Isotope composition of leaf dark-respired carbon dioxide of C3 and C4 plants in Songnen farming-pastoral zone of northern China

摘要

The C isotope composition of leaf dark respired CO2 (δ13CR) integrates short-term metabolic responses to environmental change and is potentially recorded in the isotopic signature of ecosystem-level respiration.Species differences in photosynthetic pathway and associated isotopic fractionations at metabolic branch points can influence δ13CR value and magnitude of nocturnal shift.We measured δ13CR in 22 species of Songnen grassland which were composed of 13 C3 and 9 C4 species.Significant nocturnal shift in δ13CR were detected in 20 species.There were no differences in the magnitude of nocturnal shift in δ13CR between C3 and C4 plants.Correlations between δ13CR and isotopic signature of biomass, soluble sugar and starch suggest that carbon isotope signature of leaf respired CO2 can be well estimated through measuring δ13C of biomass, soluble sugar or starch.