关键词: 杨柴; 黑沙蒿; 毛乌素沙地; 水分平衡

Abstract: 【Objective】 To reveal the soil profile water status and soil water consumption and balance pattern of Hedysarum mongolicum Turez and Artemisia ordosica shrubs in Mu Us Sandy land. 【Methods】 His study took the Hedysarum mongolicum Turez shrubs, Artemisia ordosica shrubs and mixed shrubs as the research objects and TDR method was employed to monitor soil profile and the ratio of soil water storage revenue. Soil moisture ratio was calculated by water balance equation of shrubbery. 【Results】 (1)The soil moisture content of 0-300 cm soil profile first decreased and then increased with the increase of soil depth. According to the spatial and temporal changes of soil moisture, the soil layer could be roughly divided into: rapidly active layer (0-100 cm), secondary active layer (100-200 cm) and stable layer (200-300 cm). The fast-changing active layer was greatly affected by rainfall. After a heavy rainfall event, multiple "high-moisture centers" appeared in the soil profile of the fast-changing active layer. The soil moisture of the sub-active layer and the stable layer was greatly affected by vegetation growth. The soil profiles of Hedysarum mongolicum Turez shrubs and mixed shrubs showed multiple "low-moisture centers". (2)The response mode of bare land and Hedysarum mongolicum Turez shrubs were impulse response, while that of Artemisia ordosica and mixed shrubs was delayed accumulation response. (3) The soil moisture content of the fast-changing active layer (0-100 cm) tended to be: Artemisia ordosica shrubs > mixed shrub> bare land> Hedysarum mongolicum Turez shrubs; The soil moisture content of sub-active layer (100-200 cm) tended to be: Artemisia ordosica shrubs > mixed shrub> Hedysarum mongolicum Turez shrubs > bare land, and the soil moisture content of the stable layer (200-300 cm) tended to be: bare land > Artemisia ordosica shrubs > Hedysarum mongolicum Turez shrubs > mixed shrub. (4) In 2019, the change of water storage in the sample plots was from large to small: Artemisia ordosica shrubs > Hedysarum mongolicum Turez and Artemisia ordosica mixed shrubs > bare land > Hedysarum mongolicum Turez shrubs. Artemisia ordosica shrubs was the shrubs of water accumulation type, with a total rainfall of 124 mm in 2019; the mixed shrubs was a shrubs of water balance type, the part of water was stored and the other part was evapotranspiration; The bare land and Hedysarum mongolicum Turez shrubs sample plots were water consuming type, almost the same amount of moisture as rainfall used for evapotranspiration. 【Conclusion】 In this study area, there is a negative water balance ofHedysarum mongolicum Turez shrub, and the water between atmosphere, vegetation and soil can not recycle closely. With the increase of time scale, the vegetation carrying capacity of soil water in the study area reaches the limit. The reasonable water balance strategy of the Artemisia ordosica drives the succession of the Hedysarum mongolicum Turez shrubs to the Artemisia ordosica shrubs.

Key words: Hedysarum mongolicum Turez shrubs; Artemsia ordosica shrubs; Mu Us sandy land; water balance