Pwll-y-wrach

Also within

Powys County Bannau Brycheiniog / Brecon Beacons National Park

Habitats

Coppiced woodland, Fast flowing river and stream

Geology & landscape

Rock Type: Sandstone, Tufa

Landscape processes: Karst

Birds & fish recorded

Birds

Description

Description This woodland located 1.5 km south-east of Talgarth is the best example of ash -field maple -dog’s mercury (Fraxinus excelsior - Acer campestre - Mercurialis perennis) woodland in Brecknock, here developed on the steep sloping banks of the River Ennig and tributary. The river has cut through Old Red Sandstone exposing base-rich rock outcrops. The soils reflect this base-richness in part, but leaching has resulted in the acidification of areas of the northern bank. These acidic areas support a woodland dominated by sessile oak Quercus petraea, which in its extreme form could be classified as a sessile oak-downy birch Betula pubescens -wood sorrel Oxalis acetosella type. The interrelations between this type and the ash-dominated stands of the lower slopes and southern banks are of considerable interest. Sessile oak is in places mixed with a diverse range of shrubs and trees which are normally characteristic of base-rich soils, such as spindle Euonymus europaeus, dogwood Cornus sanguinea, guelder-rose Viburnum opulus and field maple. hazel Corylus avellana is frequent throughout the wood. Wych elm Ulmus glabra, once frequent, has much decreased recently, due to Dutch elm disease. Small-leaved lime Tilia cordata and wild service-tree Sorbus torminalis occur on the steeper slopes. The diversity of canopy species is reflected in the herb and ground layers. At least 180 species of flowering plants and ferns have been recorded, including local rarities such as herb-Paris Paris quadrifolia, bird’s-nest orchid Neottia nidus-avis, alternate leaved golden-saxifrage Chrysosplenium alternifolium and meadow saxifrage Saxifraga granulata. A notable bryophyte flora is present, with some 60 species recorded. base-rich, tufa-depositing flushes with the mosses Eucladium verticillatum and Palustriella commutata, are an uncommon feature in mid Wales. Other base-loving species of note include the moss Mnium stellare, and the liverwort Porella arboris-vitae. Epiphytes are well-developed on trees and shrubs, but most notably on a number of ancient pollarded ash and oak trees supporting the lichens Catillaria sphaeroides, Peltigera Melanops horizontalis, Caloplaca lucifuga and Thelopsis rubella, amongst others. These species are characteristic of long undisturbed woodlands. The humid lower slopes around the many waterfalls on the Ennig provide an important refuge for many bryophytes. A further discrete area of woodland south-east of the main woodland block is characterised by an abundance of coppiced alder Alnus glutinosa with ash and occasional sessile oak. The understorey comprises a mixture of shrubs such as hazel, common hawthorn Crataegus monogyna, rowan Sorbus aucuparia, holly Ilex aquifolium and blackthorn Prunus spinosa. Small herbs, including yellow pimpernel Lysimachia nemorum, opposite-leaved golden-saxifrage Chrysosplenium oppositifolium, wood sorrel Oxalis acetosella, common dog-violet Viola riviniana, wood speedwell Veronica montana and barren strawberry Potentilla sterilis are prominent in the field layer. Additional structure is provided by scattered tall herbs such as meadowsweet Filipendula ulmaria, common valerian Valeriana officinalis, foxglove Digitalis purpurea and greater stitchwort Stellaria holostea. Less information is available on the mammal interest of the site, but it is one of only two presently known localities for the common dormouse in Brecknock. The site supports good breeding populations of small birds such as pied flycatcher, wood warbler, chiffchaff and willow warbler and the streams provide suitable habitat for dipper and grey wagtail. Remarks: The site lies within the Brecon Beacons National Park. Part of the site is owned and managed as a nature reserve by the Brecknock Wildlife Trust.

Species mentioned

Plant communities