Habitat account - Raised bogs and mires and fens


7120 Degraded raised bogs still capable of natural regeneration 

Background to selection

Distribution of SACs/SCIs/cSACs with habitat 7120 Degraded raised bogs still capable of natural regeneration.  Click image for enlarged map.
Distribution of SACs/SCIs/cSACs with habitat 7120 Degraded raised bogs still capable of natural regeneration. Click image for enlarged map.

Description and ecological characteristics

 

Degraded raised bogs occur where there has been widespread disruption, usually by man, to the structure and function of the peat body. This can involve changes to the hydrology, vegetation, and physical structure of the bog, leading to desiccation, oxidation and loss of species or changes in the balance of the species composition. In contrast to 7110 Active raised bogs, peat is not currently forming in degraded bog. The vegetation of degraded bog contains several, but not all, of the species typical of Active raised bogs, but the relative abundance and distribution of individual species differs.

 

The Interpretation manual of European habitats (European Commission DG Environment 1999) stresses that Degraded raised bogs only includes examples which are ‘capable of natural regeneration’, i.e. "where the hydrology can be repaired and where, with appropriate rehabilitation management, there is a reasonable expectation of re-establishing vegetation with peat-forming capability within 30 years". This has been assessed on a case-by-case basis. Provided they are capable of natural regeneration, the following land-cover types are considered to fall within the definition of Degraded raised bogs:

 

     

  1. Conifer plantations;
  2. Improved pasture;
  3. Scrub woodland (usually birch Betula spp.);
  4. Bare peat;
  5. Impoverished vegetation dominated by species including purple moor grass Molinia caerulea, hare’s-tail cottongrass Eriophorum vaginatum and heather Calluna vulgaris, and lacking significant cover of bog-mosses Sphagnum species

European status and distribution

 

Degraded raised bogs are widely distributed in Europe, and are found in most EU Member States.

UK status and distribution Click to view UK distribution of this habitat

 

Degraded raised bogs occur throughout the range of raised bogs in the UK. Obtaining an estimate of the national extent of this type is constrained by the lack of correspondence between Annex I habitat types and the condition categories used in the Lowland Raised Bog Inventory (LRBI) (Lindsay & Immirzi 1996), which does not include Northern Ireland. However, degraded raised bogs are certainly more extensive than 7110 Active raised bogs. Peatland in Northern Ireland has been classified and mapped using air photographs (Cruickshank & Tomlinson 1988). This identified 2,270 ha of intact lowland peatland and 20,042 ha of ‘cut-over’ peatland, but it is not possible to report separately on the area of ‘active’ or ‘degraded’ raised bog using this information source.

Site selection rationale

 

The importance of Degraded raised bogs in the SAC series is the habitat’s potential to be restored to 7110 Active raised bog, and thus contribute to attaining favourable conservation status for raised bogs as a whole, and fulfil the UK’s responsibility in implementing the Habitats Directive. The series of degraded raised bog sites has therefore been selected to complement the list of Active raised bogs. Sites have been selected that are considered to be sufficiently large and valuable in terms of their potential for natural regeneration, and to improve geographical coverage of raised bog within the site series. They have also been chosen to augment Active raised bog examples in areas where lowland bog is or has been particularly frequent.

 

The prospects of a site for restoration have been carefully assessed, as an important aspect of quality to be considered alongside the need to select an adequate proportion of the overall UK lowland raised bog resource and to achieve appropriate geographical representation. Prospects for site restoration have been assessed on a case by case basis, taking into account factors such as the current vegetation cover, disruption to the bog’s hydrological integrity, local climatic conditions, and the surrounding land use. Sites have not been selected if they are not judged capable of the required degree of restoration within 30 years, even where they would fill significant geographical gaps in the SAC series.

 

The Interpretation manual of European habitats (European Commission DG Environment 1999) notes that ‘sites unlikely to qualify as SACs are those that consist largely of bare peat, that are dominated by agricultural grasses or other crops, or where components of bog vegetation have been eradicated by closed canopy woodlands’. In considering such areas for SAC selection, judgements have been made about the ease of restorability if appropriate management was introduced now, or at a later date. As a result, some sites composed substantially of bare peat and some afforested sites have been selected. The large resource of former peatland now under agriculture (archaic sites) was not considered in site selection as such land is not likely to satisfy the restorability requirements.

 

Representation of Degraded raised bogs within the UK SAC network is particularly high in England. This reflects the fact that a greater proportion of the English raised bog resource has been affected by human activities than in other parts of the UK.


Site accounts

Bolton Fell Moss Cumbria
Habitat occurrence account not yet available.
Cors Caron West Wales and The Valleys
Areas of degraded raised bog occur peripheral to 7110 active raised bog at this extensive inland composite raised mire site. The vegetation cover is predominantly composed of species-poor rank swards of purple moor-grass Molinia caerulea developed over surfaces grossly modified by drainage and peat-cutting. Many of the most modified sections are subject to an extensive programme of hydrological rehabilitation aimed at elevating and stabilising water levels adjacent to the core surviving raised bog interest.
Cors Fochno West Wales and The Valleys
Substantial areas of degraded raised bog occur peripheral to 7110 active raised bog at this extensive estuarine raised mire site. Included here are a range of vegetation types in which peat formation has been arrested as a consequence of intensive drainage followed in places by peat removal and/or agricultural management. The vegetation cover of these areas is varied and includes grazed and ungrazed MoliniaMyrica swards, reed Phragmites stands, rush Juncus pasture, wet woodland and scrub, drier areas of acid grassland and bracken Pteridium aquilinum, and improved grassland over archaic deep peat.
Duddon Mosses Cumbria
This bog complex is within the tributary plains of the Duddon estuary in south Cumbria. The contiguity of the original peat domes has been severed by road construction and agricultural conversion. On some of the component bogs peat-cutting has left a drained surface which is now only partially 7110 active raised bog. The degraded raised bog is mostly dominated by purple moor grass Molinia caerulea, although pockets of raised bog plants including bog-mosses Sphagnum spp. offer good prospects for regeneration provided the hydrology is repaired. Degraded bog also occurs around the edges of discrete domes of active bog due to deep regional drainage and agricultural use of the surrounding land. There is no present-day peat-extraction on this site.
Flanders Mosses Eastern Scotland
Flanders consists of a cluster of separate bogs in the central belt of Scotland that are the remnants of one of the largest 7110 Active raised bog complexes in Britain. A variety of mire conditions, including small areas of degraded raised bog, are present within the site boundary, which collectively form the functional peatland-hydrological unit. East Flanders Moss is the largest raised bog in the UK that is still in a predominantly near-natural state. Areas previously managed for commercial peat extraction and forestry are currently being restored, agricultural drains blocked and invasive scrub removed. Collymoon Moss previously formed part of a peatland continuum with East Flanders. Killorn Moss and Shirgarton Moss form small satellites to East Flanders Moss, having once almost certainly been connected to it by fen peat which has disappeared through agricultural use. These sites have a narrow fringe of woodland giving way to open mire communities, which, in both cases, support vigorous bog-moss Sphagnum spp. vegetation and typical features of raised bog; they are therefore seen as an integral part of the site.
Hatfield Moor South Yorkshire
Like Thorne Moors, Hatfield Moors is a remnant of the once-extensive bog and fen peatlands within the Humberhead Levels, and is still the second-largest area of extant lowland raised bog peat in England. Moraines of sand occur beneath the peat, the largest of which forms Lindholme Island, in the centre of the bog. Little, if any, original bog surface has survived the massive extraction of peat over the last few decades. Peat-cutting has now ceased, and the bog is being restored over its remaining minimum average depth of 0.5 m of peat.

Refugia of vegetation have survived as rather dry heathland and as birch Betula woodland. Plants include the dwarf shrubs Calluna vulgaris, Erica tetralix, Eriophorum angustifolium, E. vaginatum, Vaccinium oxycoccos, bog-rosemary Andromeda polifolia, bog-myrtle Myrica gale, and the bog-mosses Sphagnum cuspidatum, S. recurvum, S. papillosum, S. subnitens and S. tenellum. The bog is also notable for its invertebrate fauna, which includes the mire pill beetle Curimopsis nigrita.

Manchester Mosses Cheshire, Greater Manchester
Mossland formerly covered a very large part of low-lying Greater Manchester, Merseyside and southern Lancashire, and provided a severe obstacle to industrial and agricultural expansion. While most has been converted to agriculture or lost to development, several examples have survived as degraded raised bog, such as Risley Moss, Astley & Bedford Mosses and Holcroft Moss on the Mersey floodplain. Their surfaces are now elevated above surrounding land due to shrinkage of the surrounding tilled land, and all except Holcroft Moss have been cut for peat at some time in the past. While past drainage has produced dominant purple moor grass Molinia caerulea, bracken Pteridium aquilinum and birch Betula spp. scrub or woodland, wetter pockets have enabled the peat-forming species to survive. Recent rehabilitation management on all three sites has caused these to spread.
Moine Mhor Highlands and Islands
Most peat on the west coast of Scotland is classified as 7130 Blanket bogs. The small amount of raised bog present in this area has suffered significant human impact. Mòine Mhór is the largest area of raised bog in this part of Scotland and represents the hyper-oceanic zone within the raised bog SAC series. It has been subjected to a number of damaging management activities in the past, including extensive drainage, commercial and domestic peat extraction and some afforestation, but now shows strong evidence of regeneration. A transition to saltmarsh is an unusual ecological feature of this site.
Peatlands Park Northern Ireland
Peatlands Park is a large lowland raised bog that has been extensively cut for turf in the past. It represents one of the largest areas of degraded raised bog in Northern Ireland. Regeneration is taking place over a large part of the site, with heather Calluna vulgaris and cross-leaved heath Erica tetralix together with a mixture of sedges including hare’s-tail cottongrass E. vaginatum, common cottongrass Eriophorum angustifolium and Sphagnum bog-mosses. The peatland flora includes bog-rosemary Andromeda polifolia at one of its few Northern Ireland sites. The peatland interest also incorporates an area of intact lowland raised bog at Mullenakill. Associated woodland interest includes 91A0 old sessile oak woods with Ilex and Blechnum and 91D0 Bog woodland.
Roudsea Wood and Mosses Cumbria
This is a complex of raised bogs on the northern shore of Morecambe Bay in north-west England. Although the majority of the complex has undergone extensive drainage in the past, with domestic peat-cutting around the margins, drainage was abandoned many years ago and peat-formation has resumed over much of its area. Less than 20% of the site is classified as degraded raised bog. Within the site there are transitions between acid bog and limestone woodland, with a number of scarce plant species including the rare yellow sedge Carex flava.
Solway Mosses North South Western Scotland
Solway Mosses North has two main components, Longbridge Muir and Kirkconnel Flow. Longbridge Muir is an extensive raised bog and one of the few remaining unplanted examples in this area. The site contains a large area of active mire with good quality peat-forming vegetation. Extensive surface patterning is present. While the bulk of the site is 7110 Active raised bog, Longbridge Muir includes areas which have been drained and planted but which form an integral part of the overall peat mass. Work is in progress to restore this area, supported by an EC LIFE project. Kirkconnel Flow is low-altitude estuarine moss, around one-third of which consists of 7110 Active raised bog, but the majority of the site has been invaded by tree and scrub cover. Nevertheless, extensive areas of good quality active bog remain, and this will be enhanced by work currently in progress to restore the degraded component, also supported by EC LIFE funds.
Thorne Moor East Yorkshire and Northern Lincolnshire, South Yorkshire
Thorne Moor is England’s largest area of raised bog, lying a few kilometres from the smaller Hatfield Moors, both within the former floodplain of the rivers feeding the Humber estuary (Humberhead Levels), and includes the sub-components Goole Moors and Crowle Moors. Although recent management has increased the proportion of 7110 active raised bog at Thorne Moors, the inclusion of Goole Moors, where peat-extraction has now ceased, means that the site is still predominantly degraded raised bog. The restored secondary surface is rich in species of 7110 Active raised bogs with bog-mosses Sphagnum spp., cottongrasses Eriophorum angustifolium and E. vaginatum, heather Calluna vulgaris, cross-leaved heath Erica tetralix, round-leaved sundew Drosera rotundifolia, cranberry Vaccinium oxycoccos and bog-rosemary Andromeda polifolia.
Walton Moss Cumbria
A largely intact raised bog of roughly rectangular shape, with an arm of mossland protruding westwards from the south-west corner. The peat spills over from the main basin forming blanket mire, and as such it is classified as an intermediate bog. Some peat-cutting has taken place in the south-east and south-west of the moss, lowering the surface by about 1.5 m, and it is here that the bog is degraded. This predominantly active bog is surrounded by rough pasture, and there may be up to 149 ha of archaic peatland surrounding the site on thin blanket peat.

The degraded areas tend to be dominated by purple moor-grass Molinia caerulea with common cottongrass Eriophorum angustifolium and the bog-moss Sphagnum cuspidatum colonising pools. In drier areas a bog heath community is present with moribund heather Calluna vulgaris dominating. Small areas of birch-dominated woodland or scrub are present around the margins of the site. Rush pasture is also present on the margins, with species such as the rushes Juncus effusus, J. conglomeratus, J. acutiflorus, J. squarrosus and M. caerulea.

Witherslack Mosses Cumbria
Meathop Moss, Nichols Moss and Foulshaw Moss are remnants of a formerly interconnected peat body on the west side of the Kent estuary, on its coastal plain. All retain some of the original dome structure, though each has been at least in part degraded by peat-cutting around the edges and by commercial forestry on Foulshaw Moss. Degraded raised bog predominates on Foulshaw Moss and is present around the edges on the other two, but each site contains good examples of 7110 Active raised bogs as NVC type M18a Erica tetralixSphagnum papillosum raised and blanket mire, Sphagnum magellanicumAndromeda polifolia sub-community. The forestry plantations are now being removed from Foulshaw Moss.

SACs/SCIs/cSACs where this Annex I habitat is a qualifying feature, but not a primary reason for site selection

Black Loch Moss Eastern Scotland, South Western Scotland
Blawhorn Moss Eastern Scotland
Braehead Moss South Western Scotland
Carsegowan Moss South Western Scotland
Coalburn Moss South Western Scotland
Cockinhead Moss South Western Scotland
Cranley Moss South Western Scotland
Curran Bog Northern Ireland
Dykeneuk Moss South Western Scotland
Fenn`s, Whixall, Bettisfield, Wem and Cadney Mosses East Wales, Shropshire and Staffordshire
Methven Moss Eastern Scotland
Muir of Dinnet North Eastern Scotland
North Shotts Moss South Western Scotland
Peeswit Moss Eastern Scotland
Raeburn Flow South Western Scotland
Red Moss of Netherley North Eastern Scotland
Reidside Moss North Eastern Scotland
Shelforkie Moss Eastern Scotland
South Solway Mosses Cumbria
Threepwood Moss Eastern Scotland
Turclossie Moss North Eastern Scotland
Usk Bat Sites/ Safleoedd Ystlumod Wysg East Wales, West Wales and The Valleys
Waukenwae Moss South Western Scotland
 

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