Area: 104.18 hectares.
The site lies entirely within Exmoor National Park. Parts of the site lie within North Exmoor SSSI, South Exmoor SSSI and Barle Valley SSSI.
Otter, salmon, brook lamprey and bullhead are all included on Annex IIa of the EC Habitats and Species Directive (92/43/EEC). Otter is also included on Annex IV and Salmon on Annex V (with respect to freshwater only) of that same Directive. Kingfisher is included on Annex 4.1 of the EC Wild Birds Directive.
Otter and Kingfisher are protected under Schedule 5 and Schedule 1 of the Wildlife and Countryside Act 1981 (as amended) respectively.
Description and Reasons for Notification:
The Barle is a natural river of very high quality which has hardly been modified at all by pollution, water abstraction or river engineering. The upper reaches are oligotrophic, flowing off moorland. These gradually change to a typical upland sandstone type, with mesotrophic plant communities. The flora is diverse and dominated by mosses and liverworts. The river supports a rich invertebrate fauna, including three nationally-scarce beetles. The floodplain contains a wide variety of mire, swamp, mesotrophic and acid grassland, woodland and open water communities.
The River Barle rising at about 400 m has vegetation typical of the most oligotrophic waters flowing from acid peat. Among the few purely aquatic higher plants which characterise this type of oligotrophic stream community are alternate-flowered water-milfoil Myriophyllum alterniflorum, bog pondweed Potamogeton polygonifolius and intermediate water-starwort Callitriche hamulata. The bryophytes Scapania undulata and Racomitrium aciculare are common on rocks whilst Pellia epiphylla is widespread on moist banks. Over the first 10 km of its course the river falls more than 100 m and becomes swifter and more unstable, this limits the truly aquatic higher plants to just one main species M. alterniflorum. There is, however, a natural enrichment as the water flows over the richer substrates of Devonian sandstone and in the mid section of the river Ranunculus peltatus occurs. The river bed has frequent large submerged and emergent rocks which are generally clothed with bryophytes including Platyhypnidium alopecuroides, Platyhypnidium riparioides and Thamnobryum alopecurum. The lichen communities present are those associated with clear, unpolluted upland streams. Wholly submerged crustose species of Verrucaria are abundant on the river bed rocks and Dermatocarpon luridum and Collema flaccidum are abundant species on partially submerged rocks. Of the twelve algae species recorded of Hildenbrandia, Batrachospermum, Lemanea and Heribaudiella are widespread and often abundant, indicating the unpolluted nature of the river. Occurring throughout the mid to lower reaches, attached to submerged rocks or to tree roots exposed by the erosion of the river banks, is the nationally scarce liverwort Porella pinnata. The banks support, and are often dominated by, bryophytes particularly Pellia epiphylla, Rhizomnium punctatum, Hookeria lucens and in places Hygroamblystegium fluviatile and Conocephalum conicum.
Two emergent species which are ubiquitous in the shallow water by the banks in the mid reaches of the river are hemlock water-dropwort Oenanthe crocata and reedgrass Phalaris arundinacea.
The mid reaches of the river around Withypool are bordered by areas of ground which are regularly flooded in winter, whereas elsewhere along the river the ground generally slopes more abruptly to the river channel. The vegetation of the floodplain is predominantly a mixture of various mesotrophic grassland and mire communities, with small areas of swamp and acid grassland in the wettest and driest areas respectively. The mire communities are either dominated by purple moorgrass Molinia caerulea, tufted hairgrass Deschampsia cespitosa and soft rush Juncus effusus (all usually occurring as large tussocks), sharp-flowered rush Juncus acutiflorus or
meadowsweet Filipendula ulmaria or combinations of these. Plants frequently found in these mires include: valerian Valeriana officinalis, angelica Angelica sylvestris, bog violet Viola palustris, marsh bedstraw Galium palustre. Greater bird’s-foot trefoil Lotus pedunculatus and ragged robin Lychnis flos-cuculi. The most frequently occurring swamp community is that dominated by floating sweetgrass Glyceria fluitans, but small areas of bottle sedge Carex rostrata or bogbean Menyanthes trifoliata are also present. Amongst the many plant species in the grasslands are: greater burnet Sanguisorba officinalis, a plant found very rarely in Somerset, betony Stachys officinalis, devil’s-bit Scabious Succisa pratensis and black knapweed Centaurea nigra. Bankside trees are abundant in the mid to lower reaches and are predominantly ash Fraxinus excelsior, alder Alnus glutinosa and sallow Salix cinerea. Finally small areas of swamp woodland dominated by sallow and ponds with broad-leaved pondweed Potamogeton natans add to the overall diversity of the area.
This is the largest body of upland standing water within this site and only one of three such habitats on Exmoor. It has flora typically associated with such habitats: bottle sedge and water horsetail Equisetum fluvatile grow on the fringes of the pond and aquatic plants include floating club-rush Eleogiton fluitans and small bur-reed Sparganium minimum, a plant which is rare in southern Britain.
Three species (all Coleoptera) considered as nationally scarce occur in the River Barle: Laccobius atratus and L. atrocephalus are both water beetles found in acidic conditions, at the margins of rivers. Hydrocyphon deflexicollis, also a beetle, has an aquatic larva though the adults are terrestrial and most often found on Sallow bushes.
Overall the Barle has a diverse invertebrate fauna, though none are national rarities. Many of the invertebrates are characteristic of swift flowing rivers and streams with stony substrates. These include the beautiful demoiselle Calopteryx virgo and the golden-ringed dragonfly Cordulegaster boltonii. The water beetle fauna too, shows a characteristic suite of species for a southwestern river including Oreodytes sanmarki, Platambus maculatus and Hydraena gracilis. The whirligig Orectochilus villosus is another species frequently recorded from swift flowing rivers.
The Barle is an important spawning ground for salmon Salmo salar and brown trout Salmo trutta. The other species of fish found include: brook lamprey Lampetra planeri. Bullhead Cottus gobio, grayling Thymallus thymallus, stone loach Noemacheilus barbatulus and eel Anguilla anguilla. This is a typical example of a fish community in an unpolluted, fast flowing, upland river.
The Barle provides a valuable nesting and feeding habitat for kingfisher Alcedo atthis, dipper Cinclus cinclus and grey wagtail Motacilla cinerea. The floodplain provides habitat for grasshopper warbler Locustella naevia and reed bunting Emberiza schoeniclus.
Otters Lutra lutra have been regularly recorded along the River Barle.