ALT Observed covariation between hydrogen and oxygen isotopic compositions on a delta basis for xylem water, water vapour, leaf water, leaf cellulose and branch wood cellulose; and, on a 2H-18O enrichment basis relative to xylem water, for leaf water, leaf cellulose and branch wood cellulose.

ALT Structural equation models assessing the changes in δ18O along tree isotopic pathway for the two study sites.

ALT Schematic summarizing sources of decoupling between CO2 uptake and carbon (C) sequestration across various time scales. Across scales, various processes decouple C sequestration (wood formation or woody productivity, ANPPwoody, on the ecosystems scale) from CO2 uptake (photosynthesis or gross primary productivity, GPP, on the ecosystems scale).

ALT (a) Conceptual responses of radial wood growth and photosynthesis to changes in carbon supply under supply-limitation vs sink-limitation. (b) Experimental setup including tissue sampling locations. (c) Timeline of treatments. (d) Mean temperatures for the air (red line), the phloem of chilled trees (blue line), and the phloem of control trees (green line).

ALT Schematic summarizing sources of decoupling between CO2 uptake and carbon (C) sequestration across various time scales.

ALT Seasonal dynamics of daily carbon sequestration of Norway spruce in 2014 and 2015. The tree carbon gain is represented by carbon in woody biomass production and was calculated based on daily wall thickness increments.