Leaf cuticular characters of Ginkgo and implications for paleoatmospheric CO_2 in the Jurassic

摘要

A combination of carbon isotope composition and stomatal characters of fossil leaves provides information about paleoatmospheric CO_2 levels and the physiology of fossil plants. Plant anatomy, physiology, and geochemistry have been employed to reconstruct the paleoatmospheric CO_2 concentrations throughout Jurassic time and to investigate the physiological response of fossil Ginkgo to an atmosphere of much higher CO_2 than usual. Our results show that fossil Ginkgo in China lived in an atmosphere with a CO_2 concentration 3— 5 times higher than that of today. It used a carbon isotopic discrimination similar to that of the living plant, but had much higher water use efficiency (3—5 times that of the extant). The physiological traits of Ginkgo in different atmospheres suggest that CO_2 might have played a contributory role in the rise and fall of maidenhair trees.