* 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:

Transitional Northern Hardwood Forest (CEGL006632)
Beech – Tuliptree – Sugar Maple Forest (CEGL006296)
Transitional Northern Sugar Maple – Ash Rich Mesic Forest (CEGL006637)
Central Appalachian Northern Hardwood Forest (Yellow Birch – Northern Red Oak Type) (CEGL008052)

NatureServe Ecological Systems:

None

NatureServe Group Level:

Appalachian-Northeast Mesic Forest (G742)

Origin of Concept

Faber-Langedoen, D., Sneddon, L. Fleming, G., and Gawler, S. C. 2018. Transitional Northern Sugar Maple - Ash Rich Mesic Forest (CEGL006637). NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org/. (Accessed: February 11, 2022).

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

Fike, J., Sneddon, L. A., Largay, E., and Gawler, S. C. 2006. Beech - Tuliptree - Sugar Maple Forest (CEGL006296). NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org/. (Accessed: February 11, 2022).

Fleming, G. P. 2018. Central Appalachian Northern Hardwood Forest (Yellow Birch - Northern Red Oak Type) (CEGL008502). NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org/. (Accessed: February 11, 2022).

Gawler, S. C. and Faber-Langendoen, D. 2015. Transitional Northern Hardwood Forest (CEGL006632). NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org/. (Accessed: February 11, 2022).

Pennsylvania Community Code*

BB : Northern Hardwood Forest

*(DCNR 1999, Stone 2006)

Similar Ecological Communities

Because of the species diversity of the overstory, this type can be very similar to a number of Pennsylvania community types. Often mapped as large stands, Northern Hardwood Forests may demonstrate significant microsite variation in canopy dominance. These large mapping units could include pockets of dense hemlock, black cherry, white ash, and basswood, which can make classification difficult. The Black Cherry – Northern Hardwood Forest has more than 40% black cherry cover in canopy, and typically less sugar maple, ash, and yellow birch. In northern Pennsylvania, Red Oak – Mixed Hardwood Forests may also be similar in understory composition but have a larger (greater cover or basal area) red oak component in the canopy/subcanopy than Northern Hardwood Forests. In southern Pennsylvania, particularly in the Central Appalachians and Western Allegheny Plateau, the Tuliptree – Beech – Maple Forest may less resemble the Northern Hardwood Forests. However, the dominance of Tuliptree (Liriodendron tulipifera) is a key distinguishing feature. Additionally, in southern Pennsylvania, including the Allegheny Mountains (Laurel Highlands) the Northern Hardwood Forest may be restricted to north-facing slopes, cool ravines, and/or mesic soils, and may be associated with Hemlock (white pine) – Northern Hardwood Forests, or rarely the Rich Hemlock – Mesic Hardwood Forest.

The Northern Hardwood Forest can also be similar to the Rich Northern Hardwood Forest. The Rich Northern Hardwood Forest is more consistently rich, and white ash and basswood have greater relative cover in the canopy.

Fike Crosswalk

Northern Hardwood Forest

Conservation Value

The Northern Hardwood Forest community type is common in Pennsylvania and is found in nearly all of the state’s ecoregions. Although this community type supports a number of state-listed species, the community itself does not require special conservation action. A number of state-listed plant species have been documented in Northern Hardwood Forests. Breeding bird species that prefer forest interior conditions in the Northern Hardwood Forest include the veery (Catharus fuscescens), ovenbird (Seiurus aurocapilla), red-eyed vireo (Vireo olivaceus), and scarlet tanager* (Piranga olivacea; Sargent et al., 2017).

*SGCN species

Threats

While there are no short-term conservation risks for the Northern Hardwood Forest community at this time, it could experience significant changes in the composition or distribution in a changing climate. Some authors have suggested that species that are currently dominant in our Northern Hardwood Forests, such as sugar maple, eastern hemlock, red maple, or black cherry, could become less common in both high and low emissions scenarios (Iverson et al., 2008; Peters et al., 2020). Forest pests/pathogens could significantly impact tree species in this community type, including emerald ash borer (EAB; Agrilus planipennis), hemlock wooly adelgid (HWA; Adelges tsugae), and beech bark disease. Invasive plant species such as garlic mustard (Alliaria petiolata) and Japanese barberry (Berberis thunbergii) are also a threat to Northern Hardwood Forests.

Throughout much of its range, the Northern Hardwood Forest has experienced forest fragmentation from roads, shallow gas development, and habitat conversion. Furthermore, the core range of the Northern Hardwood Forests overlaps with the shale gas region in Pennsylvania and New York. Unconventional shale gas development has resulted in significant and continued fragmentation throughout the range in Pennsylvania.

Management

Northern Hardwood Forests can be sustainably managed; however, forest conditions may require a specific plan to achieve management goals. Private landowners can consult with service foresters at the Pennsylvania Bureau of Forestry for more information on sustainable forest management practices that are best suited for their property. Invasive species management is encouraged. Management of white-tailed deer could improve forest regeneration in forests experiencing high herbivory pressure.

Range Map

Pennsylvania Range

The Northern Hardwood Forest is found in the following USEPA Level III (Level IV) Ecoregions: Erie Drift Plain, North Central Appalachians, Ridge and Valley, Central Appalachians, Western Allegheny Plateau and Eastern Great Lakes Lowlands.

Global Distribution

Massachusetts, New Jersey, New York, Pennsylvania; Ontario

Black, B. A., Ruffner, C. M., & Abrams, M. D. (2006). Native American influences on the forest composition of the Allegheny Plateau, northwest Pennsylvania. Canadian Journal of Forest Research, 36(5), 1266-1275.

Hnatkovich, A. (2014). Habitat assessment and conservation planning for Viola selkirkii (great-spurred violet) in north central Pennsylvania (Agreement #12463; p. 50). Western Pennsylvania Conservancy, Pennsylvania Natural Heritage Program.

Iverson, L. R., Prasad, A. M., Matthews, S. N., & Peters, M. (2008). Estimating potential habitat for 134 eastern US tree species under six climate scenarios. Forest Ecology and Management, 254(3), 390-406.

Peters, M. P., Prasad, A. M., Matthews, S. N., & Iverson, L. R. (2020). Climate change tree atlas, Version 4. U.S. Forest Service, Northern Research Station and Northern Institute of Applied Climate Science, Delaware, OH. https://www.fs.fed.us/nrs/atlas/tree/

Sargent, S., Yeany III, D., Michel, N., & Zimmerman, E. (2017). Forest Interior Bird Habitat Relationships in the Pennsylvania Wilds, Final Report for WRCP-14507. Audubon Pennsylvania, National Audubon Society.

Thomas-Van Gundy, M. A., Nowacki, G. J., & Cogbill, C. V. (2015). Mapping pyrophilic percentages across the northeastern United States using witness trees, with focus on four national forests. Gen. Tech. Rep. NRS-145. Newtown Square, PA: US Department of Agriculture, Forest Service, Northern Research Station. 26 p., 145, 1-26.

Using the history of Pennsylvania wildfire to inform landscape level prescribed burn planning (Final Report to the Pennsylvania Department of Conservation and Natural Resources, Wild Resource Conservation Program). (2015). Pennsylvania Natural Heritage Program.

Whitney, G. G. (1982). Vegetation-site relationships in the presettlement forests of northeastern Ohio. Botanical Gazette, 143(2), 225-237.

Whitney, G. G., & DeCant, J. P. (2003). Physical and historical determinants of the pre-and post-settlement forests of northwestern Pennsylvania. Canadian Journal of Forest Research, 33(9), 1683-1697.