Sunday, 15 December 2019

Bryophytes of Watlington Hill

Watlington Hill is a well-known site for chalk grassland bryophytes, although, despite this, relatively few recent records are available for the area (no post-2000 records for the main monad, SU7093, are in the BBS database or on the NBN Atlas for example). However, historically the site has been well searched. Ron Porley, when at English Nature, completed a thorough survey of the Hill in the early 90s, as a part of his work on the chalk grassland of the Chilterns. Porley found the Watlington & Pyrton Hill area to be the richest of the 13 sites he surveyed in terms of chalk grassland specialist bryophytes, recording 46 of his 69 such designated species at the site (although the site was also one of the largest in terms of the area of chalk grassland, estimated at 50.9 ha at that point).

Therefore it was with high expectations that five bryologists assembled at Watlington Hill for the second excursion of the Oxfordshire mossing season (1st Dec. 2019). A number of our group were relatively new to bryophytes, so we started in the woods surrounding the main carpark, demonstrating some of the commoner feather-mosses (pleurocarps) and epiphytes (tree-dwelling bryophytes).

A gentle start to the day!
Our list rapidly swelled, with a number of epiphytes available to demonstrate, including the mosses Orthotrichum stramineum, O. affine, O. diaphanum, Cryphaea heteromalla, and Zygodon conoideus var. conoideus, and the liverworts, Radula complanata, Frullania dilatata, Metzgeria furcata and M. violacea. When I was learning bryophytes around Sheffield in the late 2000s, this would have been considered an impressive haul indeed (at that point, these species were still recolonising after having been previously eradicated from the area due to acidic pollution)! Soon after, David discovered a fallen ash with a superabundance of another epiphyte, Orthotrichum lyellii, a distinctive moss with many brown gemmae covering its leaves. Whilst we often find this on our outings, we normally only find small tufts on standing trees: no doubt our impression is biased by our vision and reach, as this supine ash demonstrated that this species can clearly become locally abundant further up trees!

Orthotrichum lyellii (middle distance) abundant on fallen ash
O. lyellii close-up, showing the brown gemmae

Progressing through the woodland along a track along the edge of the wood, a number of species typical of soil or tree roots were found. The most handsome probably being the liverwort Porella platyphylla, which tends to be found on old limestone walls, graves, hard chalky soils, and the roots of trees on such soils in the Oxfordshire district.

Porella platyphylla on beech root at Watlington.
After lunch, we emerged into chalk grassland, and most of the rest of the excursion was spent crawling around this habitat, as proven by Joshua's tweet below...
A trampled path through the grassland provided us with our first chalk grassland specialists, including Microbryum curvicolle (no photo, but a nice illustration can be found here). Fissidens dubius, Weissia longifolia var. angustifolia, and the tiny stone-covering Seligeria calycina were all also found along this track or in grassland nearby, as well as several other currently infertile small cushion mosses (acrocarps). The idea of returning in the early spring was floated at this point!

Moving into a larger area of grassland on an east-facing slope, David soon located Entodon concinnus, a lovely species normally indicative of rich turf.

Entodon concinnus at Watlington
Sure enough, other species such as Trichostomum crispulum, Hypnum lacunosum and Ctenidium molluscum were all nearby. Mounting the brow of the hill, we encountered the more acid clay-with-flints that often heralds local concentrations of calcifugous species (i.e. those that prefer acid soils). Dicranum scoparium, Polytrichum juniperinum, and P. piliferum were all found in this area.

On circling back to the car park, more rich calcareous turf was found on west and north-west facing slopes, including Ditrichum gracile, Campylium protensum, Plagiomnium affine, Rhytidiadelphus triquetrus, and Brachythecium glareosum. The last was confirmed microscopically back at home, as was Brachythecium salebrosum found in the wood near the carpark at the start of the day. Other species confirmed microscopically included Bryum klinggraeffii, B. ruderale, B. rubens, Fissidens viridulus and Zygodon viridissimus. There were a number of Watlington rarities that we didn't find, but these will hopefully be targeted on the 2020 spring visit previously mentioned! The full list from the day is below.

Ditrichum gracile in chalk grassland at Watlington.
Amblystegium serpens Fissidens dubius Polytrichum piliferum
Barbula convoluta var. convoluta Fissidens incurvus Pseudoscleropodium purum
Barbula unguiculata Fissidens taxifolius Rhynchostegium confertum
Brachytheciastrum velutinum Fissidens viridulus Rhytidiadelphus squarrosus
Brachythecium glareosum Homalothecium lutescens Rhytidiadelphus triquetrus
Brachythecium rutabulum Homalothecium sericeum Seligeria calycina
Brachythecium salebrosum Hypnum cupressiforme var. cupressiforme Syntrichia laevipila
Bryum capillare Hypnum cupressiforme var. lacunosum Syntrichia ruralis var. ruralis
Bryum klinggraeffii Hypnum cupressiforme var. resupinatum Thuidium tamariscinum
Bryum rubens Isothecium myosuroides Trichostomum crispulum
Bryum ruderale Kindbergia praelonga Ulota bruchii
Calliergonella cuspidata Leptobryum pyriforme Weissia brachycarpa var. obliqua
Campylium protensum Microbryum curvicollum Weissia longifolia var. angustifolia
Campylopus introflexus Mnium hornum Zygodon conoideus var. conoideus
Ceratodon purpureus Orthotrichum affine Zygodon viridissimus var. viridissimus
Cryphaea heteromalla Orthotrichum diaphanum
Ctenidium molluscum Orthotrichum lyellii Cephalozia bicuspidata
Dicranella varia Orthotrichum stramineum Frullania dilatata
Dicranum scoparium Oxyrrhynchium hians Lophocolea heterophylla
Didymodon fallax Plagiomnium affine Metzgeria furcata
Ditrichum gracile Plagiomnium undulatum Metzgeria violacea
Entodon coccinus Plagiothecium nemorale Porella platyphylla
Eurhynchium striatum Polytrichum juniperinum Radula complanata

Wednesday, 4 December 2019

Bryophyte season kicks off in the Lye Valley

In a joint effort to be more organised and transparent, this season all our meetings are on the blog calendar! We will be emailing around the details of meetings a few days in advance, if you are on David's botanical mailing list, you'll get them. If not, get in touch!

Our first meeting of the season was to the eastern suburbs of Oxford to visit the Lye Valley (SP5405), incorporating the Local Nature Reserve of the same name. This site used to be known as Bullingdon Bog, and as such is something of a locus classicus for Oxonian botany. It was, for example, the site where L'Obel made the first record of Parnassia palustris for Britain; it was recorded by Sibthorp and Boswell, and featured in early ecological work on calcareous fens by Roy Clapham (later lead author of the primary British Flora in use from 1958 up to the early 90s, when it was superceded by Stace).

A view along the Lye Valley LNR
A view along the Lye Valley LNR. (O.L Pescott, CC0).
It seems that we are lucky to still have the site in the reasonable condition that it is in. Eustace Jones in the early 1950s commented that "Bullingdon Bog which must once have been an ideal example of a calcareous valley bog, is now a disturbed fragment lying in the middle of an Oxford housing estate, and obviously cannot survive much longer." Although the site was scrubbed over in recent years, and the valley sides slumping due to scouring of the valley bottom by a storm drain outflow directed along the stream, excellent management work has taken place in recent years, and is gradually restoring the valley mire to its former glories (thanks to David Morris for this information).

Bryologists assemble! (O.L. Pescott, CC0).
But to the bryophytes! We dropped into the valley from Coverley Road, recording the woodland and along the stream before the beginning of the LNR proper. Many common species were quickly found, including Tortula subulata on friable soil, and Rhyncostegiella tenella on stone. Along the stream the thallose liverworts Lunularia cruciata and Pellia endiviifolia were growing in close association at the bottom of a concrete embankment. An odd amblystegioid growth was also scraped from concrete, which, under the microscope, seemed to match descriptions of the coastal variety of Amblystegium serpens var. salinum. This, however, would be an odd turn-up for Oxford, and must await confirmation from the BBS Recorder for Mosses! Subsequently an old Hawthorn turned up a rich crop of epiphytes, including the ever expanding (and beautiful) species Orthotrichum stramineum and Syntrichia papillosa. An uncertain Ulota was later checked at home, but turned out to be the commonest taxon (at least locally) U. bruchii.

After lunch the reserve proper was tackled, and a new list was begun to ensure that records made would be traceable directly to the LNR. Many epiphytes and common species were again quickly added, including a number that chose to grow on the synthetic wood of the reserve boardwalk (Syntrichia latifolia, S. montana, S. virescens, Orthotrichum affine, O. diaphanum, among others). Next was the fen proper, and many of our expected species began to accumulate (Plagiomnium elatum, Cratoneuron filicinum, Palustriella commutata, P. falcata, Campylium stellatum, Fissidens adianthoides etc.) All previously known from the mire, but all lovely to see thriving. The curious epiphyte Platygyrium repens was also found on a pollarded willow along the stream. Deciduous branchlets of very fine leaves give this species a fuzzy appearance in the field.

Platygyrium repens at Lye Valley. (O. Pescott, CC-BY).
Some known species we failed to refind (e.g. we did not relocate Drepanocladus revolvens or Climacium dendroides), but many other species were added to the site list. A productive day, and a good start to the season.

The list of unique species seen was as follows:
?Amblystegium serpens var. salinum Platyhypnidium riparioides Brachythecium rivulare
Amblystegium serpens Rhynchostegiella tenella Bryum pseudotriquetrum
Barbula convoluta var. convoluta Rhynchostegium confertum Calliergonella cuspidata
Barbula convoluta var. sardoa Schistidium apocarpum s.l. Campylium stellatum s.str.
Brachythecium rutabulum Syntrichia laevipila Cirriphyllum piliferum
Bryum capillare Syntrichia papillosa Ctenidium molluscum
Bryum moravicum Tortula muralis Dicranoweisia cirrata
Cratoneuron filicinum Tortula subulata Didymodon fallax
Cryphaea heteromalla Ulota bruchii Fissidens adianthoides
Didymodon sinuosus Zygodon conoideus var. conoideus Fissidens incurvus
Fissidens bryoides Cololejeunea minutissima Orthotrichum lyellii
Fissidens taxifolius Frullania dilatata Palustriella commutata s.str.
Homalothecium sericeum Lophocolea heterophylla Plagiomnium elatum
Hypnum cupressiforme var. cupressiforme Lunularia cruciata Plagiomnium undulatum
Hypnum cupressiforme var. resupinatum Metzgeria furcata Syntrichia latifolia
Kindbergia praelonga Metzgeria violacea Syntrichia montana
Orthotrichum affine Pellia endiviifolia Syntrichia virescens
Orthotrichum diaphanum Radula complanata Thamnobryum alopecurum
Orthotrichum stramineum Platygyrium repens Cephalozia bicuspidata
Oxyrrhynchium hians
Oxyrrhynchium schleicheri
Palustriella falcata Lophocolea bidentata