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F026 Temperate Flooded & Swamp Forest Formation

The U.S. National
Vegetation Classification
Type Concept Sentence: Temperate Flooded & Swamp Forest is a tree-dominated wetland influenced by minerotrophic groundwater, either on mineral or organic (peat) soil, found in mid-latitudes of the globe.
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Common (Translated Scientific) Name: Temperate Flooded & Swamp Forest Formation
Colloquial Name: Temperate Flooded & Swamp Forest
Hierarchy Level: Formation
Type Concept: Temperate Flooded & Swamp Forest is a forested wetland and peatland. It is defined as a tree-dominated wetland in temperate climates that is influenced by minerotrophic groundwater, either on mineral or organic (peat) soils. The vegetation is dominated by broad-leaved or needle-leaved trees, generally over 10% cover, and either a wood-rich peat, more common in depressions, or a mineral soil on floodplains. In swamp forests, the water table is often below the major portion of the ground surface and the dominant ground surface is at the hummock ground surface, that is, 20 cm or more above the average summer groundwater level. It is the aerated (or partly aerated) zone of substrates above the water that is available for root growth of trees and/or tall shrubs. Flooded forests (sometimes called riverine or riparian swamps) have a more dynamic water table, with seasonal flooding inundating the vegetation for short (<7 days) to long (>1 month) periods. They are found along rivers, streams and lakes. They are subject to dramatic water fluctuations, seasonal flooding, and an influx of sediment and mineral enrichment during high water periods. Peat accumulation is usually shallow (<40 cm). The nutrient regime in swamps is highly variable, ranging from base-rich conditions with pH above 7.0, to base-poor conditions where pH can be in the range of 4.5 or lower.
Diagnostic Characteristics: Temperate Flooded & Swamp Forest is defined as a tree-dominated wetland in a temperate climate that is influenced by minerotrophic groundwater, either on mineral or organic soils. The vegetation is dominated by broad-leaved or needle-leaved trees, generally over 10% cover, and the substrate is either a wood-rich peat or a mineral soil on floodplains.
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: No distinction is made between warm- versus cool-temperate floodplain and swamp forests, because they do not have the same degree of change from broad-leaved evergreen to broad-leaved deciduous trees observed in uplands. Separation of temperate wetland from upland forests requires consideration of soils, vegetation and hydrology. At the wettest extremes, these forests are continuously flooded and aquatic vegetation growth forms may dominate the herb or field layer. Otherwise, these forests may be saturated and a peat layer may form. There are also practical user and ecological benefits to distinguishing wetland forests from upland forests at the formation level.
Similar NVC Types:
F036 Boreal Flooded & Swamp Forest, note: 1.B.3 ~Temperate Flooded & Swamp Forest Formation (F026)$$ less often contains a sphagnum peat layer and is more commonly dominated by hardwood species.
F008 Cool Temperate Forest & Woodland, note: These typically contain well-drained soils, and lack any aquatic vegetation, peat or muck layer.
F018 Warm Temperate Forest & Woodland, note: These typically contain well-drained soils, and lack any aquatic vegetation, peat or muck layer.
F013 Temperate to Polar Freshwater Marsh, Wet Meadow & Shrubland, note: Tall-shrub swamps share many structural and habitat similarities to hardwood tree swamps, especially during the tree regeneration stage.
Physiognomy and Structure: Temperate Flooded & Swamp Forest is a forested wetland and peatland. These swamps are defined as tree-dominated wetlands that are influenced by minerotrophic groundwater. The vegetation is dominated by either broad-leaved or needle-leaved trees generally over 10% cover, and a wood-rich peat or a mineral soil on floodplains (National Wetlands Working Group 1997).

There are three general physiognomic variants of forested swamps: coniferous swamps, broad-leaved deciduous (hardwood) swamps, and broad-leaved evergreen (hardwood) swamps. Mixtures of the above can also be described. Shading of the understory tends to favor shade-tolerant species. In cool-temperate regions, hardwood swamps generally occur in somewhat richer conditions, giving way to shrub swamps and marshes in somewhat wetter locations. Coniferous swamps occur across a wider range of trophic levels from rich to poor (National Wetlands Working Group 1997).
Floristics:
Dynamics: No Data Available
Environmental Description: Soil/substrate/hydrology: In swamp forests, the water table is often below the major portion of the ground surface, and the dominant ground surface is at the hummock ground surface, that is, 20 cm or more above the average summer groundwater level. It is the aerated (or partly aerated) zone of substrates above the water that is available for root growth of trees. These temperate swamps are not as wet as marshes, fens and the open bogs. The drier treed swamps grade into upland forest on mineral soil, and the wettest treed swamps grade into scrubby treed fen, which is wetter with less tree canopy cover. Scrubby tree fens may grade into tall-shrub swamps, but they are somewhat drier and have at least 10% tree canopy cover (National Wetlands Working Group 1997).

Flooded forests (sometimes called riverine or riparian swamps) have a more dynamic water table, with seasonal flooding inundating the vegetation for short (<7 days) to long (>1 month) periods. They are found along rivers, streams, and lakes. They are subject to dramatic water fluctuations, seasonal flooding, and an influx of sediment and mineral enrichment during high water periods. Peat accumulation is usually shallow, often <40 cm, but depths of 1 m can exist (National Wetlands Working Group 1997).

The temperate flooded and swamp forest occurs on mineral soils as well as on peat. In the cool-temperate regions, the texture of underlying mineral soils is variable, ranging from clays to sands, and they frequently are Gleysols. On sands, iron-rich ortsteins or fragipans are often present, acting as impermeable layers that impede water drainage. Swamps on mineral soils tend to accumulate peat by paludification. When organic soils develop, they are Histosols (U.S. system) or Mesisols or Humisols (Canadian system) that are rich in woody peat, at least in the surface layers [see Brady and Weil (2002) for a comparison of U.S. soil orders with Canadian and FAO systems]. Swamps on peat have developed either by a basin-filling process or by paludification of previously drier mineral soils. In the basin-filling process, the previous ecosystem was a marsh or fen, whereas in paludification the swamp has developed over an older, dry upland forest on mineral soil (National Wetlands Working Group 1997).

The nutrient regime in swamps is highly variable, ranging from base-rich conditions with pH above 7.0, to base-poor conditions where pH can be in the range of 4.5 or lower. Temperate swamp forms may be recognized based on the base-rich/pH gradient, i.e., calcareous rich (eutrophic), intermediate (mesotrophic), and poor (oligotrophic) (National Wetlands Working Group 1997).
Geographic Range: These forested wetlands are widely distributed throughout the mid-latitudes around the globe.
Nations: CA, MX, 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: > Cold Temperate Swamp & Riparian Forest (Brown et al. 1998) [Cool- and warm-temperate forested wetlands are distinguished, based on climate.]
>< Swamp (National Wetlands Working Group 1997) [This type includes tree swamps with >30% cover, boreal and temperate swamps, and both tree and tall-shrub (>1 m) swamps.]
> Warm Temperate Swamp & Riparian Forest (Brown et al. 1998) [Cool- and warm-temperate forested wetlands are distinguished, based on climate.]
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: 02Aug2016
References:
  • Brady, N. C., and R. R. Weil. 2002. The nature and properties of soils. Thirteenth edition. Prentice Hall, Upper Saddle River, NJ.
  • Brown, D. E., F. Reichenbacher, and S. E. Franson. 1998. A classification of North American biotic communities. The University of Utah Press, Salt Lake City. 141 pp.
  • 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.
  • 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.