An elevated CO₂ concentration (eCO₂) can increase photosynthesis (A_sat) and reduce stomatal conductance (g_s); hence, it can benefit tree growth directly by increasing carbon availability and/or indirectly by saving water. However, uncertainties remain regarding the direction and magnitude of these effects, particularly in combination with changes in temperature and water availability.

中文翻译：

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树叶气体交换对 CO2 升高的响应以及温度和水可用性的变化：全球综合

升高的 CO ₂浓度 (eCO ₂ ) 可以增加光合作用 ( A _sat ) 并降低气孔导度 ( g _s )；因此，它可以通过增加碳供应直接和/或通过节水间接促进树木生长。然而，这些影响的方向和程度仍然存在不确定性，特别是与温度和可用水量的变化相结合。