Red List habitat classification > RLD - Mires and bogs > RLD4.1c Calcareous quaking mire

Calcareous quaking mire

Quick facts

Red List habitat type code RLD4.1c
Threat status
Europe Vulnerable
EU Vulnerable
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)


Very wet mires with rich fen vegetation of topogenic basins fed by calcareous ground water from the catchment. Water pH is always high (pH 6.5-8.5) due to high alkalinity. Calcium concentrations are typically very high (>20 mg/l) but sometimes lower, especially in boreal regions. Peat layer is usually relatively thin (0.5-2 m) but also sites with thicker peat layer occur, as depending on basin and catchment topography. Calcium precipitation can take place on peat surface. Water table is always close to peat surface and open water surfaces are common. Regular surface patterning can be absent, while irregular patterns of flarks, pools and hollows are common. In boreal region, typical string-flark patterning is common. In such cases, calcareous quaking mires differ from D3.2 Aapa mires by the abundance of calciphilous species, especially among bryophytes. This also is the main distinction from D2.3a Quaking mires.

Vegetation is strongly minerotrophic and characterized by abundance of Amblystegiaceae mosses, especially Scorpidium scorpioides. Other characteristic mosses include Scorpidium revolvens, Scorpidium cossoni, Calliergon richardsonii and Pseudocalliergon trifarium. In the boreal region, weaker minerotrophy indicating species like Sphagnum contortum and Warnstorfia procera can also be frequent. Vascular plant cover is characteristically sparse. Typical species include Carex chordorrhiza, Carex diandra, Carex flava, Carex lasiocarpa, Carex limosa, Carex rostrata, Carex livida, Drosera longifolia, Equisetum fluviatile, Eriophorum gracile, Juncus stygius, Liparis loeselii, Menyanthes trifoliata, Pedicularis palustris, Potentilla palustris, Schoenus ferrugineus and Utricularia intermedia. Sometimes sparse stands of Phragmites australis are found.

Indicators of good quality:

Under natural conditions, water table is close to surface and it can always be readily observed. Open water surfaces are common. Calcite precipitation takes place in richly calcareous situations, but when calcium levels are not supersaturated, precipitation can be absent. Rich fen mosses are abundant, although not necessarily forming continuous carpets. Sphagnum mosses are mainly absent from main mire surfaces, while they may be found in hummock strings or other isolated microsites. Vascular plant cover is sparse, leaving space and light for mosses.

Drainage ditches can affect calcareous quaking mires by lowering water level or by interrupting the inflow of calcareous water from the catchment. In such cases, rich fen mosses are rapidly lost and replaced by generalist species. Eutrophication by nitrogen deposition also threatens these habitats. Over growth e.g. by Sphagnum subnitens and Calliergonella cuspidata have been observed in high N deposition areas. General increase of vascular plant biomass can also indicate weakening of habitat quality.

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

Threat status

Synthesis of Red List assessment

Calcareous quaking mires are assessed as Vulnerable (VU) based on the criterion A1. Better data cover and quality might have resulted in more critical assessment, especially by criterion A3 of historic decline in area. These habitats are estimated to have lost about one third of their area during the past 50 years. This can be an underestimate but even the upper bound of estimation was below the threshold for the Endangered (EN) category.
Red List Category Red List Criteria
Vulnerable A1
Red List Category Red List Criteria
Vulnerable A1

Confidence in the assessment

Red List of habitat categories and criteria descriptions

Pressures and threats

  • Agriculture
    • Cultivation
    • Abandonment of pastoral systems, lack of grazing
    • Fertilisation
  • Sylviculture, forestry
    • Forestry activities not referred to above
  • Mining, extraction of materials and energy production
    • Peat extraction
    • Mechanical removal of peat
  • Pollution
    • Pollution to surface waters (limnic, terrestrial, marine & brackish)
    • Diffuse pollution to surface waters due to agricultural and forestry activities
    • Nutrient enrichment (N, P, organic matter)
  • Natural System modifications
    • Human induced changes in hydraulic conditions
    • Infilling of ditches, dykes, ponds, pools, marshes or pits
    • Canalisation & water deviation
    • Modification of hydrographic functioning, general
    • Water abstractions from groundwater
    • Other human induced changes in hydraulic conditions
  • Natural biotic and abiotic processes (without catastrophes)
    • Biocenotic evolution, succession
    • Species composition change (succession)
    • Eutrophication (natural)
    • Acidification (natural)

Habitat restoration potential

When severely damaged in terms of hydrological disturbance, restoration by blocking and damming ditches can effectively help habitat recovery. Problems may arise if hydrological connection to calcareous ground water supply from the catchment is not regained or if nutrient mineralisation causes eutrofication. Liming may be necessary in some cases to prevent acidification and connected unfavourable vegetation succession. If loss of key species like characteristic mosses has taken place, reintroduction by transplantations should be considered, as well as active measures to suppress overgrowing by unwanted plant cover.

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

Establishing protected areas and restoration by improving hydrological regime of disturbed sites are the main approaches. In addition, liming may be needed in some areas to improve water quality.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Other wetland related measures
    • Restoring/Improving water quality
    • Restoring/Improving the hydrological regime
    • Managing water abstraction
  • Measures related to spatial planning
    • Establish protected areas/sites
    • Legal protection of habitats and species
  • Measures related to hunting, taking and fishing and species management
    • Regulation/Management of hunting and taking


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 2 Decreasing Decreasing
Belgium Present unknown Decreasing Decreasing
Bulgaria Present 7 Decreasing Decreasing
Czech Republic Present 0.1 Decreasing Decreasing
Denmark Present 3 Decreasing Decreasing
Estonia Present 13 Stable Stable
Finland mainland Present 320 Decreasing Decreasing
Aland Islands Present 320 Decreasing Decreasing
France mainland Present 01-May Decreasing Decreasing
Ireland Present unknown Decreasing Decreasing
Latvia Present unknown Decreasing Decreasing
Lithuania Present <1 Decreasing Decreasing
Netherlands Present 2 Decreasing Decreasing
Poland Present 10 Decreasing Decreasing
Slovakia Present 0.1 Decreasing Decreasing
Spain mainland Present unknown Unknown Unknown
Sweden Present 500 Decreasing Decreasing
United Kingdom Uncertain - -
Germany Present <1 Decreasing Decreasing
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 10 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 4778200 1318 860 Minor areas missing due to lack of data from some countries
EU28+ 1438 870 Minor areas missing due to lack of data from some countries
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
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