Variation of soil organic carbon and land use in a dry valley in Sichuan province, Southwestern China

In dry valleys in southwestern China, soil organic carbon (SOC) storage is very sensitive due to changes in land use. Characterizing SOC content variations is key to improving SOC sequestration and future land management. This study evaluated land-use changes, especially reforestation, and the effects on SOC variability in a small dry watershed in the Minjiang river valley. Multivariate methods indicate that the SOC content was affected by land uses and topographical features, including elevation, slope position, and gradient. SOC content for shrubland was significantly higher than for other land use. Reforestation greatly improves SOC content and a positive relationship was found between SOC content and the number of reforestation years. Forest restoration and shrubland restoration from farm land would increase the soil carbon storage level by 6% and 8%, respectively. Our results suggest that natural shrub restoration and plantation management are effective ways for improving soil carbon sequestration in dry valleys.