Impact of four-eyed fir bark beetle on forest stands in Western Siberia, Russia

The four-eyed fir bark beetle Polygraphus proximus Blandf. from the Russian Far East has led to the decline of Siberian fir in significant areas across several Russian regions. Presently, the four-eyed fir bark beetle is a primary factor contributing to the degradation of fir forests and the occurrence of various changes in the flat part of Western Siberia. The study was conducted in stands with varying compositions, with a mandatory inclusion of a specific proportion of Siberian fir. Reference stands were located in Central Siberia, along the border of the forest-steppe (Krasnoyarsk forest-steppe) and taiga zones (mountain-taiga region of the Eastern Sayan). A comprehensive field study was conducted on research plots (a total of 10). The stands and outbreak areas presented here serve as a reference for the study area in terms of species composition, stand characteristics, and the degree of infestation of fir trees by the pest. The analysis yielded a scale that differentiated forest stands according to species composition and the extent of damage. The four-eyed fir bark beetle’s infection and damage to stands were found to be influenced by species composition. The intensity of damage was found to vary among species, with fir forests experiencing the most significant damage, followed by Siberian pine forests, birch forests, Scots pine forests, and aspen forests. Consequently, from a forestry perspective, forests dominated by aspen and Scots pine exhibit the greatest resistance to the invasive impact of the four-eyed fir bark beetle in the Krasnoyarsk forest-steppe zone.