Abstract:

This study focused on the four typical artificial forests (Platycladus orientalis forest, Pinus tabuliformis - Amorpha fruticosa forest, Ziziphus jujuba forest and Pinus tabuliformis - Rhus typhina forest) in the loess stone mountain area of northern Shaanxi. It aimed to explore the spatio-temporal variation characteristics of soil moisture in artificial forests and their response patterns to rainfall by long-term monitoring of soil moisture content in different soil layers (10-100 cm) and rainfall events, combining with statistical and graphical analysis. The results showed that: (1) the 0-10 cm soil layer in the Platycladus orientalis forest was the most sensitive to rainfall, with the peak water content synchronizing with rainfall events, and its deep layers (40-80 cm) had the highest water storage capacity. (2) The soil moisture in the shallow soil layer (0-40 cm) of the Pinus tabuliformis - A. fruticosa forest had a delay response after heavy rainfall, and the water storage capacity in the 80-100 cm soil layer was relatively high, which might be related to the nitrogen-fixing function of the A. fruticosa. (3) The water retention capacity of the shallow layer (10 to 20 cm) in the Z. jujuba forest was limited and the water loss occurred rapidly after short-term rainfall. However, under continuous heavy rainfall, the water retention capacity of the shallow layer was increased. (4) The water retention capacity in the shallow layer (10-20 cm) of the Pinus tabuliformis - R. typhina forest was the weakest, which might because the thin litter layer or loose soil structure leads to rapid water loss. (5) The influence of different rainfall intensities was hierarchical: light to moderate rainfall (≤30 mm) primarily affected the soil moisture content of the shallow layer (10-20 cm), while heavy rainfall (>30 mm) rapidly replenishes the deep soil moisture via preferential flow. These results indicated that the Platycladus orientalis forest was more suitable for water stress environments due to its deep water storage capacity and stable water dynamics. The Pinus tabuliformis - A. fruticosa forest was suitable for improving the deep soil structure, whereas the Z. jujuba forest and the Pinus tabuliformis - R. typhina forest required water retention measures to enhance ecological benefits. This study provides a scientific basis for the optimal allocation of artificial forests and soil and water conservation in the loess stone mountain area of northern Shaanxi.

Key words: loess stone mountain area of northern Shaanxi, artificial forest, soil moisture, rainfall response