Thinning in Mixed Hardwood Forests

Research Issue

Very little was known about managing the growth and quality of hardwood forests in the east as the second- and third-growth forests were developing. Studies of “growth and yield” were established to quantify the growing capacity of these forests. Could the growing capacity of a site be focused on desirable trees by removing the smaller, poorer quality trees? How would this thinning affect the quality of the residual trees? Which trees should be removed? How many?

Our Research

The objective of this suite of studies was to determine the effects of stand density upon 1) total wood production per acre, 2) growth of the residual trees and stands, 3) quality of the trees in the residual stands, 4) the range of basal areas over which total wood production was the same, and, in some sites 5) regeneration response to different thinning treatments. Similar studies were installed at several sites during the 1950s through the 70s including those for which NRS-02 is responsible: Baldrock Experimental Forest in Kentucky, the Vinton Furnace and Mead Experimental Forests in Ohio, and the Kane Experimental Forest in Pennsylvania. Periodic measurements of growth and mortality continue to be collected on these rare long-term studies.

Expected Outcomes

The valuable data collected at these sites are being used to develop and evaluate forest growth simulators, management guidelines, above- and below-ground carbon stocks, and model baseline mortality related to climate fluctuations.  

Research Results

Several innovations have arisen from these data sets including stocking charts, three growth and yield computer simulators, and carbon stock estimates for Allegheny hardwoods. These studies form the basis for what is understood about thinning as a tool in the production of high-value sawtimber products. 

Dale, Martin E.; Hilt, Donald E.  1989.  Thinning Even-aged Upland Oak Stands  In: Clark, F. Bryan, tech. ed.; Hutchinson, Jay G., ed. Central Hardwood Notes. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station.: Note 6.06.

Marquis, David A.; Ernst, Richard L.  1991.  The effects of stand structure after thinning on the growth of an Allegheny hardwood stand  Forest Science 37(4):1182-1200.

Nowak, Christopher A.  1996.  Wood volume increment in thinned, 50- to 55-year-old, mixed-species Allegheny hardwoods  Canadian Journal of Forest Research 26: 819-835. 

Research Participants

Principal Investigators

• Stout, Susan, USDA Forest Service, Northern Research Station - Research Project Leader / Supervisory Silviculturist
• Dan Yaussy, USDA Forest Service, Northern Research Station - Supervisory Research Forester
• USDA Forest Service scientists previously associated with these studies include Ben Roach, Martin Dale, Ivan Sander, Dave Marquis, Sam Gingrich, Russ Walters, Malcolm Williamson, Don Hilt, and Rich Ernst

Research Partners

• Coeli Hoover, USDA Forest Service- Northern Research Station - Research Ecologist
• Louis Iverson, USDA Forest Service- Northern Research Station - Landscape Ecologist
• Christopher Nowak, SUNY College of Environmental Science and Forestry

For further information log on website :
http://www.nrs.fs.fed.us/sustaining_forests/conserve_enhance/timber/contrasting_silvicultural_systems/