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NATURAL HERITAGE

THE NATURAL COMMUNITIES OF VIRGINIA
CLASSIFICATION OF ECOLOGICAL COMMUNITY GROUPS


Second Approximation (Version 2.6)
Information current as of July, 2013



Upland Depression Swamps

Communities in this group generally occur on nearly level Piedmont uplands with clay hardpans, from south-central Maryland south to South Carolina. In Virginia, these wetlands are scattered throughout the eastern and central Piedmont. They are most numerous in Mesozoic basins and areas underlain by mafic rocks or acidic slates. Habitats include shallow, seasonally flooded upland basins, as well as broad, wet bottoms along small streams. Because of low relief, headwater drainages in parts of the Piedmont are very diffuse, with sluggish, usually intermittent flows and no active alluvial deposition. Within this physiographic context, it can be difficult to distinguish true isolated wetland basins from "non-alluvial" stream bottoms. Hydrologically, these topographically divergent habitats are comparable, with shallow seasonal flooding induced by perched water tables during the winter and spring months. Hydroperiods, however, can apparently be irregular and unpredictable. Maximum flooding depth is usually < 25 cm (10 in). A-horizon soils are dark brown to blackish, loamy clays which typically exhibit pronounced orange and white mottling.

Canopy cover ranges from complete to very open. In northern Virginia, pin oak (Quercus palustris), swamp white oak (Quercus bicolor), red maple (Acer rubrum) and, to a lesser extent, willow oak (Quercus phellos) are characteristic. In the southern Piedmont, willow oak, sweetgum (Liquidambar styraciflua), and overcup oak (Quercus lyrata) are typical. Shrub composition is variable but usually includes an abundance of climbing common greenbrier (Smilax rotundifolia). The herb layer is often sparse; common species include sedges (especially Carex festucacea and Carex albolutescens in the southern Piedmont, and Carex pellita in the northern Piedmont), Virginia cutgrass (Leersia virginica), manna-grasses (Glyceria spp.), and rushes (Juncus spp). Sphagnum mosses (Sphagnum spp.) frequently form large patches on slightly raised hummocks.

Upland depression swamps are isolated and semi-isolated wetlands subject to major disturbances and alterations from logging, draining, and development. All community types in the group are considered globally and/or state-rare.

Reference: Fleming (2002a), Fleming and Patterson (2004), Fleming and Weber (2003).

Click on the images below to open a larger image in a separate window.

This link opens a new browser window to display a larger photo Inundated stand of Upland Depression Swamp near Schneider Crossroads in western Fairfax County (Fairfax County Park Authority lands). Common wood reedgrass (Cinna arundinacea , in foreground) and woolly sedge (Carex pellita , in background) dominate the herb layer beneath an overstory of pin oaks (Quercus palustris). Photo: Gary P. Fleming.
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Partly drawn-down wooded depression swamp near Piney River, Amherst County. Willow oaks (Quercus phellos) dominate the overstory. Photo: Gary P. Fleming.
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Woodland of pin oak (Quercus palustris) and swamp white oak (Q. bicolor) in an exsiccated depression swamp near Gainesville, Prince William County (Manassas National Battlefield Park). Photo: Gary P. Fleming.
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An Upland Depression Swamp in the southern Piedmont of Charlotte County (Hogan Creek Wildlife Management Area, John H. Kerr Reservoir). Photo: Gary P. Fleming.

REPRESENTATIVE COMMUNITY TYPES:
Three community types are recognized based on analysis of data from 36 plots (map). Because these vegetation types occur in small, more or less isolated patches over broad areas, there are considerable differences in composition from one stand to another. The most characteristic and dominant species, however, tend to be constant. While the general concepts of these types appear to be sound, some refinements in their description and nomenclature are likely to result from the collection of substantial additional data. Click on any highlighted CEGL code below to view the global USNVC description provided by NatureServe Explorer.
  • Quercus palustris - Quercus bicolor / Viburnum prunifolium / Leersia virginica - Impatiens capensis Forest
    Piedmont Upland Depression Swamp (Pin Oak - Swamp White Oak Type)
    USNVC: = CEGL004643
    Global/State Ranks: G2/S1

  • Quercus phellos / Smilax rotundifolia / Carex (albolutescens, festucacea) Forest
    Piedmont Upland Depression Swamp (Willow Oak Type)
    USNVC: = CEGL007403
    Global/State Ranks: G2G3/S2

  • Quercus palustris - Acer rubrum - Liquidambar styraciflua / Vaccinium (fuscatum, formosum) Forest
    Outer Piedmont / Inner Coastal Plain Upland Depression Swamp (Pin Oak / Highbush Blueberry Type)
    USNVC: = CEGL006240
    Global/State Ranks: GNR/S1

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