不同尺度上植物叶气孔导度对升高CO2的响应

植物叶气孔导度对大气CO2浓度升高的响应可表现在以下几个层面：在叶水平上，叶气孔导度和气孔密度下降；在植物个体水平上，单位叶面积蒸腾下降，植株的水分利用率升高；在生态系统水平上，蒸散降低，土壤泾流和土壤水分含量增加；在全球尺度上，扩大了温室气体的增温效应，同时也降低了全球降雨量增加的趋势。正是因为植物叶气孔导度的变化会影响全球水循环，所以它在全球变化中起着非常重要的作用。但目前的研究结果还不能外推到更大的尺度上去。

Responses of plant stomatal conductance to elevated CO2 at different scales

Stomatal responses of plant to elevated CO\-2 are as follwing:from the plant to global scale,decreased stomatal conductance and density at leaf scale;reduced transpiration per unit leaf area and increased water use efficiency at plant scale;decreased evapotranspiration and elevated run off and soil moisture at ecosystem scale;and amplifying the greenhouse gas effect in increasing temperature,but inhibiting the increasing precipitation at global scale.It plays an important role in global changes by effecting the water cycle.But the current result of research at small scales cannot been scaled up directly to large ones.