Implications of frequent high intensity fire on the long-term stability of oak barrens, woodlands, and savannasThis article is part of a larger document. View the larger document here.
A study was initiated in 1963 to evaluate the stand dynamics associated with three fire frequency treatments (annual burning, 5-year periodic burning, and fire exclusion) on a pyric oak (Quercus spp.)-dominated site in south-central Tennessee. Controlled burns were conducted during the dormant season. The experimental design was a randomized block, blocked on location, with three replications of the three treatments. The purpose of this paper is to report on the overstory structural vegetation changes that accompany these burning treatments after 54 years. Overstory number of stems and basal area of the two burning treatments have gradually diminished through time and with little to no ingrowth. Presently, the overstory of both fire frequency treatments consists of sparsely populated, individual trees with <18 square feet per acre of basal area. Most of these trees are decrepit with fire scars and decay jeopardizing their longevity. Annual burns promoted an oak savanna-like structure dominated by herbaceous vegetation. The 5-year periodic burns promoted woody vegetation, which typically was top-killed and resprouted after each burn. The fire exclusion treatment had a closed overstory with basal areas greater than 78 square feet per acre and little midstory or understory. Our results suggest high intensity, small-scale, frequent fires in pyric oak systems do not support oak ingrowth and would be relatively unstable communities. To allow oak ingrowth to occur, land managers should cease burning for a greater period of time or conduct lower intensity burns.