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Manganese concentrations in silver birch leaves were studied in the Ore Mountains and several reference localities in Czechia, both mountainous (up to 950 m MSL) and lowland (ca. 300 m MSL). The studied mountainous areas have been seriously damaged by acid rains in the last decades and forests there have still not recovered from that crisis. The aim of this study was to identify the major controls on the foliar Mn concentration variability, which was more than one order of magnitude, from 200 mg kg -1 (10th percentile) to 2000 mg kg -1 (90 th percentile) in the mountainous sites, that is, under uniform environmental conditions and for the same emission history of mountainous forests. The foliar Mn concentrations in the highest 5% samples were >3000 mg kg -1 which can be close to toxicity for persistent tree growth and thus indicate actual local geochemical stress in plants. Manganese uptake by plants has been enhanced by acid rain in the last decades, inferred from low foliar Mg (ca. 0.15%) and soil acidity (soil pH down to 4.0 in aqueous extracts). Certain bedrocks in the Ore Mountains, particularly local granitic porphyry and mafic lavas, have elevated Mn concentrations; however, in the mafic lavas, the soil Mn excess is compensated by elevated concentrations of soil Mg and pH. The highest foliar Mn concentrations were found in specimens growing in soils on granitic porphyry and on certain granites. The Mn concentration in birch leaves could be proposed as a proxy for the impact of soil acidification in central European mountain forests.

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