Invalid Unit Specified
F030 Tropical Freshwater Marsh, Wet Meadow & Shrubland Formation

The U.S. National
Vegetation Classification
Type Concept Sentence: Tropical Freshwater Marsh, Wet Meadow & Shrubland includes freshwater wet meadows, shallow and deep emergent marshes, with the upper limits of salinity at 0.5 ppt, above which it is considered saltwater. The vegetation comprises evergreen emergent aquatic macrophytes, chiefly graminoids such as rushes, reeds, grasses and sedges, and shrubs and other herbaceous species such as broad-leaved emergent macrophytes, floating-leaved and submergent species, and nonvascular plants such as brown mosses, liverworts, and macroscopic algae. It is found widely throughout wetland habitats of the tropical latitudes, from the equator to about 23°N and S.
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Common (Translated Scientific) Name: Tropical Freshwater Marsh, Wet Meadow & Shrubland Formation
Colloquial Name: Tropical Freshwater Marsh, Wet Meadow & Shrubland
Hierarchy Level: Formation
Type Concept: Tropical Freshwater Marsh, Wet Meadow & Shrubland includes wet meadows, shallow and deep emergent marshes. These wetlands have shallow water and levels that usually fluctuate daily, seasonally or annually due to tides (freshwater tidal), flooding, evapotranspiration, groundwater recharge, or seepage losses, with the upper limits of salinity at 0.5 ppt, above which it is considered saltwater. The vegetation comprises evergreen emergent aquatic macrophytes, chiefly graminoids such as rushes, reeds, grasses and sedges, and shrubs and other herbaceous species such as broad-leaved emergent macrophytes, floating-leaved and submergent species, and nonvascular plants such as brown mosses, liverworts, and macroscopic algae. Vegetation is usually arranged in distinct zones of parallel or concentric patterns in response to gradients of water depth, frequency of drawdown, water chemistry or disturbance. Saline or brackish non-tidal marshes are included here. Seasonal drawdowns may expose mudflats which are revegetated by pioneering herb and grass species. The vegetation of seasonal marshes is dynamic. It shifts spatially with water levels and changes in composition over a short time, whereas the vegetation of semipermanent marshes usually is more stable, represented by stands of reeds which may persist for many years in the absence of severe drought.
Diagnostic Characteristics: The vegetation comprises evergreen emergent aquatic macrophytes, chiefly graminoids such as rushes, reeds, grasses and sedges, and shrubs and other herbaceous species such as broad-leaved emergent macrophytes, floating-leaved and submergent species, and nonvascular plants such as brown mosses, liverworts, and macroscopic algae, with tree cover <10%, with the upper limits of salinity at 0.5 ppt, above which it is considered saltwater, and where freezing temperatures are rare to absent.
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: Further review is needed of the similarities and differences between temperate and tropical freshwater marshes.
Similar NVC Types:
F013 Temperate to Polar Freshwater Marsh, Wet Meadow & Shrubland, note:
F002 Tropical Bog & Fen, note: Tropical Freshwater Marsh, Wet Meadow & Shrubland (F030) more typically contains muck soils and lacks the heath and moss layers found in this bog and fen formation (F002).
Physiognomy and Structure: Tropical Freshwater Marsh, Wet Meadow & Shrubland vegetation predominantly comprises evergreen emergent aquatic macrophytes, chiefly graminoids such as rushes, reeds, grasses and sedges, and shrubs and other herbaceous species such as broad-leaved emergent macrophytes, floating-leaved and submergent species, and nonvascular plants such as brown mosses, liverworts, and macroscopic algae. There is a greater proportion of evergreen herbaceous plants in this tropic type, as compared to the temperate type. Vegetation is usually arranged in distinct zones of parallel or concentric patterns in response to gradients of water depth, frequency of drawdown, water chemistry or disturbance. Seasonal drawdowns may expose mudflats that are revegetated by pioneering herb and grass species.
Floristics:
Dynamics: Plant communities of seasonal marshes are dynamic. They shift spatially with water levels, and change in composition over a short time, whereas communities of semipermanent marshes usually are more stable, represented by stands of reeds which may persist for many years in the absence of severe drought.
Environmental Description: These wetlands have shallow water and levels that usually fluctuate daily, seasonally or annually due to tides (freshwater tidal), flooding, evapotranspiration, groundwater recharge, or seepage losses. Salinity is 0.5 ppt, above which it is considered saltwater. Seasonal drawdowns may occur.

The occurrence of large savanna extensions in flat land (Orinoco basin and Beni savannas), as well as of numerous lakes in the Amazon basin, create some unique tropical geomorphological settings that in the seasonal savannas are occupied by permanent marshes dominated by herbs such as Cyperus giganteus and Thalia geniculata, and seasonally inundated savannas that are dominated by grasses (Hymenachne amplexicaulis, Panicum mertensii, Paspalum fasciculatum). The vegetation surrounding the Amazonian lakes varies from flooded forest to dense aquatic vegetation formations, and the freshwater marshes belong to the more stable conditions in this gradient created by the river's dynamics.
Geographic Range: This formation is found widely throughout wetland habitats of the tropical latitudes, from the equator to about 23°N and S.
Nations: PR, US
States/Provinces:
Omernik Ecoregions:
Plot Analysis Summary:
Confidence Level: Moderate
Confidence Level Comments:
Grank: GNR
Greasons:
Concept Lineage:
Predecessors:
Obsolete Names:
Obsolete Parents:
Synonomy: > Freshwater Marshes (Mitsch and Gosselink 2000) [Both tropical and temperate marshes are treated together, and inland saline marshes are included here too, and both emergent and aquatic vegetation.]
> Nontidal Freshwater Marshes (Roth 2009) [It is not clear whether non-tidal salt marshes are included here. Both tropical and temperate marshes are treated together.]
> Tidal Freshwater Marshes (Roth 2009) [Both tropical and temperate marshes are treated together.]
> Tidal Freshwater Marshes (Mitsch and Gosselink 2000) [Both tropical and temperate marshes are treated together, and both emergent and aquatic vegetation.]
Concept Author(s): Hierarchy Revisions Working Group, Federal Geographic Data Committee (Faber-Langendoen et al. 2014)
Author of Description: C. Josse and D. Faber-Langendoen, after National Wetlands Working Group (1997)
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.
  • 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.