Root decays as a potential predisposition factor of a bark beetle disaster in the Šumava Mts

Root decay infection and potential relations to Ips typographus L. outbreaks in the Šumava Mts. (Bohemian Forest) were monitored in 3 permanent sample plots. As an originator of root decays honey fungus predominated, in particular cases Heterobasidion annosum (Fr.) Bref. was also recorded. As for honey fungus species, Armillaria ostoyae (Romagn.) Herink predominated, however, A. cepistipes Velenovský and A. borealis Marxmüller et Korhonen were also determined. Other wood-destroying fungi were also recorded, e.g. Stereum sanguinolentum (ALB. & SCHW.: FR.) FR. and Climacocystis borealis (FR.) KOTL. Although Armillaria foci were localized directly in a forest edge after bark beetle disaster, it is not possible to state definite relationships between Ips typographus L. invasion and root system infection by Armillaria. The found out rate of infection is, with respect to an altitude over 1,100 m, extremely high not corresponding to existing knowledge on the behaviour of Armillaria in the region of Central Europe. The extent of Norway spruce infection by Armillaria ostoyae (Romagn.) Herink can give evidence of the chronic stress load of spruce trees in the area.