气孔参数的变异系数和影响因素

该文中的北美红杉和水杉的气孔参数（气孔密度和气孔指数）是在叶片的相同部位获得的，每一种植物统计气孔参数的区域大小也是一样的. CO2浓度和非CO2浓度因素对气孔参数的影响是一致的.研究结果表明:气孔指数的变异系数都小于气孔密度的变异系数，利用北美红杉和水杉的气孔指数指示大气CO2浓度要比用气孔密度指示更为准确. 利用气孔参数指示古大气CO2浓度时，消除非CO2浓度因素对气孔参数的影响是提高指示准确性的关键. 气孔参数的变化与环境因子有关，环境因素对气孔指数的影响较小. 气孔参数还与植物种类、叶片的着生部位、发育状况有关. 同一叶片的不同部位和角质层的大小等因素也会影响气孔参数的大小.  

Coefficients of variation and factors affecting stomatal parameters.

In this study, stomatal parameters (density and index) are obtained from the same areas, the middle part of leaves, so that CO 2 and other factors have similar influences on stomatal parameters. The coefficient of variation of stomatal index is more stable than that of stomatal density in both Sequoia sempervirens and Metasequoia glyptostroboides. The results show that the stomatal index is a more useful guide than stomatal density for indicating atmospheric CO 2 concentration based on the stomatal parameters of S. sempervirens and M. glyptostroboides. The stomatal parameters vary with changes in many factors, so it is vital to reduce these effects to a minimum while reading a CO 2 signal from leafy fossils. The stomatal parameters are affected by environmental factors and stomatal density is more sensitive to these, so that the stomatal index should provide more accurate CO 2 estimates. Stomatal parameters are also related to plant species, leaf ontogeny, leaf locations of the plant and intra-leaf areas.