Natural Communities of Virginia - Palustrine System - Alluvial Floodplain Communities: Piedmont / Mountain Swamp Forests

The Natural Communities of Virginia
Classification of Ecological Community Groups
SECOND APPROXIMATION (Version 2.2)

Piedmont / Mountain Swamp Forests
This group contains seasonally flooded deciduous forests of backswamps and sloughs in the floodplains of Piedmont and mountain-region rivers and large streams. Communities of this group are most common in the broad, clay-rich floodplain deposits of Piedmont Mesozoic basins, but occur locally throughout the central and western parts of Virginia. Habitats generally have some hummock-and-hollow microtopography, with maximum flooding depths in hollows of 50 to 70 cm (20 to 28 in). Soils are usually white- or orange-mottled clay loams and loamy clays, with moderately low to moderately high base status.

Characteristic trees of these swamps include pin oak (Quercus palustris), willow oak (Quercus phellos), green ash (Fraxinus pennsylvanica), red maple (Acer rubrum), and sweetgum (Liquidambar styraciflua). Swamp white oak (Quercus bicolor) is abundant in swamps of the northern Piedmont, while overcup oak (Quercus lyrata) is a constituent in the southern Piedmont. Small trees and shrubs include deciduous hollies (Ilex decidua and Ilex verticillata), common elderberry (Sambucus canadensis), silky dogwood (Cornus amomum ssp. amomum), and American hornbeam (Carpinus caroliniana ssp. caroliniana and ssp. virginiana). High-climbing woody vines, including poison ivy (Toxicodendron radicans ssp. radicans), grapes (Vitis spp.), and trumpet-creeper (Campsis radicans), are also typical. The herb layers of these communities are quite species-rich because of microtopographic diversity, but species tolerant of seasonal inundation are prevalent, including lizard's-tail (Saururus cernuus), false nettle (Boehmeria cylindrica), wood reedgrass (Cinna arundinacea), winged monkey-flower (Mimulus alatus), and various sedges (e.g ., Carex tribuloides var. tribuloides, Carex typhina, Carex squarrosa, Carex grayi). Large, well-developed swamp forests are somewhat uncommon in the Piedmont and rare in the mountains. Some of them, particularly along the Roanoke River in southern Virginia, have been destroyed or hydrologically altered by the creation of large reservoirs.

Reference: Fleming (2002a).

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

	Broad-leaved water-plantain (Alisma subcordatum) in a recently drawn down, seasonally flooded slough along Cub Run in Fairfax County (Cub Run Stream Valley Park). The overstory here consists primarily of pin oak (Quercus palustris) and green ash (Fraxinus pennsylvanica). Photo: Gary P. Fleming / © DCR Natural Heritage.
	Large colonies of wood reedgrass (Cinna arundinacea), growing under swamp white oak (Quercus bicolor) and American elm (Ulmus americana), characterize the drier, late-season aspect of this swamp along Elklick Run in Fairfax County (Fairfax County Park Authority lands). Photo: Gary P. Fleming / © DCR Natural Heritage.
	Seasonally flooded backswamp along South Fork Quantico Creek at Prince William Forest Park, Prince William County. The overstory is primarily pin oak (Quercus palustris) while the dominant herbs are false nettle (Boehmeria cylindrica) and blunt broom sedge (Carex tribuloides var. tribuloides). Photo: Gary P. Fleming / © DCR Natural Heritage.

REPRESENTATIVE COMMUNITY TYPES:
Documentation of this group consists of only ten plots, all of them from the northern Piedmont Mesozoic (Triassic) Basin and supporting the single classified community type listed below. This ecological group, and especially southern Piedmont and montane examples, will be a priority for future work. Click on any highlighted CEGL code below to view the global USNVC description provided by NatureServe Explorer.

Quercus palustris - Quercus bicolor - Ulmus americana / Carex tribuloides - Carex squarrosa Forest
Piedmont / Central Appalachian Floodplain Swamp
USNVC: no equivalent
Global/State Ranks: GNR/SNR

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The Natural Communities of Virginia Classification of Ecological Community Groups SECOND APPROXIMATION (Version 2.2)

The Natural Communities of Virginia
Classification of Ecological Community Groups
SECOND APPROXIMATION (Version 2.2)