Reply to comment on “Regional climate-driven C3 and C4 plant variation in the Cheollipo area, Korea, during the late Pleistocene” by J. Lim, W.-H., Nahm, J.-K., Kim, D.-Y., Yang [Palaeogeography, Palaeoclimatology, Palaeoecology 298 (2010) 370–377

Abstract

Ouyang et al. (2013--in this issue) raise two concerns regarding carbon isotope analysis and its use for reconstructing past vegetation changes recently published by Lim et al. (2010). One issue questions the formation of sedimentary organic matter by competitive contribution of C3 and C4 plants and calculation of the relative contributions of C3 and C4 plants with a binary mixing model using their mean δ13C values. The second issue questions the use of the δ13C value of flora from other regions or of the current flora as a universal reference to determine the composition of plants in the remote past, pointing out the importance of understanding the exact assemblage of local plants in the past by complete sporo-pollen assemblage analysis and molecular biomarker analysis. In response to these concerns, we provide a detailed description of the tracing process for determining the source of sedimentary organic matter using δ13C values and C/N ratios, and assess the suitability of calculating the relative contributions of C3 and C4 plants using a binary mixing model. Finally, based on its advantages compared to other biological proxies, we explain the utility of using δ13CTOC values for reconstructing past vegetation changes.