Does a strong seasonal disequilibrium exist between the oxygen isotope signals of leaf and soil CO2 exchange?
Résumé
The oxygen isotope composition (d18O) of atmospheric CO2 is among a limited number of tools available to constrain estimates of biospheric gross CO2 fluxes at large scales. However, accuracy of the partitioning depends on the extent of isotopic disequilibrium between the signals carried by photosynthesis (dA) and soil CO2 exchange (dR) We coupled branch and soil chambers with TDL techniques to capture the d18O signals of these two gross fluxes within a Maritime pine forest. Our study revealed a strong and seasonally persistent isotopic disequilibrium between dA and dR that will be compared to preliminary model simulations in this presentation.