s. We admittedly had a fairly easy-going recording session, and so I don't think we would claim that we surveyed the site anywhere near as intensively as Ron, but we recorded 53 species (67 records) across two monads, and refound a few of the characteristic species noted by Porley, as well as some species which appear to be new for the Hill.

Looking across to Aston Rowant from Beacon Hill.
Fissidens dubius
Focusing first on the west-facing slope around SU728968, we quickly picked up a slew of typical chalk grassland species, including Homalothecium lutescens, Fissidens dubius, Plagiomnium affine, and Weissia longifolia. Here we also found our first plants of Rhodobryum roseum, a particularly large and handsome moss that tends to be indicative of habitats that are of importance for nature conservation (due to its requirement for an open, low nutrient sward), and was unfortunately one of the species included in the "decreasing generally" category of Mark Hill & Chris Preston in their analysis of change in the recent Atlas of British and Irish Bryophytes.

Rhodobryum roseum
Rhodobryum in a typical anthill setting
Later on, in a "hollow way" lane cutting down the west-facing escarpment we recorded a good number of epiphytes, most new for the site, including two attractive Neckera species, N. complanata (pictured) and N. crispa. Here we also found a number of more weedy species existing on the risers and treads of wooden stairs installed for easier access, including Orthotrichum anomalum, Campylopus introflexus, Barbula sardoa, B. unguiculata, and Homalothecium sericium.

Neckera complanata
After lunch, we were back on higher-quality ground, inspecting the open expanses of grassland on the plateau of the hill, around SU727971. Here, after some patient hound dog style searching, we were rewarded with a cluster of rarer chalk grassland pleurocarps. These included Campylium protensum, Entodon cocinnus, and Hypnum cupressiforme var. lacunosum. The first of these has apparently not been reported for Beacon Hill, and is rare in chalk grassland in Oxfordshire; E. cocinnus is known from Beacon Hill, but has not been reported recently, at least according to records available from the British Bryological Society and the NBN.

Campylium protensum
Entodon cocinnus
The full list of species for the day is given below. Another visit will certainly be in order, as there are a number of nationally scarce bryophytes found by Porley that we didn't manage to rediscover.

Liverworts Fissidens dubius Zygodon conoideus var. conoideus Plagiomnium undulatum Brachythecium rutabulum Entodon concinnus
Metzgeria furcata Fissidens adianthoides Orthotrichum affine Campylium protensum Brachythecium salebrosum Cryphaea heteromalla
Radula complanata Dicranum scoparium Orthotrichum anomalum Amblystegium serpens Homalothecium sericeum Neckera crispa
Frullania dilatata Campylopus introflexus Orthotrichum diaphanum Thuidium tamariscinum Homalothecium lutescens Neckera complanata
Lophocolea bidentata Weissia longifolia Bryum pallens Pseudoscleropodium purum Calliergonella cuspidata
Mosses Barbula convoluta var. sardoa Bryum capillare Eurhynchium striatum Hypnum cupressiforme var. cupressiforme
Seligeria calycina Barbula unguiculata Bryum pseudotriquetrum Rhynchostegium confertum Hypnum cupressiforme var. lacunosum
Fissidens viridulus Didymodon vinealis Bryum dichotomum Oxyrrhynchium hians Hypnum cupressiforme var. resupinatum
Fissidens incurvus Syntrichia ruralis var. ruralis Rhodobryum roseum Oxyrrhynchium schleicheri Ctenidium molluscum
Fissidens taxifolius Zygodon viridissimus var. viridissimus Plagiomnium affine Kindbergia praelonga Rhytidiadelphus squarrosus

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