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F036 Boreal Flooded & Swamp Forest Formation

The U.S. National
Vegetation Classification
Type Concept Sentence: Boreal Flooded & Swamp Forest is a tree-dominated wetland influenced by minerotrophic groundwater (rarely ombrotrophic), either on mineral or organic (peat) soil, found in northern, high latitudes of North America and Eurasia, with extended cold winters and short mild summers.
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Common (Translated Scientific) Name: Boreal Flooded & Swamp Forest Formation
Colloquial Name: Boreal Flooded & Swamp Forest
Hierarchy Level: Formation
Type Concept: Boreal Flooded & Swamp Forest is a forested wetland and peatland. These swamps are defined as tree-dominated wetlands in a boreal climate that are influenced by minerotrophic groundwater, either on mineral or organic (peat) soils; less commonly, they occur in transitional floodplain habitats. The vegetation is generally dominated by over 10% cover by tall woody, mostly needle-leaved trees and the wood-rich (less commonly sphagnum-rich) peat that this vegetation lays down. The water table is below the major portion of the ground surface, and the dominant ground surface is at the hummock, 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. The nutrient regime in swamps is highly variable, ranging from base-rich conditions with pH above 7.0 (very rare), to base-poor conditions where pH can be in the range of 4.5 or lower. Various swamp forms may be recognized, based on the base-rich/pH gradient, i.e., calcareous-rich (eutrophic), intermediate (mesotrophic), and poor (oligotrophic to ombrotrophic).
Diagnostic Characteristics: Boreal Flooded & Swamp Forest is defined as a tree-dominated wetland in a boreal climate that is influenced by minerotrophic groundwater, either on mineral or organic (peat) soils; less commonly, they occur in transitional floodplain habitats. The vegetation is dominated by >10% cover from needle-leaved trees and the wood-rich (less commonly sphagnum-rich) peat that this vegetation lays down.
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: Subarctic and arctic (polar) flooded and swamp forests, including willow swamps (though these may not exceed 2 m), belong in this formation. Forested bogs and fens (>10% canopy) are also included here.
Similar NVC Types:
F001 Boreal Forest & Woodland, note: These typically contain better drained soils, lack any aquatic vegetation or muck layer, and, if a peat layer is present, is shallow (<40 cm).
F016 Temperate to Polar Bog & Fen, note: 1.B.5 ~Boreal Flooded & Swamp Forest Formation (F036)$$ includes forested bogs with >10% cover, along with poor swamps.
F026 Temperate Flooded & Swamp Forest, note: These forests less often contain a sphagnum peat layer and are more commonly dominated by hardwood species.
Physiognomy and Structure: Boreal Flooded & Swamp Forest is a forested or wooded wetland and peatland. These swamps are defined as tree-dominated wetlands that are influenced by minerotrophic groundwater, either on mineral or organic soils. The vegetation is dominated by >10% cover by mostly needle-leaved trees and the wood-rich peat that this vegetation lays down; less commonly, they occur in transitional floodplain habitats (National Wetlands Working Group 1997).

There are two general physiognomic variants of boreal swamps: coniferous (needle-leaved) swamps and hardwood (broad-leaved deciduous) swamps. Mixtures of the above can also be described. The understory contains shade-tolerant forest species. Generally in boreal regions, deciduous hardwoods occur in somewhat richer conditions and the deciduous swamps in drier wetland 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: The water table is below most of the ground surface, and the dominant ground surface is at the hummock, 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. Boreal 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 include tree fen, which is wetter with less tree canopy cover. Tree bogs can form on raised bogs, where the sphagnum mat may be relatively dry (National Wetlands Working Group 1997).

Boreal Flooded & Swamp Forest occurs on mineral soils as well as on peat. In the boreal region, 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 the paludification process. 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 comparison of U.S. soil orders with Canadian and FAO systems]. Swamps on peat have developed 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 open 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. Swamp forms may be recognized based on the base-rich/pH gradient, i.e., calcareous-rich (eutrophic), intermediate (mesotrophic), and poor (oligotrophic to ombrotrophic) (National Wetlands Working Group 1997).

There are two general physiognomic variants of Boreal Swamp & Flooded Forest: coniferous (needle-leaved) swamps and hardwood (broad-leaved deciduous) swamps. Mixtures of the above can also be described. The understory contains shade-tolerant forest species. Generally in boreal regions, deciduous hardwood swamps occur in somewhat richer conditions, giving way to shrub swamps and marshes as conditions get wetter. Coniferous swamps occur across a wider range of trophic levels from rich to poor (National Wetlands Working Group 1997).
Geographic Range: Boreal Flooded & Swamp Forest is found in North America, from Greenland to Newfoundland and across northern Canada into Alaska, and in Eurasia throughout most of Scandinavia and Russia, and parts of China, Kazakhstan, and Mongolia (Brandt 2009). It is absent from the Southern Hemisphere.
Nations: CA, US
States/Provinces:
Omernik Ecoregions:
Plot Analysis Summary:
Confidence Level: Moderate
Confidence Level Comments:
Grank: GNR
Greasons:
Name:Database Code:Classification Code:
Class 1 Forest & Woodland C01 1
Subclass 1.B Temperate & Boreal Forest & Woodland S15 1.B
Formation 1.B.5 Boreal Flooded & Swamp Forest F036 1.B.5
Division 1.B.5.Na North American Boreal Flooded & Swamp Forest D016 1.B.5.Na
Concept Lineage:
Predecessors:
Obsolete Names:
Obsolete Parents:
Synonomy: = Boreal Swamp and Riparian Forest (Brown et al. 1998)
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: Ken Baldwin
Version Date: 17Oct2014
References:
  • Brady, N. C., and R. R. Weil. 2002. The nature and properties of soils. Thirteenth edition. Prentice Hall, Upper Saddle River, NJ.
  • Brandt, J. P. 2009. The extent of the North American boreal zone. Environmental Review 17:101-161.
  • 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.