Climate change increases the occurrence of prolonged drought periods with large implications for forest functioning. Scots pine (Pinus sylvestris) is one of the most abundant conifers worldwide, and evidence is rising that its resilience to severe drought is limited. However, we know little about its ability to recover from drought-induced embolism. To analyze postdrought hydraulic recovery, we investigated stress and recovery dynamics of leaf gas exchange, nonstructural carbohydrates, and hydraulic properties in 2.5-year-old Scots pine seedlings. We quantified the degree of xylem embolism by combining in vivo x-ray microtomography with intrusive techniques including measurements of hydraulic conductivity and dye staining during drought progression and short-term (2 d) and long-term (4 weeks) recovery. Seedlings were grown under controlled conditions, and irrigation was withheld until stomata closed and xylem water potential declined to –3.2 MPa on average, causing a 46% loss of stem hydraulic conductivity. Following drought release, we found a gradual recovery of leaf gas exchange to 50% to 60% of control values. This partial recovery indicates hydraulic limitations due to drought-induced damage. Whereas xylem water potential recovered close to control values within 2 d, both x-ray microtomography and intrusive measurements revealed no recovery of stem hydraulic conductivity. Moreover, we did not find indications for nonstructural carbohydrate reserves limiting hydraulic recovery. Our findings demonstrate that Scots pine is able to survive severe drought and to partially recover, although we assume that xylem development during the next growing season might compensate for some of the hydraulic impairment. Such drought-induced legacy effects are important when considering vegetation responses to extreme events.

气候变化增加了长期干旱的发生，对森林功能产生重大影响。欧洲赤松 ( Pinus sylvestris ) 是世界上最丰富的针叶树之一，越来越多的证据表明其对严重干旱的抵抗力有限。然而，我们对其从干旱引起的栓塞中恢复的能力知之甚少。为了分析干旱后水力恢复，我们研究了 2.5 年生欧洲赤松幼苗的叶片气体交换、非结构碳水化合物和水力特性的胁迫和恢复动态。我们通过将体内 X 射线显微断层扫描与侵入性技术相结合来量化木质部栓塞的程度，包括在干旱进展和短期（2 天）和长期（4 周）恢复期间测量水力传导率和染料染色。幼苗在受控条件下生长，停止灌溉，直至气孔关闭且木质部水势平均下降至 –3.2 MPa，导致茎导水率损失 46%。干旱缓解后，我们发现叶片气体交换逐渐恢复至对照值的 50% 至 60%。这种部分恢复表明由于干旱造成的损害导致水力限制。尽管木质部水势在 2 天内恢复到接近控制值，但 X 射线显微断层扫描和侵入测量均显示茎水力传导性没有恢复。此外，我们没有发现非结构性碳水化合物储备限制水力恢复的迹象。我们的研究结果表明，欧洲赤松能够在严重干旱中生存并部分恢复，尽管我们假设下一个生长季节木质部的发育可能会补偿一些水力损伤。在考虑植被对极端事件的反应时，这种干旱引起的遗留影响非常重要。