Home – Home – Jornals – Siberian Journal of Forest Science 2022 number 2

The studies of Scotch pine ( Pinus sylvestris L.) needles structure and chlorophylls and carotenoid contents were carried out in four districts of the city of Krasnoyarsk, differing in the level of technogenic load. It was shown, that the length of the needles decreases with an increase in technogenic impact. The width, thickness and cross-section area of the needles and the central cylinder also decrease with an increase in the degree of air pollution. It was found that the cross-section areas of the conducting bundles in the central cylinder, as a rule, are not equal, the differences are 9-12 % and are characterized by high individual variability. No significant correlation was found between the sizes of conducting bundles and the level of technogenic load. The number of resin ducts in needles decreases with an increase in technogenic impact that indicates a decrease in the protection of the assimilation apparatus from damage by pests and diseases. Determination of the content of photosynthetic pigments in pine needles in two districts of the city, differing in the level of pollution, did not show significant differences in the content of chlorophylls and carotenoids. Perhaps this is due to the peculiarities of the weather of this growing season - abundant summer rainfalls prevented the accumulation of pollutants on the surface and inside the needles. The noted changes in the size, anatomical structure and pigment composition of pine needles can be considered as a result of adaptation to growing conditions and weather factors.

Analysis of the success of reforestation after a fire is the most important task of forestry. For these purposes, in the summer of 2021, aerial photography was carried out from a Phantom 4 pro UAV (Unmanned Aerial Vehicle) of a 15-year-old burnt-out (2006) along the north-western border of the Botanical Garden of Petrozavodsk State University (Republic of Karelia). In addition to this, a full-scale survey was carried out at the registration sites. Before the forest fire, rocky Scots pine ( Pinus sylvestris L.) trees grew. The work was carried out in order to assess the state of natural renewal after a fire along rocky outcrops by combining the processing of aerial photography data with field surveys. As a result of photogrammetric processing, an orthophotomap with a spatial resolution of 4.6 cm/pix, a height map and three-dimensional point clouds were reconstructed. To analyze the quantitative distribution of the territory according to the species composition, the trees were pinned on the orthophotomap according to the registration areas of field surveys, as a result of which the quantitative distribution of tree species was determined in the ratio of 64 % Scots pine and 23 % of drooping birch ( Betula pendula Roth) (other species were not identified). Field surveys showed that after the fire, a viable young stand of mixed composition with a predominance of Scots pine (71% of the total number of tree species) was formed. In addition to Scots pine, drooping birch (22 %), aspen ( Populus tremula L.) and gray alder ( Alnus incana (L.) Moench) (3.5 % each) participate in the formation of young stands on this burned-out area. These indicators are consistent with the analysis of the orthomosaic of the area (the error is less than 10 %). When comparing the height of plants on three-dimensional clouds of points with field measurements, it was possible to reliably determine only the height of plants for a large generally accepted category (> 1.5 m). The maximum height of Scots pine trees in the study area is 6 m, and the average values varied from 3.5 to 4.5 m, which indicates the success of reforestation after burning on rocky outcrops.

The protective forests in Karelia are concentrated mainly (80 %) around water objects. More than 50 % of these forests are presented by Scotch pine ( Pinus sylvestris L.) stands. Modern practice of forestry prefers the simplified felling types oriented on use of natural renewal potential of pine forests because artifical regeneration on stony soils are very complex. On a site of the strip-shelterwood felling (intensity of 35 %) in an uneven-age pine stand of bilberry type in 9 years after the felling three transects consisting of plots of 5 × 5 m with a total length of 1150 m across the clear-cut strips were established for an assessment of natural renewal. Under forest canopy pine undergrowth is presented poorly. At the general frequency of 15 % and average height of 1.2 m its density is less than 0.2 thousand tress per ha, and its condition does not give a hope to expect of growth improvement. The condition of spruce ( Picea A. Dietr.) undergrowth is better: its frequency - 36 %, height - 2.4 m, and density - 0.32 thousand tress per ha. On the cutted strips the pine frequency are 31 %, density and frequency of spruce and birch ( Betula L.) remained almost without changes; the participation of an aspen ( Populus tremula L.) and willow ( Salix L.) are increased sharply. The strip-roads are covered by willow weed ( Chamaenerion angustifolium (L.) Scop.), under the influence of which density and frequency of the conifers is twice lower. On the whole, the frequency and average height of a pine in the middle and at the edges of cutted strips are close. The executed felling did not provide the renewal of coniferous species sufficient for formation of a new forest stand, though emergence in recent years of the small undergrowth of a pine allows to count on his further quantitative increase. The executed assessment of increase in a radial growth of trees on cores showed his insignificance. The obtained results and literary data convince of obligatory need of a scarification of the soil surface during the strip-shelterwood felling execution.

The problem of assessing the balance of accumulated and degraded woody biomass in forest communities, the budget of C, CO₂, H₂O, and Q (energy) in primary virgin forests of different ages of spruce formations in the taiga zone of European Russia is discussed. The studies were carried out in specific biogeocenoses of different dynamic characteristics in the subzones of the northern, middle and southern taiga. The purpose of the research is to study in quantitative and volumetric terms the structural elements of the age series of primary virgin spruce biogeocenoses of different ages of different successional positions, the dynamics of the formation of the stem fraction of wood waste (deadwood), pools and flows of components deposited in the wood of the stem fraction of phytocenoses and tree waste in a single succession series. biogeocenoses of various dynamic characteristics. A cycle of studies was carried out on the trial plots, which made it possible to obtain information about the age structures of forest stands, their dynamic indicators, the volume of trees in the age generations of forest stands, the current tree waste and fallen trees. All volume values of forest stands and wood waste are converted into phytomass. The volumes of C, CO₂, H₂O and Q (energy) deposited in wood and released during its decomposition by wood-destroying fungi were calculated using the formula for mycogenic wood xylolysis. On the example of the spruce biogeocenosis of the middle taiga subzone of the climax phase of dynamics, the mass of carbon, different fractions of wood, presented in a graphic image, was calculated. It has been determined that the volumes of pools and flows of wood components in forest stands and during the decomposition of wood by fungi - destructors are determined by the structural features of the age series of forest stands, the volumes of wood waste in gradations of decomposition stages. A joint analysis of the age structures of forest stands, the structures of current tree waste and deadwood by stages of decomposition helps in a more accurate determination of the dynamic position of forest biogeocenosis in the expanded space of its successional development. In the most stable (climax) virgin spruce forests of the taiga, the values of the balance ratios of accumulation and decomposition of biomass represent an optimal budget model and can be regarded as reference values in comparison with forests of different origin and structural characteristics.

The results of long-term experiments carried out on two stationary objects of forest plantations in 1976 and 1968 in different types of forest growing conditions of the Mari Trans-Volga region are presented. The plantations of the 1967, created in a dry forest, consisted only of pine Pinus L. and birch Betula L. trees in various proportions, and the second, created on loamy soils, is of three tree species (birch, spruce Picea A. Dietr. and pine). Pure pine plantations served as a control group. The productivity of the stand, its commodity composition and tax value were estimated by calculation in terms of the average diameter, height and number of trees according to our methodology. The relevance of research is driven by the need of improving measures to optimize the species composition of forests in order to preserve biological diversity, as well as reduce the frequency and intensity of fires. It is shown that in dry and fresh pine forests, pine-birch plantations demonstrate significantly worse stand productivity and especially tax value. Until the age of 10-15 years, the height of birch trees in them is higher than that of pines, but after 25-30 years, their position changes to the opposite. On sandy loam and loamy soils, birch suppresses from the composition of the stand not only light-loving pine, but even shade-tolerant spruce, significantly exceeding them in size. It is concluded that it is impractical to create mixed pine-birch and pine-spruce-birch crops in the conditions of the Mari Volga region due to the different demands of tree species on soil fertility, as well as differences in the speed of their growth and development. These plantations also do not fulfill the functions assigned to them for increasing the biological diversity and sustainability of the functioning of plantations, as well as to reduce their fire hazard.