Natalia Pavlovna Khizhniak

Birch stands, dominated by Betula pendula Roth, are a common feature of boreal forests. Within the Krasnoyarsk (central) group of regions, they are concentrated in the taiga, subtaiga and forest steppe zones of actively managed forests, represented by stands of seed and shoot origin. The health and productivity of birch forests is often determined by the activity of wood-decay fungi, which leads to rot and decay in trees. The objective of the research is to evaluate the impact of stem rot on birch forests in the study area, with a focus on key ecological and silvicultural factors. The research methods employed included a reconnaissance survey of birch forests, a detailed forest pathology survey of forest stands on research plots (31 pcs.), comprehensive macroscopic diagnostics of stem rot, identification of xylotrophic fungi by basidiomes, integrated assessment of forest health, graph analytics and statistical data analysis. Stem rot has been identified in all birch forests in the study area. In shoot origin stands, the incidence rate has reached the stage of the disease center (i.e., more than 10% of trees are infected). The following wood-decay fungi have been detected on the trunks of living trees affected by rot: Fomes fomentarius, Fomitopsis pinicola, Inonotus obliquus, Phellinus igniarius, and Trametes versicolor. The infection typically infects trees via spores, finding entry through dying branches or mechanical and thermal wounds on trunks. In trees of shoot origin, stem rot is frequently transmitted via mycelium from stumps left after felling. This, in conjunction with diminished immunity, contributes to a substantially elevated incidence of stem rot in comparison to stands of seed origin. The research has not established a reliable correlation between the incidence of stem rot and forest stand characteristics due to the impact of human activity on birch forests (e.g., cutting, fires, tree injury). At the same time, no reliable connection has been established between the spread of stem rot and the stage of recreational disturbance. Trees of various sizes are affected by stem rot, usually proportional to their representation in the structure of the forest stand. The disease has a detrimental effect on the trees, which is clearly evident in the decline of forest health.

In the southern taiga of Siberia, periodic outbreaks of the Siberian moth Dendrolimus sibrircus Tschetv. have been observed. The outbreaks result in the defoliation of Siberian fir Abies sibirica Ledeb. and Siberian pine Pinus sibirica Du Tour. stands across approximately one million hectares, leading to dieback of the affected forests. This is largely attributable to the inability to promptly identify the onset of the pest population growth in a timely manner, particularly in the context of expansive forest areas with limited accessibility. It is feasible to enhance the efficacy of monitoring Siberian moth populations by discerning stands with the highest propensity for damage and concentrating efforts on these areas. To achieve this, we employed machine learning techniques, specifically gradient boosting, support vector machines, and decision trees, training models on two sets of predictors. One of the datasets was obtained through a field study conducted in forest stands during the previous outbreak of the Siberian moth (2015–2018), while the other was derived from the analysis of remote sensing data during the same period. In both 2015 and 2016, the defoliation was most accurately predicted using gradient boosting (XGB algorithm), with ROC-AUC values reaching 0.89–0.94. The most significant predictors derived from the ground data were the proportions of Siberian fir, Siberian spruce Picea obovata Ledeb., and Scots pine Pinus sylvestris L., phytosociological data, tree age, and site quality. Among the predictors obtained from the analysis of remote sensing data, the distance to disturbed forest stands was identified as the most significant, while the proportion of dark coniferous species (A. sibirica, P. sibirica, or Picea obovata Ledeb.), the influx of solar radiation (estimated through the CHILI index), and the position in the relief (mTPI index) were also determined to be important.

The research was aimed at studying the taxonomic diversity, habitat specialization, and trophic characteristics of mycobiota, including Basidiomycota, in the northern ecosystems of the Krasnoyarsk Krai (Central Siberia) near Norilsk. Larch forests and woodlands in the Siberian permafrost zone are distinctive and Basidiomycota, as a component of these ecosystems, plays an essential role in their functioning. Currently, there is a paucity of information about this group in Arctic ecosystems, both in terms of floristic and ecological aspects. Seventy species of macromycetes belonging to different trophic groups were discovered and identified. Only 15% of species occur regularly, while most species are found rarely or only once. The identified species belong to 44 genera, 25 families, and 8 orders, which are included in the class Agaricomycetes. The leading families in terms of the number of species are Russulaceae, Polyporaceae, Tricholomataceae, Suillaceae, Strophariaceae, and Cortinariaceae. Mycorrhizal fungi and wood decay fungi dominate the structure of mycobiota of the study area (the total share is 71%). The rest of the species (29%) are fungal decomposers inhabiting plant litter, the forest floor, and humus. The largest number of species occur in forest ecosystems, which are dominated by mycorrhizal and wood decay fungi (up to 70%), which are trophically associated with woody plants and debris. The fungal decomposers inhabiting plant litter, the forest floor, and humus dominate (about 80%) in the species composition of tundra, where, in the absence of woody substrate, wood decay fungi have not been found at all. The species richness of tree and shrub Arctic ecosystems is low, yet the taxonomical and ecological structure of Basidiomycota is similar to that observed in taiga and temperate forests. These data permit a more comprehensive description of the biodiversity of the Arctic and may prove useful in studying biological processes in these ecosystems.

Обоснование. Деградация темнохвойных лесов с преобладанием Abies sibirica Ledeb. находится в центре внимания многих специалистов. При большом объеме научной информации по данной проблеме недостаточное внимание уделяется исследованию роли патогенных организмов в темнохвойных древостоях. Цель. Оценить ценотическую роль инфекционных болезней в пихтарниках на юге Средней Сибири с учетом дифференциации деревьев. Материалы и методы. Материалами послужили данные обследования древостоев A. sibirica в темнохвойных лесах Бирюсинского участкового лесничества КГУ «Емельяновское лесничество». Методы исследования: детальное (инструментальное) лесопатологическое обследование, макроскопическая (патографическая) диагностика болезней деревьев, графоаналитический и статистический анализ рядов распределения деревьев по градациям диаметра, расчет показателей проявления болезней. Результаты. Стволовая гниль и ржавчинный рак (возбудитель – Melampsorella caryophyllacearum) – типичные фоновые болезни, приводящие к накоплению гнилевого ветролома и хроническому ослаблению деревьев. Распространенность ржавчинного рака в древостоях пихты достигает очаговых значений (10% и более) и зависит от присутствия промежуточных хозяев для возбудителя, болезнь хаотично поражает деревья разного возраста и размера. Водянка поражает преимущественно деревья I-II классов Крафта, формирует диффузные очаги с пораженностью древостоев до 20%, пораженные деревья постепенно отмирают. Возбудитель корневой гнили (Armillaria mellea s. l.) наиболее агрессивен и поражает деревья разного ценотического статуса, в результате формируются куртины усыхания древостоев. Заключение. Дендропатогенные организмы – важный эндогенный фактор состояния темнохвойных насаждений с преобладанием A. sibirica на юге Средней Сибири. Их ценотическая роль неравнозначна. Наиболее значимы возбудители некрозно-раковых болезней, и особенно корневой патоген – A. mellea, который приводит к ослаблению и усыханию большого числа деревьев разного статуса в структуре дендроценозов.

Представлен обзор существующих методических подходов к оценке расчета возможного ущерба от различных негативных факторов гибели лесов (пожары, насекомые вредители и др.).