Treatments such as the incorporation of logging residue into the mineral soil, fertilization, or planting of superior genotypes may have a large influence on the C storage capacity of managed loblolly pine plantations. The first year response following treatment initiation in C capture (pine growth) and loss from these stands maybe a strong indicator of whether these stands will act as a C source or sink. The objective of this research is to monitor the short-term effects of logging residue incorporation and fertilization on total C gain (biomass) and loss thru CO2 efflux and leaching in a microcosm study planted with two superior loblolly pine clones. A second objective is to determine how two clones, which are suspected to differ in their above and below-ground C allocation patterns, influence rates of C gain and loss. We hypothesize the immediate increase in C loss thru both CO2 efflux and leaching will be offset by an increase in pine biomass in response to the incorporation logging residue. Also, fertilization will result in increased pine biomass with a corresponding decrease in C loss. This study utilizes 48, 170 L plastic lysimeters filled with 0.17 m3 of soil arranged in a RCB design replicated 6 times. Treatments are arranged as a 2x2x2 factorial with two levels of logging residue incorporation (0 and 25 Mg ha-1), two levels of fertilization (No addition and N and P added), and two loblolly clones. Total CO2 efflux is being measured continuously for one year following treatment initiation. Additionally, total organic C lost through leaching and total seedling biomass is measured monthly to estimate short-term C balance for each treatment.