Variation in leaf anatomy, vascular traits and nanomechanical cell-wall properties among European beech ( Fagus sylvatica L.) provenances

Key message Structural and ultrastructural traits of leaf xylem vary among European beech ( Fagus sylvatica L.) provenances in relation to climate. High tracheary element lumen area was observed in central Europe and decreased towards the range margins, while tracheary element density displayed opposite trend. Leaf anatomy and xylem cell-wall deformation were associated with climate continentality at the sites of origin. Context Understanding structural and physiological properties of tree populations adapted to local climate in response to climate may be of direct relevance for forestry. Aims Identifying patterns of heritable geographical variation and phenotypic associations of leaf-anatomical, vascular and cell-wall properties in European beech, a dominant tree species of European forests. Methods Fifteen beech populations planted in a common-garden test were studied employing gas exchange and chlorophyll a fluorescence measurements as well as light and atomic force microscopies of leaf samples. Results Nanomechanical properties of leaf-xylem cell walls did not show a clear geographical trend, but were correlated with the temperature seasonality of the site of origin. Populations from eastern Germany, northern Poland and the Czech Republic showed lower tracheary element lumen area and higher tracheary element density compared with the other populations, while xylem conductivity negatively correlated with latitude. Thickness of leaf parenchyma layers increased towards the East and, consequently, correlated with temperature indicators of climate continentality. No correlation between structural and physiological traits was observed. Conclusion The observed trends and associations with climate indicate adaptive variation of the studied traits.