Coed Gorswen

Also within

Clwyd County Eryri / Snowdonia National Park

Geology & landscape

Landscape processes: Glacial

Description

Description Coed Gorswern is selected for its biological interest as an example of a slender false browm/Oak/Ash Brachypodium sylvaticum/Quercus/Fraxinus woodland type. The underlying rocks are completely masked by glacial drift from mixed sources resulting in a mixture of acidic and base-rich soils. The woodland has a range of tree species with sessile and pedunculate oak Quercus petraea and Quercus robur, wych elm Ulmus glabra, alder Alnus glutinosa, ash Fraxinus excelsior, sycamore Acer pseudoplatanus, downy birch Betula pubescens and gean Prunus avium. A well developed shrub layer is also present; blackthorn Prunus spinosa is locally dominant but with rowan Sorbus aucuparia, hawthorn Crataegus monogyna, elder Sambucus nigra, holly Ilex aquifolium, crab apple Malus sylvestris and field maple Acer campestre also occurring. The ground flora is equally rich, five main plant communities having been described. The principal species on better drained soils include wood sorrel Oxalis acetosella, bramble Rubus fruticosus, common violet Viola riviniana, slender false-brome Brachypodium sylvaticum, sanicle Sanicula europaea and enchanter's nightshade Circaea lutetiana. Among the less common plants is the orchid, broadleaved helleborine Epipactis helleborine. On wetter gleyed soils, in flushes or beside streams, the main species include lesser spearwort Ranunculus flammula, water mint Mentha aquatica, reed canary grass Phalaris arundinacea and smooth sedge Carex laevigata. Over five hundred species of Lepidoptera including twenty two species of butterfly and uncommon moth species have been recorded. The woodland also supports the nationally rare dipteran, the cranefly, Triogma trisulcata. Remarks:This site was declared as a National Nature Reserve in 1959. Within the Snowdonia National Park.

Species mentioned

Insects to look out for

These moths, butterflies and beetles are known to feed on plants recorded at this site, and carry a notable UK conservation status — but a host-plant being present doesn't mean the insect has actually been recorded here. Treat this as "worth watching for," not a confirmed sighting.

Host-plant data: Cook et al. (2025), Traits data for the butterflies and macro-moths of Great Britain and Ireland, 2024, UK Centre for Ecology & Hydrology / Butterfly Conservation; and Padovani et al. (2020), Database of Insects and their Food Plants (DBIF), UK Centre for Ecology & Hydrology (both Open Government Licence). Contains data supplied by UK Centre for Ecology & Hydrology.