Effect of Variable Organic Matter Retention On Soil Organic Matter Composition In a Southern Loblolly Pine Plantation.

Forest harvest residues and forest floor materials are significant sources of mineral soil organic matter and nutrients for regenerating and establishing forests.  These materials are often removed, piled, or burned after a forest harvest operation.  The effect of forest-floor manipulation on site productivity, foliar nutrient content, soil nutrient availability, and soil carbon has been tested since 1994 at a site near Millport, AL.  We have examined the effects of varying forest floor levels on the interaction of nitrogen availability and content and composition of soil organic matter in the context of these management activities.  Above- and below-ground productivity, soil moisture, soil temperature, and nutrient dynamics will be related to soil organic carbon and nitrogen in mineral soil size/density fractionation and lignin and cutin biomarkers from the cupric oxide (CuO)-oxidation technique.  We will present preliminary results to answer the question: Does varying the level of forest floor and slash retention affect mineral soil organic matter composition and content?  How have these treatments affected the interaction of soil organic matter and available nutrients (and therefore site productivity)?