Monday, 28 May 2012

Merioneth Naturalists: Aberdyfi Dunes (SN59) 26 April 2012 John Hughes

Present: Sarah Stille, Helen Bantock, Andrew Graham, David Elias, Isobelle Griffith, John Hughes

On a mercifully rain-free day in what, even by Meirionnydd standards was a pretty wet month (248.7mm of rain for April at Llanymawddwy at the top end of the Dyfi valley) six of us met at the car park at SN597972 to see the spring ephemerals on the Aberdyfi dunes. In the event, they proved to be past their best, perhaps because of the exceptional March warmth this year, but we had a marvellous day nevertheless.

We knew the day was going to be a well-paced one when it took us well over an hour to get west of the railway line, a mere hundred yards or so from the parking spot. The main attractions at this initial stage were some splendid stands of  Smyrnium olusatrum, as is usual quite close to the road/path edge, and abundant Valerianella carinata,with its beautiful pale mauve flowers showing at their best. It was also interesting to be able to compare a flowering clump of Urtica urens, not at all common in VC48, with the ubiquitous Urtica dioica.

Urtica urens in flower April 2012
The golfers were out in some numbers, taking advantage of the break in the wet weather, so we did not linger on the links but headed straight for the dunes. At Aberdyfi these are quite narrow compared with those at Ynyslas to the south and at Harlech to the north but one interesting fact of distribution was immediately apparent : there was frequent Eryngium maritimum, which is absent from Ynyslas, but no Euphorbia portlandica, which is quite frequent there. Indeed, the only euphorbia to be seen was Euphorbia paralias, which was common.  Carex arenaria was the only Carex that we could see on the dunes, displaying very clearly its ability to fix sand by means of its far-spread rhizomes.  Lurking here and there were clumps of  Cynoglossum officinale. After careful search, We found both Cerastium semidecandrum and Cerastium diffusum and, in particular, noticing the scarious tips to the bracts of the former, smaller species by which it may most certainly be distinguished from its slightly larger cousin.

The wind was strong off the sea so we moved into the lee of the dunes for lunch, interrupted only by the plop of the occasional golf ball, the result of a sliced shot from the links to the east.

After lunch, we moved north into SN5998 also owned by the golf club. This was mercifully free of both golfers and also ruminants at this time of year (grazing is confined to May to September). The flora was rich and provided a very welcome contrast to the bright green of the reseeded farmland just to the north. We had a thorough though fruitless search for Moenchia erecta, which had been previously recorded from this area. However, it was so refreshing in this part of the day was to have time to investigate the ecology of the frequent ant hills at first hand and in the relative warmth provided by the shelter of the dunes. It could be seen how Thymus polytrichus, in particular, was thriving on the tops of the anthills on the richer, less leached, soil brought up by the ants from below. It was also interesting to pick out the well-named Stellaria pallida, another dune-system specialist, and to come across Viola canina, which again is confined in VC46 to the Ynyslas and Penyrergyd dunes.

The land became increasingly wet as we went north, past Carex nigra in flower and a profusion of  Caltha palustris. At the edge of  a lake that probably dries out in hot summer there was Equisetum fluviatile, Potentilla palustris and Alisma plantago-aquatica.Two of our number also almost stepped on a nestful of lapwing chicks.

The final part of the day took us to an alder wood, complete with rookery. Here we found Carex riparia, distinguished from Carex acutiformis (rarer in VC48) by its blunt (not acute) ligules.

And so back to the car park just as the rain started up again, to emphasize who is boss in VC48, and the luck we had had with the weather..

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