Red List habitat classification > RLD - Mires and bogs > RLD1.1 Raised bog

Raised bog

Quick facts

Red List habitat type code RLD1.1
Threat status
Europe Vulnerable
EU Endangered
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)

Summary

In raised bogs, the water table level is elevated  by a few centimeters to metres above that of mineral rich ground water of surrounding areas and consequently there is an ombrotrophic (rain-fed) nutrient regime. The peat layer is often several metres thick and mainly composed of Sphagnum remains, highly water saturated with the water table close to the surface. High acidity (pH < 4.5) and low mineral content characterize the peat and pore water. Typically there is a pattern of alternation between micro  habitats (hummocks, lawns, carpets, hollows) that relate to topography, hydrology and peat formation. Hummock-hollow patterning can be irregular in flat plateau bogs, where hummocks remain low. In concentric and eccentric raised bog complexes, hummock-hollow patterning shows a distinct orientation perpendicular to the slope and water flow. Open water pools of secondary origin, i.e. developed on the peat after hummock ridge formation, are often found and provide important aquatic microhabitats. Raised bog habitats are most typical in central parts of raised bog complexes (EUNIS habitat X04) but they are also found in mixed complexes with D3.2 Aapa mires. Mire complex patterns may also be completely missing and often raised bog habitats are found as small undrained remnants of historically degraded bog complexes. Raised bogs differ from D1.2 Blanket bogs by being restricted to basins rather than blanketing over variable terrain. The lagg zones of raised bog complexes are considered under D2.2a Poor Fens.

Trees (Pinus sylvestris, Betula pubescens) are found only sparsely on hummocks and Sphagnum mosses dominate the ground layer of vegetation. In hummocks, Sphagnum fuscum is the most characteristic species, especially in boreal and continental areas. Other typical hummock species are S. rubellum, S. magellanicum, S. capillifolium, S. angustifolium, Dicranum bergeri  and Polytrichum strictum. Dwarf-shrub species Andromeda polifolia, Betula nana, Calluna vulgaris, Empetrum nigrum, Erica tetralix, Ledum palustre, Vaccinium microcarpon, V. oxycoccos, V. uliginosum are characteristic on hummocks, while only few herbs (Drosera rotundifolia, Rubus chamaemorus) and sedges (Carex pauciflora, Eriophorum vaginatum) are found. The wet hollows may have continuous carpets of Sphagnum or sometimes muddy peat surfaces void of mosses or with some cover of hepatics or Warnstorfia fluitans. Typical species include Sphagnum cuspidatum, S. balticum, S. jensenii, S. majus, S. tenellum among mosses and Carex limosa, Scheuchzeria palustris, Rhynchospora alba among vascular plants. Also forest mosses like Pleurozium schreberi, Hylocomium splendens, Dicranum polysetum and lichens like Cladonia spp. and Certraria islandica are found on hummocks.

Raised bogs are widely distributed from central European mountain areas to north-boreal regions, being most prominent in the hemi-boreal to south-boreal zones. The pattern of dominance and features of micro-habitat patterning vary over different climatic zonation belts.

Indicators of good quality:

  • Under natural conditions, the water table is close to surface in hollows and it can be readily observed in small pit dug in peat surface except during prolonged drought.
  • There is a gradual and logical continuum between dominant vegetation and the composition of recently (decades to centennial) formed peat, indicating that modern vegetation is forming typical Sphagnum peat.
  • Species composition differs between hummocks and hollows in a regionally characteristic way and there are no large patches of lichens or hummock mosses such as Polytrichum strictum in the hollows.
  • Ombrotrophic and acidophilic Sphagnum mosses and other characteristic species comprise substantial elements in vegetation.
  • Number of species or diversity indices of vegetation are not good indicators since raised bogs are naturally species poor habitats, while harboring unique species assemblages.
  • Occurrence of trees is limited to scattered individuals on hummocks. Drainage ditches are one main factor to cause decline of quality of raised bogs but their occurrence alone does not always indicate poor quality.

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

Threat status

Synthesis of Red List assessment

Raised bog habitats have declined markedly in area in recent and historical past. Taking into account probable effects of deficiencies and time-scales of data provided, this habitat type results in the assessment Endangered (EN) under the criterion A3 in EU28 and in Vulnerable (VU) under the criteria A1 and A3 in EU28+. In the case of Raised bogs, historic reduction in area is relevant even today, although area reduction is generally considered to have ceased. Many populations of bog biota are nevertheless continuing to decline partly due to the historic legacy. Also, quality decline is widely reported but the C/D1 criterion only indicates Near Threatened (NT) status. Data were insufficient for separation between the C and D criteria, which are difficult to assess separately because they are strongly interlinked. Main abiotic threats include altered water level/hydrology and nitrogen deposition that affect biotic structures like abundance of trees.
EU
Red List Category Red List Criteria
Endangered A3
Europe
Red List Category Red List Criteria
Vulnerable A1, A3

Confidence in the assessment

medium
Red List of habitat categories and criteria descriptions

Pressures and threats

  • Sylviculture, forestry
    • Forest planting on open ground
    • Forest planting on open ground (native trees)
    • Artificial planting on open ground (non-native trees)
  • Mining, extraction of materials and energy production
    • Peat extraction
    • Mechanical removal of peat
  • Human intrusions and disturbances
    • Other human intrusions and disturbances
  • Pollution
    • Air pollution, air-borne pollutants
    • Nitrogen-input
    • other air pollution
  • Natural System modifications
    • Human induced changes in hydraulic conditions
    • Canalisation & water deviation
    • Canalisation
    • Modification of hydrographic functioning, general
    • Reservoirs
    • Water abstractions from groundwater
    • Other human induced changes in hydraulic conditions
    • Other ecosystem modifications
    • Anthropogenic reduction of habitat connectivity
  • Natural biotic and abiotic processes (without catastrophes)
    • Biocenotic evolution, succession
    • Species composition change (succession)
    • Eutrophication (natural)
  • Climate change
    • Changes in abiotic conditions
    • Droughts and less precipitations

Habitat restoration potential

There are good experiences of restoration by blocking drainage ditches. Importantly, Sphagnum mosses recover quickly and peat accumulation can start within about ten years if water levels are kept high. Natural recovery without intervention is slow. In high-domed Raised bogs sufficient blocking or damming of ditches can be especially difficult.

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

Raised bogs are widely represented in conservation areas but many valuable sites are still without protection. Restoration of degraded bogs by blocking ditches and restoring the rain-fed water-table, has been conducted in many countries but upscaling of restoration activities is needed in order to gain more than marginal area and quality effects at the European scale. Peat extraction should be stopped in habitats that still have the natural defining features of raised bogs, in order to halt the reduction in extent.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving the hydrological regime
    • Managing water abstraction
  • Measures related to spatial planning
    • Establish protected areas/sites
    • Establishing wilderness areas/allowing succession
    • Legal protection of habitats and species
    • Manage landscape features
  • Measures related to hunting, taking and fishing and species management
    • Regulation/Management of hunting and taking
  • Measures related to urban areas, industry, energy and transport
    • Specific management of traffic and energy transport systems
  • Measures related to special resouce use
    • Other resource use measures

Distribution

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 30 Decreasing Decreasing
Belgium Present 1.6 Decreasing Stable
Croatia Present 0.01 Unknown Unknown
Czech Republic Present 25 Decreasing Decreasing
Denmark Present 73 Decreasing Decreasing
Estonia Present 1500 Decreasing Decreasing
Finland mainland Present 5600 Decreasing Decreasing
Aland Islands Present 5600 Decreasing Decreasing
France mainland Present 145 Decreasing Decreasing
Germany Present 460 Decreasing Decreasing
Hungary Present 0.03 Decreasing Decreasing
Ireland Present 499 Decreasing Decreasing
Italy mainland Present 8.9 Decreasing Decreasing
Latvia Present 2979 Decreasing Decreasing
Lithuania Present 125 Decreasing Decreasing
Netherlands Present 53 Decreasing Decreasing
Poland Present 610 Decreasing Decreasing
Romania Present 20 Decreasing Stable
Slovakia Present 0.8 Decreasing Decreasing
Slovenia Present 0.6 Stable Stable
Spain mainland Present 68 Decreasing Decreasing
Sweden Present 8000 Decreasing Decreasing
United Kingdom Present 625 Decreasing Decreasing
Northern Island Present 625 Decreasing Decreasing
Portugal Azores Present 0.2 Decreasing Decreasing
Portugal mainland Present 0.2 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)
Switzerland Present 17 Decreasing Decreasing
Bosnia and Herzegovina Present 0.2 Decreasing Decreasing
Norway Mainland Present 7100 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 8260850 4951 20660
EU28+ 5129 27760
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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