Home – Home – Jornals – Siberian Journal of Forest Science 2023 number 1

The capsule review of the scientific editor for the thematic issue of the Siberian Journal of Forest Science, 2023, is presented, dedicated to forest protection problems in Russia.

The problem of infection and death of valuable Siberian stone pine and fir stands of the Baikal specially protected natural territory as a result of the spread of bacterial dropsy of conifers over thousands of hectares is discussed. The disease was found in Zhigalovskiy, Kachugskiy, Nizhneudinskiy, Slyudyanskiy, Ust-Udinskiy and Shelekhovskiy forestry districts of Irkutsk Oblast, as well as in Gusinoozerskiy, Babushkinskiy, Ulan-Udenskiy and Pribaikal’skiy forestry districts of the Republic of Buryatia. Siberian stone pine and fir trees weakened by bacterial dropsy are damaged by secondary stem pests, such as the six-toothed bark beetle (stenographer) Ips sexdentatus Boern., the striped coniferous lumberjack Trypodendron lineatum Oliv., the black fir barbel Monochamus urussovi Fischer, which in turn weaken the damaged stands, leading them to death, creating migratory foci, and are carriers of the disease. In order to carry out the necessary health-improving forest protection measures, eliminate and prevent the spread of infection, the question is raised about the possibility of using selective forest health felling of dry stands and stands infected with bacterial dropsy in the Baikal specially protected natural territory.

Forest protection, being a practically oriented discipline of forestry, has a rich and interesting history. The first attempts to describe forest pests and measures to control them were made in the work of F .G. Fokel «Collection of Forest Science», published in 1752. «Manual for Officers of the Corps of Foresters «Forest protection»» published in 1843 by V. S. Semenov can be considered the starting point of forest protection. The tenth chapter of the work became the first instruction in Russia on the identification of harmful organisms. In 1843-1845, the Department of Ship Forests issued a «Forest Dictionary» prepared under the guidance of V. E. Wrangel. The dictionary contains a description of 76 pest species and more than 20 species of entomophages, and also describes the causes of diseases for the first time. In 1869, the «Reference book on foresters. Part 1» by A. F. Rudzkiy was published, it includes a significant section on forest protection from pests. The first specialized manual was published in 1872 - «Forest Protection» by N. S. Shafranov. This book discussed in details the causes of the insect pests outbreaks, as well as technologies to reduce their impact. Also, for the first time, attention was paid to reducing the marketable value of wood, issues of its subsequent sale, as well as the mechanisms of trees weakening and dieback. In 1875, the second edition of «Forest Protection» was published, in which a separate part was devoted to fungi that cause diseases and rot of trees. The book of N. S. Shafranov was based on the studies of G. A. de Bari, G. M. Wilkomma, and R. Hartig. In 1880 P. V. Baranetskiy published a handbook for forest owners, foresters and students of the forest protection courses. This book has set a bases for contemporary system of forest pathology.

An analysis was made of the current version of the documents that provide information on the dynamics of the density of pest populations and determine the appointment and implementation of sanitation activities in the forests of the Russian Federation, including the Procedure for the implementation of state forest pathological monitoring, the Rules for sanitation safety in forests; The procedure for conducting forest pathological examinations; Rules for the implementation of measures to prevent the spread of harmful organisms; Rules for the elimination of foci of harmful organisms. It has been established that in the zone of taiga forests, the legal framework for forest protection does not provide representative information on the state of pest populations, sanitation measures do not reduce the number of pests. A proposal has been made to change the scale of condition categories, especially categories 4 (shrinking), 5a (fresh dead tree) and 5d (dead tree). It is proposed to use the population of bark beetles and wood borer insects as the main characteristic of the state of trees along with the state of the crown. When the forest pathological unit is located in a small area inside the forest in wet forest types, it is recommended not to carry out sanitary felling, except in cases of the appearance of dangerous types of pathogens. It is proposed to remove preventive measures and other methods of controlling the spread and reproduction of pests and pathogens that are not related to tree felling from the legal framework of forest protection, and invite responsible forest users to apply these measures based on interaction with the authorized body of the subject of the Russian Federation. It is necessary to exclude from the normative documentation the possibility of burning logging residues, except for cases of development of specific diseases, in which even the transportation of logging residues poses a potential danger to the surrounding plantations.

The problems of protection of Siberian pine forests, that have arisen in connection with the recent invasion of the European pest - the small spruce bark beetle Ips amitinus (Eichh.), which formed the outbreak foci on the territory of the Tomsk and Kemerovo regions, are considered. The complexity of indication and early detection of the species, the assessment of the forest stands state, bark beetle populations indexes in foci, and the implementation of measures aimed at curbing the spread of an aggressive alien species were discussed based on the results of our research. The objective reasons for the ineffectiveness of protecting forests from the alien bark beetle at the present stage are shown: the lack of information and scientific and methodological support for it, taking into account the characteristics of the biology and ecology of the new pest; lack of a developed technology for the practical application of protective measures in the conditions of specific management in Siberian pine forests and legislative conflicts. In connection with the specifics of the invasive situation, a number of innovations in the organization and conduct of forest health monitoring and forest pathological surveys in the Siberian pine forests are proposed for consideration. The necessity of clarifying the scale of damaged trees condition categories by the small spruce bark beetle is substantiated, taking into account the peculiarities of the relationship between the pest and its new host-tree species. The possibilities and prospects of conducting remote observations of the alien bark beetle foci and its distribution with using of unmanned aerial vehicles are shown. A critical assessment is given of measures to curb the spread of pests in forests, permitted by regulatory documents, and their possibilities for solving the problem of Siberian pine forests degradation in the outbreak foci of the small spruce bark beetle. The proposals for effective protection technologies against new invasive pest in Siberian pine forests are formulated.

A laboratory method for studying the fungal phytotoxicity with cut-offs from leaves was tested for the fungus Hymenoscyphus fraxineus the causative agent of ash dieback ( Fraxinus L.) disease. We used 12 cultures of the fungus originating from the native and invasive ranges of the pathogen, and leaves of two species of ash Manchurian ( Fraxinus mandshurica Rupr.) and ash green ( F. pennsylvanica Marsh.) that differed in resistance to this phytopathogen. After cultivation of fungi on liquid nutrient media, the cultural filtrates were applied to cut-offs from ash leaves placed in moist chambers. Necrotization of photosynthetic tissues was noted after the action of exometabolites of some cultures. At the same time, large necrosis have developed only on the cut-offs from the leaves of ash green, which corresponds to the known fact that this species is less resistant to H. fraxineus in comparison with of ash Manchurian. The geographical origin and composition of the culture medium did not affect the ability of cultures to induce necrosis. The analysis of the results indicated a probable positive relationship between the necrotizing activity of the culture liquid and the indicators of the crop biomass yield. It can be assumed that the necrosis inducing factors appeared in cultures at the stationary stage of the fungus growth. No concurrence was found between the results of laboratory tests with leaf cut-offs and field experiments on the inoculation of H. fraxineus mycelium into the trunks of young ash trees. The deficiency of knowledge about the H. fraxineus physiology and the mechanisms of interaction of this phytopathogen with the host are discussed. A conclusion was made about the suitability of the laboratory technique with leaf cut-offs for factors of H. fraxineus phytopathogenicity investigation, which act during the colonization of the photosynthetic part of the crown in sensitive ash species.

Currently, in the dark coniferous forests of the Baikal region, the spread of the disease bacterial wetwood disease is noted, causing the sanitary condition deterioration in the forest stands, and leading to the forest dieback on large territories. Despite the fact that this disease has been known since the beginning of the last century, the question of its’ real pathogen is still open. It is believed that associations of various endophytic microorganisms may take part in the development of pathogenesis. In this regard, it seems relevant to study the composition of the endophytic complex of microorganisms in wood with bacterial wetwood of forest species in order to establish the types of relationships between endophytes and test their ability to initiate a pathological process in conifers. An attempt was made to identify the main endophytic microbiome representatives of the «wet wood» of Siberian stone pine ( Pinus sibirica Du Tour) affected by bacterial wetwood, to assess their phytopathogenic properties and types of relationships between them. The features of the endophytic microbiome of the Siberian stone pine affected by bacterial wetwood in the Slyudyanskoye forestry of the Irkutsk region were studied. With standard microbiological and phytopathological methods we isolated pure cultures of bacteria and studied their characteristics (including virulence). For bacterias identification molecular genetic methods were used. From the infested wood of Siberian stone pine trees affected by bacterial wetwood, a complex of pure microorganisms cultures, not previously described in other studies, was isolated. Among them, opportunistic strains include Rouxiella chamberiensis, Ewingella americana, Stenotrophomonas rhizophila and Bacillus pumilus , which exhibit pronounced virulent properties in relation to indicator plants and ambiguously affect the growth and development of Scotch pine ( Pinus sylvestris L.) seedlings. Mutual impacts of bacteria on each other were noted in the endophytic microbiome of the affected Siberian stone pine wood. Bacillus bacteria showed pronounced antagonistic properties. Basically, in the endophytic community symbiotic relationships were dominated with possible syntrophic connections.

In 2006-2018, 13 species of leaf mining gracillariid moths (Gracillariidae) caused noticeable damage to plants (mainly trees and shrubs) in Siberia, i. e. about six of all moth species known in this part of Russia. Relative damage levels of 50-75 % and > 75 % were recorded for 9 moths, of which 5 species are native pests of poplars ( Populus L.): Phyllonorycter apparella (Herrich-Schäffer), Ph. comparella (Duponchel), Ph. populifoliella (Treitschke), Phyllocnistis labyrinthella (Bjerkander), and Ph. unipunctella (Stephens). Three moth species, namely Acrocercops brongniardella Fabricius, Gracillaria syringella (Fabricius) and Phyllonorycter issikii (Kumata) are alien to Siberia. Their numerous mines were found on leaves of woody plants (oaks ( Quercus L.), lilacs ( Syringa L.), ash ( Fraxinus L.) and lime ( Tilia L.) trees) in Western Siberia (Omsk, Tyumen and Novosibirsk Oblast). Alien origin of Phyllonorycter medicaginella (Gerasimov) and Ph. lantanella (Schrank) in Siberia requires confirmation. Both native and alien moth species showed a tendency to cause significant damage to the plants in artificial (manmade) stands, i. e. in urban green plantings, parks, arboreta, botanical gardens, tree nurseries. Overall 81 % of cases of significant damage by gracillariids was documented in artificial plantings vs. 19 % in forests. The European part of Russia remains the main donor of alien gracillariid species for Siberia. Alien species distribute to Siberia directly or through bridge-effect invasions from the west of Russia.

The outbreaks history of the Siberian moth ( Dendrolimus sibiricus Tschetveraikov, 1908) in larch forests of the forest-steppe at the eastern foothills of the Kuznetsk Alatau mountains (West of the Chulym-Yenisei basin, South of Eastern Siberia, Republic of Khakassia) is reconstructed. Outbreaks of this species have repeatedly covered forests from the Urals to the Far East on an area of more than 1 million hectares. However, there is a lack of long series of observations of changes in the size of the Siberian moth populations. Data on the history of the defoliations caused by it will at least partially fill this gap. For reconstruction, we studied the radial growth in six larch stands, which in the past were subjected to intensive defoliation by the Siberian moth. Using the OUTBREAK algorithm, specific features (abrupt, deep, and prolonged declines in growth) were found in the series of radial growth, indicating defoliation in the past. In total 31 such periods were found in 1740-2017. A study of the frequency characteristics of the chronology of defoliation showed that after the end of the Little Ice Age, the interval between defoliations gradually decreased from 10-11 years at the end of the 19th century to 7 years in the 1930s. Since the 1940s, this interval has decreased to 4-6 years, which we attribute to anthropogenic impact (massive logging and, apparently, more frequent ground fires). The consequence of this was the fragmentation of forest stands and the periodic eliminations of overwintering entomophages by fires. As a result, the frequency of occurrence of the Siberian moth foci in the study area increased either due to its escape from the control of entomophages, or because of the formation of a system of migration foci that existed at different times in fragmented forest stands.

The chestnut gall wasp ( Dryocosmus kuriphilus Yasumatsu; Hymenoptera: Cynipidae) was first found in forests with the sweet chestnut ( Castanea sativa Mill.; Fagaceае) in the area of Sochi, where it became the worst pest of chestnut. By now, the chestnut gall wasp has spread to all territories in which the sweet chestnut grows in the Krasnodar Krai. Besides, the condition of chestnut orchards and forests in this region for a long time cannot be considered satisfactory to chesnat due to the development of cryphonectric necrosis ( Cryphonectria parasitica (Murrill) M. E. Barr) is causative agent of the disease). Control measures against the chestnut gall wasp have not been developed. A treat with pesticides are generally not effective because the chestnut gall wasp take cover inside the galls. And also pesticides can hurt honey bees and other beneficial insects. Moreover, pesticides use unacceptable in specially protected natural territories (SPNT), as well as near rivers, streams and settlements. The use of trunk injections is also impossible because the chemicals can make localize into the honey and nuts. To control the density of this phytophagous insect, the torymid wasp ( Torymus sinensis Kamijo; Hymenoptera: Torymidae), which is its effective specialized parasitoid, was introduced. This entomophage is used as an agent of biological pest control against the gall wasp in countries where entered earlier. The introduction of the torymid wasp allowed to significantly reduce the pest’s population density, at the same time it did not harm natural ecosystems. This is the first case in the history of Russia of targeted introduction of a biological pest control agent into SPNT. The article describes the process of making an official decision, logistics and preliminary results of the introduction of a parasitoid in the territory of the Sochi National Park and the H. G. Shaposhnikov Caucasian State Natural Biosphere Reserve.

An overview and the main content of the reports of the Third All-Russian Conference with international participation «Monitoring and biological methods for controlling pests and pathogens of woody plants: from theory to practice», held on 11-15 April, 2022 in Moscow, are presented.