To study the effect of Ips sexdentatus Börner on the state of Pinus sibirica Du Tour stands in the forests of southern Central Siberia

The aim of the work was to evaluate the influence of the six–toothed bark beetle (Ips sexdentatus Börner) on the state of Pinus sibirica Du Tour stands in dark coniferous forests in the south of Central Siberia. The object of research is an active bark beetle outbreak in dark coniferous plantations with a predominance of P. sibirica in the territory of the Mansky forestry district of the Krasnoyarsk Krai (Altai-Sayan mountain taiga forest region).

A forest pathology examination of plantings on three test areas was performed, followed by an integrated assessment of the sanitary condition of stands. The damage to cedar stands by a six-toothed bark beetle was revealed by visual signs using standard indicators, and statistical analysis of empirical tree diameter distribution series was used.

The vital condition of stands of all forest elements, including cedar, is severely weakened, and the degree of their disturbance in terms of current shrinkage is medium to severe. The damage to cedar stands in the bark beetle outbreak ranges from weak to strong, with a predominance of used trees, and the share of the trunk stock of inhabited trees is less than 10%. The six-toothed bark beetle invades trees of any size in proportion to their representation in the structure of the cedar element of the forest. In the part of cedar stands damaged by bark beetle, trees that have lost their viability predominate. According to the integral indicator, the average condition of damaged trees is shrunken or dead. The proportion of living trees in 2–3 categories was 13–19 %, which indicates an increase in the aggressiveness of the xylophagus. This is due to its high number against the background of a preliminary violation of the stability of plantations due to anthropogenic activity, negative changes in forest conditions.

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