Fig. 2. Differences in ¹³C values () between chemical residues and samples before extraction at the oak and pine lysimeters. Zero refers to the original material before extraction and a positive difference corresponds to the given chemical residue being enriched in the heavier isotope as compared to the original material; LIT = litter, FL = floatables (50–2000 µm), FS = fine silt (2–5 µm), and CL = clay (<2 µm). *indicates significance between chemical residue and the original material at p = 0.10, **at p = 0.05, and ***at p = 0.01. Error bars represent standard errors.