* limited to sites with higher soil calcium
Vascular plant nomenclature follows Rhoads and Block (2007). Bryophyte nomenclature follows Crum and Anderson (1981).

International Vegetation Classification Associations:

USNVC Crosswalk:

None

Representative Community Types:

Hemlock - Hardwood Swamp (CEGL006226)

NatureServe Ecological Systems:

North-Central Appalachian Acidic Swamp (CES202.604)

NatureServe Group Level:

None

Origin of Concept

Fike, J. 1999. Terrestrial and palustrine plant communities of Pennsylvania. Pennsylvania Natural Diversity Inventory. Harrisburg, PA. 86 pp.

Pennsylvania Community Code*

UB : Hemlock – Mixed Hardwood Palustrine Forest

*(DCNR 1999, Stone 2006)

Similar Ecological Communities

If the conifer component is less than 25% of the canopy, the community is classified as one of several broadleaf palustrine forest community types. If the conifer component is greater than 75% and dominated by Eastern hemlock, the community is regarded as the Hemlock Palustrine Forest community type. This type differs from the Hemlock – Mixed Hardwood Palustrine Woodland in that the Hemlock – Mixed Hardwood Palustrine Forest has a canopy cover greater than 60%.

Fike Crosswalk

Hemlock - mixed hardwood palustrine forest

Conservation Value

This community can host a number of rare plant species including soft-leaved sedge (Carex disperma), log fern (Dryopteris celsa), Clinton's wood fern (Dryopteris clintoniana), glade spurge (Euphorbia purpurea), creeping snowberry (Gaultheria hispidula), lesser rattlesnake-plantain (Goodyera repens), kidney-leaved twayblade (Listera smallii), bristly black currant (Ribes lacustre), and swamp red currant (Ribes triste). This community also serves as a buffer for sediment and pollution runoff from adjacent developed lands by slowing the flow of surficial water causing sediment to settle within this wetland.

Threats

Hemlock – Mixed Hardwood Palustrine Forests are threatened by habitat alteration, deposition (sedimentation, agricultural runoff) and alterations to the hydrological regime (beaver dams, lowering of water tables). Clearing and development of adjacent land can lead to accumulation of agricultural run-off and pollution, sedimentation, and insolation/thermal pollution. Eastern hemlock communities are threatened by hemlock woolly adelgid (Adelgis tsugae) infestations. A. tsugae is an exotic pest insect that feeds on the twigs of the eastern hemlocks causing defoliation, bud mortality, and, eventually, tree mortality within as little as four years (Young et al. 1995). As tree mortality occurs, light availability increases due to the widening of canopy gaps and provides opportunities for the colonization of invasive plant species within the understory (Orwig and Foster 1998).

Management

A natural buffer around the wetland should be maintained in order to minimize nutrient runoff, pollution, and sedimentation. Soil erodibility in terms of the soil texture, condition of the adjacent vegetation (mature forests vs. clearcuts) and the topography of the surrounding area (i.e. degree of slope) should be considered when establishing buffers. Impervious surfaces surrounding the wetland should be minimized to prevent thermal pollution. Direct impacts and habitat alteration should be avoided (i.e. roads, trails, filling of wetland) and low impact alternatives (i.e. elevated footpaths, boardwalks, bridges) should be utilized in situations where accessing the wetland can not be avoided. Care should also be taken to control and prevent the spread of invasive species within the wetland. Alterations to groundwater sources should be minimized.

Range Map

Pennsylvania Range

Glaciated Northeast, Glaciated Northwest, Pocono Plateau, Ridge and Valley, Unglaciated Allegheny Plateau

Global Distribution

The association is found in Connecticut, Maine, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont. It may possibly occur in Nova Scotia.

Cowardin, L.M., V. Carter, F.C. Golet, and E.T. La Roe. 1979. Classification of wetlands and deepwater habitats of the United States. U.S. Fish and Wildlife Service. Washington, D.C. 131 pp.

Edinger, Gregory J., D.J. Evans, Shane Gebauer, Timothy G. Howard, David M. Hunt, and Adele M. Olivero. 2002. Ecological Communities of New York State. Second Edition. A revised and expanded edition of Carol Reschke's Ecological Communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation. Albany, NY. 136 pp.

Fike, J. 1999. Terrestrial and palustrine plant communities of Pennsylvania. Pennsylvania Natural Diversity Inventory. Harrisburg, PA. 79 pp.

Horvath, Jamie L., Timothy A. Block, and Ann F. Rhoads. 2008. Description of the population, canopy cover, and associated vegetation of the globally rare sedge Carex polymorpha (Cyperaceae) in Nescopeck State Park, Pennsylvania. In Sedges: Uses, Diversity, and Systematics of the Cyperaceae, eds. R. Naczi and B. Ford. Missouri Botanical Garden Press, St. Louis, MO.

NatureServe. 2009. NatureServe Central Databases. Arlington, Virginia. USA

Orwig, D. A., and D. R. Foster. 1998. Forest response to the introduced hemlock woolly adelgid in southern New England, USA. Journal of the Torrey Botanical Society 125: 60:73.

Pennsylvania Department of Conservation and Natural Resources (DCNR). 1999. Inventory Manual of Procedure. For the Fourth State Forest Management Plan. Pennsylvania Bureau of Forestry, Division of Forest Advisory Service.  Harrisburg, PA. 51 ppg.

Rhoads, Ann F. and Timothy A. Block. 2002. Nescopeck State Park; Inventory of PNDI-listed Plants and Plant Communities. Report submitted to DCNR, Bureau of State Parks.

Rhoads, Ann F. and Timothy A. Block. 2005. Varden Conservation Area Vegetation Inventory. Report submitted to DCNR, Bureauof State Parks.

Stone, B., D. Gustafson, and B. Jones. 2006 (revised). Manual of Procedure for State Game Land Cover Typing.  Commonwealth of Pennsylvania Game Commission, Bureau of Wildlife Habitat Management, Forest Inventory and Analysis Section, Forestry Division.  Harrisburg, PA. 79 ppg.

Young, R. F., K. S. Shields, and G. P. Berlyn. 1995. Hemlock woolly adelgid (Homoptera, Adelgidae)-stylet bundle insertion and feeding sites. Annals of Entomological Society of America 88: 827:835.