Natural Communities of Virginia - Terrestrial System - Low-Elevation Dry and Dry - Mesic Forests and Woodlands: Basic Oak-Hickory Forests

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

Basic Oak - Hickory Forests
The principal habitats for Basic Oak-Hickory Forests in Virginia are submesic to subxeric uplands over basic rocks such as diabase, gabbro, amphibolite, and metabasalt (greenstone). Soils range from moderately acidic to circumneutral and have moderately high base status. The term “basic,” as applied by VANHP ecologists, refers high levels of base cation saturation rather than to soil pH, which analysis has proven to be a less reliable indicator of fertility and parent material. Communities in this group are scattered to locally extensive throughout the Virginia Piedmont and on low-elevation slopes of the northern Blue Ridge; their distribution elsewhere in the state is uncertain. The largest patches of this vegetation occur in the Piedmont Triassic basins; on the more extensive intrusions of mafic and ultramafic formations elsewhere in the Piedmont; and on soils derived from metabasalt (greenstone) in the Blue Ridge and foothills.

Overstory composition varies regionally, but is generally characterized by mixtures of white oak (Quercus alba), northern red oak (Quercus rubra), black oak (Quercus velutina), chestnut oak (Quercus montana, = Quercus prinus), post oak (Quercus stellata), pignut hickory (Carya glabra), red hickory (Carya ovalis), shagbark hickory (Carya ovata), mockernut hickory (Carya alba), white ash (Fraxinus americana), and tulip-poplar (Liriodendron tulipifera). Hickories are especially abundant in these forests and may dominate some stands. Dominance by tulip-poplar usually follows heavy logging or other catastrophic disturbances. Eastern redbud (Cercis canadensis var. canadensis), eastern hophornbeam (Ostrya virginiana), and flowering dogwood (Cornus florida) are common understory species. Herb layers are typically patchy but species-rich and support diverse mixtures of both mesophytic and dry-site species. In the spring, small geophytes such as cut-leaved toothwort (Cardamine concatenata), rue-anemone (Thalictrum thalictroides), star chickweed (Stellaria pubera), and spring-beauty (Claytonia virginica var. virginica) frequently carpet the ground layers of these oak-hickory forests. The summer and fall aspect is dominated by forbs and grasses such as woodland agrimony (Agrimonia rostellata), four-leaved milkweed (Asclepias quadrifolia), curly-heads (Clematis ochroleuca), Bosc's panic grass (Dichanthelium boscii), naked-flowered tick-trefoil (Desmodium nudiflorum), bottlebrush grass (Elymus hystrix var. hystrix), bedstraws (particularly Galium circaezans and Galium latifolium), solomon's-plume (Maianthemum racemosum ssp. racemosum), cliff muhly (Muhlenbergia sobolifera), goldenrods (particularly Solidago caesia and Solidago ulmifolia ulmifolia var. ulmifolia), yellow pimpernel (Taenidia integerrima), feverwort (Triosteum angustifolium), and three-lobed violet (Viola palmata var. triloba).

Basic Oak-Hickory Forests occupy more fertile soils and have higher species-richness and fewer ericaceous shrubs than do Acidic Oak-Hickory Forests. They are distinguished from Montane Oak-Hickory Forests by their restriction to low-elevation habitats and corresponding composition consisting mostly of species that do not occur at higher elevations. With a distribution in the Piedmont already restricted by limited available habitat, Basic Oak-Hickory Forests have also been reduced considerably by a long history of agriculture, conversion of hardwood forests to intensively managed pine stands, and urban development. Some of the community types in this group can be considered uncommon or rare in the state.

References: Farrell and Ware (1991), Fleming (2002a), Fleming (2002b), Fleming and Coulling (2001), Fleming and Weber (2003), Ware (1991), Ware (1992).

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

	Basic Oak-Hickory Forest (Northern Hardpan Type) is typical of diabase “flatwoods” in the northern Virginia Culpeper Basin. The grass cliff muhly (Muhlenbergia sobolifera) dominates the herb layer. Near Elklick Run, Fairfax County (Fairfax County Park Authority lands). Photo: Gary P. Fleming
	Basic Oak-Hickory Forest (Southern Piedmont Type) dominated by white oak (Quercus alba) and shagbark hickory (Carya ovata), with a diverse herb layer of forest grasses, sedges, and forbs. Near Trents Mill, Cumberland County (Cumberland State Forest). Photo: © Gary P. Fleming.

REPRESENTATIVE COMMUNITY TYPES:
This ecological group is very well represented by quantitative data and its division into community types is relatively robust. Basic Oak-Hickory Forests comprise some of Virginia's most species-rich vegetation, and the units that have been defined to date are separated largely by geography and subtle floristic differences that are often difficult to distinguish in the field. Some provinces (particularly the northern Piedmont and northern Blue Ridge) are far more intensively sampled and classified than others. Some of the community types are supported by > 45 plots each, while others are supported by < 10 plots. These inequities in quantitative documentation, as well as uncertainties about the classification of some units and the relationships between units, will be addressed by additional future sampling in the southern part of the state. Click on any highlighted CEGL code below to view the global USNVC description provided by NatureServe Explorer

Carya glabra – Quercus ( rubra , montana ) – Fraxinus americana / Viburnum rafinesquianum / Melica mutica Forest
Basic Oak-Hickory Forest (Potomac River Bedrock Terrace Type)
USNVC: = CEGL006209
Global/State Ranks: G1G2/S1
Quercus alba – Carya glabra – Fraxinus americana / Cercis canadensis / Muhlenbergia sobolifera – Elymus hystrix Forest
Basic Oak-Hickory Forest (Northern Hardpan Type)
USNVC: = CEGL006216
Global/State Ranks: G3/S3
Quercus alba – Quercus rubra – Carya alba / Carpinus caroliniana / Desmodium nudiflorum – Maianthemum racemosum Forest
Basic Oak-Hickory Forest (Submesic Piedmont Type)
USNVC: = CEGL007237
Global/State Ranks: G4?/SNR
Quercus alba – Carya alba – Carya ovata / Cercis canadensis Forest
Basic Oak-Hickory Forest (Southern Piedmont Type)
USNVC: = CEGL007232
Global/State Ranks: G3?/SNR
Quercus rubra – Quercus montana – Carya ovalis / Cercis canadensis / Solidago caesia Forest
Basic Oak-Hickory Forest (Central Appalachian Submontane / Foothills Type)
USNVC: = CEGL008514
Global/State Ranks:G3G4/S3S4

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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)