Dynamics of the number of bark beetles in the ecosystems of Polissya coniferous forests (Sumy oblast, Ukraine)
A.O. Burdulanyuk, V.I. Tatarynova, V.A. Vlasenko, V.M. Demenko, T.O. Rozhkova, O.M. Bakumenko
The research determined the influence of environmental factors on the state of the population of stem pests of the family Ipidae in Polissya pine and spruce forests (Sumy obast, Ukraine). The study used the "model trees" methodology, which is based on the artificial laying of hunting trees and the creation of attractive conditions for bark beetles. The colonization of bark beetles depended on the category of sanitary condition of trees, and the distribution of wood by categories depended on the conditions of the year and the type of ecosystem under study. Pests of the family Ipidae did not inhabit trees belonging to the category I of sanitary condition, the trees belonging to the second category, to a large extent the trees belonging to the III and IV, and 100% inhabited the plantations of V-VІ categories. The research revealed 5 species of pests from the family Ipidae: Blastophagus minor Hart., Blastophagus piniperda L., Ips acuminatus Gyll., Ips typographus L., Ips sexdentatus Boern. Dominant species were I. typographus and B. piniperda on the studied areas of pine and spruce forests. The location of I. typographus varied within 24.0-32.3% in pine plantations and 31,2-37,7% in spruce stands. The position of B. piniperda ranged from 26.1 to 28.9% in pine forests and from 26.5 to 28.0% in spruce forests. I. acuminatus populated 10.1-15.6% of pine and 8.0-9.9% of spruce trees. The occurrence of B. minor and I. sexdentatus was respectively 3.8-5.6 and 1.0-1.5%. The research revealed a significantly higher relative density of B. piniperda in the pine forest than in spruce, and a significant reduction in the indicator in each subsequent year of the study in both types of plantings. Relative density of I. typographus remained stable within all studied period on spruce forests. The ecological density depended on the volume of the feed substrate, and the volume depended on the species and taxonomic parameters of the tree, such as the length and diameter of the barrel. The ecological density of B. piniperda and I. typographus was significantly higher in pine plantations than in spruce forests, with a significant decrease in each subsequent year in both types of plantings. It is projected that climate will warm in future and forestry activities will intensify. As a result, a drastic change in tree species composition and biology of pest development will contribute to the new outbreaks of the mass distribution of bark beetles. Therefore the control and management of their numbers will require further research.