A NEW TYPE OF ENTOMOGENIC SUCCESSION IN THE FIR FORESTS OF SIBERIA
Xylophilic entomofauna invasions pose a serious threat to the biological diversity of forest ecosystems. The ar-ticle summarizes the impact of an invasive bark beetle - Polygraphus proximus Blandf. on Siberian fir Abies sibirica Ledeb. in the southern taiga of Western Siberia within the Tomsk region. The studies were conducted in 2016-2018 on 38 trial plots. The state of the tree layer and natural regeneration was assessed using the approved methods. According to the degree of fir dominance in the upper tier, the following types of stands were distinguished by the composition: monodominant (9-10 units), moderately mixed (6-8 units), multi-species (2-5 units). The occurrence of monodominant and moderately mixed forests is 36%, and polydominant - 28%. As a result of the study, it was found that fir forests are represented by 3 main types of forests: sedge (45%), forbs (28%) and shallow (27%) one. It was revealed that there was a change to low- and medium-thick spruce forests and cedar forests on 45% of the area of fir forests. Fir will restore coenotic value within 1 generation. They degrade to the state of open stands on 27% of the area of fir plantations, on which a change to birch-aspen plantations with partial participation of fir is predicted to be 20-50% of the area. And another 27% of the area is dominated by spruce, cedar, and birch, but fir recovery is projected to be only 20-30% of the area. Hardwoods will be renewed in the rest of the area.