Coedydd Beddgelert a Cheunant Aberglaslyn

Also within

Gwynedd County Eryri / Snowdonia National Park

Climate exposure

This is about exposure to a nationwide pressure this habitat type carries — not a verdict on this site's own management.

Habitats

Fast flowing river and stream

Geology & landscape

Geological Feature: Gorge / Ravine

Landscape processes: Fluvial, Glacial, Peatland / Mire

Description

Description The site is of special interest for its geomorphological and biological features. These comprise: fluvial geomorphological landforms, semi-natural broadleaved woodland, assemblages of mosses, liverworts, lichens and a population of lesser horseshoe bats. Coedydd Beddgelert a Cheunant Aberglaslyn is situated in an area of glaciated upland extending from Beddgelert to a point 2km south of Nantmor. It includes a 1.5km stretch of the Afon Glaslyn, part of the Aberglaslyn gorge and a number of native woodland blocks situated mainly on the steep valley sides. Boulders, rocky outcrops and ridges form a distinctive feature of the woods. The soils are typical of the cool, wet north-west of Britain, varying between being moist, free-draining (but not excessively leached) base-poor brown earths to becoming very acidic and thin with distinctive mor accumulation and strong leaching. Geomorphology: The Afon Glaslyn at Aberglaslyn provides an excellent example of a boulder-bed reach. Sediment transport is dominated by bedload although there is evidence of overbank sedimentation of fines especially in the lee of vegetated islands after high-magnitude flood events. The main part of the reach is confined by the gorge and is therefore laterally stable. This contrasts with both upstream and downstream sections where depositional features such as point bars and boulder islands are well developed. The composite profile of the Glaslyn is also of interest and may reflect successive stages in episodic rejuvenation of the river. Biology: The sessile oak woodlands of southern Snowdonia form one of the most important areas for woodland nature conservation in Europe. This type of Atlantic woodland is often described as “temperate rainforest” due to the prevailing damp humid climate and associated abundance of ferns, lichens and the luxuriant growth of mosses and liverworts. At Coedydd Beddgelert a Cheunant Aberglaslyn the woodland structure varies between dense, ungrazed, closed canopy woodland to open, grazed wood-pasture with veteran trees. The canopy is most frequently dominated by sessile oak Quercus petraea, accompanied by birch Betula pubescens, which in places becomes abundant. Beech Fagus sylvatica, which is not considered a native species in North Wales, is locally dominant. rowan Sorbus aucuparia and holly Ilex aquifolium are also common tree species, mainly occurring as scattered individuals. Ash and sycamore are occasionally present, being restricted to areas of woodland with less acidic soils. The shrub layer is mostly sparse comprising hazel Corylus avellana, holly and the occasional hawthorn Crataegus monogyna higher up the slopes. Rhododendron, a non-native and highly invasive species, forms a dense shrub layer in places. The field layer is variable but is usually characterised by the presence of grasses, ferns and sometimes heather Calluna vulgaris or bilberry Vaccinium myrtillus. Wavy –hair-grass Deschampsia flexuosa is common throughout together with abundant common bent grass Agrostis capillaris, sweet vernal-grass Anthoxanthum odoratum and Yorkshire fog Holcus mollis growing on the deeper soils, particularly in the grazed woodlands. Ferns form a distinctive part of the woodland field layer, these include: hard-fern Blechnum spicant, lemon scented-fern Thelypteris limbosperma and Dryopteris spp.. Two uncommon species, Wilson’s filmy fern Hymenophyllum wilsonii and the Tunbridge filmy-fern Hymenophyllum tunbrigense occur within a small ravine and on a number of ledges. Other frequent field layer plants include wood sorrel Oxalis acetosella, tormentil Potentilla erecta, heath bedstraw Galium saxatile, common cow-wheat Melampyrum pratense and bluebell Hyacinthoides non-scripta. The moss and liverwort flora often exceeds the vascular plant flora in its diversity and abundance, forming a carpet, which extends up over boulders, over the roots and bases of trees, and onto the faces of rock ledges. Different species tend to be prominent in different microhabitats. The most abundant and typical species include: Dicranum majus, Rhytidiadelphus loreus, Polytrichum formosum, Isothecium myosuroides, Hypnum cupressiforme, Thuidium tamariscinum, Pleurozium shreberii and Hylocomium splendens. A good range of oceanic species, including Lejeunea lamacerina, Saccogyna viticulosa and Bazzania trilobata occur frequently in the woodland. Eight nationally scarce mosses have been recorded. Leucobryum juniperoideum forms dull green cushions on the woodland floor; Andreaea rothii ssp. Rothii, Fissidens polyphyllus, Rhynchostegium alopecuroides and Rhabdoweisia crenulata occur on damp rocks near watercourses; Sphagnum flexuosum is also found near watercourses; and Bucklandiella affinis and R. sudeticum form extensive patches on boulders, usually in more open, unwooded situations. Two nationally scarce liverworts have also been recorded: Barbilophozia atlantica and Kurzia sylvatica. The lichen interest is found on well-lit trees associated with open areas and/or at the woodland edges. The largest numbers of rare and scarce lichen species are found growing on sessile oak, including the nationally rare: Micarea viridileprosa and M. xanthonica; the nationally scarce: Micarea stipitata, Lecidea sanguineoatra, Phaeographis inusta, Ochrolechia inversa and Rinodina isidioides. Other lichen species, including the nationally scarce Herteliana gagei, Lecanora epanora, Lepraria elobata, Porpidia rugosa and Tyothallia biformigera are found on rocky outcrops within the woodland. The nationally scarce Micarea coppinsii is recorded on the twigs of larch Larix sp.. A nursery roost of lesser horseshoe bats Rhinolophus hipposideros occurs in a building situated on the periphery of the woodland, whilst disused mine workings provide cool stable temperatures for hibernation. The woodland edges and lines of trees form important navigational flight lines for these bats. The combination of sheltered woodland and grazed pastures provides a rich source of invertebrate prey throughout the year. At least 70 adult bats were counted at the nursery roost in the summers of 1999 and 2000. The population is one of several linked colonies within the Glaslyn valley. Pipistrelle bats also use the building and there are two large nursery roosts of pipistrelles outside the site, but close to the woodland. Invertebrate surveys have indicated that a characteristic fauna of western oakwoods occurs at this site and includes the nationally scarce soldier beetle Malthodes guttifer. Remarks: The SSSI lies within Snowdonia National Park. The site is a component part of the Coedydd Derw a Safleoedd Ystlumod Meirion/ Meirionnydd Oakwoods and Bat Sites Special Area of Conservation. The SAC features present are: • Old sessile oak woods with Ilex and Blechnum in the British Isles. • Lesser horse shoe bat Rhinolophus hipposideros. • European dry heath. The lesser horseshoe bat Rhinolophus hipposideros and the otter Lutra lutra are listed on Schedule 5 of the Wildlife and Countryside Act 1981 (as amended) and Annex II of the EC Habitats Directive (92/43/EEC).

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.

Plant communities