Influence of elevation and shrub age on element accumulation in Vaccinium myrtillus in the alpine zone of the Low Tatras

Understanding how plant age and elevation influence elemental accumulation in alpine vegetation is essential for assessing long-term bioaccumulation processes and the impacts of environmental change in mountain ecosystems. This study aimed to evaluate the relationships between elevation, shrub age, and the concentrations of macro- and microelements in the stems of European blueberry (Vaccinium myrtillus) in the alpine zone of the Low Tatras (Western Carpathians, Slovakia). Stems were collected along two altitudinal transects (~ 100 m difference), and concentrations of 11 elements (S, Cl, K, Ca, Cr, Mn, Fe, Zn, Rb, Ba, Pb) were measured using energy-dispersive X-ray fluorescence (ED-XRF). Shrub age was determined from annual growth rings. Spearman's correlation analysis revealed a significant negative relationship between shrub age and elevation (ρ = -0.62, p < 0.001), with older individuals prevailing at lower altitudes. Several elements, particularly K, Mn, and Cr, showed age-related increases in concentration, whereas multiple regression analyses identified elevation as a stronger predictor than age, with significant declines in K, Mn, and Cr at higher elevations. Principal Component Analysis (PCA) indicated that the first two components explained 55.6% of the variance, separating a general enrichment gradient (PC1) from a compositional contrast between nutrient elements and metal pollutants (PC2). ANOVA of PCA scores confirmed significant differences between transects (p < 0.001), reflecting altitudinal variation in elemental composition. These findings demonstrate that both biological (age-related) and environmental (elevation-driven) factors jointly shape elemental accumulation in V. myrtillus stems, supporting their potential use as bioindicators of long-term environmental change in alpine ecosystems.