Factors influencing the wind–bark beetles’ disturbance system in the course of an Ips typographus outbreak in the Tatra Mountains

Abstract

An outbreak of spruce bark beetle (Ips typographus [L.]) in the Tatra Mountains in the Slovak Republic and Poland, Central Europe, was analysed. The study area was nearly 3000ha.The 11year outbreak lasted from 1990 to 2000. Three outbreak phases were identified: 1990–1994 (incipient epidemic), 1995–1996 (epidemic) and 1997–2000 (post-epidemic). More than 118,000m3 of trees were damaged by wind and bark beetles. The analysis considered the relationship and succession of these two types of disturbances.Discrimination analysis, a multiple linear regression and boosted regression trees were used to determine the influence of 11 variables on tree mortality initiation and severity.The wind–bark beetles disturbance system was primarily influenced by stand related factors. Tree mortality initiation primarily depends on stand age and related changes in Norway spruce size and vitality. Wind caused tree mortality severity was primarily related to the tree or stand characteristics as well. The roles of host and environmental factors in the initiation and severity of tree mortality were influenced by the I. typographus outbreak phase. Stand, site and solar radiation variables were the most important factors impacting tree mortality severity caused by this disturbance system, especially in the epidemic phase. However, the severity of tree mortality caused by wind was primarily correlated with the stand characteristics. With the exception of elevation, the roles of the studied factors were similar in all gradation phases.