Name:
Platanus occidentalis - Acer saccharinum - Fraxinus pennsylvanica / Boehmeria cylindrica - Carex emoryi Floodplain Forest
Reference:
NatureServe Biotics 2019
Description:
This community is restricted to the Ridge and Valley and Piedmont sections of the Potomac River floodplain, where it occurs on scoured shorelines in high-gradient reaches where there is a combination of control by bedrock and alluvial processes. Stands are usually on the active channel shelf but have some aspects of depositional bars. Sites are flooded annually and inundated about 3 to 7% of the year, mostly during the dormant season, and often but probably irregularly in the early growing season. Surface substrate is variable, averaging >10% cover of bedrock and boulders in 14 plot samples. Two intergrading phases have been recognized and are described according to perceived differences in net rates of sediment erosion/accretion. In the eroding phase, the channel shelf surface is actively eroding along low channels often filled with cobbles and other coarse material, with finer soil being retained around tree bases. In the stable phase, vegetation holds finer sediments in place and provides an equilibrium between erosion and accretion. Stand physiognomy ranges from wooded herbaceous vegetation to nearly closed-canopy forest. In all expressions, some combination of <i>Platanus occidentalis, Acer saccharinum, Betula nigra</i>, and/or <i>Fraxinus pennsylvanica</i> dominate as the uppermost woody layer, which tends to be a woodland to open forest in the species-rich eroding phase and woodland or wooded herbaceous vegetation in the stable phase. Less constant species include <i>Ulmus americana, Diospyros virginiana, Juglans nigra, Quercus bicolor, Populus deltoides</i>, and <i>Salix nigra</i>. The shrub layer is absent to poorly developed, with battered individuals of <i>Cornus amomum, Cephalanthus occidentalis</i>, and <i>Salix caroliniana</i> the most frequent true shrubs. Woody vines, including <i>Toxicodendron radicans, Campsis radicans</i>, and <i>Vitis riparia</i>, are frequent. The herb layer is diverse and variable. The most constant and characteristic herbs in 14 plot samples are <i>Verbesina alternifolia, Boehmeria cylindrica, Polygonum punctatum, Eupatorium serotinum, Leersia virginica, Dichanthelium clandestinum, Carex emoryi</i> (locally abundant in large clones), <i>Ambrosia artemisiifolia, Polygonum virginianum, Teucrium canadense, Polygonum pensylvanicum, Symphyotrichum lanceolatum var. lanceolatum, Pilea pumila, Chasmanthium latifolium</i>, and <i>Conoclinium coelestinum</i>.
Accession Code:
urn:lsid:vegbank.org:commConcept:35114-{C60BA739-3554-4514-B228-D63EB8A90A61}
Plot-observations of this Community Concept:
5
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