The coupling interaction of soil organic carbon stock and water storage after vegetation restoration on the Loess Plateau, China

Vegetation restoration may increase the soil organic carbon stock (SOCS) but decrease the soil water storage (SWS) of terrestrial ecosystems in arid and semiarid regions. To guarantee the sustainability of restoration, it is critical to evaluate the coupling interaction of SOCS and SWS. Here, we examined the spatial distributions of SOCS and SWS across a 0-200 cm soil profile in a grassland, forestland and shrubland on the Loess Plateau and determined the driving factors that affected their variations. Our results showed that SOCS and SWS varied across the 0-200 cm soil profile and considerably accumulated in the deep soil layers (100-200 cm). In comparison to SOCS, SWS generally had higher relative benefits in most studied plant communities, which ensured sustainable restoration. In addition, land use played a less important role than local environmental conditions in determining the variations in SOCS and SWS. Specifically, the interaction between SOCS and SWS was mainly strong in the surface soil layers (0-20 cm). Topography was a predominant factor that affected SOCS and SWS in the deep soil layers (100-200 cm), while soil texture was a stable driving factor influencing their variations across the whole soil profile (0-200 cm). Given the low moisture consumption of grasslands and the lowest root mean square deviation (RMSD) of Hippophae rhamnoides, we proposed an advanced scenario for ecological restoration on the Loess Plateau: establishing reasonably large Hippophae rhamnoides patches with fewer edges in a contiguous grassland matrix. Furthermore, this scenario should be tailored to local environmental conditions, such as soil water, texture and topography, followed by natural vegetation succession.