Can Fire Help Regenerate Oaks?
It seems as if almost everyone is ready to jump on the prescribed burning bandwagon, with fire as the answer for both reducing fuel loads and restoring ecosystems on forested land. However, a research collaboration between SRS upland hardwoods unit project leader David Loftis, University of Kentucky forest ecology professor Mary Arthur, and managers on the Daniel Boone National Forest (DBNF) suggests that fire management will not provide a simple solution for promoting oak regeneration.
There is ample evidence that fire was a prominent force in the upland hardwood- American chestnut forests of the Southern Appalachian region before Euro- American settlement, as well as during the settlement period. The eradication of the American chestnut shifted hardwood forests towards oak domination; logging combined with fire suppression allowed the rise of shade-tolerant species such as maple and yellow-poplar. Though managers are increasingly looking to fire as a tool to manage oak-dominated forests, data from prescribed burning studies show mixed and sometimes contradictory results.
In 2003, Loftis and Arthur, with the help of Daniel Boone staff officer Rex Mann, started a large-scale study to support DBNF fire management objectives of reducing white pines and red maples in the midstories of stands where oak dominates the overstory-and to test the effect of different prescribed burning frequencies on oak regeneration. Supported by two grants from the Joint Fire Science Program (JFSP), the research was designed to look at how single and repeated fires affect stand structure, the light environment, and the response of seedlings to changes in light environment.
Large-scale study areas of 1,000 to 1,200 acres on sites ranging from ridgetops to coves were burned both frequently and infrequently. The project also included small-scale ridgetop sites of 70 to 140 acres where researchers charted the long-term survival of individual chestnut oak, scarlet oak, and red maple seedlings to see if repeated burning on these dry sites would promote oak regeneration. After single and repeated fires, they found a large reduction in stem density and basal area leading to increased light, but this change in light environment was quickly offset by increased sprouting by red maples. After 5 years, the researchers found that the red maple seedlings had higher mortality rates, but showed a larger growth response when compared to oaks.
It is likely that using fire as a management tool in the oak-dominated forests in this region will require longterm burning coupled with burning during periods in the late spring (or possibly in the fall), when shade-tolerant species such as red maple are more easily killed by fire.
The research is in its final year of support from JFSP. Because managing oak-dominated forests with fire will probably require multiple burns over years, if not decades, long-term research in this area is needed. Loftis and Arthur hope to continue to follow the sites into the future in collaboration with managers on the DBNF. -ZH