Invalid Unit Specified
CEGL006283 Andropogon gerardii - Panicum virgatum - Baptisia australis Riverscour Wet Meadow

The U.S. National
Vegetation Classification
Type Concept Sentence:
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Common (Translated Scientific) Name: Big Bluestem - Switchgrass - Blue Wild Indigo Riverscour Wet Meadow
Colloquial Name: Fall-line Riverwash Bedrock Prairie
Hierarchy Level: Association
Type Concept: This community is found in the east-central United States along high-gradient sections of major rivers, such as in gorges and along the fall-line. It usually occupies rocky areas within the active channel shelf at an intermediate level above the low-water level and the bank-full level. Flood scouring and ice floods are powerful and ecologically important abrasive forces that shape the physiognomy and composition of this association. Soils are rapidly drained Psamments. Often, soil material is restricted to the narrow interstices of tightly packed boulders, or to small crevices in bedrock exposures. This community is characterized by a luxuriant growth of the robust grasses Andropogon gerardii, Sorghastrum nutans, Panicum virgatum, and Spartina pectinata which resembles prairie vegetation. Tripsacum dactyloides may also occur. Many of the forbs are also typical of prairies. Characteristic species include Baptisia australis, Allium cernuum, Aristida purpurascens, Bidens frondosa, Chasmanthium latifolium, Clematis viorna, Eleocharis compressa, Conoclinium coelestinum (= Eupatorium coelestinum), Eupatorium serotinum, Lespedeza violacea, Packera aurea, Physostegia virginiana, Pycnanthemum virginianum, Solidago rupestris, Teucrium canadense, Veronicastrum virginicum, Zizia trifoliata, and Zizia aurea. Scattered and flood-battered shrubs and tree saplings often occur.
Diagnostic Characteristics: No Data Available
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: The distinctions between this community type and Salix spp. / Andropogon gerardii - Sorghastrum nutans Riverscour Wet Meadow (CEGL005175) and (Salix caroliniana, Rhododendron arborescens) / Andropogon gerardii - Baptisia australis - (Solidago simplex ssp. randii) Riverscour Wet Meadow (CEGL008471) seem quite artificial and further study should be undertaken to determine whether these merely represent geographic subtypes of a single association. The effect of merging these types with Andropogon gerardii - Panicum virgatum - Baptisia australis Riverscour Wet Meadow (CEGL006283) would likely have no effect on the Global Conservation Status Rank, as CEGL005175 is currently ranked G2? and CEGL008471 is currently ranked G2Q. In the Central Appalachian region, the type is found predominantly on Western Allegheny Mountains (M221Be + M221Bd, Gauley M221Ca dammed).
Similar NVC Types:
(Salix caroliniana, Rhododendron arborescens) / Andropogon gerardii - Baptisia australis - (Solidago simplex ssp. randii) Riverscour Wet Meadow, note:
Salix spp. / Andropogon gerardii - Sorghastrum nutans Riverscour Wet Meadow, note:
Panicum virgatum - Andropogon gerardii Gravel Riverscour Wet Meadow, note: on gravel and cobble depositional bars along lower-gradient rivershores.
Fraxinus americana / Andropogon gerardii - Sorghastrum nutans - Schizachyrium scoparium - Pycnanthemum tenuifolium Riverscour Wet Meadow, note: on less frequently flooded, terraced or sloping outcrops above the channel shelf.
(Salix spp.) / Andropogon gerardii - Panicum virgatum - Salvia azurea Cahaba Riverscour Wet Meadow, note:
(Hypericum prolificum, Leucothoe racemosa) / Schizachyrium scoparium - Solidago simplex var. racemosa - Ionactis linariifolius Riverscour Sparse Vegetation, note:
(Betula nigra, Ilex verticillata) / Andropogon gerardii - Solidago simplex var. racemosa Riverscour Wet Meadow, note:
Southern Appalachian Bedrock Riverscour Vegetation, note:
Physiognomy and Structure: No Data Available
Floristics: This community is characterized by a luxuriant growth of the robust grasses Andropogon gerardii, Sorghastrum nutans, Panicum virgatum, and Spartina pectinata, which resembles prairie vegetation. Tripsacum dactyloides may also occur. Many of the forbs are also typical of prairies. Characteristic species include Baptisia australis, Allium cernuum, Aristida purpurascens, Bidens frondosa, Chasmanthium latifolium, Clematis viorna, Eleocharis compressa, Conoclinium coelestinum (= Eupatorium coelestinum), Eupatorium serotinum, Lespedeza violacea, Packera aurea, Physostegia virginiana, Pycnanthemum virginianum, Solidago rupestris, Teucrium canadense, Veronicastrum virginicum, Zizia trifoliata, and Zizia aurea. Additional herbs with high cover and/or constancy in some areas include Apocynum cannabinum, Coreopsis tripteris, Cyperus strigosus, Eupatorium fistulosum, Helianthus occidentalis ssp. occidentalis, Justicia americana, Lobelia cardinalis, Ludwigia alternifolia, Potentilla simplex, Pycnanthemum torrei, Rhynchospora capitellata, Rhynchospora recognita, Solidago juncea, Symphyotrichum laeve, and Viola cucullata. There may be low cover by trees, which are usually short and flood-battered, including Betula nigra, Chionanthus virginicus, Diospyros virginiana, Fraxinus americana, Fraxinus pennsylvanica, Platanus occidentalis, Ulmus americana, and Ulmus rubra. Cover in the shrub layer is likewise low and includes short individuals of the tree and shrub species, including Alnus serrulata, Cephalanthus occidentalis, Cornus amomum, Hypericum prolificum, and Salix caroliniana. Low-growing vines include Campsis radicans, Toxicodendron radicans, and Vitis rupestris. In the Potomac River drainage, Solidago simplex var. racemosa, Helianthus occidentalis, Cerastium arvense var. velutinum, and Ceanothus herbaceus are noteworthy components (Lea 2000). In the James River drainage, Orbexilum pedunculatum var. psoralioides, Silphium trifoliatum, Solidago speciosa, and Vicia americana are associated. Vascular plant species richness of sampled plots (Virginia and West Virginia sample sets) averages 43-56 taxa per 100 square meters.
Dynamics: Flash floods actively scour the floodplain, keeping the vegetation open. Available data suggest that the differences between this community and related types may be more related to flooding frequency/intensity and/or substrate chemistry than to topography (i.e., outcrop vs. cobble bar).
Environmental Description: Stands occur along high-gradient sections of major rivers, such as in gorges and along the fall-line. They occupy rocky areas within the active channel shelf subject to frequent high-energy flooding, at an intermediate level above the low-water level and the bank-full level. These positions are prone to dramatic restructuring by large floods and patches of this association may be ephemeral. Flood scouring and ice floods are powerful and ecologically important abrasive forces that shape the physiognomy and composition of this association. Soils are rapidly drained Psamments, usually with neutral to high pH. These coarse-textured substrates are potentially well-drained, but fluvial topography and a high water table often result in a mixture of well-drained and poorly drained microsites. Occurrences on flat bedrock often develop scoured out potholes which hold flood and rain water, and vegetation is confined to cracks and sediment accumulations. Soil material is restricted to the narrow interstices of tightly packed boulders, or to small crevices in bedrock exposures. However, along the Greenbrier and New rivers in West Virginia, stands of this type occupy cobble bars rather than stabilized outcrops and boulder deposits.
Geographic Range: This community is found in the east-central United States, from Pennsylvania, Maryland, West Virginia, and Virginia, and possibly Ohio.
Nations: US
States/Provinces: MD, OH, PA, VA, WV
US Forest Service Ecoregions (1994/1995)
Domain Name:
Division Name:
Province Name: Southeastern Mixed Forest Province
Province Code: 231    Occurrence Status: Confident or certain
Section Name: Southern Unglaciated Allegheny Plateau Section
Section Code: 221E     Occurrence Status: Confident or certain
Omernik Ecoregions:
Confidence Level: High
Confidence Level Comments:
Grank: G3
Greasons: There are probably fewer than 100 occurrences of this community rangewide, depending on how an occurrence is defined. It is known from Maryland, the District of Columbia, and Virginia along the Potomac River, from the James River, Shenandoah River, and various tributaries in Virginia, and from scattered patches along about 50 miles along the Greenbrier River in West Virginia. It is also reported from the Delaware River in Pennsylvania and may also occur in Ohio. This community is threatened by invasion of exotic weeds, especially Sorghum halepense, Centaurea biebersteinii, and Lythrum salicaria.
Concept Lineage:
Predecessors:
Obsolete Names:
Obsolete Parents:
Synonomy: = Andropogon gerardii - Baptisia australis riparian herbaceous vegetation (Vanderhorst 2001b)
= Andropogon gerardii - Panicum virgatum - Baptisia australis Herbaceous Vegetation (Fleming and Taverna 2006)
= Andropogon gerardii - Panicum virgatum - Rhus radicans - Baptisia australis Association (Rawinski et al. 1996)
= Cornus amomum / Andropogon gerardii - Panicum virgatum - Baptisia australis Shrub Herbaceous Vegetation (Fleming and Coulling 2001)
= Fraxinus pennsylvanica / Andropogon gerardii - Panicum virgatum - Baptisia australis Wooded Herbaceous Vegetation (Lea 2000)
< Riverwash Grasslands (Baptisia australis - Lespedeza violacea - Chasmanthium latifolium Herbaceous Vegetation) (Grossman et al. 1994)
< Willow - Indian grass riverine shrubland (Perles et al. 2004)
Concept Author(s): L.A. Sneddon, mod. G. Fleming and P. Coulling, mod. J. Vanderhorst
Author of Description: L.A. Sneddon, G. Fleming, P. Coulling and S.C. Gawler
Acknowledgements:
Version Date: 18Dec2006
References:
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