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The Natural Communities of Virginia
Classification of Ecological Community Groups

Second Approximation (Version 2.7)
Information current as of February, 2016

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Mountain / Piedmont Acidic Seepage Swamps

This group of saturated deciduous forests occupies gently sloping stream headwaters, large spring seeps, and ravine bottoms underlain by sandstone, quartzite, or base-poor granitic rocks. These communities are locally scattered throughout the Virginia mountains and western Piedmont, up to about 900 m (3,000 ft) elevation. Hummock-and-hollow microtopography, braided streams, areas of coarse gravel and cobble deposition, muck-filled depressions, and abundant Sphagnum mats are typical habitat features. Soils are very strongly to extremely acidic, with low base status. Hydrologically, these habitats are classified as "groundwater slope wetlands," where seepage discharged at the ground surface is drained away as stream flow. They differ from certain basin wetlands that are saturated strictly by perched groundwater and support somewhat similar vegetation (see the Montane Depression Wetlands ecological group description for more information).

Composition is variable over the range of this group. Red maple (Acer rubrum), blackgum (Nyssa sylvatica), and tulip-poplar (Liriodendron tulipifera), are the most typical trees, while winterberry (Ilex verticillata), swamp azalea (Rhododendron viscosum), highbush blueberries (Vaccinium corymbosum and Vaccinium fuscatum) are abundant shrubs. Pitch pine (Pinus rigida) is a characteristic tree of some Ridge and Valley stands. Skunk-cabbage (Symplocarpus foetidus) and American false-hellebore (Veratrum viride) may be as dominant in these communities as in Mountain / Piedmont Basic Seepage Swamps; herbs and low shrubs more abundant in or characteristic of acidic swamps include cinnamon fern (Osmunda cinnamomea var. cinnamomea), bristly dewberry (Rubus hispidus), kidneyleaf grass-of-parnassus (Parnassia asarifolia), yellow fringed orchid (Platanthera ciliaris) small green wood orchid (Platanthera clavellata), common tree clubmoss (Lycopodium obscurum), white-edged sedge (Carex debilis var. debilis), and long sedge (Carex folliculata). Like the very similar Coastal Plain / Piedmont Acidic Seepage Swamps, these communities support populations of the federally listed swamp-pink (Helonias bullata).

References: Allard and Leonard (1943), Carr (1939), Fleming (2002b), Fleming and Van Alstine (1999).

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False hellebore (Veratrum viride , leaning in foreground), skunk-cabbage (Symplocarpus foetidus), and cinnamon fern (Osmunda cinnamomea var. cinnamomea) are large, leafy dominants in an acidic seepage swamp along the headwaters of Bartons Creek, Bull Run Mountains, Fauquier County. Photo: Gary P. Fleming / © DCR Natural Heritage.
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Mountain / Piedmont Acidic Seepage Swamp along a small spring run at the western foot of the Blue Ridge in Augusta County (Shenandoah National Park). Red maple (Acer rubrum), black gum (Nyssa sylvatica), hairy highbush blueberry (Vaccinium fuscatum) and cinnamon fern (Osmunda cinnamomea var. cinnamomea ) are dominants in this stand. Photo: Gary P. Fleming / © DCR Natural Heritage.

This group and the single community type nested within it are supported by 18 Virginia plots from the inner Piedmont, Blue Ridge, and Ridge and Valley provinces (map), as well as by presence/absence data from 23 stands in Augusta County. Gradations in floristic composition, however, are evident both within the type and between this type and a sympatric basic seepage swamp community (see the previous ecological group). More inventory, data collection, and analysis are thus needed. Click on any highlighted CEGL code below to view the global USNVC description provided by NatureServe Explorer.
  • Acer rubrum - (Betula alleghaniensis, Tsuga canadensis) / Rhododendron maximum / Osmundastrum cinnamomeum Forest
    Southern Appalachian High-Elevation Seepage Swamp
    USNVC: = CEGL007565
    Global/State Ranks: G2/S1

  • Acer rubrum - Nyssa sylvatica / Ilex verticillata - Vaccinium fuscatum / Osmunda cinnamomea Forest
    Central Appalachian Low-Elevation Acidic Seepage Swamp
    USNVC: = CEGL007853
    Global/State Ranks: G2/S2

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