The total content of mineral substances (ash) and heavy metals (Al, Cd, Cr, Cu, Fe, Mn, Pb) in the wood of healthy and dying oak trees from different regions of Poland was subject to analysis. The material for analysis came from the 12 Forest Districts in which the main source of oak wood in our country is located. Two trees healthy and dying of the same age were cut in each stand showing symptoms of a decline trees in the past and at present. Wood samples cut out of the outer heartwood at the butt-end of the trunk of oak trees aged 60-155 were used for analysis. The content of mineral substances in the wood of healthy and dying trees was at a similar level. No statistically significant difference in the content of each of the analysed elements was found in the wood of healthy and dying trees.

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