Figure 6: Diagram showing the earthworm-mediated carbon trap.
The earthworm-mediated ‘C trap’ (ECT) diverted C flow from soil microbiota and unequally enhanced C stabilization and C mineralization. The arrow weight indicates C flow or impact magnitude; single-ended arrow with dotted-line indicates smaller relative effects of soil microbiota when earthworms are present. ‘M’ and ‘S’ represent C mineralization and C stabilization, respectively, their sizes represent the carbon flux of each process, and the dotted-line suggests that the size of the flux can be smaller. SSOC: stabilized soil organic C. ‘Equal unamplified processes’ means each unit of C mineralized naturally along with proportionally less C being stabilized, that is, Csta-m is usually less than Cmin-m, and Csta-m changes with Cmin-m by a constant range of proportions, resulting in the basal sequestration quotient (SQbasal)<1. ‘Unequal amplified processes’ means small amplification of C mineralization along with great enhancement of C stabilization, that is, Csta-w changes with Cmin-w by a constant range of proportions, which are usually higher than those in control soil, resulting in the earthworm-induced sequestration quotient (SQworm)>SQbasal. Dotted area and double-ended arrows represent possible interactions.
