Prescribed burning is a major management technique used to restore oak woodlands to previous oak savanna conditions. Burning alters biotic and biophysical variables by combusting the litter layer and heating the soil; however, the net effects of these cool fires on ecosystem processes like soil respiration (SR) are not well understood. This study examined immediate and seasonal responses of biotic variables, biophysical variables, and SR to prescribed burning in Northwest Ohio successional oak woodlands. A chronosequence of treatments (0, 1, 3, and 5 years after burning) was compared with unburned woodland to estimate the duration of fire effects. A paired design limiting landscape variability was incorporated by maintaining a burn exclusion area within the freshly burned treatment (0yr). The relationship between SR and its biotic and biophysical predictors, and the temperature sensitivity of SR (Q10) were also examined across treatments. Measurements were taken weekly between March 2005 and January 2006. Data were primarily analyzed with repeated measures analysis of variance.
This study suggested that repeated fires had persistent impacts on forest structure and species composition, and transitory impacts on litter biomass, soil temperature, soil moisture, soil nutrients, SR, and Q10. Generally, changes caused by fire were not significantly different across the chronology; instead, fire effects were only visible within the first year after burning, and were most evident by comparing the paired sites. Fire effects changed by season so that spring SR at the freshly burned site was 18% higher than the paired site, summer SR was 36% lower, and fall SR recovered to unburned rates. Relationships between SR and its predictors changed slightly after burning, but soil temperature remained the dominant predictor across all treatments and seasons. Therefore, the effects of a single fire on successional woodland SR were seen to be weak and short-lived.