Fungi and minerals occurring in heartwood discolorations in Quercus robur trees

The studied Quercus robur trees were oaks protected as monuments of nature (200-350 years old) and oaks growing in forest stands (200-300 years old). The most visible symptoms occurring in aboveground organs included defoliation (25-75%), dying of twigs and branches. Discoloured heartwood, obtained with an 80-cm Pressler borer, differed in colour intensity from normal wood and was divided into two groups: stained brown and dark brown. The brown-stained heartwood was a more active site, considering the number of fungi and their ability to produce enzymes (phenoloxidase, pectinase and cellulase) in comparison with the dark-brown-stained heartwood. This brown-stained heartwood contained also statistically more Ca, Mg and Mn.