Gully slope is one of the most active areas of soil erosion in small watershed of the Chinese Loess hilly–gully region. Although its soil erosion has been effectively controlled with the implementation of the “Grain-for-Green Program” in this region, the soil water storage and distribution have been also impacted. In particular, unreasonable revegetation model has aggravated the water shortage, which may in turn threaten the health of ecosystems. However, yet little is known about the effect mechanism of vegetation on soil water in the gully slope. In this study, we examined the relationship between two revegetation modes, including afforestation (i.e. black locust forest) and natural revegetation (i.e. the grassland), and soil water in a depth of 0–120 cm of the gully slope, during the rainy season. The results showed that the effect of the vegetation to the soil water was smaller than that of the precipitation. Furthermore, the response of soil water to the environmental factors was higher in afforestation vegetation due to its lower soil water content, resulting in higher space dependence for soil water, compared to the natural revegetation. The lower soil water content of the black locust forest was mainly caused by its higher recession rate, not its supply. The soil water was deficient for a long time, caused by afforestation, with a shallower formation depth of the dried soil layer and stronger desiccation degree. However, this deficient could not be effectively relieved until in wet year. In comparison with the ridge slope, the effect of vegetation to soil water in gully slope was stronger, with greater water consumption in afforestation vegetation and the higher water storage in natural revegetation. From the aspect of water resources conservation on the water scale, the natural revegetation was the optimal revegetation mode in the gully slope of the loess hilly region.

黄土丘陵沟壑区小流域的沟壑坡度是土壤侵蚀最活跃的地区之一。尽管该地区实施了“绿色换粮计划”，有效控制了土壤侵蚀，但土壤水的储存和分配也受到了影响。特别是，不合理的植被恢复模式加剧了水资源短缺，进而可能威胁到生态系统的健康。然而，关于沟壑区植被对土壤水分的影响机理知之甚少。在这项研究中，我们研究了雨季期间两种植被恢复方式之间的关系，包括绿化（即刺槐森林）和自然植被（即草地）以及沟壑坡度0-120 cm的土壤水分。结果表明，植被对土壤水分的影响小于降水。此外，与自然植被相比，造林植被中土壤水分对环境因子的响应更高，这是因为其土壤水分含量较低，导致土壤水对空间的依赖性更高。刺槐黑土的土壤含水量较低主要是由于其衰退率较高，而不是其供应。长期以来，由于造林，土壤缺水，土壤干层形成深度较浅，干燥度较强。但是，这种缺陷直到湿年才能得到有效缓解。与山脊坡相比，沟壑区植被对土壤水分的影响更强，造林植被的耗水量更大，自然植被的蓄水量更高。从节水水资源节约的角度来看，黄土丘陵沟壑区自然植被是最佳的植被恢复方式。