REGENERATION OF FIR IN THE FORESTS OF TOMSK OBLAST, DAMAGED BY THE four-eyed fir bark beetle
E. N. Pats
Institute of Monitoring of Climatic and Ecological Systems, Russian Academy of Sciences, Siberian Branch, Tomsk, Russian Federation
Keywords: invasion, Polygraphus proximus, fir, undergrowth, abundance, vital condition, dynamics of regeneration, Western Siberia
Abstract
The dynamics of quantitative and qualitative parameters of fir undergrowth in the indigenous South taiga fir forests of the Tomsk region, damaged by an invasive four-eyed fir bark beetle (Polygraphus proximus Blandford), has been studied. The observations were carried out twice - during the period of mass reproduction of the pest (2012-2016) and 10 years after the outbreak of reproduction (2023), on 8 test areas in phytocenoses, differing in the composition of stands, living ground cover, taxation indicators of the fir element of the mother canopy and the degree of damage. In 2012, the total number of live fir undergrowth in different phytocenoses was 500-6300 trees/ha, including the largest, most valuable, pre-renewal undergrowth of 325-1100 trees/ha. By 2023, the number of undergrowth Siberian fir ( Abies sibirica Ledeb . ) decreased by 1.5-8.5 times, mainly due to a decrease in the number of small undergrowth, and amounted to 167-4000 trees/ha, including large undergrowth 154-2500 trees/ha. The negative dynamics of the number of undergrowth is due to a complex of factors of a biogeocenotic, pathological and mechanical nature, as well as the transition of large undergrowth into a stand. The average height of small and medium-sized undergrowth changed slightly, in large undergrowth in most stands it increased by 1.2-1.7 times by 2023 and reached 4.5 m, the age of large undergrowth ranged from 14 to 36 years. A positive trend was noted in the vital condition of the undergrowth, due to the condition of large undergrowth, partially weakened during the period of mass reproduction of the beetle due to pest attacks and healthy in the post-outbreak period. The comprehensive characterization of fir undergrowth according to the studied parameters allowed us to assess the varying degrees of its success in restoring damaged stands.
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