The relevance of the study is determined by the increasing spatial differentiation of socioeconomic development at different hierarchical levels. Polarization is an objective process inherent in the modern spatial organization of society. A large number of publications are devoted to this issue, differing in content and territorial coverage. The article describes the modern features of the study of polarization. A review of publications reveals the following common features: multiscale, the degree of development of the territory, the dominance of regional centers, the identification of the “trap” of backwardness, the influence of globalization, new trends in social polarization, the identification of cycles of polarization, factors of polarization, and a number of others. Particular attention is paid to the methodology of the study of polarization. The latter is interpreted as a movement from traditional approaches to innovative ones. The use of an objective-subjective approach is noted while maintaining the demand for the space-temporal approach. Understanding polarization as a multidimensional process contributed to the enrichment of the methodology by introducing the provisions of new social-economic geography, endogenous growth theories, sociology, global studies, and so on. This is due to the effect of polarization on the associated processes of peripherization, fragmentation and marginalization. From a methodological point of view, it is important to consider the correlation between the policy of concentration of economic activity in a few large agglomerations and equalization policy. The authors define 10 directions of polarization research. The variety of polarization studies shows the preservation and even an increase in spatial unevenness.

Analysis of the transformation of settlement systems is possible according to different hierarchical levels. The Pskov region, being an example of a peripheral depressed region with a difficult demographic situation in rural areas, has been studied quite well according to municipal district and parish (“volost”) levels. This article is devoted to the study of the spatial dynamics of the region’s population at the lowest level – in the context of rural settlement points, which has not been done so far. The data of three population censuses (1989, 2002 and 2010 years) were generalized for all rural settlement points in the region, and the main spatial patterns of demographic processes at this level were revealed. Areas of negative and positive dynamics of the population are established and the factors contributing to this are identified, as well as the zones of the inner and outer periphery of the region are clarified.

The deposits of the moderate eruption of Shiveluch volcano (Kamchatka) on August 29, 2019 and their impact on vegetation were studied. According to satellite data, the dynamics of tephra ejection and the extension of the ash cloud had been revealed. The ash cloud, moving westward to the Sredinny Range, reached a length of 150 km and covered an area of about 4000 km2 with tephra. The volume of tephra that fell out in this area can be estimated at 10–20 million m3. 12–18 hours after the ashfall, brief field observations were made in the Baydarnaya River valley (southwestern sector of the volcano), where 10–13 mm of fine ash was deposited. Tephra has covered completely the crowns of trees and bushes; the load on the crown of a mature tree of the Erman’s birch (Betula emanii) was hundreds of kilograms, the branches have bent under the weight of ash. The load on the substrate in open spaces was about 10 kg/m2; the herbage has fallen on the ground under ash weight in such places. The data on the chemical and particle size composition of ash are presented. An assessment of the effect of the eruption on the dynamics of ecosystems in the area of Shiveluch volcano in a number of other eruptions of the volcano of recent decades is given

The Murmansk Region Concept for the development of the network of nature protected areas (NPAs) until 2018 and further until 2038 years envisages establishment of the regional nature monument “Mires at the Lake Alla-Akkajarvi”. The discovery of the nationally redlisted bird Limicola falcinellus in a breeding ground was the basis for establishment of the nature monument. No other information was available until recently about the ecosystems of the planned protected area (apart from the forest management data), their condition and anthropogenic pressures. In this regard, the full-scale study of the area was carried out in 2016 and revealed the high conservation value of the territory. The territory is situated at the northern limit of the northernmost expanse of unfragmented old-growth forest in the Murmansk region. Eight red-listed species have been recorded on the area, including the plants Buxbaumia aphylla, Carex laxa, Crossocalyx hellerianus, Kurzia pauciflora and Psilopilum laevigatum, and the fungi Flaviporus cf. citrinellus and Leptoporus mollis. Current anthropogenic pressure on the area is minimal, limited to extensive recreation, which does not interfere with the goals of the planned nature monument. Meanwhile, threat is formed by dumps of Allarechensky sulfide copper-nickel ore deposit situated in the adjacent territory. The results of the studies allow to conclude that the “Mires at the Lake Alla-Akkajarvi” meets the criteria for regional protected areas and the regional nature monument should be established.

In modern scientific literature and coursebooks, the statement that the Dnieper was called Borysthenes in ancient times, has never been questioned. The fact that Herodotus, when describing the “Scythian square” in the 5th century BC, pointed out that Olvia polis (now Parutino village, Ochakovsky district of the Nikolaev Region) was located at the mouth of the Borisfen River (now the Southern Bug river) is either ignored or explained by the “mistakes” of the author of “History”, Book IV “Melpomene”. Based on the historical and geographical analysis of evolution of the sea mouths of the northwestern part of the Black Sea basin, the hypothesis that the Borisfen River was the name of the Southern Bug all along the river known to the Greek colonists of the region is substantiated. The ancient Hypanis River is identified with the Berezan and Chichikleya rivers, the Pantikapa river – with the Ingul river, the Hypakiris river – with the Ingulets river, the lower reaches of the Dnieper – with the Gerr river. The proposed identification of ancient river mouths, in contrast to previous studies, does not contradict geological, hydrological, archaeological and historical data.