Carbon Isotope and Stomatal Data of Late Pliocene Betulaceae Leaves from SW China: Implications for Palaeoatmospheric CO2-levels

Authors : BAI-NIAN SUN, SU-TING DING, JING-YU WU, CHONG DONG

Pages : 237-250

Doi:10.3906/zoo-1205-13

View : 12 | Download : 7

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :The cuticular d13C values and stomatal parameters insert ignore into journalissuearticles values(stomatal density and stomatal index: SD and SI); of two Betulaceae species, Betula mioluminifera Hu et Chaney and Carpinus miofangiana Nathorst, from a suite of superposed horizons in West Yunnan, southwestern China, were measured in order to recover Late Pliocene CO2 levels. Correlations are given for d13C, SD, epidermal cell density insert ignore into journalissuearticles values(ECD);, and SI. d13C reveals a positive trend with the SD and SI in the two species, and such a positive correlation can also be observed between the d13C and ECD in C. miofangiana. However, d13C has a slightly negative correlation with the ECD in B. mioluminifera insert ignore into journalissuearticles values(R2= 0.06);, possibly influenced by their different genotypes. Reflecting the changes through time, the d13C values of B. mioluminifera and C. miofangiana significantly increase with high determination coefficients insert ignore into journalissuearticles values(R2= 0.67 and R2= 0.65, respectively);, as do SD insert ignore into journalissuearticles values(R2= 0.66 and R2= 0.51, respectively); and SI insert ignore into journalissuearticles values(R2= 0.50 and R2= 0.79, respectively);. Research on extant B. luminifera and C. fangiana shows that the SD and especially SI, exhibit a prominent negative correlation with CO2 concentration. Pliocene CO2 levels are reconstructed as 381.5-439.4 ppmv and 377.8-472.3 ppmv, respectively, based on comparisons of the two fossil species with their nearest living equivalent insert ignore into journalissuearticles values(NLE); species. The significant positive trends of the d13C, SD and SI with ascending position of the fossils in the section indicate that the atmospheric CO2 levels declined in the Late Pliocene insert ignore into journalissuearticles values(3.30-2.83 Ma);. Furthermore, the calculated CO2 levels are higher than in other studies and probably demonstrate that local CO2 enrichment can be caused by frequent volcanic eruptions over a long time scale
Keywords : d13C value, Betulaceae, stomatal parameters, atmospheric CO2 concentration, Late Pliocene, Southwest China