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CEGL006218 Quercus bicolor - Fraxinus pennsylvanica - (Platanus occidentalis) / Chasmanthium latifolium - Zizia aurea Floodplain Forest
Type Concept Sentence: No Data Available
Common (Translated Scientific) Name: Swamp White Oak - Green Ash - (American Sycamore) / Indian Woodoats - Golden Alexanders Floodplain Forest
Colloquial Name: Piedmont-Central Appalachian Riverscour Forest
Hierarchy Level: Association
Type Concept: This community type is restricted to the active channel shelves of large rivers, at localities where bedrock outcrops constrain flow and produce locally high water velocities during large floods. Average return interval of overbank flooding is less than one year to more than one year, and hydrologic regime is temporarily flooded. Woody vegetation is constantly subjected to mechanical damage from ice and other flood debris. Soils are shallow (7 to >30 cm deep) sandy loams or loamy sands, with many rock fragments and 2-20% of the surface composed of exposed bedrock or large boulders. Physiognomy is an open woodland of short-statured, flood-battered trees, with Quercus bicolor and Fraxinus pennsylvanica the leading overstory dominants in mixed stands. Acer negundo, Diospyros virginiana, Juglans nigra, Platanus occidentalis, Ulmus americana, and other trees are locally important associates. The shrub layer is sparse or absent and consists of saplings of the nominal species and other flood-tolerant species. Vines, primarily Vitis spp., Campsis radicans, Toxicodendron radicans, Lonicera japonica, and Amphicarpaea bracteata, are frequent. The herb layer is characterized by dense, tall graminoids, with mixed, variable dominance by Chasmanthium latifolium, Dichanthelium clandestinum, Elymus riparius, and Elymus virginicus. Many low-cover forbs and sedges are associated. This community type has high to exceptional species richness (90-130 species per 400 m2) but is threatened by invasive introduced weeds, particularly Phalaris arundinacea, Poa pratensis, Fallopia japonica var. japonica, Microstegium vimineum, and Ranunculus ficaria.
Diagnostic Characteristics: No Data Available
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: Classification of this type was based on analysis of 12 vegetation plots sampled by Lea (2000) along the Potomac River. Plot data from across the range of this vegetation are needed to better characterize the type.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available
Floristics: Physiognomy is an open woodland of short-statured, flood-battered trees, with Quercus bicolor and Fraxinus pennsylvanica the leading overstory dominants in mixed stands. Acer negundo, Diospyros virginiana, Juglans nigra, Platanus occidentalis, Ulmus americana, and other trees are locally important associates. The shrub layer is sparse or absent and consists of saplings of the nominal species and other flood-tolerant species. Vines, primarily Vitis spp., Campsis radicans, Toxicodendron radicans, Lonicera japonica, and Amphicarpaea bracteata, are frequent. The herb layer is characterized by dense, tall graminoids, with mixed, variable dominance by Chasmanthium latifolium, Dichanthelium clandestinum, Elymus riparius, and Elymus virginicus. Verbesina alternifolia is a constant forb. Other characteristic herbs include Zizia aurea, Thalictrum revolutum, Cerastium arvense, Cardamine bulbosa (= Cardamine rhomboidea), Tripsacum dactyloides, Symphyotrichum lanceolatum (= Aster lanceolatus), Packera aurea (= Senecio aureus), Polygonum virginianum, Lysimachia ciliata, Solidago gigantea, Desmodium perplexum, Ranunculus hispidus var. nitidus (= Ranunculus septentrionalis), Hasteola suaveolens, and many species of Carex (Carex conjuncta, Carex grisea, Carex blanda, Carex granularis, Carex vulpinoidea, Carex tribuloides, Carex jamesii, Carex radiata, Carex frankii, Carex shortiana, Carex cristatella). This community type has high to exceptional species richness (90-130 species per 400 m2) due, in part, to regularly occurring, poorly drained linear swales (flood channels) that dissect higher, better-drained areas. Phalaris arundinacea, Poa pratensis, Fallopia japonica var. japonica, Microstegium vimineum, and Ranunculus ficaria are introduced plants that have become rampantly invasive in parts of this community.
Dynamics: This community type is associated with a very restrictive set of environmental factors associated with high-gradient, bedrock-controlled floodplains. It was likely formerly more extensive or undisturbed on the Potomac River before interruption in hydrogeomorphic process by the construction of a tailrace for civic water supplies at Chain Bridge Flats (probably between 1920 and 1930). The spoil rock was placed in a ridge across the entire width of the floodplain and channel shelf, blocking frequent and scouring high water flows and allowing deeper sediment to accumulate on the downstream side of the levee. This apparently allowed fast-growing, weedy species less tolerant of shallow soils, such as Platanus occidentalis, Acer saccharinum, and Acer negundo, to become established downstream from the levee and to grow tall during relatively quiescent periods for major floods (1942-1972). Major floods, which topped the levee, would then have uprooted these trees which had not been "flood-trained." Currently, following other large floods in 1985 and 1996, much of the zone downstream from the levee, comparable in elevation to that supporting this community type upstream from the levee, is relatively treeless and dominated by weedy exotic herbaceous species, especially Phalaris arundinacea.
Environmental Description: This community type is restricted to the active channel shelves of large rivers, at localities where bedrock outcrops constrain flow and produce locally high water velocities during large floods. At Chain Bridge Flats along the Potomac River (District of Columbia and Maryland), stands are immediately channel-ward from the floodplain. Average return interval of overbank flooding is less than one year to more than one year, and hydrologic regime is temporarily flooded. Woody vegetation is constantly subjected to mechanical damage from ice and other flood debris. Soils are sandy loams or loamy sands, with many rock fragments and 2-20% of the surface composed of exposed bedrock or large boulders. Soil depth to bedrock ranges from 7 cm to more than 30 cm.
Geographic Range: This community is documented only from high-gradient stretches of the Potomac River floodplain between Washington, DC and Great Falls, with marginal putative examples also observed along the Potomac and Shenandoah rivers at Harpers Ferry.
Nations: US
States/Provinces: DC, MD
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.758662
Confidence Level: High
Confidence Level Comments: No Data Available
Grank: G1G2
Greasons: No Data Available
| Type | Name | Database Code | Classification Code |
|---|---|---|---|
| Class | 1 Forest & Woodland Class | C01 | 1 |
| Subclass | 1.B Temperate & Boreal Forest & Woodland Subclass | S15 | 1.B |
| Formation | 1.B.3 Temperate Flooded & Swamp Forest Formation | F026 | 1.B.3 |
| Division | 1.B.3.Na Eastern North American-Great Plains Flooded & Swamp Forest Division | D011 | 1.B.3.Na |
| Macrogroup | 1.B.3.Na.1 Silver Maple - American Sycamore - Hackberry species Floodplain Forest Macrogroup | M029 | 1.B.3.Na.1 |
| Group | 1.B.3.Na.1.b <i>Acer saccharinum - Platanus occidentalis - Liquidambar styraciflua</i> Floodplain Forest Group | G673 | 1.B.3.Na.1.b |
| Alliance | A3701 American Sycamore - Green Ash - Tuliptree Central Appalachian-Piedmont Floodplain Forest Alliance | A3701 | 1.B.3.Na.1.b |
| Association | CEGL006218 Swamp White Oak - Green Ash - (American Sycamore) / Indian Woodoats - Golden Alexanders Floodplain Forest | CEGL006218 | 1.B.3.Na.1.b |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: > Acer negundo - Fraxinus pennsylvanica / Elymus (riparius, virginicus) - Panicum clandestinum Woodland (Lea 2000)
> Quercus bicolor - Fraxinus pennsylvanica - Diospyros virginiana / Chasmanthium latifolium Woodland (Lea 2000)
> Quercus bicolor - Fraxinus pennsylvanica - Diospyros virginiana / Chasmanthium latifolium Woodland (Lea 2000)
- Eastern Ecology Working Group of NatureServe. No date. International Ecological Classification Standard: International Vegetation Classification. Terrestrial Vegetation. NatureServe, Boston, MA.
- Harrison, J. W. 2011. The natural communities of Maryland: 2011 working list of ecological community groups and community types. Unpublished report. Maryland Department of Natural Resources, Wildlife and Heritage Service, Natural Heritage Program, Annapolis. 33 pp.
- Harrison, J. W., compiler. 2004. Classification of vegetation communities of Maryland: First iteration. A subset of the International Classification of Ecological Communities: Terrestrial Vegetation of the United States, NatureServe. Maryland Natural Heritage Program, Maryland Department of Natural Resources, Annapolis. 243 pp.
- Lea, C. 2000. Plant communities of the Potomac Gorge and their relationship to fluvial factors. M.S. thesis, George Mason University. Fairfax, VA. 219 pp.