Phenological changes in global vegetation are often attributed to climate warming. However, climate warming and elevated atmospheric CO concentration (CO) are two co-occurring global change factors, and how CO would affect vegetation phenology has received less attention. The partial pressure of atmospheric CO on the Tibetan Plateau (TP) is lower than that in regions of lower altitudes. Consequently, the growth and phenology of alpine plants in this region could be more sensitive to CO, but this hypothesis is not yet supported by empirical evidence. Here we explored the effect of CO on plant phenology (including phenophases of green-up, budding, and flowering) through a 5-year field manipulation experiment in a high-altitude (4600 m above sea level) alpine grassland on the TP. Our results showed that CO significantly advanced the spring phenology of an early-flowering species (), while it had no impact on the phenology of two mid-flowering species ( and ). Compared to other low-altitude regions, plant phenology on the TP underwent greater alterations under CO, which supports our hypothesis that the growth of high-altitude plants is more sensitive to CO. Furthermore, we found that CO significantly reduced the overlapping of flowering between contrasting plant species, mainly due to the phenological advancement of the induced by CO. The observed advancement of the spring phenology in under CO was associated with increasing ecosystem water-use efficiency (WUE), thereby advancing its subsequent phenological development, such as budding and flowering. Our findings provide experimental evidence that atmospheric CO enrichment can accelerate plant growth processes in high-altitude regions, and suggest that large-scale model simulations should consider the effects of elevated atmospheric CO concentration on plant growth and phenology.

中文翻译：

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二氧化碳浓缩通过提高水分利用效率加速高山植物生长


全球植被的物候变化通常归因于气候变暖。然而，气候变暖和大气二氧化碳浓度（CO）升高是两个同时发生的全球变化因素，而二氧化碳如何影响植被物候却受到较少关注。青藏高原（TP）大气CO分压低于低海拔地区。因此，该地区高山植物的生长和物候可能对二氧化碳更加敏感，但这一假设尚未得到经验证据的支持。本研究通过在青藏高原高海拔（海拔4600 m）高寒草原上进行了为期5年的田间操纵试验，探讨了CO对植物物候（包括返青、现蕾和开花等物候期）的影响。我们的结果表明，CO 显着提前了早花物种的春季物候 ()，而对两种中期开花物种 ( 和 ) 的物候没有影响。与其他低海拔地区相比，高原植物物候在CO2作用下发生了更大的变化，这支持了我们的假设，即高海拔植物的生长对CO2更敏感。此外，我们发现CO显着减少了不同地区开花的重叠。对比植物物种，主要是由于CO诱导的物候进步。观察到的CO条件下春季物候的进步与生态系统水分利用效率（WUE）的提高有关，从而促进了其随后的物候发育，例如发芽和生长。开花。 我们的研究结果提供了实验证据，表明大气二氧化碳富集可以加速高海拔地区的植物生长过程，并表明大规模模型模拟应考虑大气二氧化碳浓度升高对植物生长和物候的影响。