Natural regeneration in Siberian fir (Abies sibirica Ledeb.) forests subjected to invasion of the four-eyed fir bark beetle (Polygraphus proximus Blandf.)

This study assessed the potential of natural regeneration (NR) of forests in Western Siberia, dominated by Siberian fir (Abies sibirica Ledeb.) and damaged due to the invasion of the four-eyed fir bark beetle (Polygraphus proximus Blandf.). The leading methods for investigating this problem are the sample plot method and the transect method, which allow revealing the features of NR, their morphological structure and spatial distribution. Analysis of the occurrence and structure of NR revealed a correlation between the degree of stand damage and sapling state. The spatial structure was highly heterogeneous, testifying the group location of NR and the variable density. For 63% of the sample plots, a decrease in saplings was recorded as a result of the impact of the four-eysouthern ed fir bark beetle. Most of the dead saplings were large (95%), and dead saplings accounted for 10–50%. A positive correlation was found between the decrease in saplings and the state of the fir forest. The number of saplings varied from 1,233 to 19,200 plants ha⁻¹, with fir being the dominant species. Fir forests of Western Siberia, damaged by the four-eyed fir bark beetle, have the potential for regeneration.