Quantification of time delay between damages caused by windstorms and by Ips typographus

摘要

Damages by wind and by European spruce bark beetle (I. typographus L.) were compared on the basis of the reports about the occurrence of harmful forest agents for the period 1964?1991 across former regional state forest directorates. In the given period, the quantity of salvage logging (70 million m3) was more than five times that of sanitation felling (13 million m3). Damage intensity increased over the decades. Using a cross-correlation function between the time series, an increase in the abundance of I. typographus due to windfall was demonstrated with a delay of 1–3 years. Wind damage was also shown to arise as a result of disturbed stand stability after sanitation felling with a stochastic delay of 1?5 years. Thus, disturbance of static stability of forest stands may be considered as one of the main harmful consequences of bark beetle outbreaks for the near future. Consequences for forest management are discussed.