Prediction of atmospheric δ13CO2 using fossil plant tissues

摘要: [1] Reconstruction of the carbon isotope composition atmospheric CO2 is critical to understanding long-term global cycling. We have suggested that δ13C value land plant (δ13Cp) preserved in geologic record should reflect δ13CO2 at time during which plants grew (δ13Ca), based on a meta-analysis modern data. Here we present results laboratory experiments designed quantify relationship between tissue and values under varying environmental conditions, including differential pCO2 ranging from 1 3 times today's levels. As predicted, grown elevated showed increased average biomass compared controls same temperature. Across very large range δ13Ca (≈24‰) (≈740 ppmv) observed consistent correlation δ13Cp (p < 0.001). show an isotopic depletion −25.4‰ for aboveground −23.2‰ belowground Raphanussativus L. relative atmosphere it formed. For tissue, both ∼23°C ∼29°C, was strong significant (r2 ≥ 0.98 p 0.001); variation level had little or no effect this relationship. These validate our initial conclusion absence stress, primarily reflects linearly across levels; demonstrated excellent suggests high predictive power conditions.