The influence of the Polygraphus proximus Blandford on the stock and share of fir stands in the species composition of forest plantations in the Perm Krai

In recent years, the four-eyed fir bark beetle (Polygraphus proximus Blandford, hereinafter referred to as P. proximus), a stem pest of Far Eastern origin, has been spreading rapidly across the regions of Russia, inhabiting fir stands. The P. proximus can lead to a significant reduction in the stock of fir stands, as well as to the disappearance of the species from the composition of forest plantations. The purpose of the study is to assess the changes in the stock and share of fir stands in the species composition of plantations due to the influence of the P. proximus in the conditions of the South-taiga region of the European part of the Russian Federation, Perm Krai. The objects of the study are fir stands growing on the territory of the forestries of Dobryanka and Perm. The materials of the acts of forest pathology surveys conducted by forest pathologists of SBI PK «Gosleskhoz» and the Center for Forest Protection of the Perm Krai in the period from 2022 to 2024, which recorded the drying out of fir stands from the effects of the P. proximus, were ana-lyzed. As a result, it is established that, on average, in plantations of all types of forests after the impact of P. proximus, the share of dead fir trees exceeds the share of living trees, and the participation of fir in the composition formula of forest stands decreases by 1 unit as a result of drying out. In linden spruce forests, the proportion of dead trees exceeds the proportion of living trees by an average of 2.5 times! The complete death of fir stands is noted in 21.4% of cases, with the largest proportion of completely dead fir stands recorded in linden forest type plantations (14.2%). According to the authors, the high mortality of fir trees in the conditions of the linden forest type is explained by the low share of fir stands in the species composition of the plantations of this type of forest. The weak statistically significant inverse correlation between the proportion of fir in the composition of stands and the proportion of trees affected by P. proxi-mus is found.