The Wern, Rhosgoch

Also within

Powys County

Climate exposure

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

Habitats

Carr, Fast flowing river and stream

Geology & landscape

Geological Period: Silurian · Rock Type: Glacial Till

Landscape processes: Glacial, Peatland / Mire

Description

Description This site is of outstanding importance for its semi-natural and species-rich alder carr, which is the best example known in Radnorshire. The interest is further enhanced by the range of subsidiary wetland and grassland habitat types that border on to the woodland. In all, three woodland and four semi-natural grassland and wetland plant communities are represented. This juxtaposition of vegetation communities enables a notable range of transitional types to exist, and the 'edge-effect' ensures a very high faunal diversity. The site lies about a mile north of Painscastle, in the upper part of the Bachawy valley at an altitude of 280 metres (920 feet). The underlying geology of the site is of Silurian shales, but generally these are mantled by glacial boulder clay, and the waterlogged conditions prevailing in the carr woodland have led to the formation of shallow peat deposits. In the lowest part of the site there is an area of wet alder Alnus glutinosa carr lying on either side of the Bachawy stream. In the wetter southern part of woodland, alder is co-dominant in the canopy with rusty willow Salix cinerea subsp. oleifolia and ash Fraxinus excelsior, whilst in the field and ground layers species such as nettle Urtica dioica, reed canary-grass Phalaris arundinacea, opposite-leaved golden-saxifrage Chrysosplenium alternifolium, ground ivy Glechoma hederacea, creeping buttercup Ranunculus repens and the locally scarce meadow saxifrage Saxifraga granulata occur. Where very wet springlines run through this woodland, greater tussock-sedge Carex paniculata has developed very locally under the alder canopy, and is joined by the two golden saxifrage species and water avens Geum rivale. To the north the substrate is more freely-draining and different woodland types are represented. Most commonly alder and ash are still the canopy dominants, but the shrub layer is more diverse, with hazel Corylus avellana and wych elm Ulmus glabra conspicuous, and tufted hair-grass Deschampsia cespitosa prominent in the field layer. Elsewhere, on the more well-drained slopes, an ash-field maple Acer campestre canopy has developed with hazel, holly Ilex aquifolium, hawthorn Crataegus monogyna and bird cherry Prunus padus in the shrub layer and bluebell Hyacinthoides non-scripta, wood avens Geum urbanum, yellow archangel Lamiastrum galeobdolon and herb-robert Geranium robertianum in the field layer. Very locally, ash is joined by downy birch Betula pubescens and rowan Sorbus aucuparia, with a ground flora including wood-sorrel Oxalis acetosella and lady fern Athyrium filix-femina. The drier woodland supports populations of broadleaved helleborine Epipactis helleborine and early-purple orchid Orchis mascula.

Species mentioned

Plant communities