【摘要】 许多研究表明 ,大气 CO2 浓度 ([CO2 ])的升高会导致植物气孔密度 (Stom atal Density,SD)和气孔指数 (Stom atal Index,SI)降低。这一关系成为推测地质历史时期大气 [CO2 ]变化的重要古生物指标之一。但是 ,[CO2 ]不是唯一影响 SD和 SI的环境因素。研究利用温度梯度和温度 +[CO2 ]梯度技术 ,以 7种美国中西部地区弃耕地常见草本植物和 3种美国东部落叶阔叶林优势木本植物为材料 ,其中草本包含豆科、非豆科 C3和 C4 功能型 ,就它们的 SD,SI,表皮细胞密度 (Epidermal Cell Density,ECD)和气孔孔径长度 (Stomatal Aperture L ength,APL)对 [CO2 ]和温度升高的反应进行了研究。结果表明 ,沿 [CO2 ]梯度 ,所研究物种的 SD比 SI反应敏感 ,SD显示出与 [CO2 ]正相关、负相关和无显著相关性 ,SI显示出与 [CO2 ]正相关和无显著相关性 ;沿温度梯度 ,所研究物种的 SI比 SD反应敏感 ,SI显示出与温度正相关、负相关和无显著相关性 ,SD显示出与温度正相关和无显著相关性。 ECD和 APL对 [CO2 ]和温度梯度也有不同的响应。这说明 ,除 [CO2 ]外 ,温度也对 SD,SI,ECD和 APL有显著的影响。所以在用气孔特征重建地质历史时期 [CO2 ]的变化趋势时 ,除准确建立气孔参数与 [CO2 ]关系外 ,还应考虑大气温度对这一关系的影响更多还原

【Abstract】 Many studies have reported that increases in atmospheric CO 2 concentration ([CO 2]) lead to decreases in plant stomatal density (SD) and stomatal index (SI). These correlations have become key proxies for the estimation of paleoatmospheric [CO 2]. However, [CO 2] is not the only environmental factor affecting SD and SI. In this study, we conducted an experiment with controlled temperature and [CO 2] gradients to examine the correlation between stomatal characters and both elevated [CO 2] and temperature. The materials used in our study were obtained from seven herbaceous species commonly found in oldfields of the North American Midwest, including legume, non-legume C 3 and C 4 plants, as well as three deciduous tree species from eastern North America. The results showed that SD was more sensitive to [CO 2] changes than SI for all species studied. SD showed either positive, negative or no correlation with [CO 2], whereas the SI showed either a positive or no correlation. In the temperature gradient however, SD responded with less sensitivity than SI. SI showed either positive, negative or no correlation with temperature, whereas the SD showed positive or no correlation. Additionally, correlations between ECD and temperature and between APL and temperature differed. Thus, in addition to [CO 2], air temperature also affects plant SD, SI, ECD and APL. We suggest that, when reconstructing historical atmospheric [CO 2] via analysis of stomatal characteristics, not only must the correlation between [CO 2] and stomatal parameters be examined, but the effect of temperature on the correlation should be considered as well.更多还原