Effects of fire frequency on long-term stand dynamics of an oak-hickory forest in southeastern Missouri

by

Benjamin O. Knapp; Michael A. Hullinger; John M. Kabrick

University of Missouri, Department of Forestry; Missouri Department of Conservation; USDA Forest Service, Northern Research Station

Abstract – Prescribed fire is currently being used as a management tool for reaching objectives related to ecosystem restoration and woodland management. An on-going study was established in 1949 to determine the effects of prescribed burning at different frequencies on oak-hickory forests in southeastern Missouri. The study uses a randomized complete block design with two blocks and three study treatments, including an unburned control (Control), prescribed burning every year (Annual), and prescribed burning every four years (Periodic). When the study was established, each woody stem ≥ 1.5 inches diameter at breast height (DBH) was tagged, with species and DBH recorded. The study plots were remeasured in 1964, 1972, 1984, and 2013. At the start of the study, all treatments exhibited reverse-J shaped diameter distributions. After 15 years of the study (1964), the mortality rate of small diameter stems was nearly double on Periodic plots when compared to Annual or Control plots, and only 6 stems per acre recruited into the measurement size class (≥ 1.5 inches DBH) on Periodic plots, compared to 35 trees per acre on Annual plots and 92 trees per acre on Control plots. By 2013, stand-level basal area was significantly lower on Periodic plots than on Control plots, and stocking levels on the Control were near 100%, compared to 70% stocking on Annual plots and 60% stocking on Periodic plots. Frequent prescribed burning resulted in stand structural conditions associated with woodlands, with the rate and magnitude of change greater on Periodic plots than on Annual plots.