Coupling Interaction Between Soil Water and Soil Organic Carbon Contents After Vegetation Restoration in the Loess Plateau Region of China

The soil water content (SWC) and soil organic carbon (SOC) are two important factors to consider when revegetating degraded land in arid and semiarid areas. Understanding the responses of SWC and SOC to vegetation restoration as well as their coupling interaction is important for the sustainable restoration of vegetation. However, the responses of SWC and SOC are still unclear in different plantation types, especially for the deep soil layer. In this study, three common types of mature plantations containing Pinus sylvestris, Pinus tabuliformis, and Populus simonii were selected in the Loess Plateau region of China to evaluate the responses of SWC and SOC to vegetation restoration as well as their interactions, and thus determine the factors that influenced the variations in SWC and SOC. Compared with grassland, the deep soil water deficit was exacerbated in all three plantations, and the SOC increased under Populus simonii but decreased under the other types. The tradeoff relationship between SOC and SWC had the lowest root mean squared error under Populus simonii. Therefore, Populus simonii was identified as most suitable for revegetation in the study region. Soil texture had important effects on the variations in SOC in the deep soil layers (2–5 m), and SOC and the soil texture affected the variations in SWC in the whole soil profile. The results obtained in this study may facilitate the sustainable development of artificial forests in the Loess Plateau region as well as similar arid and semiarid areas.