Invalid Unit Specified
F002 Tropical Bog & Fen Formation

The U.S. National
Vegetation Classification
Type Concept Sentence: Tropical Bog & Fen is found where peat-accumulating conditions occur in the cold, wet mountain highlands and in various floodplains of the lowlands, where trees are excluded. They are dominated by sedges, heath, and moss peat.
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Common (Translated Scientific) Name: Tropical Bog & Fen Formation
Colloquial Name: Tropical Bog & Fen
Hierarchy Level: Formation
Type Concept: In tropical regions of the world, peat-accumulating conditions occur in the cold, wet mountain highlands and in most of the floodplains of the lowlands, where peatlands have a fluctuating water table, with groundwater and surface water movements being common. "True" tropical bogs and fens, however, with sedge or moss peat are relatively rare. Tropical bogs occur in high, rainy regions, on flat to gently sloping, water-soaked ground with nearly impervious clay beneath peat of depths varying from <0.1 to >3 m. They are covered by a mixed vegetation of sedges and grasses, with scattered or clumped growth of dwarfed trees or shrubs.
Diagnostic Characteristics: Tropical Bog & Fen is found where peat-accumulating conditions occur in the cold, wet mountain highlands and in various floodplains of the lowlands, where trees are excluded. They are dominated by sedges, heath, and moss peat.
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: Tropical peat swamps, where tree cover exceeds 10%, are treated under 1.A.4. Tropical Flooded & Swamp Forest Formation (F029).
Similar NVC Types:
F030 Tropical Freshwater Marsh, Wet Meadow & Shrubland, note:
Physiognomy and Structure: "True" tropical bogs and fens, with sedge or moss peat, are relatively rare. Tropical bogs are covered by a mixed vegetation of sedges and grasses, with scattered or clumped growth of dwarfed trees or shrubs. Given the lack of information on tropical bogs and fens worldwide, a summary is provided from Hawai`i (Mueller-Dombois and Fosberg 1998).

The vegetation of most of the Hawaiian bogs may be a continuous or discontinuous dwarf-scrub interspersed with a matrix of hummocky sedges, usually with scattered emergent shrubs 1 or 2 m tall, or rarely, a bed of Sphagnum and grass with scattered shrubs and large ferns. Peatmoss (Sphagnum spp.) occurs in only a few Hawaiian bogs. Thus, peat is from sedges and grasses, with inclusions of woody peat. Most bogs are found as openings in rainforest, often next to cloud forests (Mueller-Dombois and Fosberg 1998).
Floristics:
Dynamics: More information of Hawaiian bog formation and bog dynamics may be found in Mueller-Dombois and Fosberg (1998, pp. 27-29).
Environmental Description: In tropical regions of the world, peat-accumulating conditions occur in the cold, wet highlands of the Andes and in the floodplains of the lowlands, where peatlands have a fluctuating water table, with groundwater and surface water movements being common, and trees are excluded. "True" tropical bogs and fens, however, with sedge or moss peat are relatively rare. Tropical bogs occur in high, rainy regions, on flat to gently sloping, water-soaked ground with nearly impervious clay beneath peat of depths varying from <0.1 to >3 m. Given the lack of information on tropical bogs and fens worldwide, a summary is provided from Hawai`i (Mueller-Dombois and Fosberg 1998).

Most Hawaiian bogs are on relatively flat ground underlain by more-or-less impervious clay in areas of high rainfall, usually exceeding 250 cm per year. They range in size from <1000 m2 to over 5 ha. Organic overlays may vary from <10 cm ("protobogs" or "clay bogs") to those with <40 cm ("semi-bogs") to those with >40 cm organic overlays ("true bogs"). The depth of the overlay is a function of age (some bogs originated over 11,000 years ago), temperature (with cooler locations having slower decomposition and greater peat depths) and anaerobic conditions (Mueller-Dombois and Fosberg 1998).

Two kinds of Hawaiian bogs can be distinguished: ombrogenous (fed by rainwater) and soligenous (fed by both rain- and groundwater). The first type can occur in areas of high rainfall, exceeding 12 m per year, so that the soil need not even be impervious for the bog to form. The second term, "soligenous bog" (or fen), is more appropriate for most Hawaiian bogs (Mueller-Dombois and Fosberg 1998).
Geographic Range: Tropical Bog & Fen is found where peat-accumulating conditions occur in the cold, wet mountain highlands and in various floodplains of the lowlands, where trees are excluded. In the United States, the type is found in Hawaii.
Nations: US
States/Provinces:
Omernik Ecoregions:
Plot Analysis Summary:
Confidence Level: Moderate
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.1 Tropical Bog & Fen F002 2.C.1
Division 2.C.1.Oa Polynesian Bog & Fen D017 2.C.1.Oa
Concept Lineage:
Predecessors:
Obsolete Names:
Obsolete Parents:
Synonomy: > 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 and C. Josse
Acknowledgements:
Version Date: 17Oct2014
References:
  • 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.
  • Mueller-Dombois, D., and F. R. Fosberg. 1998. Vegetation of the tropical Pacific islands. Springer-Verlag, New York. 733 pp.
  • Roth, R. A. 2009. Freshwater aquatic biomes. Greenwood Press, Westport, CT.