Monday, 6 April 2015

Merioneth Nats in Tywyn

We were six botanists who met in Tywyn, to record in a square with surprisingly few records.  SN59 is a tiny hectad in Merioneth, not much more than a single tetrad, about 4% in area, but it has a fine number of older records, with over 300 species needing updating before the new Atlas appears in 2020.

Sadly for us that day, it seems to be a very late spring, with the recent frosts holding back the new season's growth.  Even with the help of Poland's Vegetative Key to the British Flora, we only made around 50 records, but consoled ourselves with the thought that, unlike last year, there should still be plenty to see later in the summer.

We spent some time looking at some dead heads of putative Centaurea debeauxii, Chalk Knapweed, One of the defining characters is the shape of the centre of the distal  part of the phyllaries.  In C nigra it is quite broad, whereas in C debeauxii it is narrow.  In our specimen it was extremely narrow, however, the swollen part of the stem just below the capitulum was really markedly swollen.  I suspect that Stace isn't convinced by the split either! [see diagram in Stace, 2010 p. 699]

Meirionnydd Nats at Tywyn on a cool and blustery March day
On a blustery, cool day we walked from near Neptune Hall over the heavily-grazed meadows which looked promising for a later expedition,  The area is damp and slightly brackish, with drainage ditches dissecting the raised beach, and with low dunes protecting the land from the waves. We were glad to get out of the wind for our lunch and were delighted to see a large flock of Golden Plover roosting just in front of us apparently not at all disturbed by our munching.  Even when we walked on they sat tight, until they blended with the background and we could no longer see them.
Mediaeval peat-cutting on Tywyn Beach

The dunes were disappointing with almost none of the expected early ephemerals to be seen.  Only the vivid green of the Sea Mayweed, Tripleurospermum maritimum, broke the monotony of Marram Grass, Ammophila maritima, bare sand and the litter left by earlier visitors.  However, we were enchanted by the "drowned forest" in the intertidal zone just south of  Tywyn and the peat beds with the mediaeval cutting marks clearly showing. I've been reading it all up on a very illuminating report: [Smith, 2004] which explains the time scale over which the sea level rose and fell after the ice sheet had gone.

References:
Stace, C A, 2010 New Flora of the British Isles, Cambridge University Press, Cambridge
Smith, G. 2004, Tywyn Coastal Protection Scheme, Archaeological Assessment, Report No 555, Gwynedd Archaeological Trust.  Accessed on line 06 04 2015

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