Cors Caron

The assessment designated the primary feature for the selection of Cors Caron as active raised bog described as:

The Cors Caron sequence of peat domes (also known as Tregaron Bog) developed on the floodplain of the Afon (River) Teifi in mid-Wales now represents the most intact surviving example in the UK of a raised bog landscape (macrotope). The three main extant domes are hydrologically isolated by the River Teifi and associated surface drainage features, and all three have suffered extensive damage as a consequence of past drainage and peat-cutting. The river terraces associated with the component bog mesotopes are regularly flooded and support vegetation that includes reed canary-grass Phalaris arundinacea, soft rush Juncus effusus, purple moor-grass Molinia caerulea and, more rarely, water sedge Carex aquatilis. Substantial areas of the surface of each of the three component bogs still retain good quality active raised bog vegetation mainly referable to NVC type M18 Sphagnum papillosum – Erica tetralix community, with frequent bog-rosemary Andromeda polifolia and white beak-sedge Rhynchospora alba and, more locally, the bog-mosses Sphagnum magellanicum and S. pulchrum. Extensive areas with a high cover of heather Calluna vulgaris and deergrass Trichophorum cespitosum are also present, while purple moor-grass M. caerulea is particularly prominent on the more modified bog margins. Although present as an important peat-former until as recently as the 18th century, Sphagnum imbricatum is absent from the contemporary bog flora.[2]

Bog woodland designation was a qualifying feature present described as:

Under certain combinations of physical circumstances in the UK, scattered trees can occur across the surface of a bog in a relatively stable ecological relationship as open woodland, without the loss of bog species. This true Bog woodland is a much rarer condition than the progressive invasion of bogs by trees, through natural colonisation or afforestation following changes in the drainage pattern which leads eventually to the loss of the bog community. The habitat type has not previously been well described in the UK, and consequently knowledge of its ecological characteristics is limited. The principal tree species in this form of Bog woodland is Scots pine Pinus sylvestris. Pine bog woodland types are likely to be intermediate in character between NVC type W18 Pinus sylvestris – Hylocomium splendens woodland and more open mire types such as M18 Erica tetralix – Sphagnum papillosum mire or M19 Calluna vulgaris – Eriophorum vaginatum blanket mire.

Cors Caron was additionally assessed as possessing the following qualifying, non-priority habitats:

Transition mires and quaking bogs described as: The term 'transition mire' relates to vegetation that in floristic composition and general ecological characteristics is transitional between acid bog and 7230 Alkaline fens, in which the surface conditions range from markedly acidic to slightly base-rich. The vegetation normally has intimate mixtures of species considered to be acidophile and others thought of as calciphile or basophile. In some cases the mire occupies a physically transitional location between bog and fen vegetation, as for example on the marginal lagg of raised bog or associated with certain valley and basin mires. In other cases these intermediate properties may reflect the actual process of succession, as peat accumulates in groundwater-fed fen or open water to produce rainwater-fed bog isolated from groundwater influence. Many of these systems are very unstable underfoot and can therefore also be described as 'quaking bogs'.

Depressions on peat substrates of the Rhynchosporion described as: occurring in complex mosaics with lowland wet heath and valley mire vegetation, in transition mires, and on the margins of bog pools and hollows in both raised and blanket bogs. The vegetation is typically very open, usually characterised by an abundance of white beak-sedge Rhynchospora alba, often with well-developed algal mats, the bog moss Sphagnum denticulatum, round-leaved sundew Drosera rotundifolia and, in relatively base-rich sites, brown mosses such as Drepanocladus revolvens and Scorpidium scorpioides. The nationally scarce species brown beak-sedge Rhynchospora fusca and marsh clubmoss Lycopodiella inundata also occur in this habitat.

On lowland heaths in southern and eastern England this habitat occurs on humid, bare or recently exposed peat in three distinct situations:

• in and around the edges of seasonal bog pools, particularly on patterned areas of valley mire,
• in flushes on the edges of valley mires in heathlands, and
• in areas that are artificially disturbed, such as along footpaths and trackways and in old peat-cuttings and abandoned ditches.

The habitation of otter (Lutra lutra) at Cors Caron was the primary species listed in the assessment. Cors Caron is one of the largest wetland areas in Wales and feeds into the River Teifi. Historically it is a very important site for otters and has been an important source of breeding for the otters of the River Teifi and other catchments such as the rivers Severn and Dyfi. Cors Caron also provides an important amphibian food resource for breeding otters in spring. One of the last UK strongholds of the European Polecat was in this area.