Supplementary file 1_Effects of drought pretreatment on the morphology traits, biomass, and stoichiometric characteristics of the desert ephemeral plant.docx

Introduction: In the context of climate change, the frequency and intensity of droughts in arid and semi-arid areas have shown a substantially increasing trend, which inevitably affects plant survival and growth. However, it is unclear what survival and growth strategies plants subjected to drought pretreatment in the early life stages adopt when facing subsequent drought stress.
Methods: Here, we conducted a field experiment and set up two treatments, control and drought pretreatment, to investigate the effects of drought pretreatment on the survival, phenology, morphology, biomass, and stoichiometric characteristics of the ephemeral plant Erodium oxyrhinchum in the Gurbantunggut Desert, China.
Results: The results showed that the leafing, flowering, and fruiting stages under drought pretreatment occurred markedly earlier than the control treatment by 5.25 ± 1.2 d, 3.13 ± 0.84 d, and 4.75 ± 1.63 d, respectively. The life history of E. oxyrhinchum decreased 5 ± 1.38 d under drought pretreatment. Drought pretreatment accelerated seedling mortality, leading to a faster and earlier decline in survival percentage. The survival percentage of E. oxyrhinchum under drought pretreatment at the full blooming stage was approximately 18.59%, which was 5.19% higher than that of the control treatment. In addition, a positive correlation was observed between morphological traits and individual biomass, and drought pretreatment substantially increased individual biomass and reproductive output. For example, the reproductive biomass under drought pretreatment was 1.41 times than that of the control treatment during the full fruiting stage, indicating that plants subjected to drought pretreatment exhibited an overcompensation effect. Finally, from the perspective of stoichiometric characteristics, plants subjected to drought pretreatment require more phosphorus to enhance their resistance to severe drought.
Conclusion: This study provides novel insights for the conservation and restoration of desert ecosystems in the context of climate change.

引言：在气候变化背景下，干旱半干旱区域的干旱事件发生频率与强度均呈显著上升趋势，这势必对植物的存活与生长造成负面影响。然而，针对早期生活阶段经干旱预处理的植物，在遭遇后续干旱胁迫时所采取的存活与生长策略，目前仍不明晰。
方法：本研究开展田间试验，设置对照（control）与干旱预处理（drought pretreatment）两组处理，以中国古尔班通古特沙漠（Gurbantunggut Desert）的短命植物（ephemeral plant）尖喙牻牛儿苗（Erodium oxyrhinchum）为研究对象，探究干旱预处理对其存活、物候、形态特征、生物量及化学计量特征（stoichiometric characteristics）的影响。
结果：研究结果显示，干旱预处理组的展叶期、开花期与结果期较对照组分别显著提前5.25±1.2天、3.13±0.84天与4.75±1.63天。干旱预处理下，尖喙牻牛儿苗的生活史周期缩短5±1.38天。干旱预处理加速了幼苗死亡进程，致使存活率更快更早地出现下降。在盛花期，干旱预处理组尖喙牻牛儿苗的存活率约为18.59%，较对照组高出5.19%。此外，形态性状与单株生物量呈显著正相关关系，且干旱预处理显著提升了单株生物量与繁殖产出。例如，在盛果期，干旱预处理组的繁殖生物量为对照组的1.41倍，表明经干旱预处理的植物呈现出超补偿效应（overcompensation effect）。最后，从化学计量特征角度分析，经干旱预处理的植物需要更多磷元素以增强其对极端干旱的抗性。
结论：本研究为气候变化背景下荒漠生态系统的保护与修复提供了全新的理论视角。