The composition and concentration of CuO-extractable lignin phenols and substituted fatty acids (SFAs) were used to track plant biopolymer dynamics between detrital inputs, from either roots or aboveground sources, and the surface mineral soil (0-5 cm). Residual soil SFAs in the coniferous site were dominated by needle-derived cutin regardless of the detrital manipulations. In contrast, SOM SFAs indicate that both cutin-foliar and suberin-root material exert influence on SOM character within the deciduous site; however, roots exerted more influence under litter removal treatments while leaves had greater influence on SOM under doubled litter treatments. Root inputs dominate the lignin composition of the coniferous soil while no single source dominated lignin composition of the deciduous soil. Density fractionation of the mineral soil revealed the greatest amount of light fraction material (<1.6 g cm^-3) in the soil with roots removed at the deciduous site and in the soil with doubled needles at the coniferous site. In both cases, these soil treatments also resulted in the least cumulative respiration from bulk soils during a one year incubation study, indicating that the OM accumulating as light fraction may be resistant to decomposition.