Abstract Extreme seasonal droughts frequently occur in semiarid and arid areas of the world. They can exert a profound influence on the physiological state of desert plants. Short-term rainfall and long-term water shortages in the Mu Us Desert have differentiated the role of individual species with their distinct ability to resist and recover from drought. This study explores how the scale of rainfall events affects interannual variation in sap flow in three dominant desert-shrub species [i.e., Salix psammophila (SP), Artemisia ordosica (AO), and Hedysarum mongolicum (HM)], and whether the associated changes in soil-water dynamics helped to modify sap flow. As a result, interannual variation in sap flow (Js) was mostly driven by precipitation (PPT), Volumetric soil water content (VWC), and leaf area index (LAI), with their individual influences varying as a function of plant phenophases. The species acclimated to long-term summer drought (> 30 days, i.e., no rain over a 30-day period or longer) by reducing stomatal conductance in the three species by 66.5, 59.5, and 43.5%, respectively, suggesting a physiological adjustment in water conservation in response to drought. Average summer drought (June–July) reduced Js in the three species by 55.5 (in SP), 42 (AO), and 28.5% (HM), more than spring drought (May–June) at 28% in SP and 9.5% in AO. Among those species, HM exhibited the least sensitivity and the highest overall resistance and resilience to drought. The relationship between Js and VWC was modulated by the effect of PPT. Our findings provide compelling evidence that HM is seen to be better suited to future climatic warming, as the species may be capable of accessing deep groundwater reserves replenished by large PPT pulses (5–10 mm), in sustaining its physiological activity over longer periods. These results could help formulate a selection process in determining which shrub species to plant in the sustainable management of desert ecosystems.

中文翻译：

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三种干旱灌木树液对周期性干旱响应的年际变化

摘要 极端季节性干旱频繁发生在世界半干旱和干旱地区。它们可以对沙漠植物的生理状态产生深远的影响。毛乌素沙漠的短期降雨和长期缺水使单个物种的作用不同，它们具有独特的抗旱和恢复干旱能力。本研究探讨了降雨事件的规模如何影响三种主要沙漠灌木物种 [即沙柳 (SP)、青蒿 (AO) 和 Hedysarum mongolicum (HM)] 的树液流年际变化，以及相关的变化是否在土壤-水动力学中有助于改变树液流动。因此，树液流量 (Js) 的年际变化主要由降水 (PPT)、土壤体积含水量 (VWC) 和叶面积指数 (LAI) 驱动，它们的个体影响随着植物物候期的不同而变化。通过将三个物种的气孔导度分别降低 66.5、59.5 和 43.5%，该物种适应了长期的夏季干旱（> 30 天，即 30 天或更长时间没有降雨），表明存在生理调整在应对干旱的节水方面。平均夏季干旱（6 月至 7 月）使这三个物种的 Js 减少了 55.5（SP）、42（AO）和 28.5%（HM），多于春季干旱（5 月至 6 月），SP 的 28% 和 9.5%在 AO。在这些物种中，HM表现出最低的敏感性和最高的整体抗旱性和抗旱性。Js 和 VWC 之间的关系受 PPT 的影响。我们的研究结果提供了令人信服的证据，表明 HM 被认为更适合未来的气候变暖，因为该物种可能能够获得由大 PPT 脉冲（5-10 毫米）补充的深层地下水储量，从而在更长的时间内维持其生理活动。这些结果可以帮助制定一个选择过程，以确定在沙漠生态系统的可持续管理中种植哪些灌木物种。