Sustaining Forests

Oak Seedling Development

Research Issue

Regenerating mature oak forests after harvest to develop thrifty new stands with a young oak component is a serious problem throughout the range of oak in the Northeast and Midwest.  Large oak seedlings present before harvest are necessary for good regeneration, and small oak seedlings seldom grow to gain dominance in the new developing stands.  Many factors can limit good regeneration---excessive deer browsing, especially when combined with competition from understory plants or ferns (“fern deserts”), and dense shade from the midstory. 

Our Research

Five NRS scientists examined various pre-harvest silvicultural treatments such as partial overstory removal (shelterwood), herbicide application (fern control), prescribed fire, and deer exclusion (fencing) to improve the stocking of large oak seedlings for regeneration after harvest. This research was carried out at Moshannon State Forest, a site managed by the Pennsylvania Department of Conservation and Natural Resources in the Unglaciated Allegheny Plateau. The current second-growth forest was about 85 years of age and had an initial basal area of 114 to 128 ft2/ac. The dominant overstory tree is northern red oak, with white oak, chestnut oak, red maple, white ash, white pine, and hemlock as common associates. The extensive timber harvests between 1860 and 1920, followed by large-scale, intensive wildfires and the chestnut blight in the early 1920s, provided the conditions for oak to become the dominant tree species. Due to previous single-age harvesting (clear cuts) and relatively high and constant deer browsing  pressure, the understory of this study site and similar sites has been dominated by hay-scented fern since at least the late 1970s.

Expected Outcomes

Determining which of the commonly used treatments tested, or combinations thereof, results in the best regeneration of oak seedlings would be of great use to forest managers.

Research Results

Exclusion of deer by fencing resulted in increased seedling survival and growth across all other treatments compared with the unfenced treatments.  Deer exclusion combined with a moderate (12% of basal area) to high (27%) removal of the overstory led to the most promising development of advanced oak seedlings in preparation for final overstory removal.

Rebbeck, Joanne; Gottschalk, Kurt; Scherzer, Amy. 2012. Do chestnut, northern red, and white oak germinant seedlings respond similarly to light treatments? II. Gas exchange and chlorophyll responses. Canadian Journal of Forest Research 42: 1025-1037.

Willis, John L.; Walters, Michael B.; Gottschalk, Kurt W. 2015. Scarification and gap size have interacting effects on northern temperate seedling establishment. Forest Ecology and Management 347: 237-247.

Research Participants

  • Principal Investigators

    • Gary W. Miller, USDA Forest Service- Northern Research Station Research Forester
    • Cynthia Huebner, USDA Forest Service- Northern Research Station Research Botanist
    • Patrick H. Brose, USDA Forest Service- Northern Research Station Research Forester
    • Joanne Rebbeck, USDA Forest Service- Northern Research Station Physiologist

    Research Partner

    • Pennsylvania Department of Conservation and Natural Resources, Bureau of Forestry
Last Modified: April 6, 2016