The potential effects of future rainfall change on hydraulic and growth characteristics of seedlings of Sabina vulgaris, a dominant evergreen shrub of the semi-arid Mu Us sandy desert were examined in a controlled experiment simulating rainfall change conducted at the Ordos Grassland Ecological Station. Water saturated deficit (WSD) and tissue density (TD) decreased with increasing of soil water significantly, while the water loss coefficient (k) increased. This indicates that drought-resistance and water-holding ability of seedlings decreases with increasing simulated rainfall. The simulated water gradient had no significant effects on the ratio of branch to stem area, while a significant influence on the ratios of leaf mass to stem area and leaf mass to branch area was found, suggesting that the potential effects of water supply on seedlings decreases with increasing water availability. Biomass allocation was also significantly influenced by the water gradient; In contrast both morphology and the canopy productivity index showed no significant response to the water gradient. Changes in biomass increment, plant height, and basal diameter with water gradient reflected the slow-growing attributes of the seedlings. The sensitivity of roots to water change was higher than that of leaves and stems. The below-ground biomass allocation increased with increasing of water availability, implying that the seedlings may adapt to water stress through more economical use of water resource in natural habitats.%为探讨未来降雨变化对半干旱气候区毛乌素沙地常绿优势灌木沙地柏(Sabina vulgaris)实生苗水分和生长特征的可能影响，在鄂尔多斯沙地草地生态站开展了模拟降雨变化的实验。水分饱和亏缺和组织密度随土壤水分含量提高而降低，失水系数却相反，这表明沙地柏实生苗的保水抗旱性随模拟降雨量增加而降低。水分梯度对枝茎面积比无显著影响，叶质量茎面积比和叶质量枝面积比随土壤水分含量增大而降低，这意味着实生苗分枝的供水潜力随水分可利用性提高而降低。水分变化显著影响生物量分配，而对形态和植冠生产力指数均无显著影响；生物量、株高和基茎增量的变化反映了沙地柏生长的缓慢性。根系对水分变化的敏感性高于叶和茎，地下部分生物量投资随水分可利用性提高而增大，这暗示沙地柏实生苗可能通过节约利用水分方式适应自然生境中的水分胁迫。
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