Invalid Unit Specified
F016 Temperate to Polar Bog & Fen Formation

The U.S. National
Vegetation Classification
Type Concept Sentence: Temperate to Polar Bog & Fen includes temperate bogs and fens dominated by Sphagnum or brown mosses with ericaceous shrubs, graminoids, and low scrub tree growth forms, across the mid-latitudes of the Northern Hemisphere from 23° to 70°N, but is much less common in the southern mid-latitudes.
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Common (Translated Scientific) Name: Temperate to Polar Bog & Fen Formation
Colloquial Name: Temperate to Polar Bog & Fen
Hierarchy Level: Formation
Type Concept: Temperate to Polar Bog & Fen includes temperate and boreal bogs and fens dominated by Sphagnum or brown mosses with ericaceous shrubs, graminoids, and low scrub tree growth forms (<5 m). The driest bogs, especially in permafrost terrain, may be covered in dwarf-shrubs and lichens. The bog surface, which is raised or level with the surrounding terrain, is virtually unaffected by runoff waters or groundwaters from the surrounding mineral soils. Precipitation, fog and snowmelt are the primary water sources and, thus, all bogs are ombrogenous.

A temperate and boreal fen is a peatland with a fluctuating water table. The waters in fens are rich in dissolved minerals and, therefore, are minerotrophic. Groundwater and surface water movement is a common characteristic of fens. Surface flow may be directed through channels, pools, and other open waterbodies that can form characteristic surface patterns. The dominant materials are moderately decomposed sedge and brown moss peats of variable thickness. The vegetation on fens is closely related to the depth of the water table and the chemistry of the water present. The composition of vegetation may also reflect regional geographic variations. In general, graminoid vegetation and some bryophytes dominate wetter fens where the water table is above the surface. Shrubs are prominent in drier fens where the water table is lower. Trees appear on the driest fen sites where microtopographic features such as moss hummocks provide habitats as much as 20 cm above the water table.
Diagnostic Characteristics: This peatland type is dominated by Sphagnum spp. or brown mosses, with ericaceous shrubs, graminoids, and low scrub tree growth forms (<5 m). The driest bogs, especially in permafrost terrain, may be covered in dwarf-shrubs and lichens. Bogs contain raised or level sphagnum peat surfaces that are ombrotrophic or weakly minerotrophic, whereas fens are groundwater-driven, and moderately to strongly minerotrophic.
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: Subarctic and arctic (polar) bogs and fens belong in this formation.
Similar NVC Types:
F036 Boreal Flooded & Swamp Forest, note: This type includes forested bogs with >10% cover along with poor swamps.
F012 Temperate Grassland & Shrubland, note: Upland transitions to wet-mesic or moist grasslands, such as wet-mesic prairies, can be hard to place.
F013 Temperate to Polar Freshwater Marsh, Wet Meadow & Shrubland, note: Fens and marshes can be similar, especially when fen peat mats are inundated (as with "shore fens").
Physiognomy and Structure: This peatland type is dominated by Sphagnum spp. or brown mosses, with ericaceous shrubs, graminoids, and low scrub tree growth forms (<5 m). The driest bogs, especially in permafrost terrain, may be covered in dwarf-shrubs and lichens. The vegetation on fens is closely related to the depth of the water table and the chemistry of the water present. The composition of vegetation may also reflect regional geographic variations. In general, graminoid vegetation and some bryophytes dominate wetter fens where the water table is above the surface. Shrubs are prominent in drier fens where the water table is lower. Trees appear on the driest fen sites where microtopographic features such as moss hummocks provide habitats as much as 20 cm above the water table. Sites in fens with waters extremely low in dissolved minerals are poor fens and have Sphagnum mosses and ericaceous shrubs. Poor fens are sometimes placed with bogs as "acid peatlands." Fens with slightly higher concentrations of dissolved minerals are moderately rich fens and are dominated by sedges and brown mosses (such as Drepanocladus sp.). The moderate to extremely rich fens are sometimes collectively called "alkaline peatlands" or "rich peatlands" (National Wetlands Working Group 1997).
Floristics:
Dynamics: Many bogs started out as fens and may even have aquatic peat in the deepest layers. Only in transition from fen to bog will there be mixed "bog" peat with Sphagnum and ericaceous shrubs and "fen" peat with the remains of more minerotrophic plants such as brown mosses, sedges and shrubs (National Wetlands Working Group 1997).
Environmental Description: The bog surface, which is raised or level with the surrounding terrain, is virtually unaffected by runoff waters or groundwater from the surrounding mineral soils. Generally the water table is at or slightly below the bog surface. As the bog surface is raised, so is the bog water table relative to the elevation of the water table at the edges of the bog. Precipitation, fog, and snowmelt are the primary water sources and, thus, all bogs are ombrogenous. Given that precipitation does not contain dissolved minerals and is mildly acidic, the surface bog waters are consequently low in dissolved minerals and acidic. Bog water acidity, usually between pH 4.0 and 4.8 (Gorham and Janssens 1992), is enhanced due to the organic acids that form during decomposition of the peat and the acids present within Sphagnum leaves (National Wetlands Working Group 1997). The soils are mainly Histosols in the U.S. soil classification, and Fibrisols, Mesisols and Organic Cryosols (permafrost soils) in the Canadian soil classification system (National Wetlands Working Group 1997) [see Brady and Weil (2002) for comparison of Canadian soil orders with U.S. and FAO systems].

Fens are peatlands with a fluctuating water table. The waters in fens are rich in dissolved minerals and, therefore, are minerotrophic. Groundwater and surface water movement is a common characteristic of fens. Surface flow may be directed through channels, pools, and other open waterbodies that can form characteristic surface patterns. The dominant materials are moderately decomposed sedge and brown moss peats of variable thickness.
Geographic Range: This formation is found across the mid-latitudes of the Northern Hemisphere from 23° to 70°N, but is much less common in the southern mid-latitudes.
Nations: CA, US
States/Provinces:
Omernik Ecoregions:
Plot Analysis Summary:
Confidence Level: High
Confidence Level Comments:
Grank: GNR
Greasons:
Name:Database Code:Classification Code:
Class 2 Shrub & Herb Vegetation C02 2
Subclass 2.C Shrub & Herb Wetland S44 2.C
Formation 2.C.2 Temperate to Polar Bog & Fen F016 2.C.2
Division 2.C.2.Na North American Bog & Fen D029 2.C.2.Na
Division 2.C.2.Nb Atlantic & Gulf Coastal Plain Pocosin D324 2.C.2.Nb
Concept Lineage:
Predecessors:
Obsolete Names:
Obsolete Parents:
Synonomy: > Bog Wetland Class (National Wetlands Working Group 1997) [The class may include perhaps poor fens, but is otherwise synonymous with this formation.]
> Fen Wetland Class (National Wetlands Working Group 1997) [The class is synonymous with the fen part of this formation. Trees are typically <10% cover.]
> Peatlands (Mitsch and Gosselink 2000) [Bogs and fens are treated together, but tropical and temperate bogs are not separated. Forested bogs are included.]
> Peatlands (Roth 2009) [Bogs and fens are treated together, but tropical and temperate bogs are not separated. Forested bogs are included.]
Concept Author(s): Hierarchy Revisions Working Group, Federal Geographic Data Committee (Faber-Langendoen et al. 2014)
Author of Description: D. Faber-Langendoen, after National Wetlands Working Group (1997)
Acknowledgements:
Version Date: 03Aug2016
References:
  • Brady, N. C., and R. R. Weil. 2002. The nature and properties of soils. Thirteenth edition. Prentice Hall, Upper Saddle River, NJ.
  • Faber-Langendoen, D., T. Keeler-Wolf, D. Meidinger, C. Josse, A. Weakley, D. Tart, G. Navarro, B. Hoagland, S. Ponomarenko, J.-P. Saucier, G. Fults, and E. Helmer. 2015c. Classification and description of world formation types. General Technical Report RMRS-GTR-000. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO.
  • Mitsch, W. J., and J. G. Gosselink. 2000. Wetlands. Third edition. John Wiley & Sons, Inc., New York. 920 pp.
  • National Wetlands Working Group. 1997. Wetlands of Canada. C. D. A. Rubec, editor. Ecological Land Classification Series No. 24. Environment Canada, Ottawa, and Polyscience Publications, Inc., Montreal. 452 pp.
  • Roth, R. A. 2009. Freshwater aquatic biomes. Greenwood Press, Westport, CT.