The Role of the Stem Pests in Changing the Condition of Coniferous Forests of the North-West of the European Part of Russia

Abstract

The danger of stem pests’ mass reproduction in the Leningrad Region and the Republic of Karelia is increasing. However, data on their populations’ state in the northwest of the European part of Russia are scarce and very heterogeneous. They include materials from articles and reviews of the sanitary and forest pathology state, which are in turn based on completely different methodological approaches to obtaining information. Generalisation and analysis of data on the increase in the number of stem pests that pose a danger to coniferous forest stands in the north-west of the European part of Russia, taking into account the materials of scientific reports and forest pathology monitoring, is an urgent task of this paper. The greatest danger to spruce stands is the European spruce bark beetle Ips typographus (Linnaeus, 1758), which forms large-scale centres of mass reproduction. The main factors causing the beginning of the formation of breeding centres are weather conditions (hurricane-force winds and the formation of windblows, an increase in the growing season temperature and a lack of precipitation). At the end of the 20th–beginning of the 21st century, the Leningrad R-egion saw an increase in frequency of the stem pests’ mass reproduction outbreaks, especially the European spruce bark beetle. Since the second half of the 20th century, breeding outbreaks have been also observed in the Republic of Karelia. In the Murmansk region, stem pests do not have a noticeable effect on the forest stands condition. These trends correspond to the temperature increase trends in the Leningrad region and Karelia and an insignificant temperature change in the Murmansk region. Additional nutrition for the pine beetles and sawyer beetles in cases of their mass reproduction is an underestimated factor in the forest stands weakening, which significantly affects the growth and condition of surrounding plantations. The appearance of invasive species, such as the small spruce bark beetle Ips amitinus (Eichhoff, 1872) (Curculionidae: Coleoptera), is a potential danger, but at present this species does not show significant activity in pine and spruce forests in the north of the European part of Russia.