Is boreal soil carbon getting younger? Using historical samples to advance predictions of soil carbon sinks under rising atmospheric CO2

Boreal soils constitute the largest global organic carbon pool with a strong CO2 sink strength.

However, the quantitative prediction of how this sink strength will change under increasing atmospheric CO2 concentration remains highly uncertain.

Addressing this gap necessitates the development of effective modelling approaches.Using historical samples from intensive soil nitrogen manipulation experiments and an extensive soil sample archive at the national scale collected between 1980’s and 2022, and advanced computational modelling, the overarching objective of the project is to advance our understanding of how boreal carbon sinks respond to rising CO2 and soil nitrogen conditions, with a particular focus on the carbon transit time and the chemical compositions of soil organic matter.

Over this period, CO2 levels rose from 340 to 420 ppm, while the signature of atmospheric ∆14C decreased from 200‰ to 0‰, providing distinct annual ∆14C signatures of the carbon input to the soil.

By integrating estimated carbon transit time of soil organic matter with stable isotopic data (13C and 15N) and pyrolysis-GC-MS and 13C-NMR analyses, I expect to provide essential parameters to constrain current Earth system models.Given the originality of the research question and the innovative modelling tools, this project is expected to make a significant impact in the field of soil science, biogeochemical modelling, and climate projection.