Managing for oak regeneration: The effects of six common treatments in southern Illinois

Author

Brian Murphy, Southern Illinois University CarbondaleFollow

Date of Award

8-1-2012

Degree Name

Master of Science

Department

Forestry

First Advisor

Ruffner, Charles

Abstract

The current oak-hickory overstory that exists in the productive uplands of Southern Illinois is a result of a disturbance regime that lasted thousands of years. The species mix that is currently regenerating under this overstory is a consequence of the historic disturbance regime being severely altered in the last century. As the importance and value of the oak-hickory forest type is widely recognized, land managers seek effective ways to ensure the perpetuation of an oak-hickory component in future stands. Across its range, forest management activities are being implemented in an effort to promote oak, with mixed results. The current study was conducted in the eastern portion of the Shawnee National Forest on private land, with the exception of some Burn only and control stands which were located on Forest Service land. Treatments for these stands fell within five distinct groups: TSI, Burn, TSI/Burn, TSI/Harvest, TSI/Harvest/Burn, plus a control group. Data was collected on overstory, regeneration, and site characteristics. The change in height and abundance of oak seedlings across treatment groups was analyzed with an ANCOVA test. The competitive position of oak and hickory seedlings relative to all seedlings was analyzed with an ANOVA test. The results revealed that TSI only may actually put oak regeneration at a disadvantage, possibly because it only increases the amount of light enough to promote shade tolerant species. The TSI/Harvest/Burn group showed potential to increase the size and abundance of oak regeneration, suggesting the need for higher disturbance intensity in order to increase oak regeneration. When competitive position of oak and hickory seedlings were analyzed, the burn only group showed the greatest increase over the control group, reinforcing the idea that fire naturally selects for oak. Management activities should focus on using heavy disturbance to establish oak regeneration, then fire to ensure that they are competitive enough to eventually reach the overstory.