Future climate scenarios for the boreal zone project increasing temperatures and precipitation, as well as extreme weather events such as heavy rain during the growing season. This can result in more frequent short-term waterlogging (WL) leading to unfavorable conditions for tree roots. In addition, it is decisive whether short-term WL periods during the growing season occur continuously or periodically. We assessed the effects of short-termed WL on 4-year-old Scots pine (Pinus sylvestris L.) saplings after shoot elongation started. Waterlogging (WL) lasted either continuously for 2.5 weeks (ContWL) or noncontinuously for 5 weeks, consisting of three repeated 1-week-interval WL periods (IntWL). Both treatments resulted in the same duration of soil anoxia. We studied soil gases, root and shoot growth and physiology, and root survival probability and longevity during the experiment. In the final harvest, we determined shoot and root biomass and hydraulic conductance and electrical impedance spectra of the root systems. Soil CO₂ and CH₄ concentrations increased immediately after WL onset and O₂ decreased until anoxia. Waterlogging decreased fine root survival probability, but there was no difference between WL treatments. Shoot growth suffered more from ContWL and root growth more from IntWL. Needle concentrations of pinitol increased in the WL saplings, indicating stress. No WL effects were observed in photosynthesis and chlorophyll fluorescence. Increased starch concentration in needles by WL may be due to damaged roots and thus a missing belowground sink. Electrical impedance indicated suffering of WL saplings, although root hydraulic conductance did not differ between the treatments. Oxidative stress of short-term and interval WL can have long-lasting effects on shoot and root growth and the physiology of Scots pine. We conclude that even short-term WL during the growing season is a stress factor, which will probably increase in the future and can affect carbon allocation and dynamics in boreal forests.

中文翻译：

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洪水来了！生长季节连续和间歇涝期间对苏格兰松树树苗的胁迫效应。

北方地区的未来气候情景预测温度和降水会增加，并且极端天气事件（例如生长季节的大雨）也会出现。这可能导致更频繁的短期涝灾（WL），从而导致树根的不利条件。另外，决定性的是生长季节中的短期WL周期是连续发生还是周期性发生。我们评估了短期WL对4岁苏格兰松（Pinus sylvestrisL.）芽伸长后的幼树开始。内涝（WL）连续持续2.5周（ContWL）或不连续5周，包括三个重复的，每隔1周的WL周期（IntWL）。两种处理均导致土壤缺氧持续时间相同。在实验过程中，我们研究了土壤气体，根和茎的生长与生理以及根的存活概率和寿命。在最终收获期，我们确定了根系的枝条和根生物量以及水力传导率和电阻抗谱。WL和O ₂发病后土壤CO ₂和CH ₄浓度立即增加减少直至缺氧。涝渍降低了优良的根系存活率，但WL处理之间没有差异。ContWL对芽生长的影响更大，而IntWL对根生长的影响更大。WL幼树中针状醇的针状醇浓度增加，表明存在压力。在光合作用和叶绿素荧光中没有观察到WL作用。WL导致针头中淀粉浓度增加的原因可能是根部受损，从而导致地下沉没。尽管处理之间的根部水力传导率没有差异，但电阻抗表明WL幼树受苦。短期和间歇性WL的氧化胁迫可对苏格兰樟子松的根和茎生长以及生理产生长期影响。我们得出的结论是，即使在生长季节进行短期WL也是一个压力因素，