Soh Wuu Kuang, Yiotis Charilaos, Murray Michelle, Pene Sarah, Naikatini Alivereti, Dornschneider-Elkink Johan A, White Joseph D, Tuiwawa Marika, McElwain Jennifer C
National Botanic Gardens (OPW), Glasnevin, D09 VY63 Dublin, Ireland.
Department of Biological Applications and Technology, University of Ioannina, 45110 Ioannina, Greece.
Biology (Basel). 2024 Sep 19;13(9):733. doi: 10.3390/biology13090733.
Understanding plant physiological response to a rising atmospheric CO concentration () is key in predicting Earth system plant-climate feedbacks; however, the effects of long-term rising on plant gas-exchange characteristics in the tropics are largely unknown. Studying this long-term trend using herbarium records is challenging due to specimen trait variation. We assessed the impact of a rise of ~95 ppm (1927-2015) on the intrinsic water-use efficiency (iWUE) and maximum stomatal conductance () of five tropical tree species in Fiji using the isotopic composition and stomatal traits of herbarium leaves. Empirical results were compared with simulated values using models that uniquely incorporated the variation in the empirical responses and species-specific parameterisation. The magnitude of the empirical iWUE and response was species-specific, ranging from strong to negligible. Stomatal density was more influential than the pore size in determining the response to c. While our simulation results indicated that photosynthesis is the main factor contributing to the iWUE gain, stomata were driving the iWUE trend across the tree species. Generally, a stronger increase in the iWUE was accompanied by a stronger decline in stomatal response. This study demonstrates that the incorporation of variation in the in simulations is necessary for assessing an individual species' iWUE response to changing .
了解植物对大气中二氧化碳（CO₂）浓度上升的生理反应是预测地球系统中植物 - 气候反馈的关键；然而，热带地区长期二氧化碳浓度上升对植物气体交换特征的影响在很大程度上尚不清楚。由于标本性状的差异，利用植物标本记录研究这种长期趋势具有挑战性。我们利用斐济五种热带树种植物标本叶片的同位素组成和气孔特征，评估了约95 ppm（1927 - 2015年）的二氧化碳浓度上升对其内在水分利用效率（iWUE）和最大气孔导度（gₛₘₐₓ）的影响。将实证结果与使用独特纳入实证二氧化碳响应变化和物种特定参数化的模型模拟值进行比较。实证iWUE和gₛₘₐₓ响应的幅度因物种而异，范围从强烈到可忽略不计。在确定对二氧化碳的响应时，气孔密度比孔径更具影响力。虽然我们的模拟结果表明光合作用是导致iWUE增加的主要因素，但气孔驱动了不同树种间的iWUE趋势。一般来说，iWUE的更强增加伴随着气孔响应的更强下降。这项研究表明，在模拟中纳入二氧化碳的变化对于评估单个物种对变化的二氧化碳的iWUE响应是必要的。
