Red List habitat classification > RLD - Mires and bogs > RLD2.1 Oceanic valley bog

Oceanic valley bog

Quick facts

Red List habitat type code RLD2.1
Threat status
Europe Near Threatened
EU Vulnerable
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)


Oceanic valley bogs are essentially topogenous systems of permanently waterlogged, oligotrophic acid peats, maintained by a high ground water table seeping from impervious bedrocks or superficial deposits in low-relief landscapes of the oceanic parts of Europe, topographically completely isolated from other mire systems, though often embedded within landscapes of wet heath. The hydrological regime can be quite complex, with percolating waters sometimes channeled to a central soakway and outflow which has a more obviously soligenous character. The peat sustaining the valley bog habitat itself is usually thin, often less than 1.5m.

Although the valley mire flora may show some localised soligenous influence where water flow becomes more obvious, a poor-fen flora is typically sparse on the active surface and the usual dominants are peat-building Sphagnum species, which form a luxuriant carpet with a gentle hummock-hollow surface and bog pools in lower places. Compared with ombrogenous bogs, Eriophorum vaginatum and Scirpus cespitosus are very scarce and the usual monocotyledons are Eriophorum angustifolium and Molinia caerulea, both sometimes abundant, with Rhynchospora alba occurring around the pools. Erica tetralix and, on the gentle hummocks, Calluna vulgaris form a patchy canopy up to 3 dm tall and Myrica gale is locally abundant.

Among the associates, the most characteristic are Narthecium ossifragum, Drosera rotundifolia with, less commonly D. intermedia and D. anglica, Potentilla erecta and Vaccinium oxycoccos. Associated soakways may have vegetation resembling D2.3a Quaking mires with, for example, Menyanthes trifoliata, Potamogeton polygonifolius and Hypericum elodes or small sedges. Where valley mires occur within stretches of wet heath, grazing and burning often occur in the mire surrounds, but the high water table of healthy mires offers some protection against trespass of bigger herbivores .

Indicators of good quality:

  • Water-table close to surface with wetter depressions and open pools.

  • Absence of man-made ditches or gullies

  • No patterns of erosion and drying

  • (Relatively high) species richness (in flora and fauna)

  • No indicators of ground-water eutrophication.

Characteristic species
For full habitat description, please download the habitat factsheet.

Threat status

Synthesis of Red List assessment

Although the calculation for A1 reduction in extent over recent past time gives a range which extends into the Endangered (EN) category, the fragmentary nature of the data makes an assessment of Vulnerable (VU) for the EU28 the more reliable conclusion. For the EU28+ the habitat is Near Threatened (NT), because of degradation of quality, with values close to the thresholds for Vulnerable.
Red List Category Red List Criteria
Vulnerable A1
Red List Category Red List Criteria
Near Threatened C/D1

Confidence in the assessment

Red List of habitat categories and criteria descriptions

Pressures and threats

  • Agriculture
    • Modification of cultivation practices
    • Agricultural intensification
    • Grazing
    • Non intensive grazing
  • Human intrusions and disturbances
    • Outdoor sports and leisure activities, recreational activities
    • Other human intrusions and disturbances
  • Pollution
    • Pollution to groundwater (point sources and diffuse sources)
    • Air pollution, air-borne pollutants
    • Nitrogen-input
  • Natural System modifications
    • Human induced changes in hydraulic conditions

Habitat restoration potential

This habitat probably needs careful and lengthy interventions to control the flow and quality of ground water which are likely to be the most damaging threats. There is little evidence of how well restoration can work.

Trends in extent

Average current trend in quantity

Decreasing Decreasing
EU28 EU28+

Trends in quality

Average current trend in quality

Decreasing Decreasing
EU28 EU28+

Conservation and management needs

The conservation of this habitat depends upon landscape-scale control of the underlying water table and of water quality, together with an ability to influence local farming (the predation of stock) and tourism (trespass of people and horses).

List of conservation and management needs

  • Measures related to agriculture and open habitats
    • Maintaining grasslands and other open habitats
  • Measures related to forests and wooded habitats
    • Other forestry-related measures
  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
    • Restoring/Improving the hydrological regime
    • Managing water abstraction


For each habitat a distribution map was produced from a wide variety of sources indicating known and potential occurrences of the habitat in 10x10 km grids within Europe. Occurrences in grid cells were given in two classes: actual distribution from relatively reliable sources (surveys, expert knowledge), and potential distribution based on models or less reliable indicators. Please download the fact sheet to see the map.

Geographic occurrence and trends

EU28 Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)
Czech Republic Present 0.5 Stable Decreasing
Germany Present <10 Decreasing Decreasing
Ireland Present Unknown Unknown Unknown
Netherlands Present 0.1 Stable Stable
Portugal mainland Present 0.2 Decreasing Decreasing
Romania Present 5 Decreasing Stable
United Kingdom Present 22 Decreasing Stable
Belgium Uncertain Unknown Unknown Unknown
France mainland Uncertain Unknown Unknown Unknown
EU28 + Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)
Norway Mainland Present 1000 Unknown Decreasing

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 2132100 138 38
EU28+ 146 1038
AOO = the area occupied by a habitat measured in number of 10x10 km grid cells.
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).

Characteristic species

Not available

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

Not available
European Environment Agency (EEA)
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