Tracing the transfer of recently assimilated carbon into the soil after in situ 13CO2 pulse labelling of trees

International audience; The fate of carbon in the soil plant system was followed by using pulse-labelling of 10 m tall trees in the field with 13 CO2 for a short period of time. The study is conducted on three tree species (beech, oak and pine) that are among the major species in European forests. Trees are labelled at three distinct phenological phases during the growing season. The assimilated 13 C by plants during the pulse labelling was then tracked in soil CO2 efflux with a high temporal resolution using tuneable diode laser absorption spectrometry and in the microbial compartment from soil cores (root + mycorrhiza transfer) and in mesh cores that permit the ingrowth of mycorrhiza hyphae but exclude roots (no-root cores).