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Northern Research Station
One Gifford Pinchot Drive
Madison, WI 53726
(608) 231-9318
(608) 231-9544 TTY/TDD

Sustaining Forests

Regeneration of Northern and Allegheny Hardwoods

[photo:] Photo shows regeneration of multiple speciesResearch Issue

The Allegheny hardwood forest type is a variant of the northern hardwood type consisting primarily of black cherry, red maple, sugar maple and American beech. Associated species include white ash, yellow‑poplar, black birch, yellow birch, cucumber magnolia and hemlock. Black cherry and the maples usually dominate stands in Pennsylvania and southward; white ash and sugar maple tend to be more important, and red maple less important, in the New York portion of the range. Stands with at least 25% of their basal area in black cherry are classified as Allegheny hardwood, while those with less than 25% of their basal area in black cherry are classified as northern hardwood.

Most stands developed after extensive commercial clearcutting between 1890 and 1930, generally resulting in even‑aged conditions. Despite the presence of diverse species in the overstory, regeneration often is difficult. In the late 1950s and early 1960s when the stands resulting from cuts at the turn of the century began to become financially mature, harvesting began again. Clearcutting was chosen as the forest regeneration technique because it had been successful in creating today's fine stands. But this time around, about half of the stands regenerated to ferns and grasses or to species with little or no commercial value, like striped maple and beech.

Regeneration establishment is affected by a variety of factors. These include seed supply, seedbed conditions, deer browsing, interfering plants, light levels, small mammal predation, insects, diseases, and soil-site conditions. Understanding the interactions of these factors is important to establishing mixed species regeneration. High deer impact for decades has resulted in alteration of vegetation development with replacement of highly preferred browse species with species that are not preferred by deer. This legacy effect makes regeneration difficult even if deer density is reduced.

Our Research

Research on this topic has been conducted for more than 70 years, with changes in environmental conditions, introduced species, and an always changing deer herd making it difficult to reach a final conclusion for each species that will work indefinitely. Instead we must continue to study the impacts of change on regeneration so that forests can be sustained into the future. Research on the topic includes:

  • Standardized inventory techniques were developed to assess regeneration adequacy in preparation for removal harvests.
  • Use of fertilizer to accelerate growth out of the reach of deer in clearcuts.
  • Shelterwood method silviculture often combined with fencing to exclude deer.
  • Where interfering vegetation problems exist, a whole program of herbicide use was developed by the unit to effectively control species composition in conjunction with shelterwood method silviculture.
  • A simplified sustainability assessment tool was developed primarily for private landowners in partnership with Pennsylvania State University extension and the Sustainable Forestry Initiative

Expected Outcomes

Guidelines for regenerating a diverse mix of species are contained in the SILVAH system of stand inventory, analysis, and prescription for managing northern hardwood and oak forests. As conditions change, we continue to evaluate the ability of tree species to regenerate following overstory removals, either anthropogenic or natural. We expect to continue to produce guidelines for natural resource managers that will allow them to regenerate forests with diverse tree species composition even as the environment and regeneration conditions change.  Increasingly, these results will include guidelines for sustaining habitat for other plants and wildlife as well.

Research Results

Finley, James C.; Stout, Susan L.; Pierson, Timothy G.; McGuinness, Barbara J. 2007. Managing timber to promote sustainable forests: a second-level course for the Sustainable Forestry Initiative of Pennsylvania

Horsley, Stephen B. 1995. Regeneration success and plant species diversity of Allegheny hardwood stands after Roundup application and shelterwood cutting. North Jour of Appl For 11(4):109-116.

Marquis, David A. 1987. Assessing the adequacy of regeneration and understanding early development patterns. In: Nyland, Ralph D., ed. Managing northern hardwoods: Proc. Symp. 1986 June 23-25. Syracuse, NY. Syracuse, NY: State Univ. New York, CESF, Fac. For. Misc. Publ. 13: p. 143-159.

Auchmoody, L. R. 1982. Response of young black cherry stands to fertilization. Can. J. For. Res. 12:319-325.

Marquis, David A.; Bjorkbom, John C. 1982. Guidelines for evaluating regeneration before and after clearcutting Allegheny hardwoods. USDA For. Serv. Res. Note NE-307. 4p.

Marquis, David A.; Grisez, Ted J.; Bjorkbom, John C.; Roach, Benjamin  1975.  Interim guides to the regeneration of Allegheny hardwoods  Gen. Tech. Rep. NE-19. Upper Darby, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 14 p.

Grisez, Ted J.; Peace, Maurice R.  1973.  Requirements for advance reproduction in Allegheny hardwoods - an interim guide  Research Note NE-180. Upper Darby, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 5p.


Research Participants

Principal Investigators

  • Todd E. Ristau, USDA Forest Service - Northern Research Station Research Ecologist

Research Partners

Last Modified: 01/28/2016