Tuesday, 13 March 2018

Atlas 2020 update

This post is just a short announcement and advertisement of the updates I have finalised to the Atlas 2020 page describing the project and progress with recording for the Atlas in Oxfordshire. I have over-hauled the previous interactive tetrad map, as you can see below. It includes a function to display areas in need of attention as well as the more usual illustration of well-recorded areas, and provides links to full lists of taxa recorded in each tetrad. I hope this will be of use to botanists planning recording this season.

Thursday, 8 February 2018

The year in botany

Recording plants at Somerton during a field meeting in May 2017
Now that we're well into the new year I thought it about time I had a look back at 2017. Much more happened during 2017 than can be summarised here — you can get an idea of local activities during the last year by reading the blog posts. If you've any highlights you'd like to share then consider leaving a comment below this post. It was a memorable year for me, not least as it was my first full year in the post of vice county recorder. I have enjoyed beginning to get to know the county's flora and its botanists, particularly through meetings (ten of which were covered on the blog). Numerous local botanists have also been out enjoying themselves outside of meetings, and it has been a pleasure receiving their records and learning what they've been up to. It has been particularly gratifying to see new recorders find their feet (there was a beginner recorders' meeting in April), and for me to be in a position to assemble everyone's contribution to Atlas 2020.

So far 13,623 records made during 2017 have been submitted to the BSBI Distribution Database (DDb). A further 4,114 records were submitted to iRecord, but these have yet to migrate over to DDb. iRecord submissions were almost double that of last year due to new recorders taking up this platform, but 13,623 is a bit of a dip for the DDb compared with 2015 and 2016 when over 24,000 and 25,000 were submitted, respectively. If you have records please therefore send them to me! I blogged earlier in the year about the the vascular plant record sharing agreement with Thames Valley Environmental Record Centre (TVERC), which was quite a big development, making a huge difference to the BSBI's Oxon data holding, with over 340,000 records received. Many recorders over the last couple of decades have preferred to send their records to TVERC, and being able to tap this activity has made a significant contribution toward Atlas 2020. It has been and continues to be a big job to check all these records but it is worth the effort!

I'm sure you're desperate to read how the county is getting on with Atlas 2020 following the 2017 recording season — the up-to-date tetrad (2km square) progress is shown in the map to the left, based on DDb records from the beginning of 2000 to present. This shows more clearly than maps I've previously published how survey effort has been expended, with both tetrad total taxa (tetrad colour) and total recording rate (tetrad size) illustrated. While coverage of the county has continued to improve, one can see that there is work to do in terms of consolidating the recording done to date, i.e. increasing the cover of 'bigger squares' (generally a recording rate of 60% requires about 200 taxa to have been recorded), and recording in the far-flung areas around the county boundary. This is essentially the message I've communicated previously, such as on the Atlas 2020 page, so we just need to keep on working at this up to the conclusion of the Atlas recording period.

The Oxford and Otmoor areas (SP50 and SP51) exemplify the situation we would ideally like to reach but as I've said before it is not essential or possible to fill every gap. At the scale of hectads (10km square), which will be the mapped units in the published Atlas 2020, most now stand at 50-60% recording rate or better (and similarly for the re-find rate), and most have at least 20% of tetrads with 100 or more taxa recorded, which is quite a good situation; targeted recording during 2018 and 2019, including repeat visits to tetrads, will improve the recording rate. Please do get in touch if you need help identifying areas for recording in your area.

Tetrad coverage for Atlas 2020, with tetrads coloured by number of taxa recorded since 2000, and square size scaled by total recording rate, i.e. the proportion of taxa recorded since 2000 out of all taxa recorded.

Above: Potamogeton nodosus in the Thames, Frank Hunt. Right: Carex muricata subsp. muricata in the Chilterns, Geoff Toone.
Now I come onto the less dry developments of 2017, the records of notable plants. The record that stands out of course is Frank Hunt's rediscovery of Potamogeton nodosus (Loddon pondweed) in the Oxfordshire part of the River Thames, a nationally rare species which had only ever been known in the county for a short period during the 1940s. Its reappearance in the Thames it turned out had actually already been established on the Berks and Bucks reaches of the river by the Environment Agency a few years ago, but this was still a very exciting record for Oxon. This rediscovery follows that of Rosa agrestis (small-leaved sweet-briar) in the county in 2016 — I hope that we may have a rediscovery every year!

Recording meetings during the year turned up many records of note. Less satisfactory was the grotty umbellifer found growing submerged in the River Cherwell during the meeting in Somerton in May: it was suspected to be Oenanthe fluviatile (river water-dropwort), thought extinct in the county, but later searching could not relocate it and its identity remains a mystery. On the same meeting was re-found a small population of the uncommon crowd-pleaser Saxifraga granulata (meadow saxifrage), a larger population of which was also rediscovered in December at Peppard chuchyard on the New Year Plant Hunt. With the county generally quite under-recorded, there are plenty of opportunities such as these for re-finding notable plants at old localities as part of Atlas recording, e.g. Fay Banks' Sambucus ebulus (daneberry) at Garsington this last year. Recording also turns up unusual or casual plants, and this year I had an odd weekend when several records of the locally rare Anthriscus caucalis (bur chervil) were sent to me.

Finally, a little-known Oxfordshire plant, the nationally rare Carex muricata subsp. muricata (large-fruited prickly sedge), came to my attention this year when I received a batch of records from Geoff Toone and Paul Stanley from back in 2011. Only discovered in the county early in the 2000s (I think at Hartslock, though I can't find the record), this sedge is beginning to emerge as potentially quite a widespread plant of Chiltern beechwoods, and many thanks are due to Paul, Geoff and others for continuing to track it down.

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

Thursday, 11 January 2018

Hinksey Heights Bryophytes

Botanists enjoying a coffee break in the wood along the valley
Sunday was another winter outing for local botanists, this time on the Hinksey Heights south of Oxford and better attended than the last. Hinksey is in vice county 22 (Berkshire) meaning a day off recording vascular plants for me, but the meeting was focused on bryophytes anyway. The main interest was one of a series of long narrow valleys draining north off the heights, fed by calcareous groundwater emanating from the limestone along the valley sides. There is peat in the upper part of the valley, and it was once an open fen rich in plants such as grass-of-Parnassus but now mostly covered in willow and reed.

The valley is a nature reserve and can be reached from the Hinksey Heights Golf Club via a footpath and board walk leading north-west from the car park (the temptation to botanise which was resisted). The valley opens out at the entrance near its bottom where there are fabulous views of Oxford and its encircling hills to the north and east. The southern slope here supported the only area of Juncus subnodulosus (blunt-flowered rush) fen we came across, but it was rather overgrown.

The stream tumbling over its tufa weirs
This is where we set to bryologising, and as there were a few new-comers to the subject we could share the revelation that is the tiny world of bryophytes, with ample demonstration material provided by the several common species growing on the accumulated fen litter. The only fen moss we found, however, was a scrap of Bryum pseudotriquetrum. The stream within the woodland in the valley bottom had me fantasising of Eucladium and Gymnostomum species, with its spectacular tufa weirs (or barrage tufa) and drifts of petrified leaves and twigs. Tufa is formed where limey waters precipitate calcite (the principle calcium carbonate mineral) onto lower plants and debris, encasing them in stone, and has a specialist bryophyte flora adapted to this highly alkaline environment. The bryophyte flora, however, was rather dull, most surfaces being covered in the pleurocarp Cratnoneuron filicinum, or the thallose liverworts Conocephalum conicum and Pellia endiviifolia. This suite of species followed us up the valley, dominating the weirs, dripping banks of the stream and springs.

The peaty springs higher up were a little richer, but mostly covered in wefts of the common mosses Plagiomnium affine and P. undulatum. Exceptionally, however, and the highlight of the meeting, both species were producing sporophytes, which for P. affine is a very rare occurrence. Most species of Plagiomnium are dioecious (sexes on separate plants) and are shy to produce sporophytes — the only currently known record of P. affine in fruit in Oxfordshire or Berkshire is from nearby Bagley Wood, found by Watson many decades ago.

Fruiting Plagiomnium affine growing with Cratoneuron filicinum in a tufa spring
Like the two Plagiomnium species, most of the mosses and liverworts we recorded were general calcareous woodland plants rather than specialists of wet woodland or fens. We recorded a number of epiphytes such as the increasingly common Orthotrichum pulchellum and O. stramineum, as well as the uncommon and Brachythecium salebrosum growing on an elder. Altogether we recorded 9 liverwort and 38 moss species, but with a few specimens yet to be examined this is not the final tally. Thanks to everyone for an enjoyable meeting!

Brachythecium salbrosum growing on elder (left). The meeting was too early for the pretty capsules of Orthotrichum stramineum (right, April, Blenheim Park) but old dry capsules are distinctively red-brown and flask-shaped.