Name:
Nyssa sylvatica - Magnolia virginiana / Rhododendron viscosum - Toxicodendron vernix / Smilax pseudochina Swamp Woodland
Reference:
NatureServe Biotics 2019
Description:
This saturated woodland is known from a limited area at and just east of the Fall Line in Maryland, the District of Columbia, and northern Virginia. It occurs on saturated toeslopes of fluvial-estuarine terraces where sands and gravels of the Cretaceous-aged Potomac Formation are exposed. Irregular microtopography with abundant groundwater seepage forming braided channels, <i>Sphagnum</i>-covered hummocks, and mucky depressions are characteristic. Historic accounts of this vegetation describe these areas as "bogs" with <i>Magnolia virginiana</i> and various shrubs fringing and forming clumps within a more open center dominated by herbaceous plants. Historic vegetation included <i>Nyssa sylvatica, Toxicodendron vernix</i> (abundant), <i>Gaylussacia frondosa, Viburnum nudum var. nudum, Pinus rigida</i>, and <i>Eriocaulon decangulare</i> (abundant), <i>Lycopodiella appressa, Carex bullata, Asclepias rubra, Helianthus angustifolius, Rhynchospora gracilenta, Xyris torta, Pogonia ophioglossoides</i>, and <i>Utricularia</i> spp. Today, remaining examples exist mostly as open woodlands with very dense shrubs (averaging 80% cover) and very small, scattered herbaceous patches. <i>Nyssa sylvatica</i> is the most dominant species, followed by <i>Magnolia virginiana, Acer rubrum, Liriodendron tulipifera</i>, and <i>Ilex opaca var. opaca</i>. Shrub cover includes <i>Rhododendron viscosum, Vaccinium</i> spp., <i>Smilax rotundifolia, Gaylussacia frondosa, Viburnum nudum var. nudum, Eubotrys racemosa, Aronia arbutifolia, Ilex verticillata, Amelanchier canadensis, Ilex laevigata</i>, and <i>Toxicodendron vernix</i>. The only herbs that have significant cover are <i>Osmunda cinnamomea</i> and <i>Dichanthelium dichotomum var. dichotomum</i>, while many others have low cover. Regionally uncommon or rare "bog" species persisting at one or a few sites include <i>Solidago uliginosa var. uliginosa, Eurybia radula, Eriocaulon decangulare, Juncus longii, Drosera intermedia, Asclepias rubra</i>, and <i>Kalmia angustifolia</i>. Historically, fire may have been an important factor in maintaining herbaceous patches and limiting the growth of shrubs and trees, but the geohydrologic conditions and effects of permanently saturated soils ("root pruning") that cause blowdowns of large trees (except <i>Pinus rigida</i> and <i>Nyssa sylvatica</i>) have also been observed to be prominent factors. Ice storms, which are frequent over time in the natural range of this community, also maintain an open mosaic in these wetlands. This community has always had a limited distribution in the Mid-Atlantic fall-line zone and has probably always been rare. Today, less than 20 sites remain in very small patches degraded by hydrologic disturbance, non-native invasive plants, woody succession, fire exclusion, and various anthropogenic impacts. This community has similarities with the bog vegetation of the New Jersey Pine Barren region, but is likely distinguished by species with southern affinities.
Accession Code:
urn:lsid:vegbank.org:commConcept:34866-{59FAFF87-898E-4E48-85F1-37A2E16665C8}
Plot-observations of this Community Concept:
0
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