Stomatal sensitivity to CO2 diverges between angiosperm and gymnosperm tree species

The response of tree leaf gas exchange to elevated CO2 concentrations has been investigated in numerous experiments along the past 30 years. Stomatal regulation is a major plant control over leaf gas exchange, and the response to the increasing CO2 will shape the biological activity of forests in the future. Here we collected 144 records from 57 species on stomatal conductance in CO2 manipulation experiments on trees (340-980 ppm CO2). CO2-induced stomatal downregulation was calculated as the slope of the linear regression between stomatal conductance and [CO2]. Among tree species, the slope (a) of change in stomatal conductance per 100 ppm CO2 increase ranged between 0 and -151, indicating stomatal downregulation, and only four species showed upregulation. There was a significant divergence between evergreen gymnosperms (a = -3.6±1.0), deciduous angiosperms (a = -16.3±3.1), and evergreen angiosperms (a = -32.8±7.1). Gymnosperms were less sensitive to CO2 changes than deciduous angiospe...

近30年来，学界已围绕树木叶片气体交换（tree leaf gas exchange）对升高CO₂浓度的响应开展了大量实验研究。气孔调控（stomatal regulation）是植物调控叶片气体交换的核心机制，其对CO₂浓度升高的响应将决定未来森林的生物活性格局。本研究从57个树种的CO₂浓度操控实验（CO₂ manipulation experiments）中收集了144条气孔导度（stomatal conductance）相关数据，实验设置的CO₂浓度范围为340~980 ppm。CO₂诱导的气孔下调（stomatal downregulation）可通过气孔导度与[CO₂]之间的线性回归斜率计算得到。在所有受试树种中，每升高100 ppm CO₂对应的气孔导度变化斜率（a）取值区间为0至-151，整体表现为气孔下调，仅4个树种呈现气孔上调现象。常绿裸子植物（evergreen gymnosperms）、落叶被子植物（deciduous angiosperms）与常绿被子植物（evergreen angiosperms）三者间存在显著差异，对应斜率分别为-3.6±1.0、-16.3±3.1与-32.8±7.1。裸子植物对CO₂浓度变化的敏感性低于落叶被子植物……