The stomatal density and index of fossil Ginkgo leaves (Early Jurassic to Early Cretaceous) have been investigated to test whether these plant fossils provide evidence for CO2-rich atmosphere in the Mesozoic. We first assessed five sources of natural variation in the stomatal density and index of extant Gingko biloba leaves: (1) timing of leaf maturation, (2) young vs. fully developed leaves, (3) short shoots vs. long shoots, (4) position in the canopy, and (5) male vs. female trees. Our analysis indicated that some significant differences in leaf stomatal density and index were evident arising from these considerations. However, this variability was considerably less than the difference in leaf stomatal density and index between modern and fossil samples, with the stomatal index of four species of Mesozoic Ginkgo (G. coriacea, G. huttoni, G. yimaensis, and G. obrutschewii) 60–40% lower than the modern values recorded in this study for extant G. biloba. Calculated as stomatal ratios (the stomatal index of the fossil leaves relative to the modern value), the values generally tracked the CO2 variations predicted by a long-term carbon cycle model confirming the utility of this plant group to provide a reasonable measure of ancient atmospheric CO2 change.
展开▼
机译:分离的核酸(多核苷酸),反义寡核苷酸,抑制或减少编码CO2SEN蛋白的消息和/或CO2SEN蛋白或植物多聚核苷酸和多肽多糖的植物植株的表达的方法植物保护细胞,植物细胞,植物片,植物组织或植物,植物的一部分的碳吸收量和碳排量的负,正调节及增加,碳保护层和水流以及CO 2 / CO 2交换水交换或损失水开放植物,关闭植物的气孔,部分植物,器官,植物片或植物细胞,以增强或优化植物,植物片,器官,植物,植物的一部分上的生物量积累,植物,种子或植物细胞中的植物细胞或种子,板温度的降低和蒸腾强度的提高,降低了T型保护细胞中的效率降低和碳含量