Vol 26, No 4 (2023)

With rational forestry management, it is created special artificial forest plantations of high productivity for technically valuable species allowing the largest supply of grown wood. One of the ways to increase the supply of wood per unit of forest area is to regulate the initial density and planting pattern of trees. Using simulation methods, it is shown that in the absence of external influences, a checkerboard planting pattern is an optimal one providing a larger supply of wood as compared to a rectangular pattern. In real conditions, there are risks of  dying off for individual trees due to random external factors like gusts of wind and phytophages. Therefore, in real life the supply of wood grown under such optimal planting schemes would  be significantly lower as compared to the calculated values obtained.

In this regard, there arise problems aimed at studying the plantings productivity dependent on the planting pattern and the intensity of tree death during the forest stand growth as a result of the random external factors influence. To solve these problems, we used a simulation model of  tree communities dynamics, which takes into account the spatial location of each tree, in this way making it easy to simulate various forest planting schemes and remove some trees at any step of modeling. As a result of the computational experiments, the optimal values of spruce plantations initial density have been defined for different planting schemes, dependent on the intensity of the external factors influence. It is shown that at a certain intensity of the external factors impact, the maximum timber stock does not depend on the planting scheme, but is determined by the initial density of the forest stand.When the impact intensity increases,, the planting density also needs to be increased, in order to obtain the maximum reserve.

The Amur region sable sub-populations monitoring of the allelic composition in the hunting seasons of 2011–2021 showed the presence of alleles marking the differences between the sable population at the Amur River left and right banks. A pairwise comparison of seasonal collections of left- and right-bank sub-populations revealed a spread in the level of genetic differentiation from almost zero values to intermediate ones. It became clear that in order to determine the number of different genetic groups of sable in this region, we need additional mathematical methods to work with the obtained data.

The purpose of this work is to determine and visualize the most likely number of different genetic groups of sables in the territory under consideration. It was studied three sub-populations of the Bureinsky Highland sable (left bank of the Amur River). For comparison, it was taken a species sub-population from the Sikhote-Alin western slopes (the Amur River right bank). The analysis of data for two microsatellite loci Ma3 and Mer041, on the material of hunting winter seasons from 2011 to 2022, was carried out using the programs Structure 2.3.4 and Structure Harvester.

Based on the results obtained with these programs, it can be assumed that in the territory under consideration, this species is represented by two genetic groups (clusters) – “the left-bank” and “the right-bank”. The structure remains the same for both the collection material of the 2012–2013 winter hunting seasons and those of 2013–2014, as well as for the total collections of 2011–2022. The formation of such a structure is undoubtedly the result of both the historical formation of the species habitat and the genetic specifics of anthropogenic introductions from two different geographical areas.

The author gives evaluation of seismic transitional zone continent-ocean catalogs representativeness using the FIC EGS RAS summary data (Obninsk) for the period of 2003–2021. In the investigation process it has been compiled a map of the minimum representative magnitude, characteristic of the Far Eastern region. It emphasizes that a significant portion of area in the Russian Far East has a lower threshold of earthquake representation with magnitudes ranging from 1.8 to 2.0. The representative magnitude sharp increase marks the boundary of  seismic zones observations: the Sakhalin network on the border with China, the Magadan and Kamchatka networks on the Chukotka Peninsula. When comparing the periods of 2003–2015 and 2003–2021, the overall pattern of representative magnitude distribution remains consistent. In the regions with a sparse station distribution within the seismic monitoring network, new seismic stations show changes in the minimum threshold of representative magnitude. In the southern Far East, there is a decrease in the representative magnitude threshold, also noted in the northern part of Sakhalin and the Kuril Islands. The accuracy of determining the upper crustal earthquakes (range of depths 0–20 km) hypocenters depths in the Amur region is an average of ± 1.8 km, and in the Okhotsk Sea region – ± 2.5 km. At the same time, the accuracy of  estimations in the lower crustal layer (range of depths 21–50 km) is ± 3.8 km in the Middle Amur Region, and ± 7.7 km in the Okhotsk Sea region. It is found a significant reduction in the measurement error of earthquakes hypocenters depths determining, as compared to the period of 2003– 2015.

Involving new virgin soils in agricultural use requires huge capital investments and significant labor resources. The secondary return to agricultural use of fallow reclaimed lands  not used in agriculture can become a less costly method of increasing the area of agricultural arable land. In the Middle Amur Lowland, the issues of environmental assessment of fallow drained soils, re-involved in agricultural use, remain poorly studied and  practically there are  no materials devoted to this issue. To study the ecological state of abandoned drained soils in the  Jewish Autonomous region, the authors were carrying out a field research from July to September 2022. The studies showed that drained soils of agrocenoses after being out of agricultural use enter a complex process of self-healing. In fallow soils, the density of the top layer of soil decreases, which has a beneficial effect on the structure of the soil. With the fallow  age increasing in drained meadow sod-gley soils, a decrease in the structure coefficient is observed to values close to the lower limit of “good” structure. In brown 20-year-old fallow mountain-forest soils it is observed a noticeable increase in the proportion of macro aggregates, including agronomically valuable ones, which indicates an improvement in the agronomic properties of fallow soils. The condition of the examined different age meadow gley soils deposits, which form the regional arable fund basis, makes it possible to classify them as suitable for agricultural use.

The so-called "Birobidzhan project" of the Amur region settling became one of the most significant pre-war state programs for the colonization of the sparsely populated border territories of the Russian Far East. The massive influx of settlers demanded increased attention to new settlements planning at the Jewish Autonomous region (organized in 1934), and primarily to its capital Birobidzhan. Building of the town, aimed to be the centre of a new ethnically determined subject from scratch, dictated specific conditions in the cultural aspect, urban planning and architecture.

Thus, the present article makes an attempt to analyze the formation specifics of its planning structure. Having studied the first projects of the town's master plan and objects built in 1928–1942, the author defined directions of the local architecture development, its characteristics and features. The corpus of the 1930s archival materials allows us deepen our knowledge of the most significant processes in the regional design management and construction. The article also aims to reveal the reasons for the eventual failure of the initial architectural ideas. Along with this, the author provides the biographical data of key architects and engineers working in the field of design, construction and the town's urban economy decision-making. Clarifications have been made regarding the pre-war architectural heritage of Birobidzhan.

The article, based on an analysis of statistical indicators of livestock farming in the Jewish Autonomous region for 1990–2021, reveals negative dynamics in the development of the industry. When considering the  cattle livestock, including pigs, sheep and goats, vertical and horizontal methods are used.  They provide an objective assessment of the livestock industry dynamics. It is noted that in the 90s of the last century the region was a fairly large producer of agricultural products, providing both the region and other areas of the Russian Far East with agricultural products. Over the past few decades, agriculture in the region has undergone a significant decline, negatively affecting the economy of the region. It is determined that the cattle breeding development in the region, which needs capital intensity, suffers from the lack of large manufactures. The forage crops sown areas analysis also shows negative dynamics.  And this is one of the leading reasons for the cattle livestock decline. It is substantiated that the population outflow from rural areas results in the decline of agricultural production.  To the author, the predominant agricultural producers in the Jewish Autonomous region are  households. It is noted that modern state support options aimed at the regional agriculture development are not efficient enough. For its rise and development, the branch needs large cattle breeding enterprises and  participation of agricultural holdings in the production process.