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CEGL008416 Acer rubrum - Fraxinus nigra - Betula alleghaniensis / Veratrum viride - Carex bromoides Seep Forest

Type Concept Sentence: This community occupies groundwater-saturated stream headwaters, large spring seeps, and bases of slopes. Overstory composition is mixed, with Acer rubrum, Fraxinus americana, and Liriodendron tulipifera the most abundant species. Fraxinus nigra is a frequent associate. In the ground layer, Symplocarpus foetidus and Veratrum viride are usually dominant.

Common (Translated Scientific) Name: Red Maple - Black Ash - Yellow Birch / Green False Hellebore - Bromelike Sedge Seep Forest

Colloquial Name: Central Appalachian Basic Seepage Swamp Forest

Hierarchy Level:  Association

Type Concept: This community occupies groundwater-saturated stream headwaters, large spring seeps and runs, and lateral areas in ravine and stream bottoms where groundwater emerges at the base of slopes. It is most frequent and best developed on Catoctin Formation metabasalt (greenstone) of the Northern Blue Ridge and other base-rich substrates. Soil chemistry data indicate moderately high calcium and magnesium levels. Overstory composition is mixed, with Acer rubrum, Fraxinus americana, and Liriodendron tulipifera the most abundant species. Fraxinus nigra is a frequent overstory associate but more abundant and sometimes dominant in the understory, along with young Acer rubrum and Fraxinus americana. With increasing elevation, Betula alleghaniensis becomes increasingly important, codominating most stands above 760 m (2500 feet) in Virginia and in the Catoctin Mountains of Maryland. Minor tree associates include Betula lenta and Tilia americana. Canopy closure is often incomplete (mean stratum cover = 60-80%), most evidently because of blowdowns. Very wet microhabitats that impede the establishment and firm rooting of trees may also contribute to a somewhat open canopy. Shrub stratum diversity is moderately high; Lindera benzoin is usually the most abundant species, and considerable stratum cover is contributed by tree saplings. Other frequently occurring true shrubs are Alnus serrulata, Carpinus caroliniana, Hamamelis virginiana, Ilex verticillata, and Sambucus nigra ssp. canadensis. Except in local areas where shrubs are dense, herbaceous cover is high (mean stratum cover = 90%). One or both of the early-maturing forbs Symplocarpus foetidus (mostly at lower elevations) and Veratrum viride are usually dominant over substantial areas. Because of microtopographic diversity, herbaceous patch-mosaics are typical in this vegetation. More-or-less constant, sometimes locally abundant species include Eurybia schreberi, Caltha palustris, Carex bromoides, Carex gynandra, Carex prasina, Chelone glabra, Chrysosplenium americanum, Cinna arundinacea, Dryopteris carthusiana, Dryopteris goldieana, Glyceria striata, Impatiens capensis, Osmunda cinnamomea, Osmunda regalis var. spectabilis, Ranunculus recurvatus, Saxifraga pensylvanica, Packera aurea, Sphenopholis pensylvanica, Thalictrum pubescens, and Viola cucullata. Moss cover is often significant but only rarely includes Sphagnum spp. (not recorded in Virginia plots). Typical upland mesophytes commonly occur in well-drained hummock microhabitats and contribute to relatively high species-richness values for this type of wetland.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Classification of this type is supported by analysis of a 1250-plot regional dataset assembled for the NCR vegetation mapping project. In that analysis, this association is represented by 25 Virginia and Maryland plots that perform as a tight group in all analytical procedures. Distinct floristic features of calcareous seepage swamps include the prevalence of Fraxinus spp. (especially Fraxinus nigra) and nutrient-demanding species, among the most diagnostic of which are Caltha palustris, Carex bromoides, Carex laevivaginata, Pilea fontana, Poa paludigena, Ranunculus hispidus var. caricetorum, Saxifraga pensylvanica, and Trillium cernuum. These communities lack the Sphagnum mosses that characterize acidic groundwater wetlands. Moreover, many vascular plants that are common in or diagnostic of acidic seepage swamps are absent or unimportant (e.g., Pinus rigida, Nyssa sylvatica, Viburnum nudum var. nudum, Parnassia asarifolia, Platanthera ciliaris, Platanthera clavellata, Rubus hispidus, Lycopodium obscurum, Carex debilis var. debilis, and Carex folliculata) (Fleming and Van Alstine 1999).

Additionally, the spectrum of stands representing this association in Virginia shows a clear elevation gradient, with Symplocarpus foetidus and Fraxinus nigra decreasing in frequency and abundance and Betula alleghaniensis assuming codominance as elevation increases. In landscapes with suitably base-rich substrates such as Catoctin metabasalt, this type may intergrade with the higher elevation ~Tsuga canadensis - Betula alleghaniensis / Veratrum viride - Carex scabrata - Oclemena acuminata Swamp Forest (CEGL008533)$$ in a transitional zone from about 760 to 900 m (2500-3000 feet) elevation.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available

Floristics: Overstory composition is mixed, with Acer rubrum, Fraxinus americana, and Liriodendron tulipifera the most abundant species. Fraxinus nigra is a frequent overstory associate but more abundant and sometimes dominant in the understory, along with young Acer rubrum and Fraxinus americana. With increasing elevation, Betula alleghaniensis becomes increasingly important, codominating most stands above 760 m (2500 feet) in Virginia and in the Catoctin Mountains of Maryland. Minor tree associates include Betula lenta and Tilia americana. Almost all trees in plot-sampled stands were <50 cm dbh and most were <40 cm dbh; but scattered Liriodendron specimens >80 cm dbh occur, and in one plot such an individual tree accounts for the high canopy cover of this species. Canopy closure is often incomplete (mean stratum cover = 60-80%), most evidently because of blowdowns. Very wet microhabitats that impede the establishment and firm rooting of trees may also contribute to a somewhat open canopy. Shrub stratum diversity is moderately high; Lindera benzoin is usually the most abundant species, and considerable stratum cover is contributed by tree saplings. Other frequently occurring true shrubs are Alnus serrulata, Carpinus caroliniana, Hamamelis virginiana, Ilex verticillata, and Sambucus nigra ssp. canadensis. Except in local areas where shrubs are dense, herbaceous cover is high (mean stratum cover = 90%). One or both of the early-maturing forbs Symplocarpus foetidus (mostly at lower elevations) and Veratrum viride are usually dominant over substantial areas. Because of microtopographic diversity, herbaceous patch-mosaics are typical in this vegetation. More-or-less constant, sometimes locally abundant species include Eurybia schreberi (= Aster schreberi), Caltha palustris, Carex bromoides, Carex gynandra, Carex prasina, Chelone glabra, Chrysosplenium americanum, Cinna arundinacea, Dryopteris carthusiana, Dryopteris goldieana, Glyceria striata, Impatiens capensis, Osmunda cinnamomea, Osmunda regalis var. spectabilis, Ranunculus recurvatus, Saxifraga pensylvanica, Packera aurea (= Senecio aureus), Sphenopholis pensylvanica, Thalictrum pubescens, and Viola cucullata. Moss cover is often significant, but only rarely includes Sphagnum spp. (not recorded in Virginia plots). Typical upland mesophytes commonly occur in well-drained hummock microhabitats and contribute to relatively high species richness values for this type of wetland (n = 60 taxa per 400 m2 for 25 plot samples).

Dynamics:  No Data Available
Environmental Description:  This community occupies groundwater-saturated stream headwaters, large spring seeps and runs, and lateral areas in ravine and stream bottoms where groundwater emerges at the base of slopes. Hydrologically, these habitats are classified as "groundwater slope wetlands," where seepage discharged at the ground surface is drained away as streamflow (Golet et al. 1993). Habitats are usually more-or-less narrow and elongate, with considerable exposed bouldery and cobble alluvium. Soils are predominantly mineral, but local areas of organic muck sometimes accumulate in depressions. The ground surface is slightly sloping (mean slope = 3°), and drainage is usually via small, intricately braided channels with intervening hummocks. Moss mats on boulders and cobble deposits commonly provide a rooting medium for herbaceous species, and "sedge tussocks" (especially of Carex bromoides and Carex prasina) are conspicuous features of these swamps. Soils collected from 25 Virginia and Maryland plot samples ranged from strongly acidic to neutral in pH, with moderately high calcium (mean = 1358 ppm) and magnesium (mean = 211 ppm) levels. This community is most frequent and best developed on Catoctin Formation metabasalt (greenstone) of the Northern Blue Ridge. There, it occurs locally in small patches (<12 ha [30 acres]) at elevations from about 275 to 850 m (900-2800 feet) and occasionally up to 975 m (3200 feet) (Ludwig et al. 1993). It has also been documented in northwestern Virginia in the Massanutten Mountains and western Ridge and Valley region, in the western Piedmont of both Virginia and Maryland and in Maryland''s Allegheny Plateau in which stands observed and sampled occur at 800 m.. A somewhat isolated and disjunct occurrence is documented from the Dismal Creek valley in Giles County, in the southwestern Virginia Ridge and Valley. This is probably one of the southernmost occurrences for both the community type and Fraxinus nigra, a tree of pronounced northern distribution. The few known Ridge and Valley occurrences are associated with sites where Devonian or Silurian limestones are interbedded with sandstone and shale. While surficial outcrops of limestone are not evident at these sites, it is clear from both soil samples and floristic evidence that the wetlands are being supplied with calcium by groundwater.
Geographic Range: The range of this community encompasses the Central Appalachian region of Pennsylvania, Maryland, West Virginia, and Virginia, as well as Delaware and New Jersey. In Virginia, it is found primarily in the northern half of the mountains, apparently reaching its southern limits in Giles County. In Maryland, its distribution is centered in the Catoctin Mountains. The majority of occurrences are on the Northern Blue Ridge, but the type is also scattered in suitable habitats of the Ridge and Valley province, western Piedmont, and Maryland''s Allegheny Plateau.

Nations: US

States/Provinces:  DE, MD, NJ, PA, VA, WV


Confidence Level: Moderate

Confidence Level Comments: No Data Available
Grank: G3

Greasons: No Data Available
Type Name Database Code Classification Code
Class 1 Forest & Woodland Class C01 1
Subclass 1.B Temperate & Boreal Forest & Woodland Subclass S15 1.B
Formation 1.B.3 Temperate Flooded & Swamp Forest Formation F026 1.B.3
Division 1.B.3.Na Eastern North American-Great Plains Flooded & Swamp Forest Division D011 1.B.3.Na
Macrogroup 1.B.3.Na.2 Pin Oak - Green Ash - Blackgum Swamp Forest Macrogroup M503 1.B.3.Na.2
Group 1.B.3.Na.2.h <i>Quercus bicolor - Fagus grandifolia - Acer rubrum</i> Swamp Forest Group G918 1.B.3.Na.2.h
Alliance A4461 <i>Acer rubrum - Fraxinus pennsylvanica</i> Northeast Alkaline Swamp Forest Alliance A4461 1.B.3.Na.2.h
Association CEGL008416 Red Maple - Black Ash - Yellow Birch / Green False Hellebore - Bromelike Sedge Seep Forest CEGL008416 1.B.3.Na.2.h
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Acer rubrum - Betula alleghaniensis - Fraxinus (americana, nigra) / Carex bromoides Forest (Young et al. 2007a)
= Acer rubrum - Fraxinus americana - Fraxinus nigra / Carex bromoides - Carex prasina - (Caltha palustris) Forest (Fleming and Coulling 2001)
= Acer rubrum - Fraxinus nigra / Caltha palustris - Carex bromoides Forest (Fleming 1999)
< Black Ash - American Elm - Red Maple: 39 (Eyre 1980)
Concept Author(s): G.P. Fleming

Author of Description: G.P. Fleming

Acknowledgements: No Data Available

Version Date: 10-26-11
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