Fig. 4

Soil aggregate-related carbon storage at the 0–20-cm depth in the Chinese fir plantations with different stand ages (0, 9, 17, and 26 years old). Data represent the average of 3 replicates and error bars represent the standard errors. Different lowercase letters indicate significant differences among the different stand ages. OC, organic carbon; ROC, readily oxidizable carbon; POC, particulate organic carbon; MBC, microbial biomass carbon; WOC, water-soluble organic carbon; MOC, mineralized organic carbon