Fully polarimetric L-band Synthetic Aperture Radar (SAR) backscatter was collected using NASA’s Unmanned Aerial Vehicle (UAV) SAR and regressed with in situ measurements of basal area (BA) and above ground biomass (AGB) of mature loblolly pine stands in North Carolina. Results found HH polarization consistently displayed the lowest correlations where HV and VV exhibited the highest correlations in all groups for both BA and AGB. When plantation stands were analyzed separately (plantation versus natural), correlation improved significantly for both BA (R2 = 0.65, HV) and AGB (R2 = 0.66, VV). Similarly, results improved when natural stands were analyzed separately resulting in the highest correlation for AGB (R2 = 0.63, HV and VV). Data decomposition using the Freeman 3-component model indicated that the relative low correlations were due to the saturation of the L-band backscatter across the majority of the study area.