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

Sustaining Forests

Crop Tree Management

Research Issue

[photo:] The competing trees adjacent to these northern red oak crop trees have been removed, thus leaving free growing space around their crowns. With less competition for sunlight, soil moisture and nutrients, they will grow faster, produce more acorns for wildlife, and become more resistant to insect and disease attacks. (Photo by Arlyn Perkey)Crop tree management (CTM) is a widely applicable silvicultural technique used to enhance the performance of individual trees.  It offers flexibility in that it can be applied on small or large properties and, with certain modifications, it can be applied as a precommercial or commercial operation. By favoring the development of selected crop trees within a hardwood stand, the landowner can meet a variety of area-wide management objectives such as wildlife habitat, recreation, timber value, esthetic beauty, and species diversity.  CTM can be applied at various stages of development, including sapling, pole, and sawtimber stands, depending on the specific opportunities to improve stand conditions.  In some cases, it may be advisable to apply CTM more than once during the rotation.  As forest managers gain experience with CTM, many come to realize that it is a versatile silvicultural technique that can be effective in many situations.

Our Research

CTM is an intermediate silvicultural treatment intended to provide increased growing space to selected trees through the removal of crown competition from adjacent trees. CTM differs from traditional thinning in that it assures that most site resources are focused on a small number of selected trees rather than being widely distributed to all residual trees. It is applicable in any situation where the forest manager intends to reallocate site resources to selected crop trees.  While the term “crop tree” suggests a tree that has been selected for future harvest, in reality CTM can be applied to trees that will be either harvested in the future or retained for any number of years, depending on how they provide desired benefits or meet management objectives.

Two key concepts are important to consider for optimal use of this technique. These concepts include understanding how crop trees help meet management objectives and how reducing competition for site resources around individual crop trees enhances their vigor and development.  Our products provide forest managers and landowners with technical information based on long-term research and guidelines for applying CTM in hardwood forests.  Several mechanical and chemical methods for releasing crop trees are available, and useful references are provided for more in-depth coverage of specific topics.

Expected Outcomes

The CTM system focuses on promoting the vigor and development of a few trees per acre that will yield desired landowner benefits. This system also fosters an approach to land management that clarifies the landowner’s long-term goals for his or her property and the potential of the property to meet those goals.  It also provides a welcome enhancement of communication between the landowner and forest management professionals about how to plan for and accomplish multiple ownership objectives. The CTM system can be used to improve species diversity, wildlife habitat, recreation, timber quality, forest health, or any combination of such benefits as determined by the landowner.  The key is to understand how individual crop trees contribute to woodland attributes and then apply CTM to achieve the desired outcome.

Research Results

Perkey, Arlyn.W.; Miller, Gary W.; Feicht, David l. 2011. Coopers Rock Crop Tree Demonstration Area – 20-yr results. Gen. Tech. Rep. NRS-83. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 28 p.

LeDoux, C.B.; Miller, G.W. 2008. Exploring the optimal economic timing for crop tree release treatments in hardwoods: results from simulation. In: Proceedings of the 16th Central Hardwood Forest Conference; April 7-9, 2008; West Lafayette, IN: Gen. Tech. Rep. GTR-NRS-P-24; Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 265-273.

Miller, Gary W.; Stringer, Jeffrey W.; Mercker, David C. 2007. Technical guide to crop tree release in hardwood forests. Southern Regional Extension Forestry publication SREF-FM-011: 24 p.

Miller, Gary W.; Stringer, Jeffrey W. 2004. Effect of crown release on tree grade and dbh growth of white oak sawtimber in eastern Kentucky.  In: Yaussy, Daniel A.; Hix, David M.; Long, Robert P.; Goebel, P. Charles, eds. Proceedings: 14th Central Hardwood Forest Conference; March 16-19, 2004; Wooster, OH: Gen. Tech. Rep. NE-316; Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northeastern Research Station: 539 p. [CD-Rom]; 37-44.

Kochenderfer, Jeffrey D.; Zedaker, Shepard M.; Johnson, James E.; Smith, David W.; Miller, Gary W. 2001. Herbicide hardwood crop tree release in central West Virginia. Northern Journal of Applied Forestry 18(2): 46-54.

Miller, Gary W. 2000.  Effect of crown growing space on the development of young hardwood crop trees. Northern Journal of Applied Forestry 17(1): 25-35.

Miller, Gary W. 1997. Effect of crown growing space and age on the growth of northern red oak.  Keynote Address, In:  Spiecker, H.; Rogers, R.; Somogyi, Z., comps. IUFRO Proceedings: Advances in Research in Intermediate Oak Stands; July 27-30, 1997; Freiburg, Germany:  University of Freiburg, Freiburg, Germany: 140-159.

Research Participants

Principal Investigator

  • Gary W. Miller, US Forest Service-Northern Research Station Research Forester

Research Partners

  • Arlyn W. Perkey, USDA-Forest Service- Northeastern Area State & Private Forestry, Field Representative (retired)
  • Jeffrey D. Kochenderfer, USDA-Forest Service- Monongahela National Forest Silviculturist

Last Modified: 03/01/2016