Common (Translated Scientific) Name: Freshwater Aquatic Vegetation Subclass
Colloquial Name: Freshwater Aquatic Vegetation
Hierarchy Level: Subclass
Type Concept: Freshwater Aquatic Vegetation occurs in shallow to deep water habitats where emergent vegetation is <10% cover, and submerged or floating aquatic plants have >1% cover, occurring around the globe from the equator to the polar regions. The upper limits of salinity are set at approximately 0.5 ppt, above which it is typically considered saltwater. They are transitional between those wetlands that are saturated or seasonally wet (i.e., bog, fen, marsh or swamp) and permanent, deep waterbodies (i.e., lakes). Submerged or floating-aquatic plants usually dominate the vegetation. Open surface water up to 2 m deep is present for all or most of the year. Water levels are seasonally stable, permanently flooded, or intermittently exposed during droughts, low flows or intertidal periods.
Diagnostic Characteristics: Freshwater Aquatic Vegetation occurs in shallow to deep water habitats where emergent vegetation is <10% cover, and submerged or floating aquatic plants have >1% cover, with the upper limits of salinity set at 0.5 ppt, above which it is considered saltwater. Water levels are seasonally stable, permanently flooded, or intermittently exposed during droughts, low flows or intertidal periods. Freshwater Aquatic Vegetation occurs around the globe from the equator to the polar regions in freshwater habitats.
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: The concept of this subclass extends to deeper water habitats (i.e., deeper than 2 m in lakes) and to riverine bottoms, but in practice, freshwater aquatic classifications may supersede this one from a user standpoint [see Formation Class]. That is, it may be desirable to first assign a lake or river type to the aquatic system, and secondarily note the NVC vegetation type present. Vegetation found in many urban and agricultural ponds may be very similar to natural freshwater aquatic vegetation, because agricultural and urban ponds typically manipulate the physical setting, not the vegetation itself. There are distinct cultural aquatic vegetation types, but these should be limited to situations in which the vegetation itself is manipulated for horticultural (e.g., aquatic gardens) or agricultural (e.g., water chestnuts grown in impoundments, rice paddies) that are parallel with terrestrial cultural vegetation. However, many agricultural ponds may actively prevent vegetation from forming. For practical applications of classification and mapping of freshwater aquatic vegetation, the agricultural and urban ponds may be initially placed within the 7. Agricultural & Developed Vegetation Cultural Class (CCL01), and, where evidence is gathered to show they have a natural composition, they may be reclassified.
Similar NVC Types:
S09 Saltwater Aquatic Vegetation, note:
CSC03 Herbaceous & Woody Developed Vegetation, note:
CSC04 Agricultural & Developed Aquatic Vegetation, note:
S44 Shrub & Herb Wetland, note:
Physiognomy and Structure: Submerged or floating aquatic plants usually dominate the vegetation, with <10% of the surface water area covered by standing emergent or woody plants. Open surface water up to 2 m or more deep is present for all or most of the year (National Wetlands Working Group 1997).
Dynamics: No Data Available
Environmental Description: Freshwater Aquatic Vegetation is subject to aquatic processes typical of upper limnetic or infralittoral lake zones, such as nutrient and gas exchange, oxidation and decomposition. Ionic composition of waters varies widely. The upper limits of salinity for Freshwater Aquatic Vegetation are set at 0.5 ppt, above which the vegetation is considered 5.A ~Saltwater Aquatic Vegetation Subclass (S09)$$. Dissolved minerals, acid-base balances, and nutrient levels are influenced by the hydrology, underlying geological materials, nutrient fluxes, and plant communities. Freshwater Aquatic Vegetation is usually situated on substrates of limnic peat, mixed limnic organic-mineral material, and marl in stable-water regimes. Little sediment accumulation occurs in high-energy shallow waters such as tidal regimes, rivers or large lakes. In semi-arid regions, shallow waters dry up intermittently, often leaving evaporite alkaline salt deposits. Except in highly saline or acidic waters, these deposits provide a substrate for rooted submerged and floating macrophytes, algae and aquatic mosses (National Wetlands Working Group 1997).
Freshwater Aquatic Vegetation is found in shallow water that usually has standing or flowing water <2 m deep in mid-summer. Water levels are seasonally stable, permanently flooded, or intermittently exposed during droughts or low flows. Shallow-water vegetation may also occupy bays and margins of profundal zones of lakes (National Wetlands Working Group 1997).
Freshwater Aquatic Vegetation occurs in ponds, pools, shallow lakes, oxbows, sloughs, natural and artificial impoundments, or channels. Boundaries are determined by water-eroded shorelines, beaches or landward margins of mudflats, recent limnic deposits, floating mats, emergents or hydrophytic trees or shrubs. Bordering mats of rooted emergent vegetation, including inundated trees, may occupy up to 10% of the shallow-water area. Shallow waters are found in all hydrogeomorphic settings, but are usually associated with lacustrine, fluvial, stream, river, and permafrost systems (National Wetlands Working Group 1997).
Geographic Range: Freshwater Aquatic Vegetation occurs in shallow to deep freshwater habitats around the globe from the equator to the polar regions.
Nations: CA, US
Confidence Level: Moderate
Confidence Level Comments:
Synonomy: >< Freshwater Marshes (Mitsch and Gosselink 2000) [Both tropical and temperate marshes are treated together, and inland saline marshes are included here too, as are emergent and aquatic vegetation.]
>< Shallow Water Wetland Class (National Wetlands Working Group 1997) [The authors include both saltwater aquatic and freshwater aquatic vegetation in their concept and restrict the type to wetland aquatic vegetation, whereas the concept used here could extend to deeper water habitats.]
>< Tidal Freshwater Marshes (Mitsch and Gosselink 2000) [Both tropical and temperate marshes are treated together, as are emergent and aquatic vegetation.]
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)
Version Date: 17Oct2014
- 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.