“…Furthermore, age also impacts wood structure and function ( Rodriguez-Zaccaro et al, 2019 ), fibers ( Lundqvist et al, 2018 ), and wood density ( Sousa et al, 2016 ). However, most of these studies ( Li et al, 2017 ; Ren et al, 2018 ; He et al, 2019 ; Castagneri et al, 2020 ; Huang et al, 2020 ; Tabakova et al, 2020 ; Versace et al, 2020 ; Zenga et al, 2020 ) focused on exploring the effect of exogenous factors on intra-annual wood cell development. Fewer studies ( Rossi et al, 2008 ; Plavcova et al, 2013 ) investigated the effect of endogenous factors on intra-annual wood cell development although they had the non-negligible regulation on the intra-annual wood cell development, especially the effect of age on the intra-annual wood cell development.…”