Coupling Relationship between Soil Organic Carbon Storage and Soil Water Storage in Abandoned Economic Forests in the Loess Hilly Areas

The spatial distribution characteristics of soil organic carbon storage (SOCS) and soil water storage (SWS) and the factors that influence these parameters were compared and analyzed for different economic forests under varying land use practices in the study area with the same abandonment years. The widely distributed abandoned mountain jujube and apple forests at the Qijiashan jujube experimental demonstration base in Yanchuan County were the research field, and grassland was the control. The results show that (1) SOCS and SWS accumulated abundantly in the deep layer (below 100 cm) compared to the highest layer, accounting for 60.63% and 64.63%. (2) After abandonment, the SOCS and SWS were different across vegetation types and under different land preparation methods. In the study area, the SWS showed a comparative advantage compared to the SOCS. The trade-off for different vegetation types suggests that it was the highest for grassland (0.39), while the lowest for jujube (0.16). Under different land preparation methods, the RMSE values of the level terrace grassland and undisturbed slope with apple trees were the highest, while those of jujube trees were the lowest. (3) Environmental factors exerted a certain influence on different vegetation types and varying land preparation methods after abandonment. Apart from the interaction between SOCS and SWS, chemical indicators showed the greatest impact on the abandoned grassland and the SOCS of level terraces.