Red List habitat classification > RLD - Mires and bogs > RLD3.1 Palsa mire

Palsa mire

Quick facts

Red List habitat type code RLD3.1
Threat status
Europe Critically Endangered
EU Critically Endangered
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)


This habitat type is consists of mires in the subarctic region with sporadic permafrost, most characteristically palsa mounds elevated by permafrost lenses. Palsa mires are found in the discontinuous permafrost zone of Iceland, northern Fennoscandia and arctic Russia, in areas with average annual temperature below -1 °C, with climatic optimum between -3 to -5 °C and annual precipitation below 450 mm. Typically, palsa mounds occur in groups in the central, thick-peated areas of palsa mires. Palsa mounds with dome shape are 10-100 m wide and 2-7m high. Other types are longitudinal string-form or extensive plateau- form palsas that reach 1-3 m high. Palsa mound summits are covered by Sphagnum peat that insulates heat so that the active layer of thaw is limited to 30-60 cm. The perennial frozen core of palsa mounds consists of frozen peat and silt material with ice lenses and crystals. Pounikko-type hummock ridges (D3.12) formed by seasonal frost action can be found particularly in marginal areas of palsa mires. Palsas can have different successional stages: young palsa formations have Sphagnum hummock vegetation, while older palsa mounds become dry and their exposed peat surfaces are subject to erosion that may lead to melting and partial collapse. Completely melted palsas result in the formation of thermokarst ponds.

The palsa mound summits provide dry microhabitats in palsa mires. Typical species growing on the palsa mounds include Dicranum elongatum, Polytrichum strictum, Empetrum nigrum and Rubus chamaemorus and many lichens.  Sides of palsa mounds often have abundant Betula nana, Ledum palustris and Eriophorum vaginatum. Palsa mires resemble D3.2 Aapa mires in hydrology and vegetation of the wet mire surfaces of areas between the palsa mounds, but regular hummock-string patterning is usually not found. Palsa mires are usually weakly minerotrophic and vegetation types overlap with those of D2.2a Poor fens and D2.3 Quaking mires. In the wet surfaces, Sphagnum lindbergii, S. riparium, Eriophorum angustifolium and Carex rotundata are typical dominant species.

Indicators of good quality:

  • Under natural conditions, water table is very close to peat surface in fen areas between palsa mounds and carpets of mosses prevail with abundance of characteristic sedges.
  • There are no ditches that drain or disconnect water flow (seepage or overland flow) in the palsa mire complex.
  • Only few of the palsa mounds are melting and collapsing, indicating natural dynamics, while most palsa mounds remain frozen with intact peat cover.
  • Seasonal thaw of permafrost, the so called active layer, may reach 50-60 cm, while substantially deeper active layer approaching 1-m depth indicates melting and collapse.

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

Threat status

Synthesis of Red List assessment

This habitat type is assessed as Critically Endangered (CR) under Criterion E as its probability of collapse within the next 50 years is estimated to be over 50% as a result of climate warming. This quantitative analysis has been performed by reviewing and analyzing published research articles, together with unpublished contributions from experts, by including probabilistic modeling of future trends and linear extrapolation of recent trends to support model predictions.
However, there are certain comments to the assessment that need to be mentioned. First of all, monitoring of the active layer depth was possibly undertaken on big palsa mounds whose degradation may have occurred as part of their natural cycle. Furthermore, palsa mounds themselves are only components of the palsa mire habitats, while other indicators of habitat quality are poorly known and have not been considered in this assessment. In addition, extrapolation of recent trends to the future is heavily dependent on which precise recent period of climate fluctuation was included in the data. It is also noteworthy that there is no complete information available on area cover and decrease throughout the whole distribution of the habitat type.
Red List Category Red List Criteria
Critically Endangered E
Red List Category Red List Criteria
Critically Endangered E

Confidence in the assessment

Red List of habitat categories and criteria descriptions

Pressures and threats

  • Transportation and service corridors
    • Paths, tracks, cycling tracks
  • Human intrusions and disturbances
    • Off-road motorized driving
    • Trampling, overuse
  • Natural System modifications
    • Human induced changes in hydraulic conditions
  • Natural biotic and abiotic processes (without catastrophes)
    • Erosion
  • Climate change
    • Temperature changes (e.g. rise of temperature & extremes)
    • Flooding and rising precipitations

Habitat restoration potential

New palsas may form naturally if climate stays favourable or if climate cooling was expected.

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

Only strong climate change mitigation measures can be considered as an effective approach to possibly limit the decline of palsa mires in the future. In some individual cases, restoration and improvement of hydrological regime can be needed. Establishing protection for palsa mires may increase the likelihood of persistence of at least some palsa mires in localities with the most favorable conditions.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving the hydrological regime
  • Measures related to spatial planning
    • Establish protected areas/sites
    • Establishing wilderness areas/allowing succession
    • 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)
Finland mainland Present 104 Decreasing Decreasing
Sweden Present 137 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 150 Decreasing Decreasing
Iceland Present Unknown 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 104750 287 241
EU28+ 417 391 Iceland area missing
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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