Variation in wood density between mature sessile oak and English oak trees growing in different vegetation zones

Wood density isafundamental functional trait influencing ecological adaptation, hydraulic safety, and timber utilisation intemperate hardwoods. This study investigated variation inwood density (12% moisture) across mature stands oftwo economically and ecologically vital European oak species, sessile oak [<i>Quercus petraea</i> (Matt.) Liebl.] and English oak (<i>Quercus robur</i> L.), growing intheir characteristic vegetation zones inthe Czech Republic. Weassessed wood density attwo heights (at 1.3 m and atthe crown base) across six trees per plot and examined its relationship with tree-ring width and height. Results demonstrated statistically significant interspecific differences, with <i>Q. petraea</i> consistently exhibiting higher wood density (721 kg·m⁻³) than <i>Q. robur</i> (662 kg·m⁻³) at1.3 m. <i>Q. petraea </i>showed astatistically nonsignificant higher density of710 kg·m⁻³ atthe crown base and anoverall average of717 kg·m⁻³, while<i> Q.robur </i>had densities of701 kg·m⁻³ and 669 kg·m⁻³, respectively. Radial density profiles revealed species-specific patterns, with <i>Q. robur </i>showing amore uniform density distribution than the pronounced pith-to-bark gradients observed in<i>Q.</i><i>petraea</i>. Regression analysis indicated that tree-ring width explained only 12–13% of the variance in density, so other anatomical factors, such as latewood proportion and tree-ring structure (number and cell size), should be examined as anatomical drivers of wood-density variation.