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General Description:

Mires occur typically on deep peat (over 0.5 m thick) with the water table at or just below the water table at or just below the surface, but flushes and spring on shallow or incipient peats are also included in this category.

The habitat classification of peatlands has recently been revised (see NCC 1989) and the term bog is now restricted to ombrotrophic mires (blanket bog and raised bog), which are fed only by direct precipitation, unlike minerotrophic mires - fens (valley, flood-plain and basin mires), flushes and springs - which are fed by ground water or streams. The distinction between ombrotrophic and minerotrophic mires is not always clear-cut and transitional examples should be target noted. Furthermore areas of minerotrophic mires may occur within blanket and raised mires; likewise, ombrotrophic areas may occur locally within fens. Examples of these should target noted, but may be included within the major mire type for mapping purposes.

E1 Bog:

Bog Description:Unmodified bog (blanket bog and raised bog) consists of Sphagnum-rich vegetation, lying on peat more than 0.5 m deep, with the water table at or just below the surface and no input of water from the surrounding land. Modified bog contains little or no Sphagnum.

• E1.6.1 Blanket bog Description - (* This Phase 1 alphanumeric reference code differs from that used in either the 1984 NCC/RSNC classification or the 1982 SSSI mapping system.) - Blanket bog comprises Sphagnum-rich vegetation on deep peat, forming a blanket over both concave and convex surfaces, on level to moderately sloping ground in the uplands. It is widespread in the north and west of Britain, where it may be fragmentary or very extensive. The drainage is usually diffuse and undisturbed blanket bog often shows a hummock-and-hollow structure, with Sphagnum-rich pools in the hollows. Blanket bog includes watershed mires, saddle mires, terrace bog and valleyside mire and may also include other mire types, where these occur within a blanket bog complex. This habitat category is used for relatively undamaged blanket bog, with Sphagnum usually abundant (typically Sphagnum papillosum, together with other species such as Sphagnum magellanicum). A wide range of ericoids, including Calluna vulgaris, Erica tetralix, Vaccinium species and Empetrum species, may be present, mainly in the hummocks, together with Eriophorum vaginatum, Eriophorum angustifolium and Trichophorum cespitosum. Calluna and/or Eriophorum vaginatum are often dominant over large areas, but various mixtures of species occur. Dominant species should be coded. Bog pool systems and areas of peat cutting, often characterised by the presence of Sphagnum recurvum, should be target noted or mapped as open water (G1.4) or bare peat (E4) if sufficiently large Significantly damaged blanket bog, in which Sphagnum is much reduced or absent, should be classified as modified bog (E1.7 or E1.8).
• E1.6.2 Raised bog Description - (* This Phase 1 alphanumeric reference code differs from that used in either the 1984 NCC/RSNC classification or the 1982 SSSI mapping system.) - Raised bogs are found on estuarine flats, river flood plains and other level areas with impeded drainage in the lowlands, also at moderate altitudes, where they may grade into blanket mire. Many raised bogs overlie sites of glacial lakes which become infilled. In a classic raised bog, a structure now rare in Britain, the peat is several metres deep and has accumulated to form a distinctly raised dome, with peat depth greatest in the centre and decreasing towards the edges, which are marked by the more steeply sloping mire margin. Drainage tends to flow around the mire, forming a lagg stream, and the drier sloping margins of the mire may carry lagg woodland, which should be mapped as woodland.
  Undamaged raised bog vegetation is very similar to that described under blanket bog (E1.6.1). Modification of raised bogs by draining, burning and peat-cutting can lead to the formation f wet modified bog and dry modified bog, which should be mapped as E1.7 or E1.8).
• E1.7 Wet modified bog Description - (* This Phase 1 alphanumeric reference code differs from that used in either the 1984 NCC/RSNC classification or the 1982 SSSI mapping system.) - This category comprises modified bog vegetation with little or no Sphagnum, often with bare peat and patches of Trichophorum cespitosum and/or Molinia caerulea. Ericoids may be abundant, sparse or absent.This vegetation is mainly found on drying and degraded blanket bogs and cut-over raised bogs. It may resemble wet heath (D2), but is distinguished by having a peat depth greater than 0.5 m. Molinia-dominated vegetation on deep peat is included in this category rather than in marshy grassland (B5).
• E1.8 Dry modified bog Description - (* This Phase 1 alphanumeric reference code differs from that used in either the 1984 NCC/RSNC classification or the 1982 SSSI mapping system.) - The vegetation of dry modified bog is dominated by Calluna vulgaris and other ericoids, or by Eriophorum vaginatum, on peat more than 0.5 m deep. Sphagnum is notably absent, but under the dwarf shrubs there may be a carpet of hypnoid mosses, with lichens such as Cladonia portentosa and Cladonia arbuscula. Where Eriophorum vaginatum is dominant, as on many Pennine blanket bogs, other species may be sparse or absent. Essentially dry heath vegetation (or cotton-grass moor) on deep peat, this habitat type is typical of areas of blanket bog subjected to heavy grazing, burning and draining.

E2 Flush and spring:

Flush and spring Description: These types of minerotrophic mire are termed soligenous because they are associated with water movement. They may or may not form peat, but where do, the peat is often less then 0.5 m deep. Flushes occur on gently-sloping ground, or often linear or triangular and may include small watercourses. They may be extensive or too small to map, in which case they should be target noted. Where flushes feed a fen (E3) they should be target noted and mapped as an integral part of the mire complex, unless they are very large and distinct, when they may be individually mapped.

Flushes typically have an open or closed ground layer of Sphagnum and/or other bryophytes, together with small sedges and Juncus species. The presence of a well developed bryophyte grounds layer and the lack of dominant grasses distinguishes flush habitats from marshy grassland and from wet acid, neutral and calcareous grasslands. Thus, a habitat with Juncus effusus over herbs and grasses is a marsh/marshy grassland (B5). Complex mosaics of grassland and flush are quite common, particularly in the uplands, and should be mapped according to the most prevalent habitat, with the proportions of each recorded in a target note.

Flushes may be acid, neutral (mesotrophic) or basic. These categories are not always easy to distinguish.

• E2.1 Flush - acid/neutral Description - These typically support species-poor vegetation consisting of a Sphagnum carpet overlain by Carex or Juncus species. Characteristic moss species include Sphagnum recurvum, S. palustre and S. auriculatum. Overlying vegetation may consist of small Carex species (Carex echinata, C. nigra or C. curta), Carex rostrata, Juncus acutiflorus, J. effusus, J. squarrosus or Eriophorum angustifolium. Dominant species should be coded.
• E2.2 Flush - basic Description - Basic flushes typically support a carpet of pleurocarpous brown mosses, often without Sphagnum, overlain by a conspicuous small sedge layer, Carex flacca, Schoenus nigricans or a mixed-herb layer. Characteristic pleurocarpous mosses include Scorpidium, Campylium, Drepanocladus and Calliergon species, whilst characteristic herbs include Eleocharis quinqueflora, Eriophorum latifolium and Carex lepidocarpa.
• E2.3 Bryophyte-dominated spring Description - This habitat occurs only in the immediate vicinity of up-wellings and it usually consists of spongy mats or small mounds dominated by bryophytes such as Cratoneuron or Philonotis species. Areas which fall within this category are normally too small to map and should be target noted. Flushes occurring downslope of a spring should be mapped if they are large enough.

E3 Fen:

(* This Phase 1 alphanumeric reference code differs from that used in either the 1984 NCC/RSNC classification or the 1982 SSSI mapping system.)

Fen Description: Fens are defined as minerotrophic mires, usually over peat more than 0.5 m deep (but see E3.3). The water table is at or just below the surface. Three main types of fen can be distinguished, using topographical rather than vegetational criteria. These are valley mire, which, because there is obvious water flow, is classified as soligenous, and basin and flood-plain mires, which have impeded drainage and are termed topgenous. However, the distinction between these three mire types is not always clear in the field, so for Phase 1 mapping purposes their identification is optional.'Poor fen' contains acid water (pH 5 or less) and short vegetation with a high proportion of Sphagnum. 'Rich fen' contains mire calcareous water (pH above 5), Sphagnum is often absent and the vegetation usually includes patches or tall plans and species such as Juncus subnodulosus, Schoenus nigricans and Carex lepidocarpa, characteristic of base-rich situations. Where acid or basic fen can be identified, this should be made clear in a target note and basic fen should be indicated by the code 'B'.
Where there are very wet areas containing tall swamp vegetation such as Phragmites australis or large sedges, these should be target noted as swamp (F1), or marked as patches of sky blue, if large enough to map within the area delineated as fen. Parts of the mire dominated by marsh (fen meadow) or carr should be mapped or target noted as grassland (B5), woodland (A1) or scrub (A2). Springs and small flushes which feed or lie within a fen, should be treated as an integral part of the mire system and target noted (see E2). Areas of bog within a fen and patches of degraded fen should also be target noted.

• E3.1 Valley mire Description - (* This Phase 1 alphanumeric reference code differs from that used in either the 1984 NCC/RSNC classification or the 1982 SSSI mapping system.) - A valley mire develops along the lower slopes and floor of a small valley and received water from springs and seepages on the valley side, feeding a central watercourse. Such a fen can be distinguished from a flush because the former is a complex, whereas a flush is a discrete single feature, usually of limited extent.
  Valley mires are often dominated by acidophilous vegetation containing Sphagnum species, Carex species and ericoids. However, vegetation typical of base-rich conditions can also occur, for instance Schoenus nigricans and Juncus subnodulosus. Floating mats of mosses and sedges may be present. Acid watercourses often contain Hypericum elodes and Potamogeton polygonifolius. Basic fen should be indicated by the code B.
• E3.1 (B) Valley mire - basic Description - (* This Phase 1 alphanumeric reference code differs from that used in either the 1984 NCC/RSNC classification or the 1982 SSSI mapping system.) - This is a optional code if basic fen can be identified (see E3.1).
• E3.2 Basin mire Description - (* This Phase 1 alphanumeric reference code differs from that used in either the 1984 NCC/RSNC classification or the 1982 SSSI mapping system.) - This type of fen develops in a waterlogged basin and contains very little open water. The water table within the basin is level, but small flushes may occur around the edges and there is a limited through-flow of water. The vegetation may be dominated by Sphagnum species, together with Carex rostrata and ericoids, or by tall swamp plants such as Phragmites australis, Schoenoplectus (Scirpus) lacustris, Typha species and, in base-rich situations, Cladium mariscus. Basic fen should be indicated by the code B.
• E3.2 (B) Basin mire - basic Description - (* This Phase 1 alphanumeric reference code differs from that used in either the 1984 NCC/RSNC classification or the 1982 SSSI mapping system.) - This is a optional code if basic fen can be identified (see E3.2).
• E3.3 Flood-plain mire Description - (* This Phase 1 alphanumeric reference code differs from that used in either the 1984 NCC/RSNC classification or the 1982 SSSI mapping system.) - This type of fen forms on a river or stream flood-plain which is waterlogged and, typically, inundated periodically. The substrate may be peat, mineral or a mixture of both. The range of vegetation types is similar to that of a basin mire (E3.2). Basic fen should be identified by the code B.
• E3.3 (B) Flood plain mire - basic Description - (* This Phase 1 alphanumeric reference code differs from that used in either the 1984 NCC/RSNC classification or the 1982 SSSI mapping system.) - This is a optional code if basic fen can be identified (see E3.3).

E4 Bare peat:

(* This Phase 1 alphanumeric reference code differs from that used in either the 1984 NCC/RSNC classification or the 1982 SSSI mapping system.)

Bare Peat Description: - Patches of bare peat more than 0.25 ha in extent (that is, approximately 50 m x 50 m) should be mapped. Peat hagging and areas of eroding peat haggs should be target noted. Commercial peat-workings are included in this category.