In 1964, nine forest sites, known as compartments, were established and randomly assigned different frequencies of prescribed burning (Irving 1970). These compartments, ranging in size from 2.6 to 27.5 ha, plus three unburned sites in adjacent oak forest were sampled in this 1984 experiment to determine the effects of fire frequency on local vegetation and biogeochemistry. Plant density and percent cover by species, tree dbh (diameter at breast height, also by species) and mean area per shrub were measured, as well as soil pH, percent soil organic matter and soil nitrogen content at transects across the compartments. After 1984, prescribed burning treatments continued, and in 1995 the Experiment 015 compartments were annexed into Experiment 133 (Fire Effects on the Structure and Function of Oak Savanna/Woodlands).
All compartments are located within a 320-ha block of land in the southeast corner of CCESR, and share similar topography. The unburned control compartments were selected in stands believed to be typical of the entire study area. Burns, with a few exceptions, took place in the spring.
Increased frequency of burns correlated with a significant increase in soil pH (Table 1; Tester 1989). Similar results have also been reported by Viro (1974) and Daubenmire (1968). Neither soil nitrogen nor soil organic matter percent showed a significant relationship to fire frequency.
