Trait multi-functionality sets individual traits sub-optimal for specific functions \cite{Sack_2019}. Whole-tree size structural traits are typically multi-functional \cite{Poorter_2003} and may be both polygenic and pleiotropic \cite{Farnsworth_1995}, resulting from hierarchical, emergent consolidation of lower-level traits \cite{Charles_Dominique_2012}. As a result, high co-linearity is usually found among the tree size traits \cite{Martin_Ducup_2020,Verbeeck_2019}, making the contributions to individual functions hard to disentangle \cite{Messier_2017,Sack_2019}. Nonetheless, a division of the size traits into vertical and horizontal extents was proposed \cite{Seidel_2019}, reflecting the predominant linkages to functions of space exploration and light harvest, respectively \cite{Hall__2001}. A better insight into the structure-function network in trees may be provided by including the so-called relative traits, or architectural proportions \cite{Iida_2011,MacFarlane_2017}, with both a higher level of trait orthogonality and specific trade-offs (negatively correlated traits) within the major trait dimensions \cite{Martin_Ducup_2020,K_dra_2022}. Using this approach, it was revealed that trees may amplify specific functions along ontogeny and increasing size, such as for light harvest and reproduction, resulting in architecture convergence with increasing canopy position in large-statured trees \cite{Martin_Ducup_2020}. However, architecture divergence \cite{Loubota_Panzou_2018} was also reported when both large- and small-statured trees were included, suggesting two or more viable architectural trait combinations. The architecture convergence-divergence hypotheses require further testing \cite{Martin_Ducup_2020,Loubota_Panzou_2018}. Particularly, of interest are the intraspecific architecture-function trajectories in the small-statured species of mixed life-history strategy, while it appears that such species have a predominant effect on the community-level structural diversity \cite{Iida_2011,Loubota_Panzou_2018}, exhibiting more than a single architectural optimum depending on local environment and type of stress \cite{Sack_2019}.The intraspecific variability of rowan architecture has.... \cite{Laurans_2024}