4. Discussion
Our results indicated that DWC had contrasting effects on the decomposition of different SOC pools. The strong DWC (100-20% WHC) increased C release from the BF+ soil, but decreased C release from the OF and BF soils, respectively. The DWC-driven legacy effect on C release can last for at least 38 d. Both the amount of microbial biomass and labile substrates contributed to this legacy effect. When considering both the extended and the DWC periods, the 80-40% and 100-20% WHC treatments had no significant effect on SOC decomposition of OF and BF+ soils, but decreased SOC decomposition of BF soil by 12% and 14%, respectively, compared with the constant-moisture control treatment. Taken together, these results demonstrate the importance of DWC in modulating SOC dynamics and show the different vulnerability of different SOC pools to DWC.