Fig. 6. Changes in SOCFE and C-inputs retained in SOC fractions with varying shoot:root ratios.
Estimated contributions to POC and MAOC formation of different C-input sources under varying shoot:root ratios (A) and relation between soil organic C formation efficiency (SOCFE) and shoot:root ratio of analyzed experiments (B). For each shoot:root ratio, we assumed the same total input (100%) that was distributed into aboveground, root, and rhizodeposition, considering a root:net rhizodeposition ratio of 0.5 (Table 2). We then multiplied each C-input by POC and MAOC formation efficiency of our database to estimate the C-input retained from each source in both soil fractions (see Materials and Methods). The percentages indicated to the right of each bar correspond to the contribution of each fraction to the total SOC, and error bars are the SDs. Different letters indicate significant differences (P < 0.05) between fractions within each shoot:root ratio (lowercase letters) and between shoot:root ratios within each fraction (uppercase letters). The error bars correspond, from left to right, to aboveground-derived POC, root-derived POC, net rhizodeposition–derived POC, aboveground-derived MAOC, root-derived MAOC, and net rhizodeposition–derived MAOC.