Red List habitat classification > RLD - Mires and bogs > RLD2.2a Poor fen

Poor fen

Quick facts

Red List habitat type code RLD2.2a
Threat status
Europe Least Concern
EU Vulnerable
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)


Wide group of acidic (pH 3-5), minerotrophic mires, dominated by sedges and Sphagnum species. Poor fens occur in many different hydro-topographical situations and are typical components of the marginal lagg of raised bogs. In temperate Europe they also occur around mountain springs, in forest hollows, and in infertile fen-grassland complexes, but always on non-calcareous bedrock. Poor fens can also form the main type of usually small mire areas in weakly minerotrophic basins. Poor fens are the main transition type between D2.3a Quaking mires and D1.1 Raised bogs. Poor fens receive limited minerotrophic water input from upper catchments usually via non-distinct, diffuse flow paths. Poor fens can have unidirectional slope and lateral water flow but hummock-string patterning typical for D3.2 Aapa mires is missing.

Poor fens are characterized by continuous carpets of oligotrophic Sphagnum spp. combined with high abundance of sedges like Carex canescens, Carex echinata, Carex nigra, Carex lasiocarpa, Eriophorum scheuchzeri, Trichophorum cespitosum. Other abundant species are and Andromeda polifolia, Betula nana, Dactylorhiza maculata, Eriophorum vaginatum, Potentilla erecta, and Vaccinium oxycoccos. Also certain deep-rooted species more characteristic of D2.3a Quaking mires are frequent in poor fens, namely Eriophorum angustifolium, Carex rostrata and Menyanthes trifoliata. Ground layer is often dominated by Sphagnum angustifolium, Sphagnum fallax, Sphagnum flexuosum, Sphagnum papillosum and Sphagnum magellanicum, while other brown mosses can also be frequent, including Straminergon stramineum, Polytrichum commune and Warnstorfia fluitans. Higher degree of minerotrophic influence can be found only occasionally, as indicated by occurrence of e.g. Sphagnum subsecundum, Sphagnum obtusum or Sphagnum teres. In boreal zone, hummocks with Sphagnum fuscum, Polytrichum strictum, Calluna vulgaris and Empetrum nigrum are sometimes found in poor fens, with Salix spp., Rhamnus frangula, Betula pubescens or individual cranked pines (Pinus sylvestris).

Indicators of good quality:

Under natural conditions, water table is high also in summer and continuous carpets of mosses prevail with abundant sedges. Species diversity of vegetation is generally slightly higher than in D1.1 Raised bogs but clearly lower than in intermediate fens. In good hydrological condition there are no ditches that drain or disconnect water flow from the upper drainage area to the mire. Tree growth is limited to scattered individuals on hummocks or mire margins.

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

Threat status

Synthesis of Red List assessment

This habitat has been assessed as Vulnerable (VU) in the EU28, based on the decline in area over the last 50 years, and Least Concern for the EU28+. However, there is a massive reduction up to over 90% of its previous area in many European countries, and therefore the habitat is regionally much more threatened. However, in the countries of Scandinavia, where by far the largest areas of this mire type occur, the reductions are relatively low. The habitat is not as sensitive regarding reduction of quality as the calcareous counterpart Short-sedge base-rich fens. On the contrary, slight drainage often leads to acidification of mire surfaces due to the higher influence of rainfall and therefore to an expansion of poor fens at the expense of calcareous types.
Red List Category Red List Criteria
Vulnerable A1
Red List Category Red List Criteria
Least Concern -

Confidence in the assessment

Red List of habitat categories and criteria descriptions

Pressures and threats

  • Agriculture
    • Agricultural intensification
  • Pollution
    • Pollution to surface waters (limnic, terrestrial, marine & brackish)
    • Air pollution, air-borne pollutants
  • Natural System modifications
    • Modification of hydrographic functioning, general
    • Water abstractions from groundwater
  • Climate change
    • Droughts and less precipitations

Habitat restoration potential

Rewetting activities show that in general the hydrological regime of poor fens can be restored. However, depending on the status of the surrounding landscape, pollution with nutrients might have effect for a long time and regeneration of nutrient poor conditions at least in Central Europe can be expected only after decades to centuries after massive new peat accumulation or after top soil removal.

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

Huge efforts have been undertaken in the last decades to protect the last poor fen areas in Central and Southern Europe. Most important is the regeneration of the hydrological systems of the mires. In some areas and after eutrophication, poor fens depend on nutrient withdrawal by browsing or mowing.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
    • Restoring/Improving the hydrological regime
    • Managing water abstraction
  • Measures related to spatial planning
    • Legal protection of habitats and species


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)
Austria Present 13 - Decreasing
Belgium Present 0.8 Increasing Decreasing
Bulgaria Present 1 Decreasing Decreasing
Croatia Uncertain - -
Czech Republic Present 27 Decreasing Decreasing
Denmark Present 20 Stable Decreasing
Estonia Present 350 Stable Unknown
Finland mainland Present 7050 Decreasing Decreasing
Aland Islands Uncertain 7050 Decreasing Decreasing
France mainland Present unknown - -
Germany Present unknown Decreasing Decreasing
Hungary Present 0.1 Decreasing Decreasing
Ireland Present 560 Unknown Decreasing
Italy mainland Uncertain - -
Latvia Present unknown Decreasing Decreasing
Lithuania Present 7.5 Decreasing Decreasing
Luxembourg Uncertain - -
Netherlands Present 1.1 Stable Decreasing
Poland Present 300 Decreasing Decreasing
Romania Present 2 Decreasing Stable
Slovakia Present 6.2 Stable Decreasing
Slovenia Uncertain - -
Spain mainland Present 70 Unknown Decreasing
Balearic Islands Present 70 Unknown Decreasing
Sweden Present 12500 Decreasing Decreasing
United Kingdom Present 75 Unknown Decreasing
Northern Island Present 75 Unknown Decreasing
Greece (mainland and other islands) Uncertain - -
EU28 + Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)
Bosnia and Herzegovina Present 0.7 Stable Decreasing
Norway Mainland Present 15000 Decreasing 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 9973750 13692 13000 AOO and EOO incl. potential distribution
EU28+ 13711 33000 AOO and EOO incl. potential distribution
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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