Climate drivers of bark beetle outbreak dynamics in Norway spruce forests

2015, Raff a et al. 2015). Given the potential interactions of insect outbreaks with other biotic and abiotic disturbances and the potentially strong impact of changing disturbance regimes on forest resources (Buma 2015), investigating the climate drivers of bark beetle outbreaks is of paramount importance. In Europe, Ips typographus is considered one of the most destructive pests of conifer forests causing signifi cant economic losses on a regular basis (Gr é goire et al. 2015). At low population densities, I. typographus breeds in fresh wind-thrown or dying spruces and usually does not succeed in colonizing healthy trees that are protected by eff ective defense mechanisms (Krokene 2015). Extensive drought or windfall events can trigger beetle outbreaks by Ecography 40: 001–010, 2017 doi: 10.1111/ecog.02769 © 2016 Th e Authors. Ecography © 2016 Nordic Society Oikos Subject Editor: John-Arvid Grytnes. Editor-in-Chief: Miguel Ara ú jo. Accepted 22 October 2016