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Scientific Name: High Allegheny Wetland
Unique Identifier: CES202.069

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Summary: This system occurs along the high plateau of the Allegheny Mountains, immediately west of the Allegheny Front at elevations between 730 and 1430 m. Wetlands in this system are drained by low-gradient, meandering, intermittent to small headwater streams. Drainage is impounded in high, flat-lying basins by natural dams or "knickpoints" of resistant sandstone. In addition to poor moisture drainage, cold air drains from the surrounding uplands to pool in the flat basins, which function as frost pockets. Rainfall is plentiful, averaging about 1300 mm/year. Communities in this system may have substrates of shallow to deep peat or, less commonly, mineral soil. Soils are acidic to circumneutral. These high Allegheny wetlands form complex mosaics ranging in size from a few hectares to 6000 hectares. Forested swamps occupy the less disturbed margins or slightly higher "islands." This system has a distinctly northern character in its resemblance to bogs and swamps of New England. However, the striking absence of Chamaedaphne calyculata and Picea mariana, two abundant and common species of northern bogs and swamps, as well as the presence of species characteristic of the Southern Appalachians, such as Hypericum densiflorum, Vaccinium erythrocarpum, and Rhododendron maximum, distinguishes this system from its northern counterpart. Ombrotrophic bogs are rare but occur in undisturbed portions of a few of the larger wetlands. The more central, flood- or beaver-influenced portions contain shrub swamps, sedge fens, wet meadows, and open marshes. Forested swamps are dominated by Picea rubens, with varying cover by Acer rubrum, Tsuga canadensis, and Betula alleghaniensis var. alleghaniensis. It is likely that the role of Pinus strobus played a greater role in the structure and function of this system historically than it does today (Maryland Geological Survey and Curran 1902). Residual white pines in remote areas of this system in Cranesville Swamp in Maryland also suggest this possibility. Where limestone or calcareous shale influences seepage water, Abies balsamea and Fraxinus nigra are typical canopy dominants. Common shrub species are Viburnum nudum var. cassinoides, Rhododendron maximum, Vaccinium myrtilloides, Alnus incana ssp. rugosa, Hypericum densiflorum, Ilex verticillata, and Aronia melanocarpa. Herbaceous species frequently include Rubus hispidus, Solidago uliginosa, Juncus effusus, Eriophorum virginicum, Osmunda cinnamomea var. cinnamomea, Polygonum sagittatum, Carex folliculata, Carex gynandra, Leersia oryzoides, Galium tinctorium, Solidago rugosa, Symplocarpus foetidus, Lycopus uniflorus var. uniflorus, Scirpus cyperinus, Carex scoparia var. scoparia, and Carex trisperma var. trisperma. Sphagnum spp. and Polytrichum spp. dominate the bryophyte layer. This system is maintained by a spatially complex mix of seepage, low-energy flooding, beaver activity, and rainfall. Undisturbed examples exist (e.g., Cranberry Glades), where old-growth swamp buffers the central peatlands, which have been dated to 10,000 years. In presettlement time, some wetland mosaics in this system had significant forested components (e.g., Canaan Valley, Cranesville Swamp in West Virginia; Finzel Swamp, Hammel Glades in Maryland), while others (e.g., Cranberry Glades, Big Run Bog) were largely open peatlands with forested swamp only on the margins.

Classification Approach: International Terrestrial Ecological Systems Classification (ITESC)

Similar Ecological Systems
Unique Identifier Name
CES202.300 Southern and Central Appalachian Bog and Fen
CES202.317 Southern Appalachian Seepage Wetland
CES202.604 North-Central Appalachian Acidic Swamp

Component Associations
Association Unique ID Association Name
CEGL002256 Carex lacustris Midwest Wet Meadow
CEGL002257 Carex utriculata - Carex lacustris - (Carex vesicaria, Carex stricta) Wet Meadow
CEGL002472 Larix laricina / Aronia melanocarpa / Sphagnum spp. Swamp Forest
CEGL004510 Sparganium americanum - (Sparganium erectum ssp. stoloniferum) - Epilobium leptophyllum Seep
CEGL005449 Calamagrostis canadensis North-Central Wet Meadow
CEGL006003 Fraxinus nigra - Abies balsamea / Rhamnus alnifolia Swamp Forest
CEGL006132 Acer rubrum - Nyssa sylvatica High Allegheny Plateau-Central Appalachian Seep Forest
CEGL006193 Chrysosplenium americanum Seepage Meadow
CEGL006275 Schoenoplectus (tabernaemontani, acutus) Eastern Marsh
CEGL006277 Picea rubens - (Tsuga canadensis) / Rhododendron maximum Swamp Forest
CEGL006305 Salix sericea Shrub Swamp
CEGL006349 Scirpus cyperinus Wet Meadow
CEGL006412 Carex stricta - Carex vesicaria Wet Meadow
CEGL006461 Leersia oryzoides - Sagittaria latifolia Wet Meadow
CEGL006464 Hypericum densiflorum / Rubus hispidus Scrub
CEGL006545 Aronia arbutifolia - Ilex verticillata - Ilex mucronata / Osmunda cinnamomea Acidic Peatland
CEGL006546 Alnus incana - Viburnum recognitum / Calamagrostis canadensis Shrub Swamp
CEGL006549 Carex canescens - Eriophorum virginicum / Sphagnum spp. Fen
CEGL006552 Dulichium arundinaceum - Carex folliculata - Juncus spp. Seepage Meadow
CEGL006556 Picea rubens - Acer rubrum / Ilex verticillata Swamp Forest
CEGL006568 Solidago rugosa - Euthamia graminifolia Wet Meadow
CEGL006570 Eriophorum virginicum - (Carex folliculata) / Sphagnum spp. - Polytrichum spp. Fen
CEGL006571 Spiraea tomentosa - Rubus spp. / Phalaris arundinacea Ruderal Wet Shrubland
CEGL006588 Picea rubens / Rhododendron maximum - Kalmia latifolia / Eriophorum virginicum / Sphagnum spp. Swamp Forest
CEGL006589 (Andromeda polifolia var. glaucophylla) / Polytrichum strictum - Cladonia spp. - Sphagnum spp. Acidic Peatland
CEGL006590 Picea rubens / Carex trisperma / Sphagnum spp. - Polytrichum spp. Swamp Forest
CEGL006591 Abies balsamea - Picea rubens / Ilex verticillata / Sphagnum spp. Swamp Forest
CEGL006592 Abies balsamea - Picea rubens / Danthonia compressa - Lycopodium spp. / Sphagnum spp. Swamp Forest
CEGL006593 Picea rubens / Vaccinium erythrocarpum / Sphagnum spp. - Bazzania trilobata Swamp Forest
CEGL006594 Populus tremuloides / Vaccinium myrtilloides / Solidago uliginosa Swamp Forest
CEGL006595 Spiraea alba Wet Shrubland
CEGL006596 Vaccinium myrtilloides / Pteridium aquilinum / Polytrichum spp. Acidic Peatland
CEGL007771 Carex gynandra - Scirpus cyperinus - Eriophorum virginicum - Osmunda cinnamomea Herbaceous Seep
CEGL007856 Vaccinium oxycoccos - (Vaccinium macrocarpon) / Rhynchospora alba - Drosera rotundifolia / Sphagnum spp. Fen
CEGL008534 Carex echinata - Solidago uliginosa / Sphagnum spp. Seepage Meadow


Land Cover Class: Woody Wetland
Spatial Pattern: Large patch
Natural/Seminatural: No
Vegetated ( > 10% vascular cover):
Upland: No
Wetland: Yes
Isolated Wetland: No

Diagnostic Classifiers
Primary Classifier Secondary Classifier
Peat and mud  
Extensive Wet Flat  
>180-day hydroperiod  
Bog and Fen Mosaic  

At-Risk Species Reported for this Ecological System
Scientific Name
  (Common Name)
NatureServe Global Status U.S. Endangered Species Act Status
Euphorbia purpurea
  (Glade Spurge)
Ilex collina
  (Long-stalk Holly)
Polemonium vanbruntiae
  (Bog Jacob's-ladder)
Scutellaria saxatilis
  (Rock Skullcap)

Vegetation Composition (incomplete)
Species Name Rounded Global Status Growth Form Stratum Char-
Domi-nant Con-stant
Cover Class %
Fraxinus nigra G5 Broad-leaved deciduous tree Tree canopy    
Abies balsamea G5 Needle-leaved tree Tree canopy    
Picea rubens G5 Needle-leaved tree Tree canopy    
Vaccinium erythrocarpum G5 Broad-leaved deciduous shrub Shrub/sapling (tall & short)    
Viburnum nudum var. cassinoides T5 Broad-leaved deciduous shrub Shrub/sapling (tall & short)    
Hypericum densiflorum G5 Broad-leaved evergreen shrub Short shrub/sapling    
Carex trisperma var. trisperma T5 Graminoid Herb (field)    
Eriophorum virginicum G5 Graminoid Herb (field)    

Animal Species Reported for this Ecological System
Scientific Name
  (Common Name)
Global Status U.S. Endangered Species Act Status Charact-
Castor canadensis
  (American Beaver)
Napaeozapus insignis
  (Woodland Jumping Mouse)
Pseudacris brachyphona
  (Mountain Chorus Frog)

Color legend for Distribution Map
Nation: United States
United States Distribution: MD, PA, VApotentially occurs, WV
Global Range: The system occurs in a southwest/northeast-trending band about 40 km wide and 200 km long along the high, flat plateau of the Allegheny Mountains. The eastern boundary is the Allegheny Front, and the western boundary is the heavily dissected, lower elevation Allegheny Plateau. Minimum elevations range from 730 m in the north to 940 m in the south (Droop Mountain, West Virginia). The maximum elevation is 1422 m on Mount Porte Crayon, West Virginia.

Biogeographic Divisions
Division Code and Name Primary Occurrence Status
202-Central Interior and Appalachian C: Confident or certain

The Nature Conservancy's Conservation Ecoregions
Code Name Occurrence Status
59 Central Appalachian Forest Confident or certain

MRLC 2000 Mapzones
Code Name Occurrence Status
61 Northern Appalachia Confident or certain

National Mapping
ESLF Code (Ecological System Lifeform): 9356

West Landfire Legend: No
East Landfire Legend: No

Element Description Edition Date: 14Jan2014
Element Description Author(s): E.A. Byers, S.C. Gawler, L.A. Sneddon

Ecological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

  • Byers, E. A., J. P. Vanderhorst, and B. P. Streets. 2007. Classification and conservation assessment of high elevation wetland communities in the Allegheny Mountains of West Virginia. West Virginia Natural Heritage Program, West Virginia Division of Natural Resources, Elkins.

  • Comer, P., D. Faber-Langendoen, R. Evans, S. Gawler, C. Josse, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, K. Snow, J. Teague, and R. White. 2003-present. Ecological systems of the United States: A working classification of U.S. terrestrial systems. NatureServe, Arlington, VA.

  • Darlington, H. C. 1943. Vegetation and substrate of Cranberry Glades, West Virginia. Botanical Gazette 104:371-393.

  • Edens, D. L. 1973. The ecology and succession of Cranberry Glades, WV. Ph.D. dissertation, North Carolina State University, Raleigh.

  • Eyre, F. H., editor. 1980. Forest cover types of the United States and Canada. Society of American Foresters, Washington, DC. 148 pp.

  • Faber-Langendoen, D., C. Hedge, M. Kost, S. Thomas, L. Smart, R. Smyth, J. Drake, and S. Menard. 2011. Assessment of wetland ecosystem condition across landscape regions: A multi-metric approach. NatureServe, Arlington VA. plus appendices.

  • Furedi, M. A. 2011e. Pennsylvania Natural Heritage Program. Acidic Mixed Shrub - Sphagnum Wetland Factsheet. [] (accessed February 16, 2012).

  • Grafton, W. N., and O. L. Eye. 1982. Vascular flora of eight selected West Virginia wetlands with special reference to rare species. Pages 107-115 in: Proceedings of the Symposium on Wetlands of the Unglaciated Appalachian Region. West Virginia University, Morgantown.

  • Maryland Geological Survey and H. M. Curran. 1902. The forests of Garrett County. Johns Hopkins Press.

  • McPherson, J. 2011a. Pennsylvania Natural Heritage Program. Cotton-grass Poor Fen Factsheet. [] (accessed February 06, 2012)

  • Robinette, S. L. 1964. Plant ecology of an Allegheny mountain swamp. M.S. thesis, West Virginia University, Morgantown.

  • Walbridge, M. R. 1982. Vegetation patterning and community distribution in four high-elevation headwater wetlands in West Virginia. M.S. thesis, West Virginia University, Morgantown.

  • Walbridge, M. R., and G. E. Lang. 1982. Major plant communities and patterns of community distribution in four wetlands of the unglaciated Appalachian region. In: R. B. MacDonald, editor. Proceedings of the Symposium on Wetlands of the Unglaciated Appalachian Region. West Virginia University, Morgantown.

  • Wieder, R. K., A. M. McCormick, and G. E. Lang. 1981. Vegetational analysis of Big Run Bog, a nonglaciated sphagnum bog in West Virginia. Castanea 46:16-29.

  • Zimmerman, E. A., T. Davis, M. A. Furedi, B. Eichelberger, J. McPherson, S. Seymour, G. Podniesinski, N. Dewar, and J. Wagner, editors. 2012. Terrestrial and palustrine plant communities of Pennsylvania. Pennsylvania Natural Heritage Program, Pennsylvania Department of Conservation and Natural Resources, Harrisburg. []

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