Schymanski Stanislaus J, Or Dani
Department of Environmental Systems Science, ETH Zurich, Zurich, 8092, Switzerland.
Plant Cell Environ. 2016 Jul;39(7):1448-59. doi: 10.1111/pce.12700. Epub 2016 Feb 5.
A widespread perception is that, with increasing wind speed, transpiration from plant leaves increases. However, evidence suggests that increasing wind speed enhances carbon dioxide (CO2 ) uptake while reducing transpiration because of more efficient convective cooling (under high solar radiation loads). We provide theoretical and experimental evidence that leaf water use efficiency (WUE, carbon uptake per water transpired) commonly increases with increasing wind speed, thus improving plants' ability to conserve water during photosynthesis. Our leaf-scale analysis suggests that the observed global decrease in near-surface wind speeds could have reduced WUE at a magnitude similar to the increase in WUE attributed to global rise in atmospheric CO2 concentrations. However, there is indication that the effect of long-term trends in wind speed on leaf gas exchange may be compensated for by the concurrent reduction in mean leaf sizes. These unintuitive feedbacks between wind, leaf size and water use efficiency call for re-evaluation of the role of wind in plant water relations and potential re-interpretation of temporal and geographic trends in leaf sizes.
一种普遍的看法是，随着风速增加，植物叶片的蒸腾作用会增强。然而，有证据表明，由于更有效的对流冷却（在高太阳辐射负荷下），风速增加会增强二氧化碳（CO₂）的吸收，同时减少蒸腾作用。我们提供了理论和实验证据，表明叶片水分利用效率（WUE，每蒸腾单位水分的碳吸收量）通常会随着风速增加而提高，从而增强了植物在光合作用过程中节水的能力。我们的叶片尺度分析表明，观测到的全球近地表风速下降可能使水分利用效率降低，其幅度与大气CO₂浓度全球上升导致的水分利用效率增加幅度相当。然而，有迹象表明，风速长期趋势对叶片气体交换的影响可能会被叶片平均大小的同时减小所抵消。风、叶片大小和水分利用效率之间这些不直观的反馈关系，要求重新评估风在植物水分关系中的作用，并可能重新解释叶片大小的时间和地理趋势。
