近日，武汉大学张权团队揭示了提高用水效率并不能刺激树木的生产力。相关论文于2025年11月24日发表在《自然—气候变化》杂志上。
大气中CO2浓度（ca）的上升会增强植物光合作用（An）并降低气孔导度（gs）。这会提高内在水分利用效率（iWUE = An/gs），这是树木适应气候变化的重要指标。然而，关于iWUE的上升是否会伴随树木生长同步增加，学界仍存在争议，这引发了关于iWUE与树木生产力之间理论联系的研究兴趣。
研究组基于气孔开度动力学最优理论，构建了描述树木生产力最大相对增长的包络线，该增长可由iWUE的相对增长推断或预期。通过该理论推导的公式，结合操控实验数据和树木年轮同位素观测数据，研究组解析了iWUE（可观测的代理指标）与树木生长（目标变量）之间的关系。尽管ca上升确实提高了iWUE，但由于环境因素（如大气干燥度上升）和解剖生理因素（如树高）的调节作用，树木生长的同步比例增长仍难以实现。
附：英文原文
Title: Increased efficiency of water use does not stimulate tree productivity
Author: Zhang, Quan, Zhang, Jiawei, Adams, Mark A., Battipaglia, Giovanna, Cernusak, Lucas A., Fernndez-de-Ua, Laura, Ficklin, Darren L., Hietz, Peter, Camarero, J. Julio, Jungner, Hgne, Lvesque, Mathieu, Manzoni, Stefano, Maxwell, Justin T., Nock, Charles A., Peuelas, Josep, Puettmann, Klaus J., Saurer, Matthias, Urrutia-Jalabert, Rocio, van der Sleen, Peter, Wang, Lixin, Way, Danielle A., Zhou, Yang, Zuidema, Pieter A., Katul, Gabriel G.
Issue&Volume: 2025-11-24
Abstract: Rising concentrations of atmospheric CO2 (ca) increase plant photosynthesis (An) and reduce stomatal conductance (gs). This increases the intrinsic water-use efficiency (iWUE = An / gs), a major proxy of tree adaptation to climate change. However, whether an increase in iWUE leads to a concomitant increase in tree growth remains in dispute, prompting interest in theoretical links between iWUE and tree productivity. Here using an optimality theory for kinetics of stomatal aperture, we establish an envelope delineating maximal relative increases in tree productivity that can be inferred/expected from relative increases in iWUE. The resulting expressions are used to interpret relations between iWUE (an observable proxy) and tree growth (the target variable), using available experimental data from manipulation experiments and tree-ring isotopes. While rising ca increases iWUE, proportional increases in tree growth are unlikely given ameliorating environmental (for example, rising atmospheric dryness) and anatomical/physiological (for example, tree height) influences. The authors theoretically delineate the maximal increases in tree growth that can be expected from increases in plant intrinsic water-use efficiency, which increases with rising CO2. They highlight environmental and physiological limits on growth in the context of experimental data.
DOI: 10.1038/s41558-025-02504-w
Source: https://www.nature.com/articles/s41558-025-02504-w