Home – Home – Jornals – Siberian Journal of Forest Science 2019 number 5

Siberian silkmoth (eggar) Dendrolimus sibiricus Tsch., (1908) is one of the most dangerous forest pests in the Republic of Tyva. Outbreaks of this phytophage in the republic occur frequently and cause significant damage to forests. Studies in Tyva were initiated by A. I. Cherepanov, N. G. Kolomiets, N. F. Reimers and others in the 50-70s of the XX century. They described the phenology of the Siberian silkmoth, the biological and ecological aspects of its life activity. In this paper we tried to summarize all the accumulated knowledge of the Siberian silkmoth in Tyva. The chronology of the Siberian silkmoth outbreaks was restored using the collected and analyzed data. We demonstrate that outbreaks of the Siberian silkmoth in the Republic of Tyva are most frequently observed in the forests of Shagonarsky, Chadansky and Turan forestry districts. On the whole, five outbreaks were registered: in 1954-1966, 1969-1975, 1979-1985, 1997-2000, and in 2009-2011. Duration of the outbreaks was 13-7-7-4-3 years and the intervals without outbreaks were 2-1-2-1 years. The fragmented character of the obtained data on outbreaks shows the need for their verification by dendrochronological methods. Valid analysis of data is possible with the use of control tree species not susceptible to the Siberian moth damage and some parameters of the annual rings, for example, optical density of the wood.

The characteristic of forest resources of one of the most forest-provided subjects of Russia - Primorsky Krai is given. Currently, despite the presence of a large area covered by forest - 77 % of the total area of the region, the diversity of wood and non-timber resources is low-quality forests. Practically all operational plantations and part of protective forests are harvested by industrial methods of logging. Now they are represented by degraded low-grade tree stands. This is due to the fact that, the most important industries in the region are those of harvesting and processing of wood, which accounts for more than 80 % of all forestry income. Along with forest management, effective development of forest complex is associated with the use of non-timber resources, food and medicinal plants (although this market is predominantly shadow), as well as the use of the territory of the forest fund for geological study of the subsoil and mining. At the same time, the depletion of forest resources, caused by their extensive use, can lead to a significant decrease in timber harvesting and depletion of the ecological and protective potential of the territory in the near future. It is necessary to pay attention now to rational forest management and the creation of specialized farms to provide, along with the wood, nutritional and medicinal forest products.

The structure and seed bearing of stands, factors of episoil medium, quantity, vitality and age structure of Scots pine undergrowth 15 years after the disastrous crown and surface fire, which occurred in 2004 in insular pine forest in northern forest-steppe of Western Siberia (Kurgan region), were studied. The studies took place at six sample plots (0.3-0.5 ha) located in two predominant (88 %) types of pine forests - cowberry-short grasses-moss and bilberry-bracken - at four types of burns: 1) «burn under the forest canopy», 2) «thin stand burn», 3) «open burn with peripheral insemination» and 4) «open burn without insemination». The reliable differences in pine regeneration in different types of burns in both types of forests were specified. They were conditioned mainly by differences in their stand density and dissemination levels. The total pine regeneration level in forest-steppe was several times less than in pre-forest-steppe. This was connected with extreme dryness of the studied climate period and low seeding of stands, damaged by the intensive fires. The renewal role of dissemination of 2003 which took place simultaneously with the fire; absence of mouse-like rodents (main seed consumers), as well as sharp change of sex ratio in pine populations (to female dominance) due to intensive surface fire have been shown. On the whole, the total summer precipitation played the main role in pine regeneration of all burn types in forest-steppe zone of Western Siberia.

Current ages of felling in the forests of Belarus were established in 2001. In production forests they make up 81 years and more for coniferous stands, 101 years or more for hardwood, 61 years or more for birch trees, 51 years and more for black alder -, aspen - 41 years and more. The current age of logging does not correspond to high-grade assortments for coniferous and alder stands. In Belarus, due to the improvement of the structure of forests over the past 25-30 years, adequate conditions have been created for improving the methods for determining cutting ages and a certain increase in ages and turnovers. Changing the harvesting ages requires the formation of a new regulatory framework in connection with the adoption of a new Forest Code. Recently, new cutting ages for the forests of the Republic of Belarus have been developed and adopted. They are formed on the basis of quantitative and technical ripeness of the forest, taking into account ecological requirements. New logging ages for conifers (pine and spruce) of the II grade and below have been increased by 10 years; for ash, the logging ages are reduced; for black alder the ages was raised by 10 years. The adopted changes are not supposed to induce marked increase in the size of the calculated cutting area, and the output of commercial timber at the plantations of pine, spruce (site productivity grade II and below) and black alder will not rise substantially in the near future. The alignment of the age structure of tree stands due to new cutting rules is expected to produce the effect no earlier than 2050-2060.

Any movements of forest machines under the forest canopy are harmful for the stand. Their tracks and wheels damage the soil surface: strip off the litter, disturb the sequence of horizons, alter soil hydro-physical properties. These impacts affect the root content of soils. Especially sensitive in this sense is the spruce, whose roots are mostly concentrated in the topsoil which is disturbed by vehicles. To address the problem of stand damage, it is essential to wisely choose the logging technology and machinery. The widely used practices in Karelia are tree-length skidding by crawler tractors, as well as cut-to-length harvesting. The study aimed to assess the effect of various partial cut practices on soil density and the mass of spruce roots up to 3 mm thick in the middle taiga of Karelia. Soil density was studied in skid trails and in the interior of forest blocks not accessed by machines; root masses were compared. The method of soil monoliths sampled from skid trails and blocks throughout the logging area was used. Cutting to length by machines (harvester + forwarder) was found to cause the heaviest topsoil compaction, as compared to mechanized cut-to-length harvesting (chain-saw + forwarder) or tree-length skidding. Root mass in the trail and inside the block, where machines did not reach, remained different for 12 subsequent years whichever practice was used. The difference was the greatest in the first several years after logging. Soil density in the trail recovered at a faster rate than the root mass.

Climate change has a direct impact on the forest ecosystems of the boreal zone. Temperature increase has a stimulating effect on the advancement of a tree line along the elevation gradient, increase of tree radial increment and stand density. The object of the study was the stands formed by the Siberian pine growing in the forest-tundra ecotone of Kuznetsk Alatau Mountains. The rate of timberline and tree line advancement were estimated using GIS-technology and field research. It has been established, that the beginning of the Siberian pine advancement along the elevation gradient coincides with the period of air temperature increase. Estimated speed of tree line advancement is approximately 0.2-0.3 m/year; timberline ~ 0.5 m/year. The average radial increment after 1980 was 25 % higher than the radial increment over the same period of the previous years. At the same time after a marked increase of the radial increment in the early 1980s, a negative trend is observed up to the local minimum of 1999 ( r ² = 0.52). Dendroclimatic analysis indicates a negative influence of July-September temperatures ( r = -0.63) and that of winter precipitation ( r = -0.81) on radial increment, while the amount of July-September precipitation ( r = 0.54) and root zone wetness content during the vegetation period ( r = 0.73) show positive correlation with radial increment. During the previous period from 1967 to1982, a negative effect of winter precipitation on radial increment was also noted ( r = -0.69), whereas May-June temperatures demonstrated a positive effect on radial increment ( r = 0.66).

Scots pine forests are extremely fire hazardous. They show high fire frequency compared to other forest formations. This is due to their high natural fire danger, as along with high recreation activity, which is determined by a fairly dense road network and frequent forest attendance. Moreover, about 90 % of all forest fires are caused by residents. High fire frequency in the forest-steppe Scots pine stands results in silvicultural and economic waste. In the forest-steppe pine forests, partial logging (selective, gradual, etc.) is carried out quite frequently, which has a certain impact on fire danger, fire resistance and post-pyrogenic characteristics. One of the possible ways to reduce negative effects of forest fires is to improve resistance of Scots pine stands. The development of evidence-based fire prevention measures requires assessment of fire resistance. The paper identifies the main factors of fire resistance of Scots pine stands. These factors include forest fuel loads, average diameter of trees, average bark thickness, average distance to the crown, average depth of the roots, the proportion of deciduous species in the stand and in the undergrowth, density and height of regeneration. The paper provides an adequate assessment of fire resistance of partially (selectively) logged Scots pine forests of the Krasnoyarsk forest-steppe. Evaluation of fire resistance is made according to point system using the weighted sum of points.

Results of reconstructions of ground forest fires on bogs of middle taiga subzone in the Priyenisei Siberia are presented for the Holocene. The stratigraphy analysis of the peat deposit, layer-by-layer peat ¹⁴С dating and morphological study of the pyrogenic interlayers allowed to estimate the time of fires, their periodicity and intensity. It was established that the intensity and periodicity of fires were different in southern (the key plot «Krivlyak») and northern (the key plot «Razvilki - Khoiba») parts of the Sym-Dubchess interfluve. 6 pyrogenic interlayers were revealed in the bog peat deposit on the key plot «Krivlyak», and their age was the following: 8015 years ago (y. a.), 6795, 2675, 2280, 1780, 1550 y. a. The interval between fires according to the data of «Mochazhina» profile was 4515 years, the one of the «Bugor» profile was 5340, 895, 230 years. All the fires were low intensive and didn’t greatly influence bog formation process. The 16 pyrogenic interlayers were recorded in stratigraphy of the bog on the key plot «Razvilki - Khoiba». It was stated that the low intensive fires took place 7790, 7412, 5958, 5745, 5030, 2339, 1351, 1099 y. a. The high intensive fires which had a considerable impact on the change of bog phytocoenoses and on the rate of peat accumulation occurred 12237, 7174, 5940, 5427, 4914, 2187, 2072, 1957 y. a. The interval between fires in each profile of this plot varies greatly. Frequent repeatability of forest fires was noted in the Atlantic and in the first half of the Subatlantic periods. In the late Holocene the change in forest and forest-bog phytocoenoses of heavily flooded swamp hummock ridge - bog hollow complexes with dominating Sphagnum fuscum (Schimp.) H. Klinggr.in moss cover took place. The impact of forest fires on the peripheral part of bogs in key plots stopped during this period. The fires on the studied bogs contributed to the revitalization of forest forming process. Post-fire successions were mainly manifested by birch and birch-pine grass phytocoenoses.

The results of the study of isozymes variability of Scots pine populations growing in the southern taiga and forest-steppe of Central Siberia are presented. For the analysis 16 polymorphic loci were used. Two age groups (adult trees and undergrowth) are compared for the main indicators of genetic variation. The greatest deficiency of heterozygotes and a statistically significant level of inbreeding was found in the progeny of a small isolated population most disturbed by cuttings from the vicinity of the city of Achinsk. This population was distinguished by the high genetic distance of Nei (1972) between compared generations of trees, comparable to the distances between geographically remote populations. In the majority of other population samples exposed to lower anthropogenic pressure, the average level of heterozygosity was noted, or the observed heterozygosity was higher than expected in two age groups of trees, and deviations from the equilibrium state were found for individual loci, which, as a rule, do not coincide in adult trees and sprouts. The results of the study show that the genetic structure of the populations of Scotch pine Pinus sylvestris L. is quite resistant to the average level of anthropogenic (recreational) load. But the greater negative effect of using forest is associated with an increased risk of loss of allelic diversity (in 3 populations from 8 to 10.0-14.5 %) and, accordingly, the adaptive genetic polymorphism of populations. The necessity of using more sensitive than allozyme markers of genetic polymorphism of species populations (DNA markers of the nuclear and, especially, of the cytoplasmic genomes) in order to detect more subtle disturbances and initial stages of negative processes for the resumption of the gene pool of the processes was noted.

The application of biotechnological approaches for producingnumerous tree species, including pedunculate oak Quercus robur L. , may become the only way to preserve and reproduce unique breeding objects, which is of great importance for practical forestry. It is now possible to clone individual trees with valuable properties and scientifically advantageous genotypes. In experiments on clonal micro propagation of oak, juvenile plant material (seedlings) was grown in the laboratory. The use of additional stage of rearing and micropropagation of explants of one-month seedlings on media with different volume of 6-benzylaminopurine (6-BAP) showed the expediency of this procedure. When applying ex vitro media, many cultures continued to develop axillary or adventive shoots, the height of which was 11-15 mm (depending on the concentration of 6-BAP). The results of this study will help to cope with the difficulties associated with the induction and preservation of the morphogenic potential of explants in the process of repeated subculturing. The highest rhizogenic response (73 %) was achieved for the micro buds of juvenile material on BTM medium with full composition of macronutrients and indolylbutyric acid (IBA) at a concentration of 0.3 mg/l. It was also found that the combination of IBA and 1-naphthalenacetic acid (NAA) in concentrations of 0.2 and 0.1 mg/l, respectively, completely suppresses the development of roots in micro shoots of pedunculate oak. Of the 4 tested substrates, the highest increase in oak seedlings was observed in the variant with forest oak soil and sand (5.0 cm). The use of two-stage adaptation of regenerative plants ensured their 100 % survival in the laboratory and greenhouse. The use of soil as a substrate, taken from natural oak plantations, will significantly reduce the cost of the process of growing planting material.

The article represents studying the phenolic compound composition and content in leaves of white poplar Populus alba L., aspen P. tremula L. and grey poplar P. × canescens (Ait.) Sm. by high-performance liquid chromatography (HPLC) method. 24 compounds of phenolic nature were discovered, 7 of which are determined: coffee acid, quercetin glycosides - hyperoside, isoquercitrin, rutin and kaempferol glycoside - astragalin, aglycone - quercetin and galangin. The research showed that white poplar and aspen species are easily separated by HPLC on the composition and content of phenolic compounds. It is found that aspen spectrum of phenolic compounds is poorer in comparison with white and grey poplar samples occupy an intermediate position between white poplar and aspen on the composition and content of phenolic compounds, but the majority of hybrid samples evading towards white poplar. According to the cluster analysis, the studied samples are divided into 2 groups on the compound composition and content of phenolic compounds: only 4 hybrids are combined with aspen, the rest are grouped with white poplar, while the «pure» copies of white poplar is not stand out in an independent subgroup. The relation of objects grouping with their geographical origin isn’t revealed. The obtained results indicate that in the analyzed material there are not only the F1 hybrids, but backcrosses, which are closer to white poplar both on phenolic compounds content and morphological signs. These forms are most likely the result of grey and white poplars return crossings.

The wood of Scots pine after 100-600-year exposure to anaerobic conditions was studied. The samples were taken from the soil during archaeological excavations in the city of Veliky Novgorod. It has been established that the destruction of the secondary wall layers (mainly S2 layer) of tracheids in the sapwood and heartwood occurred after 100 and 400 years of exposure, respectively. Archaeological wood contained mineral particles consisting of water-insoluble compounds of iron and potassium. The results of thermogravimetry showed the changes in the relative content of hemicelluloses, cellulose and lignin in the samples of archaeological wood. The proportion of hemicelluloses and cellulose in wood decreased by 8-13 % and the proportion of lignin increased by 6-9 % under the prolonged exposure to anaerobic conditions (400 and 600 years) compared to the samples of 100 and 200-year exposure. This was also confirmed by chemical analysis data. The oxidative thermal decomposition of the carbohydrate complex, as well as lignin started at lower temperatures indicating lower thermal stability of the main components of the wood substance. All the studied wood samples were characterized by a significantly higher proportion of residual mass after thermal decomposition compared to sound wood. This fact also suggested higher content of mineral substances. The total thermal effect of oxidative thermal decomposition of carbohydrate and aromatic components of the wood substance was noticeably higher (13.1 and 12.6 kJ · g^-1) for the samples of 400 and 600-year exposure compared to those of 100 and 200-year exposure (8.9 and 10.8 kJ · g^-1). Mono-and sesquiterpenes were found in wood, as well as diterpen 18-norabietan, the most resistant one to biological degradation, which accounted for 30-64 % of the total content of volatile organic substances. The obtained results indicated significant changes in the composition and structure of Scots pine wood after 400 years of exposure to anaerobic conditions.

The results of the assessment of biological resources in the dumps of the Borodinskiy coal mine are given. The habitats of the same ecological capacity are distinguished according to the developed classification and interpretation of space imagery. The habitats are allocated according to the technology of recultivation (4 options), the tendency of the formation of post-technogenic ecosystems (succession - 4) and the age of the dump (formation stage - 4). For each type of habitat, the composition and productivity of grass cover, forest stand, berries, mushrooms, and game are determined. Grass cover is recommended to be used “in the lifetime state”, for example, as honey plants. Haymaking and grazing leads to the degradation of vegetation cover in mountain dumps. The zonal norm of recultivated arable land (with the application of PSP) is reached not earlier than 30 years later. The experiments with planting crops (potatoes, carrots, beets, cucumbers) showed productivity significantly inferior to the zonal norm. Forest plantations (pine, spruce) are developing the most productive first site class and superior zonal norm. The most productive are zoochorny berries plants, while it should be borne in mind that the productivity of sea buckthorn for natural reasons drops rapidly. In addition, it creates a fire-hazardous structure of forest plantations. The yield of edible mushrooms symbiotic with tree species (pine, birch, aspen) is higher than the zonal norm by an order of magnitude. At the same time, in the first 3-4 years entomoparasites do not affect the fruit bodies of mushrooms (there are no worms). The animal population of the dumps is under strong pressure from synanthropic species (raven, forty, black kites), which are attracted by the city dump. At the same time, the productivity of hunting grounds at dumps is 4 times higher than the zonal norm, perhaps this is due to the protection regime of the coalmine. The methodical techniques used and the data obtained with their help allow us to estimate the biological resources of any dumps and predict (modeling) their states. The materials should be applied in assessing the projected impact of mining and the formation of rock dumps on biological resources and planning their further economic use.