Soil respiration responses to topography, canopy cover, and prescribed burning in an oak-hickory forest in southeastern Ohio

Soil respiration (Rs) is an important component of carbon loss from forest ecosystems. As forest management (e.g. prescribed burning) is becoming increasingly more common, it is important to understand the relationship between Rs and prescribed fire. Unfortunately, this relationship is still misunderstood due to the heterogeneity of physical and biological factors over the landscape and between ecosystems. To examine the effects of landscape position, canopy cover (CC), and prescribed burning on soil moisture, soil temperature, and Rs, while controlling for variation in soil properties, we utilized a randomized complete block (RCB) design with five treatments within each block. Each block consisted of five 2 m × 2 m treatment subplots: control, cool burn, hot burn, lime fertilization, and leaf litter removal. A total of 20 blocks were nested within a 2 × 2 factorial design with two effects, landscape position (upland or lowland) and canopy cover (100 or 60%). Rs, soil temperature, and soil moisture were measured monthly from June to November 2004. Repeated measures analysis of variance revealed significant effects of treatment and time on Rs. However, Rs was not significantly affected by prescribed fire, landscape position, or canopy cover. Soil temperature and moisture were significantly affected by landscape position, canopy cover, and time. By eliminating within-site variability between control and prescribed burning treatments, Rs rates were found to be unchanged in burn plots during the growing season following the fire. These results highlight the importance of environmental variability in determining the effects of prescribed fire on Rs rates.