Stable Carbon Isotopic Composition of Black Carbon in Surface Soil as a Proxy for Reconstructing Vegetation on the Northern Slope of the Qinling Mountains

Abstract

AbstractBecause of the unique geographical location and important ecological effect of the Qinling Mountains, reconstruction of its vegetation and climate needs comprehensive research. We need to consider a multiple‐proxy approach to gain more information on recovering the paleovegetation and climate in the Qinling Mountains. Black carbon (BC) is produced by the incomplete combustion of vegetation and fossil fuels, and is a good proxy, recording paleoenvironmental information. However, in the Qinling Mountains, what are the characteristics of the BC, and whether BC stable carbon isotope (δ13CBC) can be used as a new proxy to study ancient vegetation, still need further study. In order to establish a sound basis for studying paleoenvironmental by BC proxy in the Qinling Mountains, we carried out systematic and detailed study on modern process of BC on the northern slope of the mountains. We analyzed stable carbon isotopes and carbon concentration of organic carbon (%SOC, δ13CSOC) and BC (%BC, δ13CBC), and identified the pollen assemblages from systematically sampled surface soil. The results show that the calculated ratio of C4 plants in the vegetation (%C4) based on the δ13CSOC data reflects a similar distribution of C4 plants in the surface vegetation and the pollen assemblage. The δ13Cbc values have a strong positive correlation with δ13Csoc values, and their difference (Δ13CSOc‐bc) is in the low range. These data indicate that δ13Cbc and δ13Csoc have very similar characteristics. Surface soil δ13Cbc values can indicate surface vegetation as effectively as δ13CSOC values, and the δ13Cbc proxy can be used effectively in paleovegetational research in the northern slope of Qinling Mountains.