Vegetation Classification and Mapping Project Report - USGS

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USGS-NPS Vegetation Mapping Program Colonial National Historical Park contain Magnolia virginiana (sweetbay) and recruitment of the overstory trees. The shrub layer varies from open to dense. and most characteristically contains Clethra alnifolia (coastal sweetpepperbush), Leucothoe racemosa (swamp doghobble), Ilex verticillata (common winterberry), Vaccinium corymbosum (highbush blueberry), Vaccinium fuscatum (black highbush blueberry), Vaccinium formosum (southern blueberry), Viburnum dentatum (southern arrowwood), Rhododendron viscosum (swamp azalea), and Viburnum nudum var. nudum (possumhaw). The herb layer is also highly variable. Some stands have a rather sparse herbaceous flora, with scattered colonies and individuals of Woodwardia areolata (netted chainfern), Osmunda cinnamomea (cinnamon fern), Osmunda regalis var. spectabilis (royal fern), Woodwardia virginica (Virginia chainfern), Saururus cernuus (lizard's tail), and various sedges. Others have a relatively dense graminoid-dominated herb layer with variable patchdominance by Chasmanthium laxum (slender woodoats), Carex debilis var. debilis (white edge sedge), Carex intumescens (greater bladder sedge), Carex seorsa (weak stellate sedge), Carex lonchocarpa (southern long sedge), and more rarely, Carex bullata (button sedge) or Carex striata var. brevis (Walter's sedge). Many stands of this association have been degraded by cutting or ditching, and extensive areas of suitable habitat have been lost to agriculture, hydrologic alterations, and conversion of hardwood forests to silvicultural pine plantations. Environmental Description: This association occurs on extensive, flat Coastal Plain terraces and very wide, ancient floodplains that are no longer subject to alluvial processes. Its hydrology is seasonally to nearly permanently saturated, with occasional ponding or groundwater sheetflows, and is maintained by a high water table rather than riverine or estuarine flooding. Shallow channels and streams are sometimes evident, and hummock and hollow microtopography may be present. On the Eastern Shore of Virginia (Accomack County), it is found in isolated and extensive but shallow upland depressions. The stands here cover many hectares and occur in slight depressions with drainage impeded by an impermeable clay layer about half a meter below the soil surface. The habitat apparently has a seasonally high water table but ponds water only intermittently or for short periods (G. Fleming pers. comm.). Surficial soils occupied by this forest are extremely acidic and infertile silt or silty-clay loams. Vegetation Description: The overstory of relatively undisturbed examples contain variable mixtures of hydrophytic oaks, most commonly Quercus phellos (willow oak), Quercus pagoda (cherrybark oak), and Quercus michauxii (swamp chestnut oak). Associated canopy species varying from site to site can include Quercus alba (white oak), Quercus palustris (pin oak), Quercus lyrata (overcup oak), Liquidambar styraciflua (sweetgum), Acer rubrum (red maple), Pinus taeda (loblolly pine), Nyssa sylvatica (blackgum), and Fraxinus pennsylvanica (green ash). Liquidambar styraciflua (sweetgum), Acer rubrum (red maple), and Pinus taeda (loblolly pine) are often abundant in stands disturbed by cutting. The subcanopy layers are usually dominated by Ilex opaca var. opaca (American holly) and also contain Magnolia virginiana (sweetbay) and recruitment of the overstory trees. The shrub layer varies from open to dense, and most characteristically contains Clethra alnifolia (coastal sweetpepperbush), Leucothoe racemosa (swamp doghobble), Ilex verticillata (common winterberry), Vaccinium corymbosum (highbush blueberry), Vaccinium fuscatum (black highbush blueberry), Vaccinium formosum (southern blueberry), Viburnum dentatum (southern arrowwood), Rhododendron viscosum (swamp azalea), and Viburnum nudum var. nudum (possumhaw). The herb layer is also highly variable. Some stands have a rather sparse herbaceous flora, with scattered colonies and individuals of Woodwardia areolata (netted chainfern), Osmunda cinnamomea (cinnamon fern), Osmunda regalis var. spectabilis (royal fern), Woodwardia virginica (Virginia chainfern), 254
USGS-NPS Vegetation Mapping Program Colonial National Historical Park Saururus cernuus (lizard's tail), and various sedges. Others have a relatively dense graminoiddominated herb layer with variable patch-dominance by Chasmanthium laxum (slender woodoats), Carex debilis var. debilis (white edge sedge), Carex intumescens (greater bladder sedge), Carex seorsa (weak stellate sedge), Carex lonchocarpa (southern long sedge), and more rarely, Carex bullata (button sedge) or Carex striata var. brevis (Walter's sedge). Many other hydrophytic herbs occur at low constancy and cover. The composition of this community is something of a "hybrid," with an overstory similar to that of oak-dominated floodplain forests and lower strata resembling those of an acidic seepage swamp. Most Abundant Species: Stratum Lifeform Species Tree subcanopy Broad-leaved evergreen tree Ilex opaca var. opaca (American holly), Magnolia virginiana (sweetbay) Herb (field) Graminoid Carex debilis var. debilis (white edge sedge), Carex intumescens (greater bladder sedge), Carex lonchocarpa (southern long sedge), Carex seorsa (weak stellate sedge), Chasmanthium laxum (slender woodoats) Characteristic Species: Clethra alnifolia (coastal sweetpepperbush), Ilex verticillata (common winterberry), Leucothoe racemosa (swamp doghobble), Osmunda cinnamomea (cinnamon fern), Osmunda regalis var. spectabilis (royal fern), Quercus michauxii (swamp chestnut oak), Quercus pagoda (cherrybark oak), Quercus phellos (willow oak), Rhododendron viscosum (swamp azalea), Saururus cernuus (lizard's tail), Vaccinium corymbosum (highbush blueberry), Viburnum dentatum (southern arrowwood), Viburnum nudum var. nudum (possumhaw), Woodwardia areolata (netted chainfern), Woodwardia virginica (Virginia chainfern). Other Noteworthy Species: Information not available. USFWS Wetland System: Palustrine. DISTRIBUTION Range: This association is known from about 25 sites in 13 counties of the Virginia central and northern Coastal Plain. It is not currently documented in Maryland, but requisite habitat conditions are present (J. Harrison pers. comm.). States/Provinces: VA. Federal Lands: DOD (Fort Lee); NPS (Colonial, Fredericksburg-Spotsylvania, George Washington Birthplace, Richmond). CONSERVATION STATUS Rank: G2? (15-Aug-1997). Reasons: This association is restricted to special wetland habitats and was probably never common on the landscape. However, extensive areas of suitable habitat have been lost to agriculture, hydrologic alterations, and conversion of hardwood forests to silvicultural pine plantations. The largest known remaining stands are all on private lands and are not protected. Mature, undisturbed examples of this type are rare. CLASSIFICATION INFORMATION Status: Standard. Confidence: 2 - Moderate. Comments: Classification of this type is based on intensive field investigation by the Virginia Natural Heritage Program (VDNH) and analysis of a 1250-plot regional dataset assembled for the NCR and mid-Atlantic national parks vegetation mapping projects. In that analysis, this 255
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Vegetation Classification and Mapping Project Report - USGS

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