Objective This study aimed to reveal the spatiotemporal variation in soil water storage and its response to rainfall under different vegetation types on the Bashang Plateau of Hebei Province, and to clarify the differences in soil water storage distribution and regulation among vegetation types.

Method Native grassland, Caragana korshinskii plantation, Populus simonii plantation, and Pinus sylvestris var. mongolica plantation in Zhangbei County, Hebei Province of northern China, were selected for this study. Based on continuous monitoring data of soil moisture and rainfall from 2019 to 2020, soil water storage in the 0−100 cm profile was calculated, and its seasonal dynamics, vertical distribution characteristics, and responses to typical rainfall events were analyzed.

Result (1) Soil water storage in the 0−100 cm profile under all vegetation types showed clear seasonal dynamics. In general, it remained relatively stable from January to February, increased rapidly from March to May, stayed at a relatively high level with noticeable fluctuations from June to November, and declined markedly in December. (2) Pronounced vertical differences in soil water storage were observed among vegetation types. In the grassland, high values mainly occurred in the 20−40 cm layer. In the Caragana korshinskii plantation, soil water storage was relatively evenly distributed and remained active throughout the 0−100 cm profile. In the Populus simonii plantation, a significant deep-soil storage advantage was found in the 80-100 cm layer. In the Pinus sylvestris var. mongolica plantation, soil water storage was relatively high in the shallow layers but low in the middle layers. (3) The effect of rainfall on soil water storage showed clear vertical stratification and was concentrated mainly in the 0−20 cm layer. Under moderate rainfall, the response was mostly confined to shallow soil, whereas under heavy or continuous rainfall, the affected depth extended to the middle and deep layers. The 60−100 cm layer responded to single rainfall events with an obvious lag and mainly showed cumulative recharge under intense or persistent rainfall. (4) The intensity and persistence of rainfall responses differed markedly among vegetation types. The grassland and Caragana korshinskii plantation showed rapid responses in shallow soil, the Populus simonii plantation exhibited strong deep-profile regulation capacity, and the Pinus sylvestris var. mongolica plantation showed relatively small overall fluctuations.

Conclusion Different vegetation types on the Bashang Plateau differed significantly in soil water storage processes, vertical distribution patterns, and rainfall response modes. Among them, the Populus simonii plantation showed relatively strong soil water storage and regulation capacity at the profile scale; the grassland and Caragana korshinskii plantation were more likely to exhibit rapid responses in shallow soil; and the Pinus sylvestris var. mongolica plantation was relatively stable overall, but its deep-soil water retention capacity was limited. Vegetation restoration and configuration in this semi-arid region should consider the water storage layers, rainfall recharge capacity, and water consumption characteristics of different vegetation types, rather than simply pursuing high vegetation coverage or large-scale monoculture plantations.