4. Conclusion
We used the dataset to determine the amount and pattern of SMBC and SMBN in global dryland regions. Here, we compiled 109 observations of SMBC (0-30 cm) and 79 observations of SMBN (0-30 cm) from 100 sites across global dryland regions with aridity index less than 0.65. The results showed that the average amount of SMBC and SMBN in global drylands were 358.47 ± 25.45 mg kg-1 and 51.86 ± 4.59 mg kg-1, respectively. The amount of SMBC and SMBN did significantly vary among different drought types and ecosystem types. A significant positive correlation was showed between the amount of SMBC and SMBN regardless of the level of drought. Meanwhile, the ratio of SMBC to SMBN in global drylands region was 8.73, which is lower than the global value (7.6). Soil sand fraction and pH had significant negative effect on the ratio of SMBC to SMBN. To further improve our understanding on how dryland regions might respond to climate changes, long-term ecosystem-scale studies on soils are urgently required. Although there are a lot number of uncertainties, this study applies a new attempt to focus on the fragile dryland regions.