Planting oaks under shelterwoods offers an important but often overlooked tool for maintaining and restoring oaks in eastern forests. Studies in several regions have demonstrated the potential usefulness of the method. However, the long-term success of this planting method depends on the growth and survival of planted trees relative to competing vegetation i.e., their competitive capacity.
We define a tree’s competitive capacity as its ability to survive and grow at a rate sufficient to attain and maintain dominance among its competitors. The concept is applied to northern red oaks that have been planted among existing trees and other naturally occurring forest vegetation. Competitive capacity is quantitatively expressed as the probability that a planted tree will attain dominance among competitors after a specified period. These probabilities take into account a planted tree’s initial characteristics together with its planting environment.
The latter includes site quality and environmental changes resulting from silvicultural practices such as weeding and thinning before and after planting. To be silviculturally useful in this context, the derived probabilities must reflect potential changes in the relative competitive position (social status) of both the planted trees and the competing naturally regenerated trees. The social status among species and individual trees changes over time (through succession) and rates of change may vary among ecosystems.
Outcomes of the interspecific competition between planted trees and natural vegetation occur as a function of site factors, associated differences in growth rates of co-occurring species, the genetics of plant populations, and the state of the vegetation complex when silviculturally or naturally imposed disturbances occur. The competitive capacity of a species, therefore, may vary as those factors vary in time and space. The objective of this study was to evaluate the competitive capacity of northern red oaks planted under shelterwoods from which they were released 3 years after planting.
This competition-centered approach integrates environmental influences, survival and growth into a single silviculturally and environmentally useful expression. We interpreted dominance probability as a measure of the competitive capacity of an individual seedling. This value is the seedling’s likelihood of attaining dominance in a specified environment at a specified future time. This concept may be useful in determining planting strategies to meet forest planning objectives. Overall, it allows us to take a more holistic view of what underplanting is all about: the ability to predict the outcome of the competitive struggle between planted trees and natural vegetation.
We have proven the viability of this method across a broad region and are now incorporating the underplanting method into other studies to further refine optimum success.
Expected outcomes include management guides and recommendations to be used by professional foresters and forest landowners for restoring and managing oak forests.
- Spetich, M.A.; Dey, D.C.; Johnson, P.S.; and Graney, D.L. 2002. Competitive capacity of Quercus rubra L. planted in Arkansas’ Boston Mountains. Forest Science 48(3):504-517
- Spetich, M.A.; Dey, D.C.; Johnson, P.S.; and Graney, D.L. 2004. Success of underplanting northern red oaks. In Spetich, Martin A. (ed.) Proceedings, Upland Oak Ecology Symposium: History, Current Conditions, and Sustainability. Gen. Tech. Rep. SRS-73. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station: 206-211
- Dey, D.C.; Spetich, M.A.; Weigel, D.R.; Johnson, P.S.; Graney, D.L; and Kabrick, J.M. 2009. A suggested approach for design of oak (Quercus L.) regeneration research considering regional differences. New Forests 37: 123-135
- Spetich, M.A.; Dey, D.C.; and Lootens, J. 2009. Getting science out – a Boston Mountains forest underplanting tool online. In Ashton, S.F.; Hubbard, W.G.; Rauscher, H.M (eds.) 2009 proceedings of A southern region conference on technology transfer and extension . Gen. Tech. Rep. SRS-116. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. pp 197-202
- Spetich, M.A.; Dey, D.C.; and Johnson, P.S. 2009. Shelterwood-Planted Northern Red Oaks: Integrated Costs and Options. Southern Journal of Applied Forestry. 33(4):182-187
- Dey, Daniel C.; Royo, A. A.; Brose, P.H.; Hutchinson, T. F.; Spetich, M. A.; Stoleson, S. H. 2010. An ecologically based approach to oak silviculture: a synthesis of 50 years of oak ecosystem research in North America. Revista Columbia Forestal. 13(2): 201-222.
Martin A. Spetich, Research Forest Ecologist, US Forest Service, Southern Research Station at 501-623-1180 ext 105
- Dan C. Dey, Research Forester and Project Leader, US Forest Service, Northern Research Station
- Paul S. Johnson, Research Forester (retired), US Forest Service, Northern Research Station