Spruce radial increment and risk to Ips typographus L. attacks.

摘要

Tree vigour indicated by tree ring increment could be one of the most important factors predisposing spruce (Picea) trees to bark beetle attacks. In this study conducted during 2000-02 in Lithuania, tree ring analysis shows that spruce trees attacked by Ips typographus were growing faster most of their studied life time in comparison with unattacked ones nearby, except the last five-year period before attack. Attacked and unattacked spruce trees with codominant crown (Kraft class 2) showed the biggest differences in the annual radial increment. Spruce, killed by I. typographus, suffered more severe drought stress a few years prior to attack and recovered growth slower and weaker than survived trees..