Invalid Unit Specified
M033 Nyssa biflora - Quercus michauxii - Taxodium distichum Basin Swamp & Flatwoods Macrogroup

The U.S. National
Vegetation Classification
Type Concept Sentence: These are forests of poorly drained basins and wet flats in the coastal plains of the southeastern United States, including nonriverine wetland hardwood forests, dominated by some combination of Quercus species and Nyssa species, with Liquidambar styraciflua, Taxodium distichum, and other trees and shrubs that can tolerate wet conditions.
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Common (Translated Scientific) Name: Swamp Tupelo - Swamp Chestnut Oak - Bald-cypress Basin Swamp & Flatwoods Macrogroup
Colloquial Name: Southern Coastal Plain Basin Swamp & Flatwoods
Hierarchy Level: Macrogroup
Type Concept: These are forests of poorly drained basins and wet flats in the coastal plains of the southeastern United States, including nonriverine wetland hardwood forests, dominated by some combination of Quercus species and Nyssa species, with Chamaecyparis thyoides, Liquidambar styraciflua, Pinus serotina, Pinus taeda, Taxodium distichum, and other trees that tolerate wetland conditions. Basin swamps (G038) tend to experience longer periods of saturation and their dominant flora reflects this, with the Quercus species including Quercus laurifolia, Quercus michauxii, and Quercus phellos, with Nyssa biflora, Nyssa ogeche, and/or Nyssa sylvatica. Wet flatwoods (G130) vary more in their hydroperiod and the associated species sort along this moisture gradient, with more mesic zones including Quercus alba, Quercus falcata, Quercus michauxii, Quercus nigra, Quercus pagoda, and Quercus shumardii, with Quercus laurifolia and Quercus phellos in wetter zones. Other woody species that may occur in basin swamps (G038) include Acer rubrum var. trilobum, Fraxinus profunda, Liriodendron tulipifera, and Populus heterophylla. Typical species in the moderate to dense understory include Clethra alnifolia, Cyrilla racemiflora, Ilex opaca var. opaca, Lyonia lucida, Magnolia virginiana, Persea palustris, and Smilax laurifolia. Vines are conspicuous components, with important species including Parthenocissus quinquefolia, Smilax smallii, Toxicodendron radicans, Vitis rotundifolia, and Vitis aestivalis. Herbaceous species in basin swamps are more limited due to the extended hydroperiods, and may include Carex spp., Sphagnum spp., Woodwardia areolata, and Woodwardia virginica. Flatwoods may be more diverse, and their ground layers can include Agrimonia rostellata, Aristolochia serpentaria, Botrychium virginianum, Carex cherokeensis, Chasmanthium sessiliflorum, Clematis virginiana, Clitoria mariana, Dichanthelium boscii, Dioscorea villosa, Elephantopus carolinianus, Elephantopus tomentosus, Geum canadense, Galium circaezans, Passiflora lutea, Phryma leptostachya, Podophyllum peltatum, Ruellia caroliniensis, Sanicula canadensis, Scleria oligantha, Smallanthus uvedalius, and Spigelia marilandica. The environment for this vegetation encompasses two more-or-less distinct habitats types. Basin swamps (G038) occupy large, seasonally inundated nonriverine basins with peaty substrates, as well as less well-defined broad interfluvial flats and smaller areas near headwater streams in the coastal plains. These flatter areas may have some conceptual overlap with wet flatwoods (G130) in terms of their environment. Wet flatwoods (G130) occur in flat terrain where soils are seasonally to nearly semipermanently saturated because of low relief, poor soil drainage, and the seasonally high water table. The hydrology is dominated by groundwater seepage, rainfall and sheetflow. Overbank and tidal flooding, if they occur, have little to no influence on the vegetation. The available soil moisture fluctuates widely throughout the growing season, from saturated to very dry, a condition sometimes referred to as xerohydric or hydroxeric. The largest areas are on broad interfluvial flats; examples also occur on sites above modern floodplains but with poor internal drainage: nonriverine Pleistocene high terraces, as well as in broad, low flats, in small to large depressions, and along small, ill-defined drainages.
Diagnostic Characteristics: The combination of the suite of canopy species with nonriverine hydrology helps distinguish this vegetation from related riverine/floodplain vegetation. Examples of this vegetation have generally closed canopies dominated by deciduous trees, particularly Nyssa and Taxodium in the case of hardwood basin swamps (G038), and Quercus and Pinus species in the case of pine and hardwood wet flatwoods, but the shrub strata may have a significant broad-leaved evergreen component. The hydrology is nonriverine, with water coming from rainwater and groundwater rather than from overbank flooding. The environmental settings include depressions and wet flats.
Rationale for Nominal Species or Physiognomic Features: Nyssa biflora, Quercus michauxii, and Taxodium distichum collectively span the range of hydrologic conditions represented by this macrogroup, and characterize its range as being in the southern coastal plains of the United States. The "Basin Swamp & Flatwoods" modifier is needed to distinguish this from riverine or floodplain vegetation with a similar species composition.
Classification Comments: Two groups constitute this macrogroup: basin swamps, Coastal Plain Hardwood Basin Swamp Group (G038), and wet flatwoods, Hardwood - Loblolly Pine Nonriverine Wet Flatwoods Group (G130). The "wet flatwoods" are wetter than dry or mesic flatwoods but not as wet as "basin swamps." This vegetation is also referred to as "nonriverine wet hardwood forest" (Schafale and Weakley 1990). In some examples, Pinus taeda may attain greater dominance in relation to hardwoods either due to management (preferential removal of the Quercus component) or to other stochastic events (fire, windstorm).
Similar NVC Types:
M031 Southern Coastal Plain Floodplain Forest, note:
M032 Southern Coastal Plain Evergreen Hardwood - Conifer Swamp, note:
M310 Southeastern North American Ruderal Flooded & Swamp Forest, note:
Physiognomy and Structure: These are generally closed-canopy forests dominated by deciduous trees, particularly Nyssa and Taxodium in the case of hardwood basin swamps (G038), and Quercus and Pinus species in the case of pine and hardwood wet flatwoods, but the shrub strata may have a significant broad-leaved evergreen component. Basin swamps (G038) are dominated by broad-leaved deciduous hardwoods with needle-leaved deciduous conifers (Taxodium spp.). Wet flatwoods (G130) have generally closed canopies dominated by broad-leaved deciduous trees, particularly Quercus species.
Floristics: Examples of this vegetation are primarily dominated by deciduous hardwood trees, including Quercus species and Nyssa species, with Chamaecyparis thyoides, Liquidambar styraciflua, Pinus serotina, Pinus taeda, Taxodium distichum, and other trees that tolerate wetland conditions. Basin swamps (G038) tend to experience longer periods of saturation and their dominant flora reflects this, with the Quercus species including Quercus laurifolia, Quercus michauxii, and Quercus phellos, with Nyssa biflora, Nyssa ogeche, and/or Nyssa sylvatica. Wet flatwoods (G130) vary more in their hydroperiod and the associated species sort along this moisture gradient, with more mesic zones including Quercus alba, Quercus falcata, Quercus michauxii, Quercus nigra, Quercus pagoda, and Quercus shumardii, with Quercus laurifolia and Quercus phellos in wetter zones. Other woody species that may occur in basin swamps (G038) include Acer rubrum var. trilobum, Fraxinus profunda, Liriodendron tulipifera, and Populus heterophylla. Typical species in the moderate to dense understory include Clethra alnifolia, Cyrilla racemiflora, Ilex opaca var. opaca, Lyonia lucida, Magnolia virginiana, Persea palustris, and Smilax laurifolia. Vines are conspicuous components, with important species including Parthenocissus quinquefolia, Smilax smallii, Toxicodendron radicans, Vitis rotundifolia, and Vitis aestivalis. Parthenocissus quinquefolia and Toxicodendron radicans may cover the ground, as well as being represented by high-climbing individuals. Herbaceous species in basin swamps are more limited due to the extended hydroperiods, and may include Carex spp., Sphagnum spp., Woodwardia areolata, and Woodwardia virginica. Flatwoods may be more diverse, and their ground layers can include Agrimonia rostellata, Aristolochia serpentaria, Botrychium virginianum, Carex cherokeensis, Chasmanthium sessiliflorum, Clematis virginiana, Clitoria mariana, Dichanthelium boscii, Dioscorea villosa, Elephantopus carolinianus, Elephantopus tomentosus, Geum canadense, Galium circaezans, Passiflora lutea, Phryma leptostachya, Podophyllum peltatum, Ruellia caroliniensis, Sanicula canadensis, Scleria oligantha, Smallanthus uvedalius, and Spigelia marilandica.
Dynamics: In basin swamps (G038), the predominant ecological processes are related to soil texture and moisture and disturbance history. These wetlands hold standing water for variable periods after rainfall events. In the wetter Taxodium- and Nyssa-dominated vegetation, fire is probably of little ecological significance because the vegetation is not flammable. Without fire as a major factor, most communities probably occur naturally as old-growth multi-aged forests dominated by gap-phase regeneration. Hurricanes may create larger canopy gaps occasionally. Examples in drowned river valleys are subject to influence by rising sea level and can be expected to evolve into tidal swamp systems, sometimes fairly quickly. Some of the sites where this vegetation is found today were formerly occupied by stands of Chamaecyparis thyoides. These depended on fire for regeneration of the canopy. The occurrence of fires on the time scale of several decades to a century or more may have determined the mosaic of Chamaecyparis forests versus other vegetation types. Some areas may once have been canebrakes, with dominance of Arundinaria determined by more frequent fire. Similarly, in wet oak-dominated flatwoods (G130), fire is probably of little ecological significance because the vegetation is not particularly flammable. There is some uncertainty about the role of fire, and low-intensity surface fires may have been ecologically important in some examples. The fire regime in dry and mesic flatwoods may be characterized as medium- to long-interval, low-intensity, and high-severity; and in wetter flatwoods as short-interval, low-intensity, and low-severity (D. Zollner pers. comm. 2006).
Environmental Description: The environment for this vegetation encompasses two more-or-less distinct habitats types. Basin swamps (G038) occupy large, seasonally inundated nonriverine basins with peaty substrates, as well as less well-defined broad interfluvial flats and smaller areas near headwater streams in the coastal plains. These flatter areas may have some conceptual overlap with wet flatwoods (G130) in terms of their environment. Wet flatwoods (G130) occur in flat terrain where soils are seasonally to nearly semipermanently saturated because of low relief, poor soil drainage, and the seasonally high water table. The hydrology is dominated by groundwater seepage, rainfall and sheetflow. Overbank and tidal flooding, if they occur, have little to no influence on the vegetation. The available soil moisture fluctuates widely throughout the growing season, from saturated to very dry, a condition sometimes referred to as xerohydric or hydroxeric. The largest areas are on broad interfluvial flats; examples also occur on sites above modern floodplains but with poor internal drainage: nonriverine Pleistocene high terraces, as well as in broad, low flats, in small to large depressions, and along small, ill-defined drainages (locally known as "slashes" in Louisiana). Some examples found near small drainageways have hydrology that is not influenced by overbank flooding. Soils may be loamy to clayey, shallow to deep.
Geographic Range: The vegetation of this macrogroup is most abundant in the Atlantic and Gulf coastal plains from southeastern Virginia to Texas, extending down the Florida peninsula; it also extends north along the coast to Long Island, New York, and north in the interior to Arkansas, southeastern Oklahoma, and the Missouri "bootheel."
Nations: US
States/Provinces: AL, AR, DE, FL, GA, LA, MD, MO, MS, NC, NJ, NY, OK, PA, SC, TX, VA
US Forest Service Ecoregions (2007)
Domain Name:
Division Name:
Province Name: Southeastern Mixed Forest Province
Province Code: 231    Occurrence Status: Confident or certain
Section Name: Southern Mississippi Alluvial Plain Section
Section Code: 234A     Occurrence Status: Confident or certain
Omernik Ecoregions:
Plot Analysis Summary:
Confidence Level: Moderate
Confidence Level Comments:
Grank: GNR
Greasons:
Concept Lineage:
Predecessors:
Obsolete Names:
Obsolete Parents:
Synonomy: >< Basin Swamp (FNAI 1990)
? Flatland Hardwood Forest (Marks and Harcombe 1981)
= Nonriverine Wet Hardwood Forest (Schafale and Weakley 1990)
Concept Author(s): M.P. Schafale and A.S. Weakley (1990)
Author of Description: M. Pyne
Acknowledgements: We have incorporated significant descriptive information previously compiled by M.P. Schafale and A.S. Weakley.
Version Date: 15Oct2014
References:
  • Faber-Langendoen, D., J. Drake, S. Gawler, M. Hall, C. Josse, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, L. Sneddon, K. Schulz, J. Teague, M. Russo, K. Snow, and P. Comer, editors. 2010-2019a. Divisions, Macrogroups and Groups for the Revised U.S. National Vegetation Classification. NatureServe, Arlington, VA. plus appendices. [in preparation]
  • FNAI [Florida Natural Areas Inventory]. 1990. Guide to the natural communities of Florida. Florida Natural Areas Inventory and Florida Department of Natural Resources, Tallahassee. 111 pp.
  • Foti, Tom. Personal communication. Ecologist [retired]. Arkansas Natural Heritage Commission, Little Rock.
  • Frost, Cecil, Dr. Personal communication. Plant ecologist, North Carolina Plant Conservation Program, North Carolina Department of Agriculture & Consumer Service, Raleigh.
  • Hoagland, Bruce W. Personal communication. Ecologist, Oklahoma Natural Heritage Inventory, University of Oklahoma, Norman.
  • Marks, P. L., and P. A. Harcombe. 1981. Forest vegetation of the Big Thicket, southeast Texas. Ecological Monographs 51:287-305.
  • Schafale, M. P., and A. S. Weakley. 1990. Classification of the natural communities of North Carolina. Third approximation. North Carolina Department of Environment, Health, and Natural Resources, Division of Parks and Recreation, Natural Heritage Program, Raleigh. 325 pp.
  • Singhurst, Jason. Personal communication. Botanist/Landscape Ecologist, Texas Parks & Wildlife Department, Nongame and Rare Species Program, Texas Wildlife Diversity Program - Nongame and Rare Species, Austin, TX.
  • Zollner, Douglas. Personal communication. Ecologist, The Nature Conservancy, Arkansas Field Office, Little Rock.