Unravelling δ13C signal in Scots pine trees for climate change and tree physiology studies

Stable carbon isotope composition (δ13C) recorded in trees responds sensitively to the changing environmental conditions and thus provides a powerful tool for paleoenvironmental reconstructions. The retrospective interpretation of tree δ13C signal depends on comprehensive understanding how physiological signals are during photosynthesis is modified after photosynthesis. This thesis aims improve photosynthetic post-photosynthetic fractionation processes, examine suitability ring intra-seasonal reconstructions intrinsic water use efficiency (iWUE). former goal was studied by combining compound-specific analysis organic matter with discrimination models online measurements leaf CO2 fluxes field-grown mature Scots pine (Pinus sylvestris L.). latter achieved via comparing 18-year-long iWUE chronologies estimated from laser ablation derived δ13C, gas exchange eddy covariance data. Mesophyll conductance time-integral effect assimilates had clear impact dynamics sugar δ13C. No significant reserves observed biomass growth needles, stem or roots pine. Unlike sucrose, bulk matters offset new assimilates, leading distorted documented their reliability data supported an agreement patterns across estimation methods. These results broaden our knowledge less well-known isotopic demonstrate benefits analysing sucrose plant responses, show that based can be extended scale. information not only helps better unravel trees, but also improves reliable