Effect of Prescribed Burning and Thinning Treatments On the Composition of Organic Matter in a Forest Soil.

Biomass burning during forest management practices is suggested to produce structurally modified organic carbon compounds including incomplete combustion products such as soil black carbon (BC). Heat-induced structural modification of organic matter (OM) during forest burning can have effects on changing the solubility properties of highly insoluble macromolecular materials. This study was conducted to obtain information on heat-induced structural modification of OM in a Southern Appalachian Forest ecosystem subjected to different prescribed thinning and burning treatments.Spectroscopic analysis such as 13C NMR and FTIR is useful in getting information regarding major organic C forms present in soil and any changes occurred due to prescribed burning and thinning treatments. The ¹³C NMR analysis of humic acid and humin fractions separated from surface soils shows that greater proportions of soil organic C existed as alkyl C and O-alkyl C followed by aromatic C. Relative to soils in control sites (no thinning/no burn), soils from areas subjected to burning alone or thinning/burning treatments had a similar organic C distribution pattern indicating that the low intensity burning or thinning treatments may not have a significant impact in changing the distribution of major organic-C forms in humic acid, humin or whole soils. FTIR analysis data will also be discussed