Tuesday, November 6, 2007 - 1:00 PM
214-1
Fire Severity Effects on Soil Organic Matter: Carbon Mineralization and Decomposition Products.
Soil organic matter (SOM) in fire-prone forested systems is affected by fire severity which has consequences on soil processes. This study investigated the changes in SOM composition by controlling fire severity of laboratory burns on reconstructed soil profiles (O, A1 (0-1 cm), and A2 (1-2 cm)). Soil profiles were burned at varying severity by changing fuel moisture content and air temperature. Incubations were conducted to examine the decomposition characteristics of each soil horizon. In the O horizon, increasing fire intensity was associated with increased consumption of C and N and a higher proportion of recalcitrant SOM that depressed C mineralization rates. Mineral soil C content was unaffected by burning; however, composition shifted to more labile forms with burn intensity leading to an increase in short-term C mineralization rates. After incubation, O horizon SOM composition remained different from the control; however, mineral soil SOM composition returned to control characteristics. Overall, prescribed fire impacted SOM of the O horizon and that any fire-caused changes occurring in the mineral soil were not persistent. Recalcitrant forms of C produced by burning O horizons, e.g. charcoal, may accumulate in the soil if this material is not reburned.
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