Tuesday, 27 December 2016

Usnea articulata heading ever further east

A family walk up the Sugarloaf, above Abergavenny on 27th, produced a single medium-sized tuft of Usnea articulata (Sausage Beard-lichen) in its typical windy Hawthorn habitat.  This was on one of the few Hawthorns we walked past, and there were several other suspicious-looking grey patches in more distant bushes.  I have been waiting for the first Monmouthshire record of this species as it romps eastwards from its former range in Pembrokeshire and Gower, and my anticipation was heightened by George's find in easternmost Radnorshire this summer and an NRW colleague's record at Craig y Cilau NNR a few weeks ago.  My colony was at SO27181666, just above the eastern carpark, but I'm sure there are more to be found here and elsewhere in north-western VC35.

The general consensus is that Usnea articulata declined catastrophically in Wales because of Sulphur Dioxide pollution, to remnant colonies in Pembrokeshire and a couple of dune sites in Glamorgan (plus an outlier in Ceredigion).  With declines in SO2 pollution, this highly distinctive lichen has spread north-east and east, with over 100 new colonies discovered in south Wales, especially in Carmarthenshire and the southern Brecon Beacons.  Of course, some of these colonies may have been present for years, missed because of the paucity of local lichenologists, but many of them have been spotted from roads and are so obvious that general naturalists would surely have reported them.  Windy Hawthorns are favoured, but the Usnea also grows in the top of Oaks (see Barry's Penllergaer record on the Blog), in willows in wetlands (see Charles' record from Jersey Marine), and on Larch.

1 comment:

  1. That is very good news and no doubt there are less conspicuous species also benefiting for the same reasons.