Effects of log length on Polygraphus proximus attack

Polygraphus proximus Blandford (Coleoptera: Curculionidae: Scolytinae), a non-aggressive bark beetle, has caused mortality of Abies spp. in Western Siberia, Central Asia, European Russia as well as Japan. Removing dead trees (i.e. salvage logging) and thinning stands are considered one of the best practices to reduce the risk of bark beetle outbreaks. However, salvaging or removing dead and thinned trees requires significant effort. Thus, to determine whether cutting trees shorter would reduce P. proximus infestation, we exposed A. sachalinensis logs of various lengths on the ground in a forest stand. The attack density of P. proximus significantly decreased with shorter log lengths. It can be concluded that cutting into short logs and leaving them on the ground are effective practices to reduce the chance of P. proximus outbreaks after natural disturbances and thinning.