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.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.
Partly drawn-down wooded depression swamp near Piney River, Amherst County. Willow oaks (Quercus phellos) dominate the overstory. Photo: Gary P. Fleming.
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.
An Upland Depression Swamp in the southern Piedmont of Charlotte County (Hogan Creek Wildlife Management Area, John H. Kerr Reservoir). Photo: Gary P. Fleming.