Abstract
Premise: Nonstructural carbohydrates (NSC) play a key role in tree performance and functioning. NSC are stored in radial and axial parenchyma (RAP) cells, but it is not known if this relationship is altered among species and climates, or is linked to functional traits describing xylem structure (wood density) and tree stature.Methods: In a systematic review, we collated data for NSC content and RAP fractions in stems for 68 tree species. To examine their relationships with climate factors and other functional traits, we also recovered climate data at each tree's location, as well as wood density and maximum height. A phylogenetic tree was established to examine the role of species’ evolutionary relationships on the associations between NSC, RAP and functional traits.Key Results: Across all 68 tree species, NSC was positively correlated with RAP and mean annual temperature. but relationships were only weakly significant in temperate species and angiosperms. When separating RAP into radial parenchyma (RP) and axial parenchyma (AP), both NSC and wood density were positively correlated with RP but not with AP. Taller trees had less dense wood and lower RAP, but no relationship with NSC.Conclusions: NSC is stored mostly in radial parenchyma that increases in warmer climates, but this relationship was only weakly linked to wood density and tree height. Our analysis of evolutionary relationships demonstrated that RAP fractions and NSC content were always closely related, suggesting that RAP can act as a reliable proxy for potential NSC storage capacity in tree stems.