THE INFLUENCE OF THE TYPE OF FOREST ON THE RESISTANCE OF FIR STANDS IN THE SOUTHERN TAIGA SUBZONE OF PERM KRAI TO COLONIZATION BY THE FOUR-EYED FIR BARK BEETLE

Abstract

In recent years, the four-eyed fir bark beetle (Polygraphus proximus Blandford, 1894), a fir tree pest ofFar Eastern origin, has been rapidly spreading across the regions of Russia. Perm Krai is no exception in this regard: thedangerous invader was discovered in its territory in 2022. The type of forest is an important taxation indicator that affectsthe resistance of plantations to unfavorable factors. The aim of the study was to establish, using the example of fir standsgrowing in the South-taiga zone of Perm Krai (European part of the Russian Federation), how the forest type influencesthe resistance of fir stands to drying out caused by the impact of the four-eyed fir bark beetle. The objects of the studywere fir stands growing on the territory of the Dobryanka and Perm forestries. The authors analyzed materials of forestpathology surveys conducted by forest pathologists in the period from 2022 to 2024, which showed the drying out of firstands from the effects of the four-eyed fir bark beetle. The foci of the beetle’s mass reproduction were detected in theterritory of distribution of 4 types of forests: green moss spruce forest, wood sorrel spruce forest, linden spruce forest,and broad-grass spruce forest. All the types of forests, except for the green moss spruce one, are the most widespread inthe study area. The sanitary condition of fir stands growing under the linden forest type conditions is characterized as theworst: the most common are linden spruce stands with a completely dead fir stand. In the authors’ opinion, this is due tothe share of fir in the composition of the stands: in linden spruce stands, the average share of fir in the composition formulaof forest stands is 1 unit lower than in stands of other forest types. There is an inverse correlation between the proportionof fir in the stand composition and the percentage of trees killed by the effects of the four-eyed fir bark beetle.