Figure 2
(a and b) Organic carbon (OC) and nitrogen (ON) stocks in organic layers (O horizons), (c and d) the light fraction (LF; i.e. particulate organic matter), and (e and f) the heavy fraction (HF; i.e., mineral-organic associations) of mineral topsoil (A horizons) and subsoil horizons (E, B, and C). Open circles in (a,b,e and f) represent microbial carbon and nitrogen in organic layers and topsoils whereas open squares in (e and f) represent the ratio of light fraction carbon to heavy fraction carbon in topsoils. Error bars represent standard deviation of replicated soil profiles (stocks) or soil horizons (microbial C and N, and light fraction carbon-to-heavy fraction carbon ratio). Error bars in case of the light fraction carbon-to-heavy fraction carbon ratio were calculated according to the rules of error propagation. Carbon-normalized concentrations of (g) lignin-derived VSC phenols, (h) amino sugars, and (i) amino acids in organic layers and heavy fractions of diagnostic soil horizons. Whiskers correspond to the standard deviation of the mean derived from replicated soil horizons. Note, there was no A horizon at the youngest site but a transition OA horizon, which was categorized as O horizon.
