Element accumulation patterns and bioindicator potential of Soldanella carpatica along a montane-alpine gradient

This study analyzed the multielement composition of Soldanella carpatica and the surrounding soils along a montane-alpine gradient (1137-1861 m a.s.l.) across seven sampling sites in the Tatra Mountains (Western Carpathians, Slovakia) to understand how altitude with associated habitat conditions, seasonality, and soil chemistry influence element accumulation and distribution patterns. The aim was to explore multielement relationships and possible environmental drivers affecting the uptake and distribution of selected elements within plant organs (roots, stems, and leaves) and surrounding soils. Portable energy-dispersive X-ray fluorescence was used to quantify biogenic (S, Cl, K, Ca, and Mn) and trace elements (Sr, Ba, Zn, and Pb). Total mercury was analyzed separately using a direct mercury analyzer (DMA-80), with mean concentrations around 0.02 ± 0.01 mg kg⁻¹ (dry weight) in plant tissues and 0.14 ± 0.08 mg kg⁻¹ (dry weight) in soils. Eighty-nine plant samples and associated soil samples were analyzed along the gradient. Biogenic elements (S, Cl, K, and Ca) were most abundant in aboveground tissues, indicating efficient uptake and translocation. In contrast, potentially toxic trace elements (Hg, Pb, Zn, Sr, and Ba) primarily accumulated in roots and rhizospheric soil, suggesting limited mobility and protective retention mechanisms. Elemental patterns varied with vegetation type and altitude: open meadows showed higher Cl, K, Ca, and Ba concentrations, consistent with greater exposure to atmospheric inputs, while forested sites exhibited Mn enrichment linked to acidic soils and canopy throughfall. Principal component analysis explained approximately 85% of the total variance, revealing an antagonistic Mn-Sr relationship and a shared loading pattern of Zn and Pb. These patterns may partly reflect contrasting geochemical behaviour and possible atmospheric influences rather than direct source attribution. The element-specific allocation patterns of S. carpatica highlight its potential as a sensitive bioindicator of element accumulation in high-elevation ecosystems.