Monday, 24 April 2017

Waterend and Beacon's Bottom

Botanists using the BRC's iRecord app to record bush vetch (right) growing on a road verge in Waterend.
The first meeting of the year is always an event to look forward to, and Sunday 23rd was the first of the botanical recording meetings I will be organising this season. The meeting was based in Waterend, a small hamlet to the east of Stokenchurch (SU79), and was attended by seven botanists.

For the morning we were very kindly hosted by a member of the party, and tea was a welcome accompaniment to the serious matter of the meeting: the where, how and what of botanical recording! For this was no ordinary square bash, but an opportunity to learn in a more focused (I hesitate to call it structured) way how to go about gathering botanical records.  Ostensibly this was to provide help and encouragement to locals interested in recording for Atlas 2020, for which there is much to do in Oxfordshire, particularly in the Chilterns where the meeting was held.

Where a record is from is perhaps the most important piece of information attached to it, and gathered round the garden table in bright sunshine and with the Ordnance Survey map of SU79 spread before us we started at the very basics of how to read a map reference. Then, what is this mysterious talk of 10km (hectad), 1km (monad) and 2km (tetrad) squares that recorders deal in? The published Atlas 2020 will, like previous BSBI atlases, consist of dot maps at 10km resolution, so the importance of the hectad as the main recording unit was emphasized. We discussed how to approach sampling such a large area by means of tetrads: this is quite a lot of work and the discussion was tempered with a reminder that we are all volunteers and recording is supposed to feel fun. None of us who take on squares to record should therefore feel over-burdened by the responsibility, and contribute whatever we are able to or find interesting.

Monday, 17 April 2017

Weekend highlights

The hybrid violet Viola x scabra showing a mix of hairy and sweet violet traits, notably the hairy petioles and presence of stolons, respectively.
I'd really like the Oxfordshire Botany blog to be a place for local recorders to share their interesting finds and experiences whilst recording. As the recording season is definitely now upon us I therefore thought I'd start with some reflections on my weekend out botanising. Please do let me know if you would like to do a write-up for the blog in future.

One of my main recording objectives for this year is to get the hectad SP42 up to scratch: as one can see on the Atlas 2020 page it is a very under-recorded part of the county. I made a start on that objective this weekend by recording around Tackley in the south-east corner of SP42. Nobody seems to have recorded there since the 1960s, not for the BSBI anyway. The two tetrads that cover most of Tackley (SP42Q and SP42V) have a good mix of habitats, with the village, to the east the River Cherwell, its floodplain and the Oxford canal, a Local Wildlife Site (LWS) in SP42Q and two in SP42V, and large and small woodlands scattered through mixed farmland in the area. Given this diversity of habitats, semi-natural and artificial, I felt the area was a good one to choose as part of my recording of SP42. I mostly focused this weekend on SP42V but the churchyard of St Nicholas' in SP42Q looked enticing and so I recorded there also. Of the local wildlife sites, Tackley Heath (SP42Q) and Crecy Hill are open access, which is useful, and a public right of way passes through part of Northbrook Marsh.

Sunday, 9 April 2017

Vernal Violets

Last week I received my copy of the BSBI's new handbook Violas of Britain and Ireland, by Mike Porter and Michael Foley. It's a pretty little photographic guide, and as it's the time of year for many violets I thought a blog post would be apposite. I hope it prompts a few readers to buy a copy and/or to have a closer look at the violets growing around them.

In Oxfordshire we have ten of the fifteen UK Viola species and six of the eleven hybrids. The species have been variously divided at subspecies and variety level but these have not traditionally been recorded in the county, or records are only of the nominate species (e.g. Viola tricolor subsp. tricolor). The other infraspecific taxa tend to be found in habitat types that we don't have (e.g. the dunes favoured by Viola tricolor subsp. curtisii), but four of the at least six varieties of the sweet violet Viola odorata have been recorded. I will just talk about the eight taxa (five species) I have found around Islip - were I to venture to Otmoor then I'd be able to add a few others, such as the rare fen violet Viola persicifolia.

As quite a large genus by British standards it is best to start by dividing the species up into groups: first the pansies and violets, and then subdivisions of the latter. This is how all the keys work and is easy to remember.

Thursday, 23 March 2017

Blysmus intervention

Blysmus compressus grows in only one place in Oxfordshire (V.C. 23), in Old Marston within the complex of meadows and floodplain grassland along the River Cherwell designated as the Almonds Farm and Burnt Mill Meadows Local Wildlife Site. The population of Blysmus is quite healthy, extending over about 30m of the bank and with  thousands of inflorescences produced last summer. However, its future has been uncertain for several years with the cessation of grazing following the lapse of the previous tenancy and there has been no management for the last six years.

Not any more! This last weekend volunteers mowed the bank on which Blysmus grows in order to set back the coarse sedges and grasses beginning to overwhelm the smaller plants requiring shorter, finer vegetation, Blysmus included. Without this cutting Blysmus will eventually disappear under a thatch of coarse grasses and sedges, joining the list of Oxfordshire's extinct plants. Repeated again toward the end of summer and again in future seasons this management should result in a diverse sward of herbs and short sedges, just as it ought to look!

Many thanks to the volunteers who helped with this conservation intervention, to the owners Oxford City Council for their permission and assistance, and to the tenant farmer for his permission and sympathy for the cause of this threatened plant. Judy Webb who helped to organise the day has put some excellent photos and videos of scything in action on her website — except for the clothes and the kind of scythes used, the scene could be medieval.

Vegetation supporting Blysmus at Marston, dominated by grasses and with abundant Equisetum arvense and Potentilla anserina. According to results of the Threatened Plants Project the latter is a common associate of Blysmus compressus.