Temporal dynamics of the carbon isotope composition in a Pinus sylvestris stand: From newly assimilated organic carbon to respired carbon dioxide

Abstract

The 13C isotopic signature (C stable isotope ratio; δ13C) of CO2 respired from forest ecosystems and their particular compartments are known to be influenced by temporal changes in environmental conditions affecting C isotope fractionation during photosynthesis. Whereas most studies have assessed temporal variation in δ13C of ecosystem-respired CO2 on a day-to-day scale, not much information is available on its diel dynamics. We investigated environmental and physiological controls over potential temporal changes in δ13C of respired CO2 by following the short-term dynamics of the 13C signature from newly assimilated organic matter pools in the needles, via phloem-transported organic matter i..